[BuildLibrary] allow prefixing/renaming/postprocessing in BuildCellsView

- use consistent deduplicated target name
- remove shape indices per dedup

MIGRATION.md

@@ -0,0 +1,856 @@
+# Migration Guide
+
+This guide covers changes between the `master` branch and the current tree.
+Both `master` and the current tree report `masque.__version__ == '3.4'`; the
+version string has not yet been bumped for these changes.
+
+Most downstream changes are in `masque/builder/*`, but there are a few other
+API changes that may require code updates.
+
+## Routing API: renamed and consolidated
+
+The routing helpers were consolidated into a single implementation in
+`masque/builder/pather.py`.
+
+The biggest migration point is that the old routing verbs were renamed:
+
+| Old API | New API |
+| --- | --- |
+| `Pather.path(...)` | `Pather.trace(...)` |
+| `Pather.path_to(...)` | `Pather.trace_to(...)` |
+| `Pather.mpath(...)` | `Pather.trace(...)` / `Pather.trace_to(...)` with multiple ports |
+| `Pather.pathS(...)` | `Pather.jog(...)` |
+| `Pather.pathU(...)` | `Pather.uturn(...)` |
+| `Pather.path_into(...)` | `Pather.trace_into(...)` |
+| `Pather.path_from(src, dst)` | `Pather.at(src).trace_into(dst)` |
+| `RenderPather.path(...)` | `Pather(..., render='deferred').trace(...)` |
+| `RenderPather.path_to(...)` | `Pather(..., render='deferred').trace_to(...)` |
+| `RenderPather.mpath(...)` | `Pather(..., render='deferred').trace(...)` / `Pather(..., render='deferred').trace_to(...)` |
+| `RenderPather.pathS(...)` | `Pather(..., render='deferred').jog(...)` |
+| `RenderPather.pathU(...)` | `Pather(..., render='deferred').uturn(...)` |
+| `RenderPather.path_into(...)` | `Pather(..., render='deferred').trace_into(...)` |
+| `RenderPather.path_from(src, dst)` | `Pather(..., render='deferred').at(src).trace_into(dst)` |
+
+There are also new convenience wrappers:
+
+- `straight(...)` for `trace_to(..., ccw=None, ...)`
+- `ccw(...)` for `trace_to(..., ccw=True, ...)`
+- `cw(...)` for `trace_to(..., ccw=False, ...)`
+- `jog(...)` for S-bends
+- `uturn(...)` for U-bends
+
+Important: `Pather.path()` is no longer the routing API. It now forwards to
+`Pattern.path()` and creates a geometric `Path` element. Any old routing code
+that still calls `pather.path(...)` must be renamed.
+
+### Common rewrites
+
+```python
+# old
+pather.path('VCC', False, 6_000)
+pather.path_to('VCC', None, x=0)
+pather.mpath(['GND', 'VCC'], True, xmax=-10_000, spacing=5_000)
+pather.pathS('VCC', offset=-2_000, length=8_000)
+pather.pathU('VCC', offset=4_000, length=5_000)
+pather.path_into('src', 'dst')
+pather.path_from('src', 'dst')
+
+# new
+pather.cw('VCC', 6_000)
+pather.straight('VCC', x=0)
+pather.ccw(['GND', 'VCC'], xmax=-10_000, spacing=5_000)
+pather.jog('VCC', offset=-2_000, length=8_000)
+pather.uturn('VCC', offset=4_000, length=5_000)
+pather.trace_into('src', 'dst')
+pather.at('src').trace_into('dst')
+```
+
+If you prefer the more explicit spelling, `trace(...)` and `trace_to(...)`
+remain the underlying primitives:
+
+```python
+pather.trace('VCC', False, 6_000)
+pather.trace_to('VCC', None, x=0)
+```
+
+## `PortPather` and `.at(...)`
+
+Routing can now be written in a fluent style via `.at(...)`, which returns a
+`PortPather`.
+
+```python
+(rpather.at('VCC')
+    .trace(False, length=6_000)
+    .trace_to(None, x=0)
+)
+```
+
+This is additive, not required for migration. Existing code can stay with the
+non-fluent `Pather` methods after renaming the verbs above.
+
+Old `PortPather` helper names were also cleaned up:
+
+| Old API | New API |
+| --- | --- |
+| `save_copy(...)` | `mark(...)` |
+| `rename_to(...)` | `rename(...)` |
+
+Example:
+
+```python
+# old
+pp.save_copy('branch')
+pp.rename_to('feed')
+
+# new
+pp.mark('branch')
+pp.rename('feed')
+```
+
+## Imports and module layout
+
+`Pather` now provides the remaining builder/routing surface in
+`masque/builder/pather.py`. The old module files
+`masque/builder/builder.py` and `masque/builder/renderpather.py` were removed.
+
+Update imports like this:
+
+```python
+# old
+from masque.builder.builder import Builder
+from masque.builder.renderpather import RenderPather
+
+# new
+from masque.builder import Pather
+
+builder = Pather(...)
+deferred = Pather(..., render='deferred')
+```
+
+The new `Pather` remains importable from both `masque` and `masque.builder`.
+The removed `Builder` and `RenderPather` names are no longer exported from
+either location.
+
+`Pather` now defaults to `render='auto'`, so plain construction replaces the
+old `Builder` behavior. Use `Pather(..., render='deferred')` where you
+previously used `RenderPather`.
+
+## `SimpleTool` was removed and `AutoTool` registration changed
+
+`SimpleTool` is no longer exported. `AutoTool` remains, but its old public
+descriptor classes and constructor-oriented configuration were replaced by
+registration methods. Use it for generated straights and S-bends and reusable
+bends, U-turns, and transitions.
+
+### Old `AutoTool`
+
+```python
+from masque.builder import AutoTool
+
+tool = AutoTool(
+    straights=[
+        AutoTool.Straight('m1wire', make_straight, 'input', 'output'),
+    ],
+    bends=[
+        AutoTool.Bend(lib.abstract('bend'), 'input', 'output'),
+    ],
+    sbends=[],
+    transitions={
+        ('m2wire', 'm1wire'): AutoTool.Transition(
+            lib.abstract('via'), 'top', 'bottom'
+        ),
+    },
+    default_out_ptype='m1wire',
+)
+```
+
+### New `AutoTool`
+
+```python
+from masque.builder import AutoTool
+
+tool = (
+    AutoTool()
+    .add_straight(make_straight, 'm1wire', 'input')
+    .add_bend(lib.abstract('bend'), 'input', 'output', clockwise=True)
+    .add_transition(lib.abstract('via'), 'top', 'bottom')
+)
+```
+
+The key differences are:
+
+- `SimpleTool` was removed; use `AutoTool` or implement the new `Tool`
+  primitive-offer interface
+- `AutoTool.Straight(...)` -> `add_straight(fn, ptype, in_name)`
+- `AutoTool.Bend(...)` -> `add_bend(abstract, in_name, out_name)`
+- `AutoTool.SBend(...)` -> `add_sbend(fn, ptype, in_name, out_name)`
+- reusable native U-turns can be registered with `add_uturn(...)`
+- transitions are registered with `add_transition(abstract, external_port, internal_port)`
+- transitions are bidirectional by default; pass `one_way=True` to inhibit the reverse adapter
+
+Primitive costs are now explicit and independent of `AutoTool` registration
+order. Every `add_*()` method accepts `cost=`, as do the concrete offer
+factories. A numeric value scales the default geometric cost; for example,
+`cost=2` makes a primitive twice as expensive. A callable receives the
+canonical primitive parameter and local endpoint and returns the complete
+cost:
+
+```python
+tool.add_straight(make_straight, 'm1wire', 'input', cost=1.5)
+tool.add_sbend(
+    make_sbend,
+    'm1wire',
+    'input',
+    'output',
+    cost=lambda jog, endpoint: abs(jog) + 2 * abs(endpoint.x),
+)
+```
+
+`PrimitiveOffer.priority_bias` was removed; custom offers should use `cost`
+instead. Exact equal-cost candidates still use deterministic discovery order
+as the final tie-break, but registration order no longer changes their
+reported cost.
+
+For two-port primitives, `AutoTool` can infer omitted port names and, for
+generated straight/S-bend primitives, omitted ptype metadata by sampling an
+in-domain example. Supply those values explicitly when generation requires
+route-specific keyword arguments, because metadata inference does not receive
+`tool_options`.
+
+## Custom `Tool` subclasses
+
+If you maintain your own `Tool` subclass, the interface changed:
+
+- `primitive_offers()` is now the planning boundary
+- `render()` consumes committed primitive render tokens
+- `Tool.path(...)`, `traceL()`, `traceS()`, `traceU()`, `planL()`,
+  `planS()`, and `planU()` are no longer part of the public `Tool` API
+
+In practice, a minimal old implementation like:
+
+```python
+class MyTool(Tool):
+    def path(self, ccw, length, **kwargs):
+        ...
+```
+
+should now become:
+
+```python
+from collections.abc import Sequence
+from typing import Any
+
+from masque import Port
+from masque.builder import RenderStep, StraightOffer, Tool
+
+
+class MyTool(Tool):
+    def primitive_offers(self, kind, *, in_ptype=None, out_ptype=None, **kwargs):
+        if kind != 'straight':
+            return ()
+
+        def endpoint(length):
+            ptype = out_ptype or in_ptype
+            return Port((length, 0), rotation=3.141592653589793, ptype=ptype)
+
+        def commit(length):
+            return {'length': length}
+
+        return (StraightOffer(
+            in_ptype=in_ptype,
+            out_ptype=out_ptype or in_ptype,
+            endpoint_planner=endpoint,
+            commit_planner=commit,
+            ),)
+
+    def render(self, batch: Sequence[RenderStep]):
+        ...
+```
+
+If a tool does not provide a primitive kind, return `()` for that kind. `Pather`
+will compose available primitive offers where the route family allows it.
+
+### Primitive offers
+
+Tools describe legal routing primitives through `Tool.primitive_offers()`.
+`Pather` composes those primitive offers to implement `trace()`, `jog()`,
+`uturn()`, and `trace_into()`.
+
+For custom tools, construct the concrete offer class that matches the primitive
+you are exposing:
+
+- `StraightOffer` for non-turning length-parameterized primitives
+- `BendOffer` for single-turn length-parameterized primitives
+- `SOffer` for S-like jog-parameterized primitives
+- `UOffer` for U-like jog-parameterized primitives
+
+`PrimitiveOffer` is the shared base type used for generic annotations and
+common callback behavior. It is not the normal class users should instantiate.
+The concrete offer classes carry the semantic fields (`length_domain`,
+`jog_domain`, `ccw`) so tools do not need to encode primitive identity in
+strings. Each concrete offer now also exposes a class-level canonical `kind`.
+Tools must return the matching offer kind for the discovery query; for example,
+`primitive_offers('s', ...)` must return only `SOffer` instances. Mismatches are
+reported as fatal `ToolContractError`s rather than silently ignored.
+
+`RenderStep` now stores that same canonical kind. Code that constructs render
+steps directly must use the kind rather than a legacy opcode:
+
+```python
+# old
+RenderStep('L', tool, start, end, data)
+
+# new
+RenderStep('straight', tool, start, end, data)
+```
+
+Use `'bend'`, `'s'`, `'u'`, or `'plug'` for the other step types. The read-only
+`RenderStep.opcode` and `PrimitiveOffer.opcode` properties remain available for
+code that only consumes steps, but opcodes are now derived rather than stored.
+
+Minimal straight-only example:
+
+```python
+from collections.abc import Sequence
+from typing import Literal
+
+from masque import Port
+from masque.builder import RenderStep, StraightOffer, Tool
+
+
+class MyTool(Tool):
+    def primitive_offers(
+            self,
+            kind: Literal['straight', 'bend', 's', 'u'],
+            *,
+            in_ptype=None,
+            out_ptype=None,
+            **kwargs,
+            ):
+        if kind != 'straight':
+            return ()
+
+        def endpoint(length):
+            ptype = out_ptype or in_ptype
+            return Port((length, 0), rotation=3.141592653589793, ptype=ptype)
+
+        def commit(length):
+            return {'length': length}
+
+        return (StraightOffer(
+            in_ptype=in_ptype,
+            out_ptype=out_ptype or in_ptype,
+            endpoint_planner=endpoint,
+            commit_planner=commit,
+            ),)
+
+    def render(self, batch: Sequence[RenderStep]):
+        ...
+```
+
+Routing entry points now name every supported route argument explicitly.
+Custom per-route Tool values must be placed under `tool_options`:
+
+```python
+pather.jog('A', 4, length=10, tool_options={'process_corner': 'slow'})
+```
+
+The mapping is unpacked only for `Tool.primitive_offers()`. Route arguments do
+not leak into that namespace, and tool options are not forwarded to
+`Tool.render()`. An offer that needs route-specific render behavior must capture
+the selected value in its `commit()` result (`RenderStep.data`). `AutoTool`
+does this automatically for generated straight and S-bend primitives: the
+mapping is deep-copied per offer discovery and passed to its generator as
+keyword arguments during rendering. Consequently every AutoTool option value
+must be deep-copyable, and later mutation of nested caller-owned values does
+not affect a pending route. AutoTool options must not change generated
+ports or endpoint geometry. `PathTool` defines no tool options and rejects
+nonempty mappings.
+
+AutoTool does not validate generator keyword signatures during planning. A bad
+keyword therefore raises when the generator runs, normally during rendering.
+Generators that require route options must provide explicit port metadata at
+registration; S-bend generators must also provide an explicit `endpoint`.
+
+Primitive offers are local planning objects:
+
+- `endpoint_at(parameter)` returns the local output `Port`
+- `cost_at(parameter)` returns an additive scalar route-selection cost
+- `bbox_at(parameter)` returns local primitive bounds when a footprint hook is supplied
+- `parameterized_bbox` may carry opaque future-router footprint metadata
+- `commit(parameter)` returns opaque render data consumed later by `render()`
+- `(min, max)` parameter domains are half-open; `(value, value)` is a fixed singleton
+- domains are validated when an offer is constructed, not when it is first evaluated
+- selected parameter values must be finite; domains may use infinite open bounds but not `NaN`
+- straight/bend domains require a finite nonnegative minimum; fixed singleton domains must be finite
+- `None` and `"unk"` ptypes are wildcards; concrete ptype mismatches reject an offer
+
+`AutoTool.add_straight(length_range=...)` and
+`AutoTool.add_sbend(jog_range=...)` now validate their ranges before metadata
+inference. `jog_range` is an absolute-magnitude range and must have a finite,
+nonnegative lower bound; AutoTool creates the corresponding positive and
+negative S offers itself. Invalid ranges now raise immediately instead of
+registering no offers.
+
+`ToolContractError` is exported from `masque` and `masque.builder`. It marks a
+broken Tool contract—such as an endpoint ptype that disagrees with its offer,
+an invalid evaluated cost, or rendered output that disagrees with the planned
+endpoint—and is fatal to route fallback. Ordinary `BuildError` raised by a
+planning callback remains a recoverable candidate rejection. Rendered output
+rotations are compared modulo one full turn; a port facing exactly backward is
+no longer accepted as equivalent. A `None` rotation remains an explicit
+wildcard.
+
+Custom Tool authors can exercise discovery, offer callbacks, committed data,
+and one-step rendering without depending on pytest:
+
+```python
+from masque.builder import ToolContractCase, validate_tool_contract
+
+validate_tool_contract(my_tool, (
+    ToolContractCase('straight', in_ptype='wire', probe_parameters=(10,)),
+    ToolContractCase('bend', in_ptype='wire', ccw=False),
+    ToolContractCase('bend', in_ptype='wire', ccw=True),
+    ToolContractCase('s', in_ptype='wire', require_offers=False),
+))
+```
+
+Cases derive representative parameters from each returned offer domain and
+may add explicit probes. Empty discovery is an error unless
+`require_offers=False`; bbox support is required only with `check_bbox=True`.
+Validation returns normally on success and otherwise raises an
+`ExceptionGroup` of contextual `ToolContractError`s.
+
+Run this validation during Tool development, testing, or application startup.
+It is the comprehensive semantic preflight for custom Tools; those checks are
+intentionally not repeated for every offer evaluation in the routing hot path.
+
+Positional routing bounds (`p`, `pos`, `position`, `x`, and `y`) now require a
+nearly Manhattan input-port direction. Arbitrarily angled ports remain valid
+for non-positional/extension routing.
+
+Heterogeneous `StraightOffer` and `SOffer` objects may be used as ptype
+adapters. Requested `out_ptype` constrains only the final route endpoint; any
+intermediate ptypes are chosen by the route solver.
+
+`Tool` subclasses must override `primitive_offers()` and return `()` themselves
+for recognized unsupported kinds. There is no route-level `plan*()` fallback.
+Omitted-length S/U behavior comes from direct `SOffer` and `UOffer` endpoint
+domains or from composed straight/bend primitives.
+
+Offer constructors accept split `endpoint_planner` and `commit_planner`
+callbacks. Provide both callbacks or override the offer methods in a subclass;
+partial callback configurations are rejected during offer construction.
+
+When writing direct primitive offers, declare the actual endpoint ptype
+produced by the offer if it can differ from the requested value; `Pather`
+validates evaluated endpoints against the declared offer ptype.
+
+Stable imports for custom tool authors live in `masque.builder`. The
+`masque.builder.planner` module is an internal planner implementation; do not
+import it from user code.
+
+`trace_into()` uses the same primitive-offer route selection and defaults to
+the minimal main-route bend count required by the endpoint relationship: zero
+for a straight, one for a quarter-turn, and two for S- and U-like connections.
+Ptype adapters do not consume this bend budget. Set
+`plan_options={'bend_policy': 'flexible'}` to search bounded route topologies
+with up to four bend roles, including dogleg and loop-like fallbacks.
+Bend-family requests then search one-bend routes before three-bend routes;
+other families search zero-to-two-bend routes before four-bend routes. The
+first band with a legal route wins. Within that band, candidates are ordered
+by total primitive-offer cost, adapter count, step count, and deterministic
+discovery order. The default planner's `strategy` option affects only that
+final discovery-order tie-break and is also supplied through `plan_options`.
+
+`plan_options` is reserved for planner-specific per-route policy, while
+`tool_options` is forwarded only to `Tool.primitive_offers()`. For example:
+
+```python
+pather.jog('A', 4, length=10, plan_options={'strategy': 'turn_first'})
+```
+
+Explicit-length `jog()` routes may also be satisfied by composing a straight
+primitive before or after an omitted-length native S primitive. `uturn()` routes
+may compose a straight primitive before an omitted-length native U primitive.
+These compositions are used when they are the lowest-cost legal route for the
+explicit request.
+
+`AutoTool` can attach `bbox_at()` hooks to its primitive offers by rendering the
+selected primitive into a temporary pattern and measuring it. If the rendered
+primitive contains reusable refs, pass the source library as `bbox_library=...`;
+normal routing does not require this.
+
+### Omitted-length routing
+
+Single-port omitted-length calls now evaluate legal primitive routes at their
+minimum legal length-like parameter, or at their intrinsic endpoint length when
+the requested offset fixes the primitive geometry. Cost then selects among
+those minimum-length candidates:
+
+```python
+pather.trace('A', None)     # minimum straight-like route
+pather.jog('A', offset=2)   # minimum S-like route for that offset
+pather.uturn('A', offset=4) # minimum U-like route for that offset
+```
+
+For U-turns, use explicit `length=0` to request the old zero-public-length
+shape:
+
+```python
+pather.uturn('A', offset=4, length=0)
+```
+
+## Transform semantics changed
+
+The other major user-visible change is that `mirror()` and `rotate()` are now
+treated more consistently as intrinsic transforms on low-level objects.
+
+The practical migration rule is:
+
+- use `mirror()` / `rotate()` when you want to change the object relative to its
+  own origin
+- use `flip_across(...)`, `rotate_around(...)`, or container-level transforms
+  when you want to move the object in its parent coordinate system
+
+### Example: `Port`
+
+Old behavior:
+
+```python
+port.mirror(0)   # changed both offset and orientation
+```
+
+New behavior:
+
+```python
+port.mirror(0)          # changes orientation only
+port.flip_across(axis=0)  # old "mirror in the parent pattern" behavior
+```
+
+### What to audit
+
+Check code that calls:
+
+- `Port.mirror(...)`
+- `Ref.rotate(...)`
+- `Ref.mirror(...)`
+- `Label.rotate_around(...)` / `Label.mirror(...)`
+- `Abstract.mirror_port_offsets(...)` / `Abstract.mirror_ports(...)`
+
+If that code expected offsets or repetition grids to move automatically, it
+needs updating. For whole-pattern transforms, prefer calling `Pattern.mirror()`
+or `Pattern.rotate_around(...)` at the container level.
+
+`Abstract.mirror_port_offsets()` and `Abstract.mirror_ports()` were removed.
+Use `Abstract.mirror(axis)` to mirror both port locations and orientations. If
+you intentionally need only one half of that operation, update the individual
+ports explicitly with `Port.flip_across(...)` or `Port.mirror(...)`.
+
+## Library hierarchy and graph behavior
+
+`masque/library.py` was split into the `masque.library` package. Imports from
+the public module remain stable:
+
+```python
+from masque import Library, LazyLibrary
+# or
+from masque.library import Library, LazyLibrary
+```
+
+Code importing the implementation file itself must move to the public package;
+do not depend on the new internal `base`, `mapping`, or `lazy` module paths.
+
+Hierarchy helpers now handle dangling references explicitly. The following
+methods accept `dangling='error' | 'ignore' | 'include'` and default to
+`'error'`:
+
+- `child_graph()`
+- `parent_graph()`
+- `child_order()`
+- `find_refs_local()`
+- `find_refs_global()`
+- `prune_empty()`
+
+On `master`, graph construction could expose missing targets implicitly or
+fail later with a `KeyError`. If dangling refs are intentional, choose the
+behavior explicitly, for example:
+
+```python
+graph = library.child_graph(dangling='include')
+order = library.child_order(dangling='ignore')
+```
+
+Graph cycles and invalid hierarchy states are now reported as `LibraryError`
+with context. Audit code that caught `KeyError` or `graphlib.CycleError` from
+these helpers.
+
+Invalid `dangling=` strings now raise `ValueError`; they no longer fall through
+to the `include` behavior. Empty lists stored in `Pattern.refs` are consistently
+treated as absent references by hierarchy and geometry traversal. Code that
+uses a `defaultdict` lookup such as `pattern.refs[name]` without appending a
+`Ref` will therefore not create an edge or force that target to be loaded.
+
+`Library.add()` now resolves the full name plan and remaps references before it
+starts inserting cells. Name-resolution and preparation failures no longer
+leave partially-added cells behind. A `rename_theirs` callback now receives an
+`INameView` containing both existing names and names reserved earlier in the
+same addition. Use membership, iteration, `len()`, or `get_name()`; the callback
+argument is not the destination object and does not support pattern lookup or
+mapping helpers such as `keys()` and `items()`. Update callback annotations from
+`ILibraryView` to `INameView`. Custom `_merge()` implementations remain
+responsible for their own rollback if they fail during the final commit.
+
+Reference transforms returned by `find_refs_local()` and
+`find_refs_global()` are now Nx5 arrays. The fifth column is the cumulative
+scale, so rows have the form `(x, y, rotation, mirrored, scale)` rather than the
+old Nx4 form.
+
+`BuildReport` mapping fields are now defensively copied and read-only. Copy a
+field to a new `dict` before adding or removing report entries.
+
+`PortLoadView`, `LayerMappedView`, `OverlayLibrary`, and source-backed outputs
+returned by `LibraryBuilder.build()` borrow their sources. They do not close
+source resources, and the views are not context managers. Keep each lazy
+source open and unchanged until every borrowing view or overlay is finished,
+then close the owning source explicitly. An eager `build(output='library')`
+result is detached and does not need its sources afterward.
+
+Lazy GDS sources no longer provide `with_ports_from_data()` or
+`with_port_overrides()` convenience methods. Construct the generic view
+directly instead: `PortLoadView(source, layers=...)` imports port data, and
+`PortLoadView(source, ports=..., replace=...)` applies explicit overrides.
+
+`LayerMappedView(source, map_layer)` lazily remaps shape and label layers while
+leaving the source untouched. Its default `copy_through=False` forces mapped
+serialization of every cell. Set `copy_through=True` only when source-aware
+writers may copy untouched cells unchanged and intentionally skip their layer
+mapping; persistently accessed cells are mapped and no longer copied through.
+
+`preflight_source_aware(...)` preserves that per-cell provenance. It returns a
+borrowing `OverlayLibrary`, skips source-backed cells completely, and applies
+pattern sorting, named-layer validation, safe empty-cell pruning, and
+repeated-shape wrapping only to cells without reusable source provenance.
+Library name order is retained because sorting source-backed cells would
+require loading them. Always use the returned overlay for writing, and keep the
+original lazy source open until the write finishes. The comprehensive
+`preflight(...)` operation continues to materialize every cell when sorting is
+enabled.
+
+Generic borrowing views no longer expose GDS-specific `raw_struct_bytes()`,
+`can_copy_raw_struct()`, or forwarded `library_info` attributes. Keep the
+owning GDS source or the metadata returned by `readfile()` when direct access is
+needed. `IBorrowing.source_cell()` now provides format-neutral per-cell
+provenance; GDS writers use it internally to preserve safe raw copy-through.
+
+Read-only `subtree()` results are now borrowed lazy views rather than eager
+`LibraryView` snapshots. Creating one no longer loads its reachable patterns,
+and the view preserves source ordering, hierarchy metadata, and lazy GDS
+copy-through. Mutable `Library`, `LazyLibrary`, and `OverlayLibrary` subtrees
+return the same writable type as their source. Overlay subtrees retain their
+source layers and lazy GDS capabilities. Mutable subtree containers are
+structurally independent, but already-materialized patterns remain shared.
+Keep borrowed sources open and structurally unchanged for the subtree's
+lifetime.
+
+`ILibrary` no longer inherits `collections.abc.MutableMapping`. It remains a
+readable `Mapping` with explicit insert-only item assignment and deletion, but
+generic mutation helpers such as `update()`, `setdefault()`, `pop()`,
+`popitem()`, and `clear()` are no longer supplied. Use `add()`, `rename()`,
+`delete()`, item insertion, and item deletion so library name and reference
+invariants remain explicit.
+
+Library-level `referenced_patterns()` and `dangling_refs()` now report only
+named cell targets and return `set[str]`. Populated refs whose target is `None`
+are ignored, matching `child_graph()` and recursive geometry behavior;
+`Pattern.referenced_patterns()` continues to report `None` locally.
+
+Port-importing views now always process detached patterns, including when the
+raw source cell was already cached. Code can safely retain and compare raw and
+processed views without port overrides leaking back into the raw pattern.
+Once a processed cell is persistently materialized, lazy GDS writers no longer
+copy the raw source structure for that cell, so later mutations to the returned
+`Pattern` are serialized. Non-persistent materialization does not mark the cell
+as changed.
+
+Underscore-prefixed declarations work through the attribute authoring surface:
+`builder.cells._helper = pattern` now declares `_helper`. Only the view's exact
+internal `_library` attribute is reserved.
+
+Recursive geometry operations now reject cyclic reference hierarchies with a
+contextual `PatternError` instead of eventually leaking `RecursionError`. This
+applies to bounds calculation, flattened layer polygon extraction, and
+visualization as well as the existing flattening checks.
+
+`LibraryBuilder.validate(names=...)` now accepts either one string or a sequence
+of strings. Non-string roots raise `TypeError`, and duplicate roots are reduced
+to their first occurrence. A recipe may build a different `LibraryBuilder`, but
+calling `build()` or `validate()` recursively on its own active builder now
+raises `BuildError` before starting another session.
+
+`LibraryBuilder` is an authoring registry, not an `ILibraryView` or mapping.
+Use membership, iteration, `keys()`, `get_name()`, assignment, and deletion to
+manage declarations, then use the library returned by `build()` for reads and
+hierarchy operations. Recipes that need an active library must receive the
+builder-owned placeholder as a direct argument:
+
+```python
+def make_top(lib: ILibrary) -> Pattern:
+    return Pather(library=lib, ports='device').pattern
+
+builder.cells.top = cell(make_top)(builder.library)
+builder.cells.device = cell(factory)(hole_lib=builder.library)
+```
+
+The builder-owned `builder.library` placeholder is read-only. Only direct
+positional and keyword values equal to it are substituted; placeholders nested
+inside containers are not interpreted. A placeholder from another builder is
+rejected when the recipe is assigned.
+
+`IMaterializable` now identifies libraries which support explicit
+`materialize()` and `materialize_many()` operations. `LibraryBuilder.add()`
+borrows these marked inputs, while ordinary mappings and `ILibraryView`
+instances are copied eagerly. Use `add_source()` to force borrowing of an
+unmarked view. Wrapping a materializable library in `LibraryView` intentionally
+erases the marker.
+
+`IBorrowing` separately identifies composite views which retain direct source
+libraries and expose them through `borrowed_sources()`. Keep those sources open
+and unchanged for the lifetime of the borrowing view. Owner libraries such as
+`LazyLibrary` and the lazy GDS readers are materializable but do not implement
+`IBorrowing`. Borrowing views may expose unchanged per-cell layout provenance
+through `source_cell()`; format writers decide whether that provenance permits
+raw copy-through. Raw GDS structure access remains confined to GDS sources and
+writers.
+
+`LibraryBuilder`, `OverlayLibrary`, `PortLoadView`, and `LayerMappedView` are new
+additive library implementations. `LibraryBuilder` supports declarative `@cell`
+recipes and dependency-aware builds; `OverlayLibrary` composes source libraries
+without eagerly copying all patterns; `PortLoadView` loads port metadata from
+labels and/or explicit mappings; `LayerMappedView` remaps shape and label layers
+on detached materialization.
+
+Flattening with `flatten_ports=True` now rejects repeated refs whose target has
+ports, because expanding them would create duplicate port names. Resolve the
+repetition and assign unique port names before flattening, or use
+`flatten_ports=False`.
+
+## GDSII module and lazy-loading changes
+
+`masque.file.gdsii` changed from a module into a package. The eager klamath
+API remains available at the old import path, so ordinary `read`, `readfile`,
+`write`, and `writefile` calls do not need to change:
+
+```python
+from masque.file import gdsii
+library, info = gdsii.readfile('layout.gds')
+```
+
+The old `gdsii.load_library()` and `gdsii.load_libraryfile()` entry points were
+removed. Use the source-backed lazy reader instead:
+
+```python
+# old
+library, info = gdsii.load_libraryfile('layout.gds')
+
+# new
+from masque.file.gdsii import lazy
+
+library, info = lazy.readfile('layout.gds')
+try:
+    pattern = library['TOP']
+finally:
+    library.close()
+```
+
+`lazy.read(stream)` and `lazy.readfile(path, use_mmap=...)` return a read-only
+`GdsLibrarySource`. It owns file resources when it opens them and also supports
+the context-manager protocol. The old `full_load` and `postprocess` arguments
+are gone; materialize/copy the desired cells and post-process them explicitly.
+
+An optional Arrow/native backend is available through
+`masque.file.gdsii.arrow` and `masque.file.gdsii.lazy_arrow`; install the new
+`arrow` extra to use it. These modules are additive and are not a transparent
+replacement unless their additional dependencies and native library are
+available.
+
+GDS writing now has one entry point for eager and lazy libraries. Use
+`masque.file.gdsii.write()` or `masque.file.gdsii.writefile()` regardless of
+which reader produced the library. The `lazy` and `lazy_arrow` modules no
+longer re-export writer functions. Source-backed libraries continue to infer
+their header metadata and copy untouched structures directly.
+
+## Shape construction and geometry additions
+
+The public `raw=True` constructor shortcut was removed from `Arc`, `Circle`,
+`Ellipse`, `Path`, `Polygon`, `PolyCollection`, and `Text`. Call their normal
+constructors without `raw`; `_from_raw()` is an internal fast path and is not a
+compatibility API.
+
+```python
+# old
+polygon = Polygon(vertices, raw=True)
+
+# new
+polygon = Polygon(vertices)
+```
+
+`Arc` radii must now be strictly positive rather than merely non-negative.
+`Arc.angle_ref` is additive and defaults to `Arc.AngleRef.Center`, preserving
+the previous center-referenced angle interpretation.
+
+`RectCollection` is a new shape for batches of axis-aligned rectangles and is
+exported from both `masque` and `masque.shapes`. `Polygon.boolean()` and the
+top-level `masque.boolean()` helper are also new; install the `boolean` extra
+for their `pyclipper` dependency.
+
+## Other user-facing changes
+
+### File writers
+
+SVG writing no longer polygonizes or flattens caller-owned patterns in place;
+it works from detached copies. `svg.writefile(..., annotate_ports=True)` can
+add port arrows. DXF writing now expands shape repetitions into individual DXF
+entities, so callers no longer need to wrap repeated shapes solely for DXF
+output.
+
+### DXF environments
+
+If you install the DXF extra, the supported `ezdxf` baseline moved from
+`~=1.0.2` to `~=1.4`. Any pinned environments should be updated accordingly.
+
+### Optional dependency names
+
+The misspelled `manhatanize_slow` extra was corrected to
+`manhattanize_slow`. A separate `manhattanize` extra now installs the
+scikit-image implementation. The `arrow` and `boolean` extras are also new.
+
+### New exports
+
+These are additive, but available now from `masque` and `masque.builder`:
+
+- from `masque`: `RectCollection`, `boolean`, `OverlayLibrary`,
+  `PortLoadView`, `LayerMappedView`, `IMaterializable`, `IBorrowing`, `LibraryBuilder`,
+  `BuildReport`, `CellProvenance`, and `cell`
+- from `masque.builder`: `CostCallable`, `RenderStepKind`, the concrete
+  primitive-offer classes, structured route error/status types,
+  `ToolContractCase`, and `validate_tool_contract`
+
+## Minimal migration checklist
+
+If your code uses the routing stack, do these first:
+
+1. Replace `path`/`path_to`/`mpath`/`path_into` calls with
+   `trace`/`trace_to`/multi-port `trace`/`trace_into`.
+2. Replace `SimpleTool` and old `AutoTool` descriptor construction with the
+   new `AutoTool.add_*()` methods.
+3. Fix imports that still reference `masque.builder.builder` or
+   `masque.builder.renderpather`.
+4. Audit any low-level `mirror()` usage, especially on `Port` and `Ref`.
+5. Move lazy GDS calls from `gdsii.load_library*()` to
+   `masque.file.gdsii.lazy`.
+6. Remove `raw=True` from public shape constructors.
+
+If your code only uses `Pattern`, `Library`, `place()`, and `plug()` without the
+routing helpers, audit transforms, dangling-reference graph calls, raw shape
+construction, and any stale imports.

README.md

@@ -145,7 +145,7 @@ References are accomplished by listing the target's name, not its `Pattern` obje
     in order to create a reference, but they also need to access the pattern's ports.
     * One way to provide this data is through an `Abstract`, generated via
         `Library.abstract()` or through a `Library.abstract_view()`.
-    * Another way is use `Builder.place()` or `Builder.plug()`, which automatically creates
+    * Another way is use `Pather.place()` or `Pather.plug()`, which automatically creates
         an `Abstract` from its internally-referenced `Library`.
 
 
@@ -193,8 +193,8 @@ my_pattern.ref(new_name, ...)       # instantiate the cell
 # In practice, you may do lots of
 my_pattern.ref(lib << make_tree(...), ...)
 
-# With a `Builder` and `place()`/`plug()` the `lib <<` portion can be implicit:
-my_builder = Builder(library=lib, ...)
+# With a `Pather` and `place()`/`plug()` the `lib <<` portion can be implicit:
+my_builder = Pather(library=lib, ...)
 ...
 my_builder.place(make_tree(...))
 ```
@@ -275,14 +275,6 @@ my_pattern.ref(_make_my_subpattern(), offset=..., ...)
 ```
 
 
-## TODO
+## Development
 
-* Rework naming/args for path-related (Builder, PortPather, path/pathL/pathS/pathU, path_to, mpath)
-* PolyCollection & arrow-based read/write
-* pather and renderpather examples, including .at() (PortPather)
-* Bus-to-bus connections?
-* Tests tests tests
-* Better interface for polygon operations (e.g. with `pyclipper`)
-    - de-embedding
-    - boolean ops
-* tuple / string layer auto-translation
+Project-level planned work is tracked in [TODO.md](TODO.md).

examples/ellip_grating.py

@@ -6,7 +6,7 @@ from masque.file import gdsii
 from masque import Arc, Pattern
 
 
-def main():
+def main() -> None:
     pat = Pattern()
     layer = (0, 0)
     pat.shapes[layer].extend([

examples/nested_poly_test.py

@@ -1,7 +1,5 @@
-import numpy
 from pyclipper import (
-    Pyclipper, PT_CLIP, PT_SUBJECT, CT_UNION, CT_INTERSECTION, PFT_NONZERO,
-    scale_to_clipper, scale_from_clipper,
+    Pyclipper, PT_SUBJECT, CT_UNION, PFT_NONZERO,
     )
 p = Pyclipper()
 p.AddPaths([
@@ -12,8 +10,8 @@ p.AddPaths([
   ], PT_SUBJECT, closed=True)
 #p.Execute2?
 #p.Execute?
-p.Execute(PT_UNION, PT_NONZERO, PT_NONZERO)
-p.Execute(CT_UNION, PT_NONZERO, PT_NONZERO)
+p.Execute(CT_UNION, PFT_NONZERO, PFT_NONZERO)
+p.Execute(CT_UNION, PFT_NONZERO, PFT_NONZERO)
 p.Execute(CT_UNION, PFT_NONZERO, PFT_NONZERO)
 
 p = Pyclipper()

examples/profile_gdsii_readers.py

@@ -0,0 +1,131 @@
+from __future__ import annotations
+
+import argparse
+import importlib
+import json
+import time
+from pathlib import Path
+from typing import Any
+
+from masque import LibraryError
+
+
+READERS: dict[str, tuple[str, tuple[str, ...]]] = {
+    'gdsii': ('masque.file.gdsii', ('readfile',)),
+    'gdsii_arrow': ('masque.file.gdsii.arrow', ('readfile', 'arrow_import', 'arrow_convert')),
+    }
+
+
+def _summarize_library(path: Path, elapsed_s: float, info: dict[str, object], lib: object) -> dict[str, object]:
+    assert hasattr(lib, '__len__')
+    assert hasattr(lib, 'tops')
+    tops = lib.tops()      # type: ignore[no-any-return, attr-defined]
+    try:
+        unique_top = lib.top()      # type: ignore[no-any-return, attr-defined]
+    except LibraryError:
+        unique_top = None
+
+    return {
+        'path': str(path),
+        'elapsed_s': elapsed_s,
+        'library_name': info['name'],
+        'cell_count': len(lib),     # type: ignore[arg-type]
+        'topcells': tops,
+        'topcell': unique_top,
+        }
+
+
+def _summarize_arrow_import(path: Path, elapsed_s: float, arrow_arr: Any) -> dict[str, object]:
+    libarr = arrow_arr[0]
+    return {
+        'path': str(path),
+        'elapsed_s': elapsed_s,
+        'arrow_rows': len(arrow_arr),
+        'library_name': libarr['lib_name'].as_py(),
+        'cell_count': len(libarr['cells']),
+        'layer_count': len(libarr['layers']),
+        }
+
+
+def _profile_stage(module: Any, stage: str, path: Path) -> dict[str, object]:
+    start = time.perf_counter()
+
+    if stage == 'readfile':
+        lib, info = module.readfile(path)
+        elapsed_s = time.perf_counter() - start
+        return _summarize_library(path, elapsed_s, info, lib)
+
+    if stage == 'arrow_import':
+        if hasattr(module, 'readfile_arrow'):
+            libarr, _info = module.readfile_arrow(path)
+            elapsed_s = time.perf_counter() - start
+            return {
+                'path': str(path),
+                'elapsed_s': elapsed_s,
+                'arrow_rows': 1,
+                'library_name': libarr['lib_name'].as_py(),
+                'cell_count': len(libarr['cells']),
+                'layer_count': len(libarr['layers']),
+                }
+
+        arrow_arr = module._read_to_arrow(path)
+        elapsed_s = time.perf_counter() - start
+        return _summarize_arrow_import(path, elapsed_s, arrow_arr)
+
+    if stage == 'arrow_convert':
+        arrow_arr = module._read_to_arrow(path)
+        libarr = arrow_arr[0]
+        start = time.perf_counter()
+        lib, info = module.read_arrow(libarr)
+        elapsed_s = time.perf_counter() - start
+        return _summarize_library(path, elapsed_s, info, lib)
+
+    raise ValueError(f'Unsupported stage {stage!r}')
+
+
+def build_arg_parser() -> argparse.ArgumentParser:
+    parser = argparse.ArgumentParser(description='Profile GDS readers with a stable end-to-end workload.')
+    parser.add_argument('--reader', choices=sorted(READERS), required=True)
+    parser.add_argument('--stage', default='readfile')
+    parser.add_argument('--path', type=Path, required=True)
+    parser.add_argument('--warmup', type=int, default=1)
+    parser.add_argument('--repeat', type=int, default=1)
+    parser.add_argument('--output-json', type=Path)
+    return parser
+
+
+def main(argv: list[str] | None = None) -> int:
+    parser = build_arg_parser()
+    args = parser.parse_args(argv)
+
+    module_name, stages = READERS[args.reader]
+    if args.stage not in stages:
+        parser.error(f'reader {args.reader!r} only supports stages: {", ".join(stages)}')
+
+    module = importlib.import_module(module_name)
+    path = args.path.expanduser().resolve()
+
+    for _ in range(args.warmup):
+        _profile_stage(module, args.stage, path)
+
+    runs = []
+    for _ in range(args.repeat):
+        runs.append(_profile_stage(module, args.stage, path))
+
+    payload = {
+        'reader': args.reader,
+        'stage': args.stage,
+        'warmup': args.warmup,
+        'repeat': args.repeat,
+        'runs': runs,
+        }
+    rendered = json.dumps(payload, indent=2, sort_keys=True)
+    if args.output_json is not None:
+        args.output_json.parent.mkdir(parents=True, exist_ok=True)
+        args.output_json.write_text(rendered + '\n')
+    print(rendered)
+    return 0
+
+
+if __name__ == '__main__':
+    raise SystemExit(main())

examples/test_rep.py

@@ -11,7 +11,7 @@ from masque.file import gdsii, dxf, oasis
 
 
 
-def main():
+def main() -> None:
     lib = Library()
 
     cell_name = 'ellip_grating'

examples/tutorial/README.md

@@ -1,6 +1,12 @@
 masque Tutorial
 ===============
 
+These examples are meant to be read roughly in order.
+
+- Start with `basic_shapes.py` for the core `Pattern` / GDS concepts.
+- Then read `devices.py` and `library.py` for hierarchical composition and libraries.
+- Read the `pather*` tutorials separately when you want routing helpers.
+
 Contents
 --------
 
@@ -8,24 +14,30 @@ Contents
     * Draw basic geometry
     * Export to GDS
 - [devices](devices.py)
+    * Build hierarchical photonic-crystal example devices
     * Reference other patterns
     * Add ports to a pattern
-    * Snap ports together to build a circuit
+    * Use `Pather` to snap ports together into a circuit
     * Check for dangling references
 - [library](library.py)
-    * Create a `LazyLibrary`, which loads / generates patterns only when they are first used
+    * Continue from `devices.py` by declaring a mixed library with `LibraryBuilder`
+    * Import source-backed GDS cells and register python-generated recipes together
+    * Call `build()` to produce a normal library and report for downstream `Pather` usage and writing
     * Explore alternate ways of specifying a pattern for `.plug()` and `.place()`
-    * Design a pattern which is meant to plug into an existing pattern (via `.interface()`)
 - [pather](pather.py)
     * Use `Pather` to route individual wires and wire bundles
-    * Use `BasicTool` to generate paths
-    * Use `BasicTool` to automatically transition between path types
-- [renderpather](rendpather.py)
-    * Use `RenderPather` and `PathTool` to build a layout similar to the one in [pather](pather.py),
+    * Define a custom `Tool` that exposes primitive routing offers
+    * Use primitive offers to automatically transition between path types
+- [renderpather](renderpather.py)
+    * Use `Pather(render='deferred')` and `PathTool` to build a layout similar to the one in [pather](pather.py),
         but using `Path` shapes instead of `Polygon`s.
+- [port_pather](port_pather.py)
+    * Use `PortPather` and the `.at()` syntax for more concise routing
+    * Advanced port manipulation and connections
 
 
-Additionaly, [pcgen](pcgen.py) is a utility module for generating photonic crystal lattices.
+Additionally, [pcgen](pcgen.py) is a utility module used by `devices.py` for generating
+photonic-crystal lattices; it is support code rather than a step-by-step tutorial.
 
 
 Running
@@ -37,3 +49,6 @@ cd examples/tutorial
 python3 basic_shapes.py
 klayout -e basic_shapes.gds
 ```
+
+Some tutorials depend on outputs from earlier ones. In particular, `library.py`
+expects `circuit.gds`, which is generated by `devices.py`.

examples/tutorial/basic_shapes.py

@@ -1,12 +1,9 @@
-from collections.abc import Sequence
 
 import numpy
 from numpy import pi
 
-from masque import (
-    layer_t, Pattern, Label, Port,
-    Circle, Arc, Polygon,
-    )
+from masque import layer_t, Pattern, Circle, Arc, Ref
+from masque.repetition import Grid
 import masque.file.gdsii
 
 
@@ -39,6 +36,45 @@ def hole(
     return pat
 
 
+def hole_array(
+        radius: float,
+        num_x: int = 5,
+        num_y: int = 3,
+        pitch: float = 2000,
+        layer: layer_t = (1, 0),
+        ) -> Pattern:
+    """
+    Generate an array of circular holes using `Repetition`.
+
+    Args:
+        radius: Circle radius.
+        num_x, num_y: Number of holes in x and y.
+        pitch: Center-to-center spacing.
+        layer: Layer to draw the holes on.
+
+    Returns:
+        Pattern containing a grid of holes.
+    """
+    # First, make a pattern for a single hole
+    hpat = hole(radius, layer)
+
+    # Now, create a pattern that references it multiple times using a Grid
+    pat = Pattern()
+    pat.refs['hole'] = [
+        Ref(
+            offset=(0, 0),
+            repetition=Grid(a_vector=(pitch, 0), a_count=num_x,
+                            b_vector=(0, pitch), b_count=num_y)
+        )]
+
+    # We can also add transformed references (rotation, mirroring, etc.)
+    pat.refs['hole'].append(
+        Ref(offset=(0, -pitch), rotation=pi / 4, mirrored=True)
+    )
+
+    return pat, hpat
+
+
 def triangle(
         radius: float,
         layer: layer_t = (1, 0),
@@ -60,9 +96,7 @@ def triangle(
         ]) * radius
 
     pat = Pattern()
-    pat.shapes[layer].extend([
-        Polygon(offset=(0, 0), vertices=vertices),
-        ])
+    pat.polygon(layer, vertices=vertices)
     return pat
 
 
@@ -111,9 +145,13 @@ def main() -> None:
     lib['smile'] = smile(1000)
     lib['triangle'] = triangle(1000)
 
+    # Use a Grid to make many holes efficiently
+    lib['grid'], lib['hole'] = hole_array(1000)
+
     masque.file.gdsii.writefile(lib, 'basic_shapes.gds', **GDS_OPTS)
 
     lib['triangle'].visualize()
+    lib['grid'].visualize(lib)
 
 
 if __name__ == '__main__':

examples/tutorial/devices.py

@@ -1,11 +1,19 @@
+"""
+Tutorial: building hierarchical devices with `Pattern`, `Port`, and `Pather`.
+
+This file uses photonic-crystal components as the concrete example, so some of
+the geometry-generation code is domain-specific. The tutorial value is in the
+Masque patterns around it: creating reusable cells, annotating ports, composing
+hierarchy with references, and snapping ports together to build a larger circuit.
+"""
 from collections.abc import Sequence, Mapping
 
 import numpy
 from numpy import pi
 
 from masque import (
-    layer_t, Pattern, Ref, Label, Builder, Port, Polygon,
-    Library, ILibraryView,
+    layer_t, Pattern, Ref, Pather, Port, Polygon,
+    Library,
     )
 from masque.utils import ports2data
 from masque.file.gdsii import writefile, check_valid_names
@@ -64,9 +72,9 @@ def perturbed_l3(
             Provided sequence should have same length as `shifts_a`.
         xy_size: `(x, y)` number of mirror periods in each direction; total size is
                 `2 * n + 1` holes in each direction. Default (10, 10).
-        perturbed_radius: radius of holes perturbed to form an upwards-driected beam
+        perturbed_radius: radius of holes perturbed to form an upwards-directed beam
                 (multiplicative factor). Default 1.1.
-        trench width: Width of the undercut trenches. Default 1200.
+        trench_width: Width of the undercut trenches. Default 1200.
 
     Returns:
         `Pattern` object representing the L3 design.
@@ -79,14 +87,15 @@ def perturbed_l3(
                                           shifts_a=shifts_a,
                                           shifts_r=shifts_r)
 
-    # Build L3 cavity, using references to the provided hole pattern
+    # Build the cavity by instancing the supplied `hole` pattern many times.
+    # Using references keeps the pattern compact even though it contains many holes.
     pat = Pattern()
     pat.refs[hole] += [
         Ref(scale=r, offset=(lattice_constant * x,
                              lattice_constant * y))
         for x, y, r in xyr]
 
-    # Add rectangular undercut aids
+    # Add rectangular undercut aids based on the referenced hole extents.
     min_xy, max_xy = pat.get_bounds_nonempty(hole_lib)
     trench_dx = max_xy[0] - min_xy[0]
 
@@ -95,7 +104,7 @@ def perturbed_l3(
         Polygon.rect(ymax=min_xy[1], xmin=min_xy[0], lx=trench_dx, ly=trench_width),
         ]
 
-    # Ports are at outer extents of the device (with y=0)
+    # Define the interface in Masque terms: two ports at the left/right extents.
     extent = lattice_constant * xy_size[0]
     pat.ports = dict(
         input=Port((-extent, 0), rotation=0, ptype='pcwg'),
@@ -125,17 +134,17 @@ def waveguide(
     Returns:
         `Pattern` object representing the waveguide.
     """
-    # Generate hole locations
+    # Generate the normalized lattice locations for the line defect.
     xy = pcgen.waveguide(length=length, num_mirror=mirror_periods)
 
-    # Build the pattern
+    # Build the pattern by placing repeated references to the same hole cell.
     pat = Pattern()
     pat.refs[hole] += [
         Ref(offset=(lattice_constant * x,
                     lattice_constant * y))
         for x, y in xy]
 
-    # Ports are at outer edges, with y=0
+    # Publish the device interface as two ports at the outer edges.
     extent = lattice_constant * length / 2
     pat.ports = dict(
         left=Port((-extent, 0), rotation=0, ptype='pcwg'),
@@ -164,17 +173,17 @@ def bend(
         `Pattern` object representing the waveguide bend.
         Ports are named 'left' (input) and 'right' (output).
     """
-    # Generate hole locations
+    # Generate the normalized lattice locations for the bend.
     xy = pcgen.wgbend(num_mirror=mirror_periods)
 
-    # Build the pattern
+    # Build the pattern by instancing the shared hole cell.
     pat = Pattern()
     pat.refs[hole] += [
         Ref(offset=(lattice_constant * x,
                     lattice_constant * y))
         for x, y in xy]
 
-    # Figure out port locations.
+    # Publish the bend interface as two ports.
     extent = lattice_constant * mirror_periods
     pat.ports = dict(
         left=Port((-extent, 0), rotation=0, ptype='pcwg'),
@@ -203,17 +212,17 @@ def y_splitter(
         `Pattern` object representing the y-splitter.
         Ports are named 'in', 'top', and 'bottom'.
     """
-    # Generate hole locations
+    # Generate the normalized lattice locations for the splitter.
     xy = pcgen.y_splitter(num_mirror=mirror_periods)
 
-    # Build pattern
+    # Build the pattern by instancing the shared hole cell.
     pat = Pattern()
     pat.refs[hole] += [
         Ref(offset=(lattice_constant * x,
                     lattice_constant * y))
         for x, y in xy]
 
-    # Determine port locations
+    # Publish the splitter interface as one input and two outputs.
     extent = lattice_constant * mirror_periods
     pat.ports = {
         'in': Port((-extent, 0), rotation=0, ptype='pcwg'),
@@ -227,13 +236,13 @@ def y_splitter(
 
 
 def main(interactive: bool = True) -> None:
-    # Generate some basic hole patterns
+    # First make a couple of reusable primitive cells.
     shape_lib = {
         'smile': basic_shapes.smile(RADIUS),
         'hole': basic_shapes.hole(RADIUS),
         }
 
-    # Build some devices
+    # Then build a small library of higher-level devices from those primitives.
     a = LATTICE_CONSTANT
 
     devices = {}
@@ -245,22 +254,23 @@ def main(interactive: bool = True) -> None:
     devices['ysplit'] = y_splitter(lattice_constant=a, hole='hole', mirror_periods=5)
     devices['l3cav'] = perturbed_l3(lattice_constant=a, hole='smile', hole_lib=shape_lib, xy_size=(4, 10))   # uses smile :)
 
-    # Turn our dict of devices into a Library.
-    # This provides some convenience functions in the future!
+    # Turn the device mapping into a `Library`.
+    # That gives us convenience helpers for hierarchy inspection and abstract views.
     lib = Library(devices)
 
     #
     # Build a circuit
     #
-    # Create a `Builder`, and add the circuit to our library as "my_circuit".
-    circ = Builder(library=lib, name='my_circuit')
+    # Create a `Pather`, and register the resulting top cell as "my_circuit".
+    circ = Pather(library=lib, name='my_circuit')
 
-    # Start by placing a waveguide. Call its ports "in" and "signal".
+    # Start by placing a waveguide and renaming its ports to match the circuit-level
+    # names we want to use while assembling the design.
     circ.place('wg10', offset=(0, 0), port_map={'left': 'in', 'right': 'signal'})
 
-    # Extend the signal path by attaching the "left" port of a waveguide.
-    #   Since there is only one other port ("right") on the waveguide we
-    # are attaching (wg10), it automatically inherits the name "signal".
+    # Extend the signal path by attaching another waveguide.
+    # Because `wg10` only has one unattached port left after the plug, Masque can
+    # infer that it should keep the name `signal`.
     circ.plug('wg10', {'signal': 'left'})
 
     # We could have done the following instead:
@@ -268,8 +278,8 @@ def main(interactive: bool = True) -> None:
     #   lib['my_circuit'] = circ_pat
     #   circ_pat.place(lib.abstract('wg10'), ...)
     #   circ_pat.plug(lib.abstract('wg10'), ...)
-    # but `Builder` lets us omit some of the repetition of `lib.abstract(...)`, and uses similar
-    # syntax to `Pather` and `RenderPather`, which add wire/waveguide routing functionality.
+    # but `Pather` removes some repeated `lib.abstract(...)` boilerplate and keeps
+    # the assembly code focused on port-level intent.
 
     # Attach a y-splitter to the signal path.
     #   Since the y-splitter has 3 ports total, we can't auto-inherit the
@@ -281,13 +291,10 @@ def main(interactive: bool = True) -> None:
     circ.plug('wg05', {'signal1': 'left'})
     circ.plug('wg05', {'signal2': 'left'})
 
-    # Add a bend to both ports.
-    #   Our bend's ports "left" and "right" refer to the original counterclockwise
-    # orientation. We want the bends to turn in opposite directions, so we attach
-    # the "right" port to "signal1" to bend clockwise, and the "left" port
-    # to "signal2" to bend counterclockwise.
-    #   We could also use `mirrored=(True, False)` to mirror one of the devices
-    # and then use same device port on both paths.
+    # Add a bend to both branches.
+    # Our bend primitive is defined with a specific orientation, so choosing which
+    # port to plug determines whether the path turns clockwise or counterclockwise.
+    # We could also mirror one instance instead of using opposite ports.
     circ.plug('bend0', {'signal1': 'right'})
     circ.plug('bend0', {'signal2': 'left'})
 
@@ -296,29 +303,26 @@ def main(interactive: bool = True) -> None:
     circ.plug('l3cav', {'signal1': 'input'})
     circ.plug('wg10', {'signal1': 'left'})
 
-    # "signal2" just gets a single of equivalent length
+    # `signal2` gets a single waveguide of equivalent overall length.
     circ.plug('wg28', {'signal2': 'left'})
 
-    # Now we bend both waveguides back towards each other
+    # Now bend both branches back towards each other.
     circ.plug('bend0', {'signal1': 'right'})
     circ.plug('bend0', {'signal2': 'left'})
     circ.plug('wg05', {'signal1': 'left'})
     circ.plug('wg05', {'signal2': 'left'})
 
-    # To join the waveguides, we attach a second y-junction.
-    #   We plug "signal1" into the "bot" port, and "signal2" into the "top" port.
-    # The remaining port gets named "signal_out".
-    #   This operation would raise an exception if the ports did not line up
-    # correctly (i.e. they required different rotations or translations of the
-    # y-junction device).
+    # To join the branches, attach a second y-junction.
+    # This succeeds only if both chosen ports agree on the same translation and
+    # rotation for the inserted device; otherwise Masque raises an exception.
     circ.plug('ysplit', {'signal1': 'bot', 'signal2': 'top'}, {'in': 'signal_out'})
 
     # Finally, add some more waveguide to "signal_out".
     circ.plug('wg10', {'signal_out': 'left'})
 
-    # We can also add text labels for our circuit's ports.
-    #   They will appear at the uppermost hierarchy level, while the individual
-    # device ports will appear further down, in their respective cells.
+    # Bake the top-level port metadata into labels so it survives GDS export.
+    # These labels appear on the circuit cell; individual child devices keep their
+    # own port labels in their own cells.
     ports_to_data(circ.pattern)
 
     # Check if we forgot to include any patterns... ooops!
@@ -330,12 +334,12 @@ def main(interactive: bool = True) -> None:
         lib.add(shape_lib)
         assert not lib.dangling_refs()
 
-    # We can visualize the design. Usually it's easier to just view the GDS.
+    # We can visualize the design directly, though opening the written GDS is often easier.
     if interactive:
         print('Visualizing... this step may be slow')
         circ.pattern.visualize(lib)
 
-    #Write out to GDS, only keeping patterns referenced by our circuit (including itself)
+    # Write out only the subtree reachable from our top cell.
     subtree = lib.subtree('my_circuit')     # don't include wg90, which we don't use
     check_valid_names(subtree.keys())
     writefile(subtree, 'circuit.gds', **GDS_OPTS)

examples/tutorial/library.py

@@ -1,135 +1,133 @@
+"""
+Tutorial: authoring a mixed library with `LibraryBuilder`.
+
+This example assumes you have already read `devices.py` and generated the
+`circuit.gds` file it writes. The goal here is not the photonic-crystal geometry
+itself, but rather how Masque lets you combine imported GDS cells with
+python-generated recipes, then turn that declaration set into a normal library
+for downstream assembly and writing.
+"""
 from typing import Any
-from collections.abc import Sequence, Callable
 from pprint import pformat
 
-import numpy
-from numpy import pi
 
-from masque import Pattern, Builder, LazyLibrary
-from masque.file.gdsii import writefile, load_libraryfile
+from masque import ILibrary, LibraryBuilder, Pather, Pattern, PortLoadView, cell
+from masque.file.gdsii import writefile
+from masque.file.gdsii.lazy import readfile
 
-import pcgen
 import basic_shapes
 import devices
-from devices import ports_to_data, data_to_ports
 from basic_shapes import GDS_OPTS
 
 
+def make_mixed_waveguide(lib: ILibrary) -> Pattern:
+    """
+    Recipe which assembles imported and generated cells behind the builder API.
+    """
+    circ = Pather(library=lib, ports='tri_l3cav')
+
+    # First way to specify what we are plugging in: request an explicit abstract.
+    circ.plug(lib.abstract('wg10'), {'input': 'right'})
+
+    # Second way: use an AbstractView, which behaves like a mapping of names
+    # to abstracts.
+    abstracts = lib.abstract_view()
+    circ.plug(abstracts['wg10'], {'output': 'left'})
+
+    # Third way: let Pather resolve a pattern name through its own library.
+    circ.plug('tri_wg10', {'input': 'right'})
+    circ.plug('tri_wg10', {'output': 'left'})
+
+    return circ.pattern
+
+
 def main() -> None:
-    # Define a `LazyLibrary`, which provides lazy evaluation for generating
-    #   patterns and lazy-loading of GDS contents.
-    lib = LazyLibrary()
+    builder = LibraryBuilder()
+    cells = builder.cells
+
+    # Naming and export policy can be bound once without changing individual
+    # declarations. For example, a foundry-specific group could use:
+    #
+    # cells = builder.cells.prefixed(
+    #     'foundry_',
+    #     facade=lambda proxy: devices.ports_to_data(proxy),
+    #     )
+    #
+    # Dynamic names use the same view: cells[generated_name] = cell(factory)(...)
 
     #
     # Load some devices from a GDS file
     #
 
-    # Scan circuit.gds and prepare to lazy-load its contents
-    gds_lib, _properties = load_libraryfile('circuit.gds', postprocess=data_to_ports)
+    # Scan circuit.gds and prepare to lazy-load its contents. Port labels are
+    # imported on first materialization, but the raw source remains untouched
+    # until we build the final library.
+    gds_lib, _properties = readfile('circuit.gds')
+    builder.add_source(PortLoadView(gds_lib, layers=[(3, 0)], max_depth=1))
 
-    # Add it into the device library by providing a way to read port info
-    #   This maintains the lazy evaluation from above, so no patterns
-    # are actually read yet.
-    lib.add(gds_lib)
-
-    print('Patterns loaded from GDS into library:\n' + pformat(list(lib.keys())))
+    print('Registered imported cells:\n' + pformat(list(gds_lib.keys())))
 
     #
-    # Add some new devices to the library, this time from python code rather than GDS
+    # Register some new devices, this time from python code rather than GDS.
     #
 
-    lib['triangle'] = lambda: basic_shapes.triangle(devices.RADIUS)
+    cells.triangle = basic_shapes.triangle(devices.RADIUS)
     opts: dict[str, Any] = dict(
         lattice_constant=devices.LATTICE_CONSTANT,
         hole='triangle',
     )
 
-    # Triangle-based variants. These are defined here, but they won't run until they're
-    #   retrieved from the library.
-    lib['tri_wg10'] = lambda: devices.waveguide(length=10, mirror_periods=5, **opts)
-    lib['tri_wg05'] = lambda: devices.waveguide(length=5, mirror_periods=5, **opts)
-    lib['tri_wg28'] = lambda: devices.waveguide(length=28, mirror_periods=5, **opts)
-    lib['tri_bend0'] = lambda: devices.bend(mirror_periods=5, **opts)
-    lib['tri_ysplit'] = lambda: devices.y_splitter(mirror_periods=5, **opts)
-    lib['tri_l3cav'] = lambda: devices.perturbed_l3(xy_size=(4, 10), **opts, hole_lib=lib)
+    cells.tri_wg10 = cell(devices.waveguide)(length=10, mirror_periods=5, **opts)
+    cells.tri_wg05 = cell(devices.waveguide)(length=5, mirror_periods=5, **opts)
+    cells.tri_wg28 = cell(devices.waveguide)(length=28, mirror_periods=5, **opts)
+    cells.tri_bend0 = cell(devices.bend)(mirror_periods=5, **opts)
+    cells.tri_ysplit = cell(devices.y_splitter)(mirror_periods=5, **opts)
+    cells.tri_l3cav = cell(devices.perturbed_l3)(
+        xy_size=(4, 10),
+        **opts,
+        hole_lib=builder.library,
+        )
+    cells.mixed_wg_cav = cell(make_mixed_waveguide)(builder.library)
+
+    print('Declared cells waiting to be built:\n' + pformat(list(builder.keys())))
 
     #
-    # Build a mixed waveguide with an L3 cavity in the middle
+    # Build the declaration set into a normal library.
     #
 
-    # Immediately start building from an instance of the L3 cavity
-    circ2 = Builder(library=lib, ports='tri_l3cav')
-
-    #   First way to get abstracts is `lib.abstract(name)`
-    # We can use this syntax directly with `Pattern.plug()` and `Pattern.place()` as well as through `Builder`.
-    circ2.plug(lib.abstract('wg10'), {'input': 'right'})
-
-    #   Second way to get abstracts is to use an AbstractView
-    # This also works directly with `Pattern.plug()` / `Pattern.place()`.
-    abstracts = lib.abstract_view()
-    circ2.plug(abstracts['wg10'], {'output': 'left'})
-
-    # Third way to specify an abstract works by automatically getting
-    # it from the library already within the Builder object.
-    # This wouldn't work if we only had a `Pattern` (not a `Builder`).
-    # Just pass the pattern name!
-    circ2.plug('tri_wg10', {'input': 'right'})
-    circ2.plug('tri_wg10', {'output': 'left'})
-
-    # Add the circuit to the device library.
-    lib['mixed_wg_cav'] = circ2.pattern
-
+    built, report = builder.build()
+    print('Built library contains:\n' + pformat(list(built.keys())))
+    print('Build dependency graph:\n' + pformat(report.dependency_graph))
 
     #
-    # Build a device that could plug into our mixed_wg_cav and joins the two ports
+    # Continue designing against the built library.
     #
 
-    # We'll be designing against an existing device's interface...
-    circ3 = Builder.interface(source=circ2)
-
-    # ... that lets us continue from where we left off.
-    circ3.plug('tri_bend0', {'input': 'right'})
-    circ3.plug('tri_bend0', {'input': 'left'}, mirrored=True) # mirror since no tri y-symmetry
-    circ3.plug('tri_bend0', {'input': 'right'})
-    circ3.plug('bend0', {'output': 'left'})
-    circ3.plug('bend0', {'output': 'left'})
-    circ3.plug('bend0', {'output': 'left'})
-    circ3.plug('tri_wg10', {'input': 'right'})
-    circ3.plug('tri_wg28', {'input': 'right'})
-    circ3.plug('tri_wg10', {'input': 'right', 'output': 'left'})
-
-    lib['loop_segment'] = circ3.pattern
+    # The built result behaves like a normal mutable library, so downstream code
+    # can use Pather, abstract views, and writing without going back through the
+    # builder interface.
+    circ = Pather.interface(source='mixed_wg_cav', library=built)
+    circ.plug('tri_bend0', {'input': 'right'})
+    circ.plug('tri_bend0', {'input': 'left'}, mirrored=True)   # mirror since no tri y-symmetry
+    circ.plug('tri_bend0', {'input': 'right'})
+    circ.plug('bend0', {'output': 'left'})
+    circ.plug('bend0', {'output': 'left'})
+    circ.plug('bend0', {'output': 'left'})
+    circ.plug('tri_wg10', {'input': 'right'})
+    circ.plug('tri_wg28', {'input': 'right'})
+    circ.plug('tri_wg10', {'input': 'right', 'output': 'left'})
+    built['loop_segment'] = circ.pattern
 
     #
-    # Write all devices into a GDS file
+    # Write all devices into a GDS file.
     #
     print('Writing library to file...')
-    writefile(lib, 'library.gds', **GDS_OPTS)
+    writefile(built, 'library.gds', **GDS_OPTS)
+
+    # The default build output is an overlay which borrows its lazy sources.
+    # Close the owning GDS source only after the overlay is no longer needed.
+    gds_lib.close()
 
 
 if __name__ == '__main__':
     main()
-
-
-#
-#class prout:
-#    def place(
-#            self,
-#            other: Pattern,
-#            label_layer: layer_t = 'WATLAYER',
-#            *,
-#            port_map: Dict[str, str | None] | None = None,
-#            **kwargs,
-#            ) -> 'prout':
-#
-#        Pattern.place(self, other, port_map=port_map, **kwargs)
-#        name: str | None
-#        for name in other.ports:
-#            if port_map:
-#                assert(name is not None)
-#                name = port_map.get(name, name)
-#            if name is None:
-#                continue
-#            self.pattern.label(string=name, offset=self.ports[name].offset, layer=label_layer)
-#        return self
-#

examples/tutorial/pather.py

@@ -1,11 +1,20 @@
 """
-Manual wire routing tutorial: Pather and BasicTool
+Manual wire routing tutorial: Pather and primitive offers
 """
-from collections.abc import Callable
+from collections.abc import Sequence
+from dataclasses import dataclass
+from typing import Any, Literal
+
+import numpy
 from numpy import pi
-from masque import Pather, RenderPather, Library, Pattern, Port, layer_t, map_layers
-from masque.builder.tools import BasicTool, PathTool
+from masque import Pather, Library, Pattern, Port, layer_t
+from masque.abstract import Abstract
+from masque.builder import (
+    BendOffer, RenderStep, StraightOffer, Tool, ToolContractCase, validate_tool_contract,
+    )
+from masque.error import BuildError
 from masque.file.gdsii import writefile
+from masque.library import ILibrary, SINGLE_USE_PREFIX
 
 from basic_shapes import GDS_OPTS
 
@@ -107,17 +116,265 @@ def map_layer(layer: layer_t) -> layer_t:
         'M2': (20, 0),
         'V1': (30, 0),
         }
+    if isinstance(layer, str):
         return layer_mapping.get(layer, layer)
+    return layer
 
 
-#
-# Now we can start building up our library (collection of static cells) and pathing tools.
-#
-#   If any of the operations below are confusing, you can cross-reference against the `RenderPather`
-# tutorial, which handles some things more explicitly (e.g. via placement) and simplifies others
-# (e.g. geometry definition).
-#
-def main() -> None:
+@dataclass(frozen=True, slots=True)
+class WireStraightData:
+    length: float
+    out_transition: 'WireTransitionSpec | None' = None
+
+
+@dataclass(frozen=True, slots=True)
+class WireBendData:
+    straight_length: float
+    ccw: bool
+
+
+@dataclass(frozen=True, slots=True)
+class WireTransitionSpec:
+    abstract: Abstract
+    in_port_name: str
+    out_port_name: str
+
+    @property
+    def in_port(self) -> Port:
+        return self.abstract.ports[self.in_port_name]
+
+    @property
+    def out_port(self) -> Port:
+        return self.abstract.ports[self.out_port_name]
+
+
+@dataclass(frozen=True, slots=True)
+class WireTransitionData:
+    spec: WireTransitionSpec
+
+
+@dataclass
+class PrimitiveWireTool(Tool):
+    """
+    Minimal routing tool that exposes local routing primitives directly.
+
+    The high-level `Pather` methods below still decide how to compose straights,
+    bends, and ptype transitions. This tool only describes which one-step
+    primitives it can draw and how selected primitives should be rendered.
+    """
+    layer: layer_t
+    width: float
+    ptype: str
+    bend: Abstract
+    transitions: Sequence[WireTransitionSpec]
+
+    def _straight_pattern(self, length: float) -> Pattern:
+        return make_straight_wire(layer=self.layer, width=self.width, ptype=self.ptype, length=length)
+
+    @staticmethod
+    def _transition_length(spec: WireTransitionSpec) -> float | None:
+        dxy, angle = spec.in_port.measure_travel(spec.out_port)
+        if angle is None or not numpy.isclose(angle, pi) or not numpy.isclose(dxy[1], 0):
+            return None
+        return float(dxy[0])
+
+    def _transition_offers(self, in_ptype: str | None) -> tuple[StraightOffer, ...]:
+        offers: list[StraightOffer] = []
+        for spec in self.transitions:
+            if spec.out_port.ptype != self.ptype:
+                continue
+            if in_ptype not in (None, 'unk', spec.in_port.ptype):
+                continue
+
+            length = self._transition_length(spec)
+            if length is None:
+                continue
+
+            def endpoint_planner(
+                    parameter: float,
+                    *,
+                    spec: WireTransitionSpec = spec,
+                    length: float = length,
+                    ) -> Port:
+                _ = parameter
+                return Port((length, 0), rotation=pi, ptype=spec.out_port.ptype)
+
+            def commit_planner(
+                    parameter: float,
+                    *,
+                    spec: WireTransitionSpec = spec,
+                    ) -> WireTransitionData:
+                _ = parameter
+                return WireTransitionData(spec)
+
+            offers.append(StraightOffer(
+                in_ptype = spec.in_port.ptype,
+                out_ptype = spec.out_port.ptype,
+                length_domain = (length, length),
+                endpoint_planner = endpoint_planner,
+                commit_planner = commit_planner,
+                ))
+        return tuple(offers)
+
+    def _out_transition_offers(self, out_ptype: str | None) -> tuple[StraightOffer, ...]:
+        if out_ptype in ('unk', self.ptype):
+            return ()
+
+        offers: list[StraightOffer] = []
+        for spec in self.transitions:
+            if spec.in_port.ptype != self.ptype:
+                continue
+            if out_ptype is not None and spec.out_port.ptype != out_ptype:
+                continue
+
+            transition_length = self._transition_length(spec)
+            if transition_length is None:
+                continue
+
+            def endpoint_planner(
+                    length: float,
+                    *,
+                    spec: WireTransitionSpec = spec,
+                    transition_length: float = transition_length,
+                    ) -> Port:
+                straight_length = length - transition_length
+                if straight_length < 0:
+                    raise BuildError(
+                        f'Asked to draw straight path with total length {length:,g}, shorter than required transition: {transition_length:,g}'
+                        )
+                return Port((length, 0), rotation=pi, ptype=spec.out_port.ptype)
+
+            def commit_planner(
+                    length: float,
+                    *,
+                    spec: WireTransitionSpec = spec,
+                    transition_length: float = transition_length,
+                    ) -> WireStraightData:
+                endpoint_planner(length)
+                return WireStraightData(length - transition_length, spec)
+
+            offers.append(StraightOffer(
+                in_ptype = self.ptype,
+                out_ptype = spec.out_port.ptype,
+                length_domain = (transition_length, numpy.inf),
+                endpoint_planner = endpoint_planner,
+                commit_planner = commit_planner,
+                ))
+        return tuple(offers)
+
+    def primitive_offers(
+            self,
+            kind: Literal['straight', 'bend', 's', 'u'],
+            *,
+            in_ptype: str | None = None,
+            out_ptype: str | None = None,       # noqa: ARG002 (Pather validates selected output ptypes)
+            **kwargs: Any,
+            ) -> tuple[StraightOffer | BendOffer, ...]:
+        if kind == 'straight':
+            tool_options = dict(kwargs)
+
+            def endpoint_planner(length: float) -> Port:
+                return Port((length, 0), rotation=pi, ptype=self.ptype)
+
+            def commit_planner(length: float) -> WireStraightData:
+                _ = tool_options
+                return WireStraightData(length)
+
+            native_offer = StraightOffer(
+                in_ptype = self.ptype,
+                out_ptype = self.ptype,
+                endpoint_planner = endpoint_planner,
+                commit_planner = commit_planner,
+                )
+            return (*self._transition_offers(in_ptype), native_offer, *self._out_transition_offers(out_ptype))
+
+        if kind == 'bend':
+            ccw = bool(kwargs.pop('ccw'))
+            bend_forward = self.width / 2
+            bend_run = bend_forward if ccw else -bend_forward
+            bend_rotation = -pi / 2 if ccw else pi / 2
+
+            def endpoint_planner(length: float) -> Port:
+                straight_length = length - bend_forward
+                if straight_length < 0:
+                    raise BuildError(
+                        f'Asked to draw L-path with total length {length:,g}, shorter than required bend: {bend_forward:,g}'
+                        )
+                return Port((length, bend_run), rotation=bend_rotation, ptype=self.ptype)
+
+            def commit_planner(length: float) -> WireBendData:
+                endpoint_planner(length)
+                return WireBendData(straight_length=length - bend_forward, ccw=ccw)
+
+            return (BendOffer(
+                in_ptype = self.ptype,
+                out_ptype = self.ptype,
+                ccw = ccw,
+                length_domain = (bend_forward, numpy.inf),
+                endpoint_planner = endpoint_planner,
+                commit_planner = commit_planner,
+                ),)
+
+        if kind in ('s', 'u'):
+            return ()
+
+        raise BuildError(f'Unrecognized primitive offer kind {kind!r}')
+
+    def _render_straight(self, tree: ILibrary, port_names: tuple[str, str], data: WireStraightData) -> None:
+        if numpy.isclose(data.length, 0) and data.out_transition is None:
+            return
+
+        if not numpy.isclose(data.length, 0):
+            tree.top_pattern().plug(
+                self._straight_pattern(data.length),
+                {port_names[1]: 'input'},
+                append=True,
+                )
+
+        if data.out_transition is not None:
+            self._render_transition(tree, port_names, WireTransitionData(data.out_transition))
+
+    def _render_bend(self, tree: ILibrary, port_names: tuple[str, str], data: WireBendData) -> None:
+        self._render_straight(tree, port_names, WireStraightData(data.straight_length))
+        tree.top_pattern().plug(
+            self.bend,
+            {port_names[1]: 'input'},
+            mirrored=data.ccw,
+            )
+
+    @staticmethod
+    def _render_transition(tree: ILibrary, port_names: tuple[str, str], data: WireTransitionData) -> None:
+        tree.top_pattern().plug(
+            data.spec.abstract,
+            {port_names[1]: data.spec.in_port_name},
+            )
+
+    def render(
+            self,
+            batch: Sequence[RenderStep],
+            *,
+            port_names: tuple[str, str] = ('A', 'B'),
+            ) -> ILibrary:
+        tree, pat = Library.mktree(SINGLE_USE_PREFIX + 'primitive_wire')
+        pat.add_port_pair(names=port_names, ptype=batch[0].start_port.ptype if batch else self.ptype)
+
+        for step in batch:
+            assert step.tool == self
+            if isinstance(step.data, WireTransitionData):
+                self._render_transition(tree, port_names, step.data)
+            elif isinstance(step.data, WireStraightData):
+                self._render_straight(tree, port_names, step.data)
+            elif isinstance(step.data, WireBendData):
+                self._render_bend(tree, port_names, step.data)
+            else:
+                raise BuildError(f'Unexpected primitive render data {type(step.data)}')
+        return tree
+
+
+def prepare_tools() -> tuple[Library, Tool, Tool]:
+    """
+    Create some basic library elements and tools for drawing M1 and M2
+    """
     # Build some patterns (static cells) using the above functions and store them in a library
     library = Library()
     library['pad'] = make_pad()
@@ -136,58 +393,59 @@ def main() -> None:
 
     #
     # Now, define two tools.
-    # M1_tool will route on M1, using wires with M1_WIDTH
-    # M2_tool will route on M2, using wires with M2_WIDTH
-    # Both tools are able to automatically transition from the other wire type (with a via)
+    # M1_tool will route on M1, using wires with M1_WIDTH.
+    # M2_tool will route on M2, using wires with M2_WIDTH.
     #
-    #   Note that while we use BasicTool for this tutorial, you can define your own `Tool`
-    # with arbitrary logic inside -- e.g. with single-use bends, complex transition rules,
-    # transmission line geometry, or other features.
+    # Unlike the reusable `AutoTool`, this tutorial tool exposes primitive offers
+    # directly: it tells `Pather` about native straight/bend primitives and about
+    # via adapters that can transition between M1 and M2 port types.
     #
-    M1_tool = BasicTool(
-        straight = (
-            # First, we need a function which takes in a length and spits out an M1 wire
-            lambda length: make_straight_wire(layer='M1', ptype='m1wire', width=M1_WIDTH, length=length),
-            'input',    # When we get a pattern from make_straight_wire, use the port named 'input' as the input
-            'output',   # and use the port named 'output' as the output
-            ),
-        bend = (
-            library.abstract('m1_bend'),    # When we need a bend, we'll reference the pattern we generated earlier
-            'input',    # To orient it clockwise, use the port named 'input' as the input
-            'output',   # and 'output' as the output
-            ),
-        transitions = {  # We can automate transitions for different (normally incompatible) port types
-            'm2wire': (  # For example, when we're attaching to a port with type 'm2wire'
-                library.abstract('v1_via'),   # we can place a V1 via
-                'top',     # using the port named 'top' as the input (i.e. the M2 side of the via)
-                'bottom',  # and using the port named 'bottom' as the output
-                ),
-            },
-        default_out_ptype = 'm1wire',   # Unless otherwise requested, we'll default to trying to stay on M1
+    via = library.abstract('v1_via')
+    via_transitions = (
+        WireTransitionSpec(via, 'top', 'bottom'),
+        WireTransitionSpec(via, 'bottom', 'top'),
         )
 
-    M2_tool = BasicTool(
-        straight = (
-            # Again, we use make_straight_wire, but this time we set parameters for M2
-            lambda length: make_straight_wire(layer='M2', ptype='m2wire', width=M2_WIDTH, length=length),
-            'input',
-            'output',
-            ),
-        bend = (
-            library.abstract('m2_bend'),    # and we use an M2 bend
-            'input',
-            'output',
-            ),
-        transitions = {
-            'm1wire': (
-                library.abstract('v1_via'),     # We still use the same via,
-                'bottom',                       # but the input port is now 'bottom'
-                'top',                          # and the output port is now 'top'
-                ),
-            },
-        default_out_ptype = 'm2wire',       # We default to trying to stay on M2
+    M1_tool = PrimitiveWireTool(
+        layer = 'M1',
+        width = M1_WIDTH,
+        ptype = 'm1wire',
+        bend = library.abstract('m1_bend'),
+        transitions = via_transitions,
         )
 
+    M2_tool = PrimitiveWireTool(
+        layer = 'M2',
+        width = M2_WIDTH,
+        ptype = 'm2wire',
+        bend = library.abstract('m2_bend'),
+        transitions = via_transitions,
+        )
+
+    # Custom tools can be checked independently of Pather or pytest. Automatic
+    # probes cover each offer domain; explicit probes can target useful process
+    # dimensions. Unsupported primitive families opt out with require_offers=False.
+    for tool in (M1_tool, M2_tool):
+        validate_tool_contract(tool, (
+            ToolContractCase('straight', in_ptype=tool.ptype, probe_parameters=(10_000,)),
+            ToolContractCase('bend', in_ptype=tool.ptype, ccw=False),
+            ToolContractCase('bend', in_ptype=tool.ptype, ccw=True),
+            ToolContractCase('s', in_ptype=tool.ptype, require_offers=False),
+            ToolContractCase('u', in_ptype=tool.ptype, require_offers=False),
+            ))
+    return library, M1_tool, M2_tool
+
+
+#
+# Now we can start building up our library (collection of static cells) and pathing tools.
+#
+#   If any of the operations below are confusing, you can cross-reference against the deferred
+# `Pather` tutorial, which handles some things more explicitly (e.g. via placement) and simplifies
+# others (e.g. geometry definition).
+#
+def main() -> None:
+    library, M1_tool, M2_tool = prepare_tools()
+
     #
     # Create a new pather which writes to `library` and uses `M2_tool` as its default tool.
     # Then, place some pads and start routing wires!
@@ -203,27 +461,25 @@ def main() -> None:
 
     # Path VCC forward (in this case south) and turn clockwise 90 degrees (ccw=False)
     # The total distance forward (including the bend's forward component) must be 6um
-    pather.path('VCC', ccw=False, length=6_000)
+    pather.cw('VCC', 6_000)
 
-    # Now path VCC to x=0. This time, don't include any bend (ccw=None).
+    # Now path VCC to x=0. This time, don't include any bend.
     # Note that if we tried y=0 here, we would get an error since the VCC port is facing in the x-direction.
-    pather.path_to('VCC', ccw=None, x=0)
+    pather.straight('VCC', x=0)
 
     # Path GND forward by 5um, turning clockwise 90 degrees.
-    # This time we use shorthand (bool(0) == False) and omit the parameter labels
-    # Note that although ccw=0 is equivalent to ccw=False, ccw=None is not!
-    pather.path('GND', 0, 5_000)
+    pather.cw('GND', 5_000)
 
     # This time, path GND until it matches the current x-coordinate of VCC. Don't place a bend.
-    pather.path_to('GND', None, x=pather['VCC'].offset[0])
+    pather.straight('GND', x=pather['VCC'].offset[0])
 
     # Now, start using M1_tool for GND.
-    # Since we have defined an M2-to-M1 transition for BasicPather, we don't need to place one ourselves.
+    # Since we have defined an M2-to-M1 transition for Pather, we don't need to place one ourselves.
     #   If we wanted to place our via manually, we could add `pather.plug('m1_via', {'GND': 'top'})` here
     # and achieve the same result without having to define any transitions in M1_tool.
     #   Note that even though we have changed the tool used for GND, the via doesn't get placed until
-    # the next time we draw a path on GND (the pather.mpath() statement below).
-    pather.retool(M1_tool, keys=['GND'])
+    # the next time we route GND (the `pather.ccw()` call below).
+    pather.retool(M1_tool, keys='GND')
 
     # Bundle together GND and VCC, and path the bundle forward and counterclockwise.
     #   Pick the distance so that the leading/outermost wire (in this case GND) ends up at x=-10_000.
@@ -231,7 +487,7 @@ def main() -> None:
     #
     #  Since we recently retooled GND, its path starts with a via down to M1 (included in the distance
     # calculation), and its straight segment and bend will be drawn using M1 while VCC's are drawn with M2.
-    pather.mpath(['GND', 'VCC'], ccw=True, xmax=-10_000, spacing=5_000)
+    pather.ccw(['GND', 'VCC'], xmax=-10_000, spacing=5_000)
 
     # Now use M1_tool as the default tool for all ports/signals.
     # Since VCC does not have an explicitly assigned tool, it will now transition down to M1.
@@ -241,38 +497,37 @@ def main() -> None:
     #   The total extension (travel distance along the forward direction) for the longest segment (in
     # this case the segment being added to GND) should be exactly 50um.
     # After turning, the wire pitch should be reduced only 1.2um.
-    pather.mpath(['GND', 'VCC'], ccw=True, emax=50_000, spacing=1_200)
+    pather.ccw(['GND', 'VCC'], emax=50_000, spacing=1_200)
 
     # Make a U-turn with the bundle and expand back out to 4.5um wire pitch.
-    #   Here, emin specifies the travel distance for the shortest segment. For the first mpath() call
-    # that applies to VCC, and for teh second call, that applies to GND; the relative lengths of the
+    #   Here, emin specifies the travel distance for the shortest segment. For the first call
+    # that applies to VCC, and for the second call, that applies to GND; the relative lengths of the
     # segments depend on their starting positions and their ordering within the bundle.
-    pather.mpath(['GND', 'VCC'], ccw=False, emin=1_000, spacing=1_200)
-    pather.mpath(['GND', 'VCC'], ccw=False, emin=2_000, spacing=4_500)
+    pather.cw(['GND', 'VCC'], emin=1_000, spacing=1_200)
+    pather.cw(['GND', 'VCC'], emin=2_000, spacing=4_500)
 
     # Now, set the default tool back to M2_tool. Note that GND remains on M1 since it has been
-    # explicitly assigned a tool. We could `del pather.tools['GND']` to force it to use the default.
+    # explicitly assigned a tool.
     pather.retool(M2_tool)
 
     # Now path both ports to x=-28_000.
-    #   When ccw is not None, xmin constrains the trailing/innermost port to stop at the target x coordinate,
-    # However, with ccw=None, all ports stop at the same coordinate, and so specifying xmin= or xmax= is
+    #   With ccw=None, all ports stop at the same coordinate, and so specifying xmin= or xmax= is
     # equivalent.
-    pather.mpath(['GND', 'VCC'], None, xmin=-28_000)
+    pather.straight(['GND', 'VCC'], xmin=-28_000)
 
     # Further extend VCC out to x=-50_000, and specify that we would like to get an output on M1.
     #  This results in a via at the end of the wire (instead of having one at the start like we got
     # when using pather.retool().
-    pather.path_to('VCC', None, -50_000, out_ptype='m1wire')
+    pather.straight('VCC', x=-50_000, out_ptype='m1wire')
 
     # Now extend GND out to x=-50_000, using M2 for a portion of the path.
     # We can use `pather.toolctx()` to temporarily retool, instead of calling `retool()` twice.
-    with pather.toolctx(M2_tool, keys=['GND']):
-        pather.path_to('GND', None, -40_000)
-    pather.path_to('GND', None, -50_000)
+    with pather.toolctx(M2_tool, keys='GND'):
+        pather.straight('GND', x=-40_000)
+    pather.straight('GND', x=-50_000)
 
     # Save the pather's pattern into our library
-    library['Pather_and_BasicTool'] = pather.pattern
+    library['Pather_and_PrimitiveOffers'] = pather.pattern
 
     # Convert from text-based layers to numeric layers for GDS, and output the file
     library.map_layers(map_layer)

examples/tutorial/pcgen.py

@@ -2,7 +2,7 @@
 Routines for creating normalized 2D lattices and common photonic crystal
  cavity designs.
 """
-from collection.abc import Sequence
+from collections.abc import Sequence
 
 import numpy
 from numpy.typing import ArrayLike, NDArray
@@ -50,7 +50,7 @@ def triangular_lattice(
     elif origin == 'corner':
         pass
     else:
-        raise Exception(f'Invalid value for `origin`: {origin}')
+        raise ValueError(f'Invalid value for `origin`: {origin}')
 
     return xy[xy[:, 0].argsort(), :]
 
@@ -197,12 +197,12 @@ def ln_defect(
         `[[x0, y0], [x1, y1], ...]` for all the holes
     """
     if defect_length % 2 != 1:
-        raise Exception('defect_length must be odd!')
-    p = triangular_lattice([2 * d + 1 for d in mirror_dims])
+        raise ValueError('defect_length must be odd!')
+    pp = triangular_lattice([2 * dd + 1 for dd in mirror_dims])
     half_length = numpy.floor(defect_length / 2)
     hole_nums = numpy.arange(-half_length, half_length + 1)
-    holes_to_keep = numpy.in1d(p[:, 0], hole_nums, invert=True)
-    return p[numpy.logical_or(holes_to_keep, p[:, 1] != 0), ]
+    holes_to_keep = numpy.isin(pp[:, 0], hole_nums, invert=True)
+    return pp[numpy.logical_or(holes_to_keep, pp[:, 1] != 0), :]
 
 
 def ln_shift_defect(
@@ -248,7 +248,7 @@ def ln_shift_defect(
         for sign in (-1, 1):
             x_val = sign * (x_removed + ind + 1)
             which = numpy.logical_and(xyr[:, 0] == x_val, xyr[:, 1] == 0)
-            xyr[which, ] = (x_val + numpy.sign(x_val) * shifts_a[ind], 0, shifts_r[ind])
+            xyr[which, :] = (x_val + numpy.sign(x_val) * shifts_a[ind], 0, shifts_r[ind])
 
     return xyr
 
@@ -309,7 +309,7 @@ def l3_shift_perturbed_defect(
 
     # which holes should be perturbed? (xs[[3, 7]], ys[1]) and (xs[[2, 6]], ys[2])
     perturbed_holes = ((xs[a], ys[b]) for a, b in ((3, 1), (7, 1), (2, 2), (6, 2)))
-    for row in xyr:
-        if numpy.fabs(row) in perturbed_holes:
-            row[2] = perturbed_radius
+    for xy in perturbed_holes:
+        which = (numpy.fabs(xyr[:, :2]) == xy).all(axis=1)
+        xyr[which, 2] = perturbed_radius
     return xyr

examples/tutorial/port_pather.py

@@ -0,0 +1,170 @@
+"""
+PortPather tutorial: Using .at() syntax
+"""
+from masque import Pather, Pattern, Port, R90
+from masque.file.gdsii import writefile
+
+from basic_shapes import GDS_OPTS
+from pather import map_layer, prepare_tools
+
+
+def main() -> None:
+    # Reuse the same patterns (pads, bends, vias) and tools as in pather.py
+    library, M1_tool, M2_tool = prepare_tools()
+
+    # Create a deferred Pather and place some initial pads (same as Pather tutorial)
+    rpather = Pather(library, tools=M2_tool, render='deferred')
+
+    rpather.place('pad', offset=(18_000, 30_000), port_map={'wire_port': 'VCC'})
+    rpather.place('pad', offset=(18_000, 60_000), port_map={'wire_port': 'GND'})
+    rpather.pattern.label(layer='M2', string='VCC', offset=(18e3, 30e3))
+    rpather.pattern.label(layer='M2', string='GND', offset=(18e3, 60e3))
+
+    #
+    # Routing with .at() chaining
+    #
+    # The .at(port_name) method returns a PortPather object which wraps the Pather
+    # and remembers the selected port(s). This allows method chaining.
+
+    # Route VCC: 6um South, then West to x=0.
+    # (Note: since the port points North into the pad, trace() moves South by default)
+    (rpather.at('VCC')
+        .trace(False, length=6_000)      # Move South, turn West (Clockwise)
+        .trace_to(None, x=0)             # Continue West to x=0
+        )
+
+    # Route GND: 5um South, then West to match VCC's x-coordinate.
+    rpather.at('GND').trace(False, length=5_000).trace_to(None, x=rpather['VCC'].x)
+
+
+    #
+    # Tool management and manual plugging
+    #
+    # We can use .retool() to change the tool for specific ports.
+    # We can also use .plug() directly on a PortPather.
+
+    # Manually add a via to GND and switch to M1_tool for subsequent segments
+    (rpather.at('GND')
+        .plug('v1_via', 'top')
+        .retool(M1_tool)                # this only retools the 'GND' port
+        )
+
+    # We can also pass multiple ports to .at(), and then route them together.
+    # Here we bundle them, turn South, and retool both to M1 (VCC gets an auto-via).
+    (rpather.at(['GND', 'VCC'])
+        .trace(True, xmax=-10_000, spacing=5_000)   # Move West to -10k, turn South
+        .retool(M1_tool)                            # Retools both GND and VCC
+        .set_spacing(1_200)                         # Default bundle spacing for later bends
+        .trace(True, emax=50_000)                   # Turn East, moves 50um extension
+        .trace(False, emin=1_000)                   # U-turn back South
+        .trace(False, emin=2_000, spacing=4_500)    # U-turn back West, overriding the default spacing
+        )
+
+    # Retool VCC back to M2 and move both to x=-28k
+    rpather.at('VCC').retool(M2_tool)
+    rpather.at(['GND', 'VCC']).trace(None, xmin=-28_000)
+
+    # Final segments to -50k
+    rpather.at('VCC').trace_to(None, x=-50_000, out_ptype='m1wire')
+    with rpather.at('GND').toolctx(M2_tool):
+        rpather.at('GND').trace_to(None, x=-40_000)
+    rpather.at('GND').trace_to(None, x=-50_000)
+
+
+    #
+    # Branching with mark and fork
+    #
+    # .mark(new_name) creates a port copy and keeps the original selected.
+    # .fork(new_name) creates a port copy and selects the new one.
+
+    # Create a tap on GND
+    (rpather.at('GND')
+        .trace(None, length=5_000)           # Move GND further West
+        .mark('GND_TAP')                     # Mark this location for a later branch
+        .jog(offset=-10_000, length=10_000)  # Continue GND with an S-bend
+        )
+
+    # Branch VCC and follow the new branch
+    (rpather.at('VCC')
+        .trace(None, length=5_000)
+        .fork('VCC_BRANCH')                  # We are now manipulating 'VCC_BRANCH'
+        .trace(True, length=5_000)           # VCC_BRANCH turns South
+        )
+    # The original 'VCC' port remains at x=-55k, y=VCC.y
+
+
+    #
+    # Port set management: add, drop, rename, delete
+    #
+
+    # Route the GND_TAP we saved earlier.
+    (rpather.at('GND_TAP')
+        .retool(M1_tool)
+        .trace(True, length=10_000)          # Turn South
+        .rename('GND_FEED')                  # Give it a more descriptive name
+        .retool(M1_tool)                     # Re-apply tool to the new name
+        )
+
+    # We can manage the active set of ports in a PortPather
+    pp = rpather.at(['VCC_BRANCH', 'GND_FEED'])
+    pp.select('GND')                         # Now tracking 3 ports
+    pp.deselect('VCC_BRANCH')                # Now tracking 2 ports: GND_FEED, GND
+    pp.trace(None, each=5_000)               # Move both 5um forward (length > transition size)
+
+    # We can also delete ports from the pather entirely
+    rpather.at('VCC').delete()               # VCC is gone (we have VCC_BRANCH instead)
+
+
+    #
+    # Advanced Connections: trace_into
+    #
+    # trace_into routes FROM the selected port TO a target port.
+
+    # Create a destination component
+    dest_ports = {
+        'in_A': Port((0, 0), rotation=R90, ptype='m2wire'),
+        'in_B': Port((5_000, 0), rotation=R90, ptype='m2wire')
+        }
+    library['dest'] = Pattern(ports=dest_ports)
+    # Place dest so that its ports are to the West and South of our current wires.
+    # Rotating by pi/2 makes the ports face West (pointing East).
+    rpather.place('dest', offset=(-100_000, -100_000), rotation=R90, port_map={'in_A': 'DEST_A', 'in_B': 'DEST_B'})
+
+    # Connect GND_FEED to DEST_A
+    # Since GND_FEED is moving South and DEST_A faces West, a single bend will suffice.
+    rpather.at('GND_FEED').trace_into('DEST_A')
+
+    # Connect VCC_BRANCH to DEST_B
+    rpather.at('VCC_BRANCH').trace_into('DEST_B')
+
+
+    #
+    # Direct Port Transformations and Metadata
+    #
+    (rpather.at('GND')
+        .set_ptype('m1wire')                 # Change metadata
+        .translate((1000, 0))                # Shift the port 1um East
+        .rotate(R90 / 2)                     # Rotate it 45 degrees
+        .set_rotation(R90)                   # Force it to face West
+        )
+
+    # Demonstrate .plugged() to acknowledge a manual connection
+    # (Normally used when you place components so their ports perfectly overlap)
+    rpather.add_port_pair(offset=(0, 0), names=('TMP1', 'TMP2'))
+    rpather.at('TMP1').plugged('TMP2')       # Removes both ports
+
+
+    #
+    # Rendering and Saving
+    #
+    # Since routing is deferred, we must call .render() to generate the geometry.
+    rpather.render()
+
+    library['PortPather_Tutorial'] = rpather.pattern
+    library.map_layers(map_layer)
+    writefile(library, 'port_pather.gds', **GDS_OPTS)
+    print("Tutorial complete. Output written to port_pather.gds")
+
+
+if __name__ == '__main__':
+    main()

examples/tutorial/renderpather.py

@@ -1,9 +1,8 @@
 """
-Manual wire routing tutorial: RenderPather an PathTool
+Manual wire routing tutorial: deferred Pather and PathTool
 """
-from collections.abc import Callable
-from masque import RenderPather, Library, Pattern, Port, layer_t, map_layers
-from masque.builder.tools import PathTool
+from masque import Pather, Library
+from masque.builder import PathTool
 from masque.file.gdsii import writefile
 
 from basic_shapes import GDS_OPTS
@@ -12,9 +11,9 @@ from pather import M1_WIDTH, V1_WIDTH, M2_WIDTH, map_layer, make_pad, make_via
 
 def main() -> None:
     #
-    #   To illustrate the advantages of using `RenderPather`, we use `PathTool` instead
-    # of `BasicTool`. `PathTool` lacks some sophistication (e.g. no automatic transitions)
-    # but when used with `RenderPather`, it can consolidate multiple routing steps into
+    #   To illustrate deferred routing with `Pather`, we use `PathTool` instead
+    # of `AutoTool`. `PathTool` lacks some sophistication (e.g. no automatic transitions)
+    # but when used with `Pather(render='deferred')`, it can consolidate multiple routing steps into
     # a single `Path` shape.
     #
     #   We'll try to nearly replicate the layout from the `Pather` tutorial; see `pather.py`
@@ -35,56 +34,58 @@ def main() -> None:
         ptype_top = 'm2wire',
         )
 
-    #   `PathTool` is more limited than `BasicTool`. It only generates one type of shape
+    #   `PathTool` is more limited than `AutoTool`. It only generates one type of shape
     # (`Path`), so it only needs to know what layer to draw on, what width to draw with,
     # and what port type to present.
     M1_ptool = PathTool(layer='M1', width=M1_WIDTH, ptype='m1wire')
     M2_ptool = PathTool(layer='M2', width=M2_WIDTH, ptype='m2wire')
-    rpather = RenderPather(tools=M2_ptool, library=library)
+    rpather = Pather(tools=M2_ptool, library=library, render='deferred')
 
-    # As in the pather tutorial, we make soem pads and labels...
+    # As in the pather tutorial, we make some pads and labels...
     rpather.place('pad', offset=(18_000, 30_000), port_map={'wire_port': 'VCC'})
     rpather.place('pad', offset=(18_000, 60_000), port_map={'wire_port': 'GND'})
     rpather.pattern.label(layer='M2', string='VCC', offset=(18e3, 30e3))
     rpather.pattern.label(layer='M2', string='GND', offset=(18e3, 60e3))
 
     # ...and start routing the signals.
-    rpather.path('VCC', ccw=False, length=6_000)
-    rpather.path_to('VCC', ccw=None, x=0)
-    rpather.path('GND', 0, 5_000)
-    rpather.path_to('GND', None, x=rpather['VCC'].offset[0])
+    rpather.cw('VCC', 6_000)
+    rpather.straight('VCC', x=0)
+    rpather.cw('GND', 5_000)
+    rpather.straight('GND', x=rpather.pattern['VCC'].x)
 
     # `PathTool` doesn't know how to transition betwen metal layers, so we have to
     # `plug` the via into the GND wire ourselves.
     rpather.plug('v1_via', {'GND': 'top'})
-    rpather.retool(M1_ptool, keys=['GND'])
-    rpather.mpath(['GND', 'VCC'], ccw=True, xmax=-10_000, spacing=5_000)
+    rpather.retool(M1_ptool, keys='GND')
+    rpather.ccw(['GND', 'VCC'], xmax=-10_000, spacing=5_000)
 
     # Same thing on the VCC wire when it goes down to M1.
     rpather.plug('v1_via', {'VCC': 'top'})
     rpather.retool(M1_ptool)
-    rpather.mpath(['GND', 'VCC'], ccw=True, emax=50_000, spacing=1_200)
-    rpather.mpath(['GND', 'VCC'], ccw=False, emin=1_000, spacing=1_200)
-    rpather.mpath(['GND', 'VCC'], ccw=False, emin=2_000, spacing=4_500)
+    rpather.ccw(['GND', 'VCC'], emax=50_000, spacing=1_200)
+    rpather.cw(['GND', 'VCC'], emin=1_000, spacing=1_200)
+    rpather.cw(['GND', 'VCC'], emin=2_000, spacing=4_500)
 
     # And again when VCC goes back up to M2.
     rpather.plug('v1_via', {'VCC': 'bottom'})
     rpather.retool(M2_ptool)
-    rpather.mpath(['GND', 'VCC'], None, xmin=-28_000)
+    rpather.straight(['GND', 'VCC'], xmin=-28_000)
 
     #   Finally, since PathTool has no conception of transitions, we can't
     # just ask it to transition to an 'm1wire' port at the end of the final VCC segment.
     # Instead, we have to calculate the via size ourselves, and adjust the final position
     # to account for it.
-    via_size = abs(
-          library['v1_via'].ports['top'].offset[0]
-        - library['v1_via'].ports['bottom'].offset[0]
-        )
-    rpather.path_to('VCC', None, -50_000 + via_size)
+    v1pat = library['v1_via']
+    via_size = abs(v1pat.ports['top'].x - v1pat.ports['bottom'].x)
+
+    # alternatively, via_size = v1pat.ports['top'].measure_travel(v1pat.ports['bottom'])[0][0]
+    #  would take into account the port orientations if we didn't already know they're along x
+    rpather.straight('VCC', x=-50_000 + via_size)
     rpather.plug('v1_via', {'VCC': 'top'})
 
+    # Render the path we defined
     rpather.render()
-    library['RenderPather_and_PathTool'] = rpather.pattern
+    library['Deferred_Pather_and_PathTool'] = rpather.pattern
 
 
     # Convert from text-based layers to numeric layers for GDS, and output the file

masque/__init__.py

@@ -42,6 +42,7 @@ from .error import (
 from .shapes import (
     Shape as Shape,
     Polygon as Polygon,
+    RectCollection as RectCollection,
     Path as Path,
     Circle as Circle,
     Arc as Arc,
@@ -55,16 +56,27 @@ from .pattern import (
     map_targets as map_targets,
     chain_elements as chain_elements,
     )
+from .utils.boolean import boolean as boolean
 
 from .library import (
+    INameView as INameView,
     ILibraryView as ILibraryView,
     ILibrary as ILibrary,
+    IBorrowing as IBorrowing,
+    IMaterializable as IMaterializable,
     LibraryView as LibraryView,
     Library as Library,
+    OverlayLibrary as OverlayLibrary,
+    PortLoadView as PortLoadView,
+    LayerMappedView as LayerMappedView,
+    LibraryBuilder as LibraryBuilder,
+    BuildReport as BuildReport,
+    CellProvenance as CellProvenance,
     LazyLibrary as LazyLibrary,
     AbstractView as AbstractView,
     TreeView as TreeView,
     Tree as Tree,
+    cell as cell,
     )
 from .ports import (
     Port as Port,
@@ -72,12 +84,14 @@ from .ports import (
     )
 from .abstract import Abstract as Abstract
 from .builder import (
-    Builder as Builder,
     Tool as Tool,
+    ToolContractError as ToolContractError,
     Pather as Pather,
-    RenderPather as RenderPather,
+    RouteError as RouteError,
+    RouteFailureDetails as RouteFailureDetails,
+    RouteFailurePolicy as RouteFailurePolicy,
+    MinimumStatus as MinimumStatus,
     RenderStep as RenderStep,
-    SimpleTool as SimpleTool,
     AutoTool as AutoTool,
     PathTool as PathTool,
     PortPather as PortPather,

masque/abstract.py

@@ -8,16 +8,13 @@ from numpy.typing import ArrayLike
 from .ref import Ref
 from .ports import PortList, Port
 from .utils import rotation_matrix_2d
-
-#if TYPE_CHECKING:
-#    from .builder import Builder, Tool
-#    from .library import ILibrary
+from .traits import Mirrorable
 
 
 logger = logging.getLogger(__name__)
 
 
-class Abstract(PortList):
+class Abstract(PortList, Mirrorable):
     """
     An `Abstract` is a container for a name and associated ports.
 
@@ -131,50 +128,18 @@ class Abstract(PortList):
             port.rotate(rotation)
         return self
 
-    def mirror_port_offsets(self, across_axis: int = 0) -> Self:
+    def mirror(self, axis: int = 0) -> Self:
         """
-        Mirror the offsets of all shapes, labels, and refs across an axis
+        Mirror the Abstract across an axis through its origin.
 
         Args:
-            across_axis: Axis to mirror across
-                (0: mirror across x axis, 1: mirror across y axis)
+            axis: Axis to mirror across (0: x-axis, 1: y-axis).
 
         Returns:
             self
         """
         for port in self.ports.values():
-            port.offset[across_axis - 1] *= -1
-        return self
-
-    def mirror_ports(self, across_axis: int = 0) -> Self:
-        """
-        Mirror each port's rotation across an axis, relative to its
-          offset
-
-        Args:
-            across_axis: Axis to mirror across
-                (0: mirror across x axis, 1: mirror across y axis)
-
-        Returns:
-            self
-        """
-        for port in self.ports.values():
-            port.mirror(across_axis)
-        return self
-
-    def mirror(self, across_axis: int = 0) -> Self:
-        """
-        Mirror the Pattern across an axis
-
-        Args:
-            axis: Axis to mirror across
-                (0: mirror across x axis, 1: mirror across y axis)
-
-        Returns:
-            self
-        """
-        self.mirror_ports(across_axis)
-        self.mirror_port_offsets(across_axis)
+            port.flip_across(axis=axis)
         return self
 
     def apply_ref_transform(self, ref: Ref) -> Self:
@@ -192,6 +157,8 @@ class Abstract(PortList):
             self.mirror()
         self.rotate_ports(ref.rotation)
         self.rotate_port_offsets(ref.rotation)
+        if ref.scale != 1:
+            self.scale_by(ref.scale)
         self.translate_ports(ref.offset)
         return self
 
@@ -209,6 +176,8 @@ class Abstract(PortList):
         # TODO test undo_ref_transform
         """
         self.translate_ports(-ref.offset)
+        if ref.scale != 1:
+            self.scale_by(1 / ref.scale)
         self.rotate_port_offsets(-ref.rotation)
         self.rotate_ports(-ref.rotation)
         if ref.mirrored:

masque/builder/__init__.py

@@ -1,12 +1,90 @@
-from .builder import Builder as Builder
-from .pather import Pather as Pather
-from .renderpather import RenderPather as RenderPather
-from .pather_mixin import PortPather as PortPather
+"""
+Builder helpers for port-based assembly and primitive-offer routing.
+
+A routing `Tool` describes the primitive route families it can provide by
+returning `PrimitiveOffer` objects. Each offer is a parameterized planning
+candidate: it exposes legal parameter domains, endpoint behavior, ptypes, cost,
+optional footprint metadata, and a commit hook for producing tool-specific
+render data after a concrete parameter has been selected.
+
+`Pather` owns user-facing route operations such as `trace()`, `jog()`,
+`uturn()`, and `trace_into()`. The internal planner resolves each operation into
+one or more `SolverRequest`s. This normalization is why the public routing API
+can remain a convenient keyword-based interface without making the solver
+stringly typed internally. A pure solver search selects a `Candidate`, and a
+`RouteLeg` attaches that candidate to its copied source port and Tool. Only
+after selection succeeds are the chosen offers materialized through
+`offer.commit(parameter)` into a `PreparedRouteResult` containing
+`RenderStep.data`. `Pather` then applies that prepared result to its live ports
+and pending render queue.
+
+Selection is pure with respect to caller-owned Pattern, Library, and Pather
+state. Tool offer discovery and endpoint/cost/bbox callbacks must likewise be
+deterministic and must not mutate that state. `commit()` is the first
+selected-offer materialization hook, but it still must not mutate the live
+layout. `Tool.render()` is the geometry mutation boundary: later,
+`Pather.render()` batches compatible `RenderStep`s and inserts the resulting
+geometry into the Pattern and Library.
+
+`PrimitiveOffer` and `RenderStep.data` are the tool-facing contract.
+`RenderStep` is `Pather`'s deferred-render record, and
+`masque.builder.planner` is an internal planner implementation rather than a
+stable public API.
+
+Custom Tool authors should run `validate_tool_contract()` as a development or
+application-startup preflight. It performs the comprehensive semantic checks
+that are intentionally not repeated during route selection, keeping the normal
+routing path focused on search rather than contract verification.
+
+The practical layering is:
+- user code drives `Pather` and chooses Tools per port or by default,
+- Tools describe local legal motion primitives without touching Pather state,
+- the internal router composes those primitives into high-level route shapes,
+- Pather applies the prepared result to ports, deferred render queues, and the
+  target pattern/library.
+
+`Pather` intentionally remains a Pattern-oriented facade rather than exposing
+separate assembly and routing objects: its user model is a working Pattern with
+routing tools attached. The ownership phases above are internal boundaries,
+not additional objects callers must coordinate.
+
+Code outside the builder package should prefer the exports here over importing
+from `masque.builder.planner`. The planner package is intentionally available
+for tests and internal maintenance, but it is not the compatibility boundary
+for custom Tools.
+"""
+
+from .pather import (
+    Pather as Pather,
+    PortPather as PortPather,
+    RouteCompletionCallback as RouteCompletionCallback,
+)
+from .error import (
+    ToolContractError as ToolContractError,
+    RouteError as RouteError,
+    RouteFailureDetails as RouteFailureDetails,
+    RouteOperation as RouteOperation,
+    RouteFailurePolicy as RouteFailurePolicy,
+    MinimumStatus as MinimumStatus,
+)
 from .utils import ell as ell
+from .tool_testing import (
+    ToolContractCase as ToolContractCase,
+    validate_tool_contract as validate_tool_contract,
+)
 from .tools import (
     Tool as Tool,
-    RenderStep as RenderStep,
-    SimpleTool as SimpleTool,
     AutoTool as AutoTool,
     PathTool as PathTool,
+    RenderStep as RenderStep,
+    RenderStepKind as RenderStepKind,
+    PrimitiveKind as PrimitiveKind,
+    CostCallable as CostCallable,
+    GeneratedEndpointFn as GeneratedEndpointFn,
+    PrimitiveOffer as PrimitiveOffer,
+    StraightOffer as StraightOffer,
+    BendOffer as BendOffer,
+    SOffer as SOffer,
+    UOffer as UOffer,
+    circular_arc_sbend_endpoint as circular_arc_sbend_endpoint,
 )

masque/builder/_tolerances.py

@@ -0,0 +1,48 @@
+"""Shared numeric tolerances for builder geometry and parameter comparisons."""
+from math import isclose, remainder, tau
+from typing import Any
+
+import numpy
+
+
+GEOMETRY_RTOL = 1e-5
+GEOMETRY_ATOL = 1e-8
+DOMAIN_RTOL = 1e-9
+DOMAIN_ATOL = 1e-12
+MANHATTAN_ANGLE_RTOL = 1e-9
+MANHATTAN_ANGLE_ATOL = 1e-9
+
+
+def scalar_close(a: float, b: float) -> bool:
+    """Match the solver's existing scalar-comparison behavior."""
+    return isclose(float(a), float(b), rel_tol=GEOMETRY_RTOL, abs_tol=GEOMETRY_ATOL)
+
+
+def array_close(a: Any, b: Any) -> bool:
+    """Match NumPy's historical builder geometry-comparison behavior."""
+    return bool(numpy.allclose(a, b, rtol=GEOMETRY_RTOL, atol=GEOMETRY_ATOL))
+
+
+def angles_equal(a: float, b: float) -> bool:
+    """Return true when two rotations are equal modulo one full turn."""
+    delta = remainder(float(a) - float(b), tau)
+    return isclose(delta, 0.0, rel_tol=GEOMETRY_RTOL, abs_tol=GEOMETRY_ATOL)
+
+
+def manhattan_axis(rotation: float) -> int | None:
+    """Return 0 for horizontal, 1 for vertical, or None for a non-cardinal angle."""
+    angle = float(rotation) % (numpy.pi / 2)
+    if isclose(
+            angle,
+            0.0,
+            rel_tol=MANHATTAN_ANGLE_RTOL,
+            abs_tol=MANHATTAN_ANGLE_ATOL,
+            ) or isclose(
+                angle,
+                numpy.pi / 2,
+                rel_tol=MANHATTAN_ANGLE_RTOL,
+                abs_tol=MANHATTAN_ANGLE_ATOL,
+                ):
+        quarter_turn = round(float(rotation) / (numpy.pi / 2))
+        return quarter_turn % 2
+    return None

masque/builder/builder.py

@@ -1,448 +0,0 @@
-"""
-Simplified Pattern assembly (`Builder`)
-"""
-from typing import Self
-from collections.abc import Iterable, Sequence, Mapping
-import copy
-import logging
-from functools import wraps
-
-from numpy.typing import ArrayLike
-
-from ..pattern import Pattern
-from ..library import ILibrary, TreeView
-from ..error import BuildError
-from ..ports import PortList, Port
-from ..abstract import Abstract
-
-
-logger = logging.getLogger(__name__)
-
-
-class Builder(PortList):
-    """
-      A `Builder` is a helper object used for snapping together multiple
-    lower-level patterns at their `Port`s.
-
-      The `Builder` mostly just holds context, in the form of a `Library`,
-    in addition to its underlying pattern. This simplifies some calls
-    to `plug` and `place`, by making the library implicit.
-
-    `Builder` can also be `set_dead()`, at which point further calls to `plug()`
-    and `place()` are ignored (intended for debugging).
-
-
-    Examples: Creating a Builder
-    ===========================
-    - `Builder(library, ports={'A': port_a, 'C': port_c}, name='mypat')` makes
-        an empty pattern, adds the given ports, and places it into `library`
-        under the name `'mypat'`.
-
-    - `Builder(library)` makes an empty pattern with no ports. The pattern
-        is not added into `library` and must later be added with e.g.
-        `library['mypat'] = builder.pattern`
-
-    - `Builder(library, pattern=pattern, name='mypat')` uses an existing
-        pattern (including its ports) and sets `library['mypat'] = pattern`.
-
-    - `Builder.interface(other_pat, port_map=['A', 'B'], library=library)`
-        makes a new (empty) pattern, copies over ports 'A' and 'B' from
-        `other_pat`, and creates additional ports 'in_A' and 'in_B' facing
-        in the opposite directions. This can be used to build a device which
-        can plug into `other_pat` (using the 'in_*' ports) but which does not
-        itself include `other_pat` as a subcomponent.
-
-    - `Builder.interface(other_builder, ...)` does the same thing as
-        `Builder.interface(other_builder.pattern, ...)` but also uses
-        `other_builder.library` as its library by default.
-
-
-    Examples: Adding to a pattern
-    =============================
-    - `my_device.plug(subdevice, {'A': 'C', 'B': 'B'}, map_out={'D': 'myport'})`
-        instantiates `subdevice` into `my_device`, plugging ports 'A' and 'B'
-        of `my_device` into ports 'C' and 'B' of `subdevice`. The connected ports
-        are removed and any unconnected ports from `subdevice` are added to
-        `my_device`. Port 'D' of `subdevice` (unconnected) is renamed to 'myport'.
-
-    - `my_device.plug(wire, {'myport': 'A'})` places port 'A' of `wire` at 'myport'
-        of `my_device`. If `wire` has only two ports (e.g. 'A' and 'B'), no `map_out`,
-        argument is provided, and the `thru` argument is not explicitly
-        set to `False`, the unconnected port of `wire` is automatically renamed to
-        'myport'. This allows easy extension of existing ports without changing
-        their names or having to provide `map_out` each time `plug` is called.
-
-    - `my_device.place(pad, offset=(10, 10), rotation=pi / 2, port_map={'A': 'gnd'})`
-        instantiates `pad` at the specified (x, y) offset and with the specified
-        rotation, adding its ports to those of `my_device`. Port 'A' of `pad` is
-        renamed to 'gnd' so that further routing can use this signal or net name
-        rather than the port name on the original `pad` device.
-    """
-    __slots__ = ('pattern', 'library', '_dead')
-
-    pattern: Pattern
-    """ Layout of this device """
-
-    library: ILibrary
-    """
-    Library from which patterns should be referenced
-    """
-
-    _dead: bool
-    """ If True, plug()/place() are skipped (for debugging)"""
-
-    @property
-    def ports(self) -> dict[str, Port]:
-        return self.pattern.ports
-
-    @ports.setter
-    def ports(self, value: dict[str, Port]) -> None:
-        self.pattern.ports = value
-
-    def __init__(
-            self,
-            library: ILibrary,
-            *,
-            pattern: Pattern | None = None,
-            ports: str | Mapping[str, Port] | None = None,
-            name: str | None = None,
-            ) -> None:
-        """
-        Args:
-            library: The library from which referenced patterns will be taken
-            pattern: The pattern which will be modified by subsequent operations.
-                If `None` (default), a new pattern is created.
-            ports: Allows specifying the initial set of ports, if `pattern` does
-                not already have any ports (or is not provided). May be a string,
-                in which case it is interpreted as a name in `library`.
-                Default `None` (no ports).
-            name: If specified, `library[name]` is set to `self.pattern`.
-        """
-        self._dead = False
-        self.library = library
-        if pattern is not None:
-            self.pattern = pattern
-        else:
-            self.pattern = Pattern()
-
-        if ports is not None:
-            if self.pattern.ports:
-                raise BuildError('Ports supplied for pattern with pre-existing ports!')
-            if isinstance(ports, str):
-                ports = library.abstract(ports).ports
-
-            self.pattern.ports.update(copy.deepcopy(dict(ports)))
-
-        if name is not None:
-            library[name] = self.pattern
-
-    @classmethod
-    def interface(
-            cls: type['Builder'],
-            source: PortList | Mapping[str, Port] | str,
-            *,
-            library: ILibrary | None = None,
-            in_prefix: str = 'in_',
-            out_prefix: str = '',
-            port_map: dict[str, str] | Sequence[str] | None = None,
-            name: str | None = None,
-            ) -> 'Builder':
-        """
-        Wrapper for `Pattern.interface()`, which returns a Builder instead.
-
-        Args:
-            source: A collection of ports (e.g. Pattern, Builder, or dict)
-                from which to create the interface. May be a pattern name if
-                `library` is provided.
-            library: Library from which existing patterns should be referenced,
-                and to which the new one should be added (if named). If not provided,
-                `source.library` must exist and will be used.
-            in_prefix: Prepended to port names for newly-created ports with
-                reversed directions compared to the current device.
-            out_prefix: Prepended to port names for ports which are directly
-                copied from the current device.
-            port_map: Specification for ports to copy into the new device:
-                - If `None`, all ports are copied.
-                - If a sequence, only the listed ports are copied
-                - If a mapping, the listed ports (keys) are copied and
-                    renamed (to the values).
-
-        Returns:
-            The new builder, with an empty pattern and 2x as many ports as
-              listed in port_map.
-
-        Raises:
-            `PortError` if `port_map` contains port names not present in the
-                current device.
-            `PortError` if applying the prefixes results in duplicate port
-                names.
-        """
-        if library is None:
-            if hasattr(source, 'library') and isinstance(source.library, ILibrary):
-                library = source.library
-            else:
-                raise BuildError('No library was given, and `source.library` does not have one either.')
-
-        if isinstance(source, str):
-            source = library.abstract(source).ports
-
-        pat = Pattern.interface(source, in_prefix=in_prefix, out_prefix=out_prefix, port_map=port_map)
-        new = Builder(library=library, pattern=pat, name=name)
-        return new
-
-    @wraps(Pattern.label)
-    def label(self, *args, **kwargs) -> Self:
-        self.pattern.label(*args, **kwargs)
-        return self
-
-    @wraps(Pattern.ref)
-    def ref(self, *args, **kwargs) -> Self:
-        self.pattern.ref(*args, **kwargs)
-        return self
-
-    @wraps(Pattern.polygon)
-    def polygon(self, *args, **kwargs) -> Self:
-        self.pattern.polygon(*args, **kwargs)
-        return self
-
-    @wraps(Pattern.rect)
-    def rect(self, *args, **kwargs) -> Self:
-        self.pattern.rect(*args, **kwargs)
-        return self
-
-    # Note: We're a superclass of `Pather`, where path() means something different,
-    #  so we shouldn't wrap Pattern.path()
-    #@wraps(Pattern.path)
-    #def path(self, *args, **kwargs) -> Self:
-    #    self.pattern.path(*args, **kwargs)
-    #    return self
-
-    def plug(
-            self,
-            other: Abstract | str | Pattern | TreeView,
-            map_in: dict[str, str],
-            map_out: dict[str, str | None] | None = None,
-            *,
-            mirrored: bool = False,
-            thru: bool | str = True,
-            set_rotation: bool | None = None,
-            append: bool = False,
-            ok_connections: Iterable[tuple[str, str]] = (),
-            ) -> Self:
-        """
-        Wrapper around `Pattern.plug` which allows a string for `other`.
-
-        The `Builder`'s library is used to dereference the string (or `Abstract`, if
-        one is passed with `append=True`). If a `TreeView` is passed, it is first
-        added into `self.library`.
-
-        Args:
-            other: An `Abstract`, string, `Pattern`, or `TreeView` describing the
-                device to be instatiated. If it is a `TreeView`, it is first
-                added into `self.library`, after which the topcell is plugged;
-                an equivalent statement is `self.plug(self.library << other, ...)`.
-            map_in: dict of `{'self_port': 'other_port'}` mappings, specifying
-                port connections between the two devices.
-            map_out: dict of `{'old_name': 'new_name'}` mappings, specifying
-                new names for ports in `other`.
-            mirrored: Enables mirroring `other` across the x axis prior to
-                connecting any ports.
-            thru: If map_in specifies only a single port, `thru` provides a mechainsm
-                to avoid repeating the port name. Eg, for `map_in={'myport': 'A'}`,
-                - If True (default), and `other` has only two ports total, and map_out
-                doesn't specify a name for the other port, its name is set to the key
-                in `map_in`, i.e. 'myport'.
-                - If a string, `map_out[thru]` is set to the key in `map_in` (i.e. 'myport').
-                An error is raised if that entry already exists.
-
-                This makes it easy to extend a pattern with simple 2-port devices
-                (e.g. wires) without providing `map_out` each time `plug` is
-                called. See "Examples" above for more info. Default `True`.
-            set_rotation: If the necessary rotation cannot be determined from
-                the ports being connected (i.e. all pairs have at least one
-                port with `rotation=None`), `set_rotation` must be provided
-                to indicate how much `other` should be rotated. Otherwise,
-                `set_rotation` must remain `None`.
-            append: If `True`, `other` is appended instead of being referenced.
-                Note that this does not flatten  `other`, so its refs will still
-                be refs (now inside `self`).
-            ok_connections: Set of "allowed" ptype combinations. Identical
-                ptypes are always allowed to connect, as is `'unk'` with
-                any other ptypte. Non-allowed ptype connections will emit a
-                warning. Order is ignored, i.e. `(a, b)` is equivalent to
-                `(b, a)`.
-
-        Returns:
-            self
-
-        Raises:
-            `PortError` if any ports specified in `map_in` or `map_out` do not
-                exist in `self.ports` or `other_names`.
-            `PortError` if there are any duplicate names after `map_in` and `map_out`
-                are applied.
-            `PortError` if the specified port mapping is not achieveable (the ports
-                do not line up)
-        """
-        if self._dead:
-            logger.error('Skipping plug() since device is dead')
-            return self
-
-        if not isinstance(other, str | Abstract | Pattern):
-            # We got a Tree; add it into self.library and grab an Abstract for it
-            other = self.library << other
-
-        if isinstance(other, str):
-            other = self.library.abstract(other)
-        if append and isinstance(other, Abstract):
-            other = self.library[other.name]
-
-        self.pattern.plug(
-            other = other,
-            map_in = map_in,
-            map_out = map_out,
-            mirrored = mirrored,
-            thru = thru,
-            set_rotation = set_rotation,
-            append = append,
-            ok_connections = ok_connections,
-            )
-        return self
-
-    def place(
-            self,
-            other: Abstract | str | Pattern | TreeView,
-            *,
-            offset: ArrayLike = (0, 0),
-            rotation: float = 0,
-            pivot: ArrayLike = (0, 0),
-            mirrored: bool = False,
-            port_map: dict[str, str | None] | None = None,
-            skip_port_check: bool = False,
-            append: bool = False,
-            ) -> Self:
-        """
-        Wrapper around `Pattern.place` which allows a string or `TreeView` for `other`.
-
-        The `Builder`'s library is used to dereference the string (or `Abstract`, if
-        one is passed with `append=True`). If a `TreeView` is passed, it is first
-        added into `self.library`.
-
-        Args:
-            other: An `Abstract`, string, `Pattern`, or `TreeView` describing the
-                device to be instatiated. If it is a `TreeView`, it is first
-                added into `self.library`, after which the topcell is plugged;
-                an equivalent statement is `self.plug(self.library << other, ...)`.
-            offset: Offset at which to place the instance. Default (0, 0).
-            rotation: Rotation applied to the instance before placement. Default 0.
-            pivot: Rotation is applied around this pivot point (default (0, 0)).
-                Rotation is applied prior to translation (`offset`).
-            mirrored: Whether theinstance should be mirrored across the x axis.
-                Mirroring is applied before translation and rotation.
-            port_map: dict of `{'old_name': 'new_name'}` mappings, specifying
-                new names for ports in the instantiated device. New names can be
-                `None`, which will delete those ports.
-            skip_port_check: Can be used to skip the internal call to `check_ports`,
-                in case it has already been performed elsewhere.
-            append: If `True`, `other` is appended instead of being referenced.
-                Note that this does not flatten  `other`, so its refs will still
-                be refs (now inside `self`).
-
-        Returns:
-            self
-
-        Raises:
-            `PortError` if any ports specified in `map_in` or `map_out` do not
-                exist in `self.ports` or `other.ports`.
-            `PortError` if there are any duplicate names after `map_in` and `map_out`
-                are applied.
-        """
-        if self._dead:
-            logger.error('Skipping place() since device is dead')
-            return self
-
-        if not isinstance(other, str | Abstract | Pattern):
-            # We got a Tree; add it into self.library and grab an Abstract for it
-            other = self.library << other
-
-        if isinstance(other, str):
-            other = self.library.abstract(other)
-        if append and isinstance(other, Abstract):
-            other = self.library[other.name]
-
-        self.pattern.place(
-            other = other,
-            offset = offset,
-            rotation = rotation,
-            pivot = pivot,
-            mirrored = mirrored,
-            port_map = port_map,
-            skip_port_check = skip_port_check,
-            append = append,
-            )
-        return self
-
-    def translate(self, offset: ArrayLike) -> Self:
-        """
-        Translate the pattern and all ports.
-
-        Args:
-            offset: (x, y) distance to translate by
-
-        Returns:
-            self
-        """
-        self.pattern.translate_elements(offset)
-        return self
-
-    def rotate_around(self, pivot: ArrayLike, angle: float) -> Self:
-        """
-        Rotate the pattern and all ports.
-
-        Args:
-            angle: angle (radians, counterclockwise) to rotate by
-            pivot: location to rotate around
-
-        Returns:
-            self
-        """
-        self.pattern.rotate_around(pivot, angle)
-        for port in self.ports.values():
-            port.rotate_around(pivot, angle)
-        return self
-
-    def mirror(self, axis: int = 0) -> Self:
-        """
-        Mirror the pattern and all ports across the specified axis.
-
-        Args:
-            axis: Axis to mirror across (x=0, y=1)
-
-        Returns:
-            self
-        """
-        self.pattern.mirror(axis)
-        return self
-
-    def set_dead(self) -> Self:
-        """
-        Disallows further changes through `plug()` or `place()`.
-        This is meant for debugging:
-        ```
-            dev.plug(a, ...)
-            dev.set_dead()      # added for debug purposes
-            dev.plug(b, ...)    # usually raises an error, but now skipped
-            dev.plug(c, ...)    # also skipped
-            dev.pattern.visualize()     # shows the device as of the set_dead() call
-        ```
-
-        Returns:
-            self
-        """
-        self._dead = True
-        return self
-
-    def __repr__(self) -> str:
-        s = f'<Builder {self.pattern} L({len(self.library)})>'
-        return s
-
-

masque/builder/error.py

@@ -0,0 +1,109 @@
+"""Public routing failure diagnostics."""
+from typing import Any, Literal
+from collections.abc import Mapping
+from dataclasses import dataclass
+from enum import Enum, auto
+from pprint import pformat
+from types import MappingProxyType
+import traceback
+
+from ..error import BuildError
+
+
+RouteOperation = Literal['trace', 'trace_to', 'jog', 'uturn']
+
+
+class ToolContractError(BuildError):
+    """A Tool returned data inconsistent with its routing contract."""
+
+
+class RouteFailurePolicy(Enum):
+    """Whether route failure may be recovered through alternate/dead planning.
+
+    `RECOVERABLE` means a caller-controlled fallback may try another planning
+    branch. `FATAL` marks an invalid request or broken planning contract that
+    must be reported directly.
+    """
+
+    RECOVERABLE = auto()
+    FATAL = auto()
+
+
+class MinimumStatus(Enum):
+    """Outcome of preferred-minimum-length diagnosis.
+
+    `NOT_EVALUATED` is used when diagnosis is inapplicable, notably for an
+    invalid resolved length. `FOUND` carries `minimum_length`; `NO_ROUTE` means
+    exhaustive planning found no legal unconstrained route; `FAILED` means the
+    secondary diagnostic calculation itself raised a recoverable error.
+    """
+
+    NOT_EVALUATED = auto()
+    FOUND = auto()
+    NO_ROUTE = auto()
+    FAILED = auto()
+
+
+@dataclass(frozen=True, slots=True)
+class RouteFailureDetails:
+    """Structured context for a failed Pather routing request."""
+
+    operation: RouteOperation
+    portspec: str
+    in_ptype: str | None
+    out_ptype: str | None
+    request: Mapping[str, Any]
+    resolved_length: float | None
+    resolved_jog: float | None
+    minimum_length: float | None
+    minimum_status: MinimumStatus
+    cause: str
+    minimum_cause: str | None = None
+
+    def __post_init__(self) -> None:
+        if self.minimum_status is MinimumStatus.FOUND and self.minimum_length is None:
+            raise BuildError('MinimumStatus.FOUND requires minimum_length')
+        if self.minimum_status is not MinimumStatus.FOUND and self.minimum_length is not None:
+            raise BuildError(f'{self.minimum_status} requires minimum_length=None')
+        object.__setattr__(self, 'request', MappingProxyType(dict(self.request)))
+
+
+class RouteError(BuildError):
+    """A route-selection failure with structured request and saved call-stack diagnostics."""
+
+    details: RouteFailureDetails
+    policy: RouteFailurePolicy
+    _call_stack: tuple[traceback.FrameSummary, ...]
+
+    def __init__(
+            self,
+            details: RouteFailureDetails,
+            *,
+            policy: RouteFailurePolicy = RouteFailurePolicy.RECOVERABLE,
+            ) -> None:
+        self.details = details
+        self.policy = policy
+        if details.minimum_status is MinimumStatus.NOT_EVALUATED:
+            minimum = 'not evaluated'
+        elif details.minimum_status is MinimumStatus.FOUND:
+            assert details.minimum_length is not None
+            minimum = f'{details.minimum_length:g}'
+        elif details.minimum_status is MinimumStatus.NO_ROUTE:
+            minimum = 'unavailable (no legal route exists at any length)'
+        else:
+            minimum = 'unavailable (minimum-length calculation failed)'
+
+        lines = [
+            f'Unable to plan {details.operation} route for port {details.portspec!r}:',
+            f'  in_ptype: {details.in_ptype!r}',
+            f'  out_ptype: {details.out_ptype!r}',
+            f'  request: {pformat(dict(details.request), compact=True)}',
+            f'  resolved_length: {details.resolved_length!r}',
+            f'  resolved_jog: {details.resolved_jog!r}',
+            f'  preferred_minimum_length: {minimum}',
+            f'  cause: {details.cause}',
+            ]
+        if details.minimum_cause is not None:
+            lines.append(f'  minimum_failure: {details.minimum_cause}')
+        self._call_stack = tuple(traceback.extract_stack()[:-1])
+        super().__init__('\n'.join(lines))

masque/builder/logging.py

@@ -0,0 +1,80 @@
+"""Logging helpers for Pather."""
+from typing import TYPE_CHECKING, Any
+from collections.abc import Iterator, Sequence
+import logging
+import numpy
+from contextlib import contextmanager
+
+if TYPE_CHECKING:
+    from .pather import Pather
+
+
+def _format_log_args(**kwargs) -> str:
+    arg_strs = []
+    for k, v in kwargs.items():
+        if isinstance(v, str | int | float | bool | None):
+            arg_strs.append(f"{k}={v}")
+        elif isinstance(v, numpy.ndarray):
+            arg_strs.append(f"{k}={v.tolist()}")
+        elif isinstance(v, list | tuple) and len(v) <= 10:
+            arg_strs.append(f"{k}={v}")
+        else:
+            arg_strs.append(f"{k}=...")
+    return ", ".join(arg_strs)
+
+
+class PatherLogger:
+    """
+    Encapsulates state for Pather diagnostic logging.
+    """
+    debug: bool
+    indent: int
+    depth: int
+
+    def __init__(self, debug: bool = False) -> None:
+        self.debug = debug
+        self.indent = 0
+        self.depth = 0
+
+    def _log(self, module_name: str, msg: str) -> None:
+        if self.debug and self.depth <= 1:
+            log_obj = logging.getLogger(module_name)
+            log_obj.info('  ' * self.indent + msg)
+
+    @contextmanager
+    def log_operation(
+            self,
+            pather: 'Pather',
+            op: str,
+            portspec: str | Sequence[str] | None = None,
+            **kwargs: Any,
+            ) -> Iterator[None]:
+        if not self.debug or self.depth > 0:
+            self.depth += 1
+            try:
+                yield
+            finally:
+                self.depth -= 1
+            return
+
+        target = f"({portspec})" if portspec else ""
+        module_name = pather.__class__.__module__
+        self._log(module_name, f"Operation: {op}{target} {_format_log_args(**kwargs)}")
+
+        before_ports = {name: port.copy() for name, port in pather.ports.items()}
+        self.depth += 1
+        self.indent += 1
+
+        try:
+            yield
+        finally:
+            after_ports = pather.ports
+            for name in sorted(after_ports.keys()):
+                if name not in before_ports or after_ports[name] != before_ports[name]:
+                    self._log(module_name, f"Port {name}: {pather.ports[name].describe()}")
+            for name in sorted(before_ports.keys()):
+                if name not in after_ports:
+                    self._log(module_name, f"Port {name}: removed")
+
+            self.indent -= 1
+            self.depth -= 1

masque/builder/pather_mixin.py

@@ -1,677 +0,0 @@
-from typing import Self, overload
-from collections.abc import Sequence, Iterator, Iterable
-import logging
-from contextlib import contextmanager
-from abc import abstractmethod, ABCMeta
-
-import numpy
-from numpy import pi
-from numpy.typing import ArrayLike
-
-from ..pattern import Pattern
-from ..library import ILibrary, TreeView
-from ..error import PortError, BuildError
-from ..utils import SupportsBool
-from ..abstract import Abstract
-from .tools import Tool
-from .utils import ell
-from ..ports import PortList
-
-
-logger = logging.getLogger(__name__)
-
-
-class PatherMixin(PortList, metaclass=ABCMeta):
-    pattern: Pattern
-    """ Layout of this device """
-
-    library: ILibrary
-    """ Library from which patterns should be referenced """
-
-    _dead: bool
-    """ If True, plug()/place() are skipped (for debugging) """
-
-    tools: dict[str | None, Tool]
-    """
-    Tool objects are used to dynamically generate new single-use Devices
-    (e.g wires or waveguides) to be plugged into this device.
-    """
-
-    @abstractmethod
-    def path(
-            self,
-            portspec: str,
-            ccw: SupportsBool | None,
-            length: float,
-            *,
-            plug_into: str | None = None,
-            **kwargs,
-            ) -> Self:
-        pass
-
-    @abstractmethod
-    def pathS(
-            self,
-            portspec: str,
-            length: float,
-            jog: float,
-            *,
-            plug_into: str | None = None,
-            **kwargs,
-            ) -> Self:
-        pass
-
-    @abstractmethod
-    def plug(
-            self,
-            other: Abstract | str | Pattern | TreeView,
-            map_in: dict[str, str],
-            map_out: dict[str, str | None] | None = None,
-            *,
-            mirrored: bool = False,
-            thru: bool | str = True,
-            set_rotation: bool | None = None,
-            append: bool = False,
-            ok_connections: Iterable[tuple[str, str]] = (),
-            ) -> Self:
-        pass
-
-    def retool(
-            self,
-            tool: Tool,
-            keys: str | Sequence[str | None] | None = None,
-            ) -> Self:
-        """
-        Update the `Tool` which will be used when generating `Pattern`s for the ports
-        given by `keys`.
-
-        Args:
-            tool: The new `Tool` to use for the given ports.
-            keys: Which ports the tool should apply to. `None` indicates the default tool,
-                used when there is no matching entry in `self.tools` for the port in question.
-
-        Returns:
-            self
-        """
-        if keys is None or isinstance(keys, str):
-            self.tools[keys] = tool
-        else:
-            for key in keys:
-                self.tools[key] = tool
-        return self
-
-    @contextmanager
-    def toolctx(
-            self,
-            tool: Tool,
-            keys: str | Sequence[str | None] | None = None,
-            ) -> Iterator[Self]:
-        """
-          Context manager for temporarily `retool`-ing and reverting the `retool`
-        upon exiting the context.
-
-        Args:
-            tool: The new `Tool` to use for the given ports.
-            keys: Which ports the tool should apply to. `None` indicates the default tool,
-                used when there is no matching entry in `self.tools` for the port in question.
-
-        Returns:
-            self
-        """
-        if keys is None or isinstance(keys, str):
-            keys = [keys]
-        saved_tools = {kk: self.tools.get(kk, None) for kk in keys}      # If not in self.tools, save `None`
-        try:
-            yield self.retool(tool=tool, keys=keys)
-        finally:
-            for kk, tt in saved_tools.items():
-                if tt is None:
-                    # delete if present
-                    self.tools.pop(kk, None)
-                else:
-                    self.tools[kk] = tt
-
-    def path_to(
-            self,
-            portspec: str,
-            ccw: SupportsBool | None,
-            position: float | None = None,
-            *,
-            x: float | None = None,
-            y: float | None = None,
-            plug_into: str | None = None,
-            **kwargs,
-            ) -> Self:
-        """
-        Build  a "wire"/"waveguide" extending from the port `portspec`, with the aim
-        of ending exactly at a target position.
-
-        The wire will travel so that the output port will be placed at exactly the target
-        position along the input port's axis. There can be an unspecified (tool-dependent)
-        offset in the perpendicular direction. The output port will be rotated (or not)
-        based on the `ccw` parameter.
-
-        If using `RenderPather`, `RenderPather.render` must be called after all paths have been fully planned.
-
-        Args:
-            portspec: The name of the port into which the wire will be plugged.
-            ccw: If `None`, the output should be along the same axis as the input.
-                Otherwise, cast to bool and turn counterclockwise if True
-                and clockwise otherwise.
-            position: The final port position, along the input's axis only.
-                (There may be a tool-dependent offset along the other axis.)
-                Only one of `position`, `x`, and `y` may be specified.
-            x: The final port position along the x axis.
-                `portspec` must refer to a horizontal port if `x` is passed, otherwise a
-                BuildError will be raised.
-            y: The final port position along the y axis.
-                `portspec` must refer to a vertical port if `y` is passed, otherwise a
-                BuildError will be raised.
-            plug_into: If not None, attempts to plug the wire's output port into the provided
-                port on `self`.
-
-        Returns:
-            self
-
-        Raises:
-            BuildError if `position`, `x`, or `y` is too close to fit the bend (if a bend
-                is present).
-            BuildError if `x` or `y` is specified but does not match the axis of `portspec`.
-            BuildError if more than one of `x`, `y`, and `position` is specified.
-        """
-        if self._dead:
-            logger.error('Skipping path_to() since device is dead')
-            return self
-
-        pos_count = sum(vv is not None for vv in (position, x, y))
-        if pos_count > 1:
-            raise BuildError('Only one of `position`, `x`, and `y` may be specified at once')
-        if pos_count < 1:
-            raise BuildError('One of `position`, `x`, and `y` must be specified')
-
-        port = self.pattern[portspec]
-        if port.rotation is None:
-            raise PortError(f'Port {portspec} has no rotation and cannot be used for path_to()')
-
-        if not numpy.isclose(port.rotation % (pi / 2), 0):
-            raise BuildError('path_to was asked to route from non-manhattan port')
-
-        is_horizontal = numpy.isclose(port.rotation % pi, 0)
-        if is_horizontal:
-            if y is not None:
-                raise BuildError('Asked to path to y-coordinate, but port is horizontal')
-            if position is None:
-                position = x
-        else:
-            if x is not None:
-                raise BuildError('Asked to path to x-coordinate, but port is vertical')
-            if position is None:
-                position = y
-
-        x0, y0 = port.offset
-        if is_horizontal:
-            if numpy.sign(numpy.cos(port.rotation)) == numpy.sign(position - x0):
-                raise BuildError(f'path_to routing to behind source port: x0={x0:g} to {position:g}')
-            length = numpy.abs(position - x0)
-        else:
-            if numpy.sign(numpy.sin(port.rotation)) == numpy.sign(position - y0):
-                raise BuildError(f'path_to routing to behind source port: y0={y0:g} to {position:g}')
-            length = numpy.abs(position - y0)
-
-        return self.path(
-            portspec,
-            ccw,
-            length,
-            plug_into = plug_into,
-            **kwargs,
-            )
-
-    def path_into(
-            self,
-            portspec_src: str,
-            portspec_dst: str,
-            *,
-            out_ptype: str | None = None,
-            plug_destination: bool = True,
-            thru: str | None = None,
-            **kwargs,
-            ) -> Self:
-        """
-        Create a "wire"/"waveguide" traveling between the ports `portspec_src` and
-        `portspec_dst`, and `plug` it into both (or just the source port).
-
-        Only unambiguous scenarios are allowed:
-            - Straight connector between facing ports
-            - Single 90 degree bend
-            - Jog between facing ports
-                (jog is done as late as possible, i.e. only 2 L-shaped segments are used)
-
-        By default, the destination's `pytpe` will be used as the `out_ptype` for the
-        wire, and the `portspec_dst` will be plugged (i.e. removed).
-
-        If using `RenderPather`, `RenderPather.render` must be called after all paths have been fully planned.
-
-        Args:
-            portspec_src: The name of the starting port into which the wire will be plugged.
-            portspec_dst: The name of the destination port.
-            out_ptype: Passed to the pathing tool in order to specify the desired port type
-                to be generated at the destination end. If `None` (default), the destination
-                port's `ptype` will be used.
-            thru: If not `None`, the port by this name will be rename to `portspec_src`.
-                This can be used when routing a signal through a pre-placed 2-port device.
-
-        Returns:
-            self
-
-        Raises:
-            PortError if either port does not have a specified rotation.
-            BuildError if and invalid port config is encountered:
-                - Non-manhattan ports
-                - U-bend
-                - Destination too close to (or behind) source
-        """
-        if self._dead:
-            logger.error('Skipping path_into() since device is dead')
-            return self
-
-        port_src = self.pattern[portspec_src]
-        port_dst = self.pattern[portspec_dst]
-
-        if out_ptype is None:
-            out_ptype = port_dst.ptype
-
-        if port_src.rotation is None:
-            raise PortError(f'Port {portspec_src} has no rotation and cannot be used for path_into()')
-        if port_dst.rotation is None:
-            raise PortError(f'Port {portspec_dst} has no rotation and cannot be used for path_into()')
-
-        if not numpy.isclose(port_src.rotation % (pi / 2), 0):
-            raise BuildError('path_into was asked to route from non-manhattan port')
-        if not numpy.isclose(port_dst.rotation % (pi / 2), 0):
-            raise BuildError('path_into was asked to route to non-manhattan port')
-
-        src_is_horizontal = numpy.isclose(port_src.rotation % pi, 0)
-        dst_is_horizontal = numpy.isclose(port_dst.rotation % pi, 0)
-        xs, ys = port_src.offset
-        xd, yd = port_dst.offset
-
-        angle = (port_dst.rotation - port_src.rotation) % (2 * pi)
-
-        dst_extra_args = {'out_ptype': out_ptype}
-        if plug_destination:
-            dst_extra_args['plug_into'] = portspec_dst
-
-        src_args = {**kwargs}
-        dst_args = {**src_args, **dst_extra_args}
-        if src_is_horizontal and not dst_is_horizontal:
-            # single bend should suffice
-            self.path_to(portspec_src, angle > pi, x=xd, **src_args)
-            self.path_to(portspec_src, None, y=yd, **dst_args)
-        elif dst_is_horizontal and not src_is_horizontal:
-            # single bend should suffice
-            self.path_to(portspec_src, angle > pi, y=yd, **src_args)
-            self.path_to(portspec_src, None, x=xd, **dst_args)
-        elif numpy.isclose(angle, pi):
-            if src_is_horizontal and ys == yd:
-                # straight connector
-                self.path_to(portspec_src, None, x=xd, **dst_args)
-            elif not src_is_horizontal and xs == xd:
-                # straight connector
-                self.path_to(portspec_src, None, y=yd, **dst_args)
-            else:
-                # S-bend, delegate to implementations
-                (travel, jog), _ = port_src.measure_travel(port_dst)
-                self.pathS(portspec_src, -travel, -jog, **dst_args)
-        elif numpy.isclose(angle, 0):
-            raise BuildError('Don\'t know how to route a U-bend yet (TODO)!')
-        else:
-            raise BuildError(f'Don\'t know how to route ports with relative angle {angle}')
-
-        if thru is not None:
-            self.rename_ports({thru: portspec_src})
-
-        return self
-
-    def mpath(
-            self,
-            portspec: str | Sequence[str],
-            ccw: SupportsBool | None,
-            *,
-            spacing: float | ArrayLike | None = None,
-            set_rotation: float | None = None,
-            **kwargs,
-            ) -> Self:
-        """
-        `mpath` is a superset of `path` and `path_to` which can act on bundles or buses
-        of "wires or "waveguides".
-
-        The wires will travel so that the output ports will be placed at well-defined
-        locations along the axis of their input ports, but may have arbitrary (tool-
-        dependent) offsets in the perpendicular direction.
-
-        If `ccw` is not `None`, the wire bundle will turn 90 degres in either the
-        clockwise (`ccw=False`) or counter-clockwise (`ccw=True`) direction. Within the
-        bundle, the center-to-center wire spacings after the turn are set by `spacing`,
-        which is required when `ccw` is not `None`. The final position of bundle as a
-        whole can be set in a number of ways:
-
-             =A>---------------------------V     turn direction: `ccw=False`
-                       =B>-------------V   |
-         =C>-----------------------V   |
-           =D=>----------------V   |
-                               |
-
-                               x---x---x---x  `spacing` (can be scalar or array)
-
-                        <-------------->      `emin=`
-                        <------>              `bound_type='min_past_furthest', bound=`
-          <-------------------------------->  `emax=`
-                               x              `pmin=`
-                                           x  `pmax=`
-
-            - `emin=`, equivalent to `bound_type='min_extension', bound=`
-                The total extension value for the furthest-out port (B in the diagram).
-            - `emax=`, equivalent to `bound_type='max_extension', bound=`:
-                The total extension value for the closest-in port (C in the diagram).
-            - `pmin=`, equivalent to `xmin=`, `ymin=`, or `bound_type='min_position', bound=`:
-                The coordinate of the innermost bend (D's bend).
-                The x/y versions throw an error if they do not match the port axis (for debug)
-            - `pmax=`, `xmax=`, `ymax=`, or `bound_type='max_position', bound=`:
-                The coordinate of the outermost bend (A's bend).
-                The x/y versions throw an error if they do not match the port axis (for debug)
-            - `bound_type='min_past_furthest', bound=`:
-                The distance between furthest out-port (B) and the innermost bend (D's bend).
-
-        If `ccw=None`, final output positions (along the input axis) of all wires will be
-        identical (i.e. wires will all be cut off evenly). In this case, `spacing=None` is
-        required. In this case, `emin=` and `emax=` are equivalent to each other, and
-        `pmin=`, `pmax=`, `xmin=`, etc. are also equivalent to each other.
-
-        If using `RenderPather`, `RenderPather.render` must be called after all paths have been fully planned.
-
-        Args:
-            portspec: The names of the ports which are to be routed.
-            ccw: If `None`, the outputs should be along the same axis as the inputs.
-                Otherwise, cast to bool and turn 90 degrees counterclockwise if `True`
-                and clockwise otherwise.
-            spacing: Center-to-center distance between output ports along the input port's axis.
-                Must be provided if (and only if) `ccw` is not `None`.
-            set_rotation: If the provided ports have `rotation=None`, this can be used
-                to set a rotation for them.
-
-        Returns:
-            self
-
-        Raises:
-            BuildError if the implied length for any wire is too close to fit the bend
-                (if a bend is requested).
-            BuildError if `xmin`/`xmax` or `ymin`/`ymax` is specified but does not
-                match the axis of `portspec`.
-            BuildError if an incorrect bound type or spacing is specified.
-        """
-        if self._dead:
-            logger.error('Skipping mpath() since device is dead')
-            return self
-
-        bound_types = set()
-        if 'bound_type' in kwargs:
-            bound_types.add(kwargs.pop('bound_type'))
-            bound = kwargs.pop('bound')
-        for bt in ('emin', 'emax', 'pmin', 'pmax', 'xmin', 'xmax', 'ymin', 'ymax', 'min_past_furthest'):
-            if bt in kwargs:
-                bound_types.add(bt)
-                bound = kwargs.pop(bt)
-
-        if not bound_types:
-            raise BuildError('No bound type specified for mpath')
-        if len(bound_types) > 1:
-            raise BuildError(f'Too many bound types specified for mpath: {bound_types}')
-        bound_type = tuple(bound_types)[0]
-
-        if isinstance(portspec, str):
-            portspec = [portspec]
-        ports = self.pattern[tuple(portspec)]
-
-        extensions = ell(ports, ccw, spacing=spacing, bound=bound, bound_type=bound_type, set_rotation=set_rotation)
-
-        #if container:
-        #    assert not getattr(self, 'render'), 'Containers not implemented for RenderPather'
-        #    bld = self.interface(source=ports, library=self.library, tools=self.tools)
-        #    for port_name, length in extensions.items():
-        #        bld.path(port_name, ccw, length, **kwargs)
-        #    self.library[container] = bld.pattern
-        #    self.plug(Abstract(container, bld.pattern.ports), {sp: 'in_' + sp for sp in ports})       # TODO safe to use 'in_'?
-        #else:
-        for port_name, length in extensions.items():
-            self.path(port_name, ccw, length, **kwargs)
-        return self
-
-    # TODO def bus_join()?
-
-    def flatten(self) -> Self:
-        """
-        Flatten the contained pattern, using the contained library to resolve references.
-
-        Returns:
-            self
-        """
-        self.pattern.flatten(self.library)
-        return self
-
-    def at(self, portspec: str | Iterable[str]) -> 'PortPather':
-        return PortPather(portspec, self)
-
-
-class PortPather:
-    """
-    Port state manager
-
-      This class provides a convenient way to perform multiple pathing operations on a
-    set of ports without needing to repeatedly pass their names.
-    """
-    ports: list[str]
-    pather: PatherMixin
-
-    def __init__(self, ports: str | Iterable[str], pather: PatherMixin) -> None:
-        self.ports = [ports] if isinstance(ports, str) else list(ports)
-        self.pather = pather
-
-    #
-    # Delegate to pather
-    #
-    def retool(self, tool: Tool) -> Self:
-        self.pather.retool(tool, keys=self.ports)
-        return self
-
-    @contextmanager
-    def toolctx(self, tool: Tool) -> Iterator[Self]:
-        with self.pather.toolctx(tool, keys=self.ports):
-            yield self
-
-    def path(self, *args, **kwargs) -> Self:
-        if len(self.ports) > 1:
-            logger.warning('Use path_each() when pathing multiple ports independently')
-        for port in self.ports:
-            self.pather.path(port, *args, **kwargs)
-        return self
-
-    def path_each(self, *args, **kwargs) -> Self:
-        for port in self.ports:
-            self.pather.path(port, *args, **kwargs)
-        return self
-
-    def pathS(self, *args, **kwargs) -> Self:
-        if len(self.ports) > 1:
-            logger.warning('Use pathS_each() when pathing multiple ports independently')
-        for port in self.ports:
-            self.pather.pathS(port, *args, **kwargs)
-        return self
-
-    def pathS_each(self, *args, **kwargs) -> Self:
-        for port in self.ports:
-            self.pather.pathS(port, *args, **kwargs)
-        return self
-
-    def path_to(self, *args, **kwargs) -> Self:
-        if len(self.ports) > 1:
-            logger.warning('Use path_each_to() when pathing multiple ports independently')
-        for port in self.ports:
-            self.pather.path_to(port, *args, **kwargs)
-        return self
-
-    def path_each_to(self, *args, **kwargs) -> Self:
-        for port in self.ports:
-            self.pather.path_to(port, *args, **kwargs)
-        return self
-
-    def mpath(self, *args, **kwargs) -> Self:
-        self.pather.mpath(self.ports, *args, **kwargs)
-        return self
-
-    def path_into(self, *args, **kwargs) -> Self:
-        """ Path_into, using the current port as the source """
-        if len(self.ports) > 1:
-            raise BuildError(f'Unable use implicit path_into() with {len(self.ports)} (>1) ports.')
-        self.pather.path_into(self.ports[0], *args, **kwargs)
-        return self
-
-    def path_from(self, *args, **kwargs) -> Self:
-        """ Path_into, using the current port as the destination """
-        if len(self.ports) > 1:
-            raise BuildError(f'Unable use implicit path_from() with {len(self.ports)} (>1) ports.')
-        thru = kwargs.pop('thru', None)
-        self.pather.path_into(args[0], self.ports[0], *args[1:], **kwargs)
-        if thru is not None:
-            self.rename_from(thru)
-        return self
-
-    def plug(
-            self,
-            other: Abstract | str,
-            other_port: str,
-            *args,
-            **kwargs,
-            ) -> Self:
-        if len(self.ports) > 1:
-            raise BuildError(f'Unable use implicit plug() with {len(self.ports)} ports.'
-                             'Use the pather or pattern directly to plug multiple ports.')
-        self.pather.plug(other, {self.ports[0]: other_port}, *args, **kwargs)
-        return self
-
-    def plugged(self, other_port: str) -> Self:
-        if len(self.ports) > 1:
-            raise BuildError(f'Unable use implicit plugged() with {len(self.ports)} (>1) ports.')
-        self.pather.plugged({self.ports[0]: other_port})
-        return self
-
-    #
-    # Delegate to port
-    #
-    def set_ptype(self, ptype: str) -> Self:
-        for port in self.ports:
-            self.pather[port].set_ptype(ptype)
-        return self
-
-    def translate(self, *args, **kwargs) -> Self:
-        for port in self.ports:
-            self.pather[port].translate(*args, **kwargs)
-        return self
-
-    def mirror(self, *args, **kwargs) -> Self:
-        for port in self.ports:
-            self.pather[port].mirror(*args, **kwargs)
-        return self
-
-    def rotate(self, rotation: float) -> Self:
-        for port in self.ports:
-            self.pather[port].rotate(rotation)
-        return self
-
-    def set_rotation(self, rotation: float | None) -> Self:
-        for port in self.ports:
-            self.pather[port].set_rotation(rotation)
-        return self
-
-    def rename_to(self, new_name: str) -> Self:
-        if len(self.ports) > 1:
-            BuildError('Use rename_ports() for >1 port')
-        self.pather.rename_ports({self.ports[0]: new_name})
-        self.ports[0] = new_name
-        return self
-
-    def rename_from(self, old_name: str) -> Self:
-        if len(self.ports) > 1:
-            BuildError('Use rename_ports() for >1 port')
-        self.pather.rename_ports({old_name: self.ports[0]})
-        return self
-
-    def rename_ports(self, name_map: dict[str, str | None]) -> Self:
-        self.pather.rename_ports(name_map)
-        self.ports = [mm for mm in [name_map.get(pp, pp) for pp in self.ports] if mm is not None]
-        return self
-
-    def add_ports(self, ports: Iterable[str]) -> Self:
-        ports = list(ports)
-        conflicts = set(ports) & set(self.ports)
-        if conflicts:
-            raise BuildError(f'ports {conflicts} already selected')
-        self.ports += ports
-        return self
-
-    def add_port(self, port: str, index: int | None = None) -> Self:
-        if port in self.ports:
-            raise BuildError(f'{port=} already selected')
-        if index is not None:
-            self.ports.insert(index, port)
-        else:
-            self.ports.append(port)
-        return self
-
-    def drop_port(self, port: str) -> Self:
-        if port not in self.ports:
-            raise BuildError(f'{port=} already not selected')
-        self.ports = [pp for pp in self.ports if pp != port]
-        return self
-
-    def into_copy(self, new_name: str, src: str | None = None) -> Self:
-        """ Copy a port and replace it with the copy """
-        if not self.ports:
-            raise BuildError('Have no ports to copy')
-        if len(self.ports) == 1:
-            src = self.ports[0]
-        elif src is None:
-            raise BuildError('Must specify src when >1 port is available')
-        if src not in self.ports:
-            raise BuildError(f'{src=} not available')
-        self.pather.ports[new_name] = self.pather[src].copy()
-        self.ports = [(new_name if pp == src else pp) for pp in self.ports]
-        return self
-
-    def save_copy(self, new_name: str, src: str | None = None) -> Self:
-        """ Copy a port and but keep using the original """
-        if not self.ports:
-            raise BuildError('Have no ports to copy')
-        if len(self.ports) == 1:
-            src = self.ports[0]
-        elif src is None:
-            raise BuildError('Must specify src when >1 port is available')
-        if src not in self.ports:
-            raise BuildError(f'{src=} not available')
-        self.pather.ports[new_name] = self.pather[src].copy()
-        return self
-
-    @overload
-    def delete(self, name: None) -> None: ...
-
-    @overload
-    def delete(self, name: str) -> Self: ...
-
-    def delete(self, name: str | None = None) -> Self | None:
-        if name is None:
-            for pp in self.ports:
-                del self.pather.ports[pp]
-            return None
-        del self.pather.ports[name]
-        self.ports = [pp for pp in self.ports if pp != name]
-        return self
-

masque/builder/planner/__init__.py

@@ -0,0 +1,17 @@
+"""
+Simplified primitive-offer route planner used by `Pather`.
+
+This package is the Pather-facing route-selection implementation.  It keeps
+the public Tool contract narrow: offers are evaluated during planning, and
+offer commits are deferred until after a complete route is selected.
+"""
+from .interface import (
+    PreparedRouteAction as PreparedRouteAction,
+    PreparedRouteResult as PreparedRouteResult,
+    RoutePlanningError as RoutePlanningError,
+    RoutePortContext as RoutePortContext,
+    route_failure_policy as route_failure_policy,
+    )
+from .planner import RouteTieBreakStrategy as RouteTieBreakStrategy
+from .planner import TraceIntoBendPolicy as TraceIntoBendPolicy
+from .planner import RoutingPlanner as RoutingPlanner

masque/builder/planner/bounds.py

@@ -0,0 +1,284 @@
+"""
+Argument validation and bound resolution for Pather routing calls.
+
+This module keeps user-facing mode validation outside the solver. It converts
+single-port positional bounds into local travel lengths and derives multi-port
+S/U bundle specs before primitive offers are considered.
+
+The solver expects one coherent route intent at a time. This module enforces
+that public routing modes are not mixed: explicit length, per-port `each`,
+positional bounds, and bundle bounds are mutually constrained before any Tool
+offers are queried. Multi-port S/U bundles are also normalized here into exact
+per-port public lengths and offsets.
+"""
+from __future__ import annotations
+
+# ruff: noqa: TC001,TC002,TC003
+from typing import Any
+from collections.abc import Mapping, Sequence
+from pprint import pformat
+
+import numpy
+from numpy import pi
+from numpy.typing import ArrayLike, NDArray
+
+from ...error import BuildError, PortError
+from ...ports import Port
+from ...utils import rotation_matrix_2d
+from .._tolerances import manhattan_axis
+from .interface import RoutePortContext
+
+
+POSITION_KEYS: tuple[str, ...] = ('p', 'x', 'y', 'pos', 'position')
+BUNDLE_BOUND_KEYS: tuple[str, ...] = (
+    'emin', 'emax', 'pmin', 'pmax', 'xmin', 'xmax', 'ymin', 'ymax', 'min_past_furthest',
+    )
+
+
+def finite_scalar(value: Any, name: str, *, nonnegative: bool = False) -> float:
+    """Return a finite scalar, preserving duck-typed numeric inputs."""
+    try:
+        array = numpy.asarray(value, dtype=float)
+    except (TypeError, ValueError) as err:
+        raise BuildError(f'{name} must be a finite numeric scalar') from err
+    if array.size != 1:
+        raise BuildError(f'{name} must be a scalar; got {array.size} values')
+    result = float(array.reshape(-1)[0])
+    if not numpy.isfinite(result):
+        raise BuildError(f'{name} must be finite')
+    if nonnegative and result < 0:
+        raise BuildError(f'{name} must be nonnegative')
+    return result
+
+
+def resolved_position_bound(
+        port: Port,
+        bounds: Mapping[str, Any],
+        *,
+        allow_length: bool,
+        ) -> tuple[str, Any, float] | None:
+    """Resolve a single positional bound for a single port into a travel length."""
+    present = [(key, bounds[key]) for key in POSITION_KEYS if bounds.get(key) is not None]
+    if not present:
+        return None
+    if len(present) > 1:
+        keys = ', '.join(key for key, _value in present)
+        raise BuildError(f'Provide exactly one positional bound; got {keys}')
+    if not allow_length and bounds.get('length') is not None:
+        raise BuildError('length cannot be combined with a positional bound')
+
+    key, raw_value = present[0]
+    value = finite_scalar(raw_value, f'{key} positional bound')
+    if port.rotation is None:
+        raise BuildError('Ports must have rotation')
+    axis = manhattan_axis(port.rotation)
+    if axis is None:
+        raise BuildError(
+            'Positional bounds require a nearly Manhattan port direction; '
+            f'got rotation {port.rotation:g}'
+            )
+    if axis == 0:
+        if key == 'y':
+            raise BuildError('Port is horizontal')
+        target = Port((value, port.offset[1]), rotation=None)
+    else:
+        if key == 'x':
+            raise BuildError('Port is vertical')
+        target = Port((port.offset[0], value), rotation=None)
+    (travel, _jog), _ = port.measure_travel(target)
+    return key, value, -float(travel)
+
+
+def present_keys(bounds: Mapping[str, Any], keys: Sequence[str]) -> list[str]:
+    """Return keys whose bound value is explicitly present and non-None."""
+    return [key for key in keys if bounds.get(key) is not None]
+
+
+def present_bundle_bounds(bounds: Mapping[str, Any]) -> list[str]:
+    """Return active multi-port trace bound keys."""
+    return present_keys(bounds, BUNDLE_BOUND_KEYS)
+
+
+def validate_trace_args(
+        portspec: Sequence[str],
+        *,
+        length: float | None,
+        spacing: float | ArrayLike | None,
+        bounds: Mapping[str, Any],
+        ) -> None:
+    """
+    Validate mutually-exclusive `trace()` routing modes.
+
+    A trace request is either an explicit single-port length, an `each` length
+    for all ports, a single-port omitted-length solve, or a bundle solve with
+    exactly one bundle bound.
+    """
+    bundle_bounds = present_bundle_bounds(bounds)
+    if len(bundle_bounds) > 1:
+        args = ', '.join(bundle_bounds)
+        raise BuildError(f'Provide exactly one bundle bound for trace(); got {args}')
+
+    invalid_with_length = present_keys(bounds, ('each', 'set_rotation')) + bundle_bounds
+    invalid_with_each = present_keys(bounds, ('set_rotation',)) + bundle_bounds
+
+    if length is not None:
+        if len(portspec) > 1:
+            raise BuildError('length only allowed with a single port')
+        if spacing is not None:
+            invalid_with_length.append('spacing')
+        if invalid_with_length:
+            args = ', '.join(invalid_with_length)
+            raise BuildError(f'length cannot be combined with other routing bounds: {args}')
+        return
+
+    if bounds.get('each') is not None:
+        if spacing is not None:
+            invalid_with_each.append('spacing')
+        if invalid_with_each:
+            args = ', '.join(invalid_with_each)
+            raise BuildError(f'each cannot be combined with other routing bounds: {args}')
+        return
+
+    if not bundle_bounds and len(portspec) == 1:
+        if spacing is not None:
+            raise BuildError('spacing cannot be combined with omitted-length single-port trace()')
+        invalid = present_keys(bounds, ('set_rotation',))
+        if invalid:
+            args = ', '.join(invalid)
+            raise BuildError(f'Unsupported routing bounds for omitted-length trace(): {args}')
+        return
+
+    if not bundle_bounds:
+        raise BuildError('No bound type specified for trace()')
+
+
+def validate_trace_to_positional_args(
+        *,
+        spacing: float | ArrayLike | None,
+        bounds: Mapping[str, Any],
+        ) -> None:
+    """Reject bound combinations that cannot be mixed with a single positional `trace_to()` target."""
+    invalid = present_keys(bounds, ('each', 'set_rotation')) + present_bundle_bounds(bounds)
+    if spacing is not None:
+        invalid.append('spacing')
+    if invalid:
+        args = ', '.join(invalid)
+        raise BuildError(f'Positional bounds cannot be combined with other routing bounds: {args}')
+
+
+def validate_jog_args(
+        portspec: Sequence[str],
+        *,
+        length: float | None,
+        spacing: float | ArrayLike | None,
+        bounds: Mapping[str, Any],
+        ) -> None:
+    """
+    Validate `jog()` mode constraints before S-route planning.
+
+    Single-port jogs may derive length from a positional bound. Multi-port jogs
+    require spacing and cannot combine omitted length with positional bounds.
+    """
+    invalid = present_keys(bounds, ('each', 'set_rotation')) + present_bundle_bounds(bounds)
+    if len(portspec) == 1 and spacing is not None:
+        invalid.append('spacing')
+    if len(portspec) > 1 and length is None:
+        invalid += present_keys(bounds, POSITION_KEYS)
+    if length is not None:
+        invalid = present_keys(bounds, POSITION_KEYS) + invalid
+        if invalid:
+            args = ', '.join(invalid)
+            raise BuildError(f'length cannot be combined with other routing bounds in jog(): {args}')
+        return
+
+    if invalid:
+        args = ', '.join(invalid)
+        raise BuildError(f'Unsupported routing bounds for jog(): {args}')
+
+
+def validate_uturn_args(
+        portspec: Sequence[str],
+        *,
+        spacing: float | ArrayLike | None,
+        bounds: Mapping[str, Any],
+        ) -> None:
+    """Validate `uturn()` arguments, which do not support positional or bundle-bound keywords."""
+    invalid = present_keys(bounds, POSITION_KEYS + ('each', 'set_rotation')) + present_bundle_bounds(bounds)
+    if len(portspec) == 1 and spacing is not None:
+        invalid.append('spacing')
+    if invalid:
+        args = ', '.join(invalid)
+        raise BuildError(f'Unsupported routing bounds for uturn(): {args}')
+
+
+def su_bundle_specs(
+        contexts: Sequence[RoutePortContext],
+        offset: float,
+        length: float,
+        spacing: float | ArrayLike | None,
+        *,
+        route_name: str,
+        ) -> tuple[tuple[str, float, float], ...]:
+    """
+    Normalize a multi-port S/U bundle into per-port `(name, length, offset)` specs.
+
+    Ports are ordered from the inside of the first bend outward. The first spec
+    receives the requested base route; later specs add cumulative spacing to
+    both route length and lateral offset so the bundle keeps the requested
+    separation.
+    """
+    if spacing is None:
+        raise BuildError(f'Must provide spacing for multi-port {route_name}()')
+    finite_scalar(offset, 'offset')
+    finite_scalar(length, 'length', nonnegative=True)
+
+    ports = {context.portspec: context.port for context in contexts}
+    has_rotation = numpy.array([port.rotation is not None for port in ports.values()], dtype=bool)
+    if not has_rotation.all():
+        raise PortError(f'Ports must have rotation for multi-port {route_name}()')
+
+    rotations = numpy.array([port.rotation for port in ports.values()], dtype=float)
+    if not numpy.allclose(rotations[0], rotations):
+        port_rotations = {name: numpy.rad2deg(port.rotation) for name, port in ports.items()}
+        raise BuildError(
+            f'Asked to find multi-port {route_name}() bundle for ports that face in different directions:\n'
+            + pformat(port_rotations)
+            )
+
+    direction = rotations[0] + pi
+    rot_matrix = rotation_matrix_2d(-direction)
+    orig_offsets = numpy.array([port.offset for port in ports.values()])
+    rot_offsets = (rot_matrix @ orig_offsets.T).T
+
+    first_ccw = bool(offset > 0)
+    y_order = ((-1 if first_ccw else 1) * rot_offsets[:, 1]).argsort(kind='stable')
+
+    spacing_arr = numpy.asarray(spacing, dtype=float).reshape(-1)
+    if numpy.any(spacing_arr < 0):
+        raise BuildError('spacing must be nonnegative')
+    steps: NDArray[numpy.float64] = numpy.zeros(len(ports), dtype=float)
+    if spacing_arr.size == 1:
+        steps[1:] = spacing_arr[0]
+    elif spacing_arr.size == len(ports) - 1:
+        steps[1:] = spacing_arr
+    else:
+        raise BuildError(
+            f'spacing must be scalar or have length {len(ports) - 1} for {len(ports)} ports; '
+            f'got length {spacing_arr.size}'
+            )
+    if not numpy.all(numpy.isfinite(steps)):
+        raise BuildError('spacing must contain only finite values')
+
+    names = tuple(ports.keys())
+    ordered_spacings = numpy.cumsum(steps)
+    anchor_y = float(rot_offsets[y_order[0], 1])
+    specs: list[tuple[str, float, float]] = []
+    for order_index, port_index in enumerate(y_order):
+        spacing_offset = float(ordered_spacings[order_index])
+        start_y = float(rot_offsets[port_index, 1])
+        specs.append((
+            names[port_index],
+            float(length) + spacing_offset,
+            float(offset) - start_y + anchor_y + spacing_offset,
+            ))
+    return tuple(specs)

masque/builder/planner/interface.py

@@ -0,0 +1,96 @@
+"""
+Planner/Pather exchange types.
+
+`Pather` snapshots live routing state into these records before calling the
+planner. The planner returns prepared actions that `Pather` can apply without
+needing to know solver internals.
+"""
+
+from __future__ import annotations
+
+# ruff: noqa: TC001
+
+from dataclasses import dataclass
+
+from ...error import BuildError
+from ...ports import Port
+from ..tools import RenderStep, Tool
+from ..error import RouteError, RouteFailurePolicy, ToolContractError
+
+
+class RoutePlanningError(BuildError):
+    """Route-planning error with fallback policy metadata."""
+
+    policy: RouteFailurePolicy
+
+    def __init__(
+            self,
+            *args: object,
+            policy: RouteFailurePolicy = RouteFailurePolicy.RECOVERABLE,
+            ) -> None:
+        super().__init__(*args)
+        self.policy = policy
+
+
+def route_failure_policy(err: Exception) -> RouteFailurePolicy:
+    """Return typed route recovery policy, defaulting generic errors to recoverable."""
+    if isinstance(err, ToolContractError):
+        return RouteFailurePolicy.FATAL
+    if isinstance(err, RoutePlanningError):
+        return err.policy
+    if isinstance(err, RouteError):
+        return err.policy
+    return RouteFailurePolicy.RECOVERABLE
+
+
+@dataclass(frozen=True, slots=True)
+class RoutePortContext:
+    """
+    Immutable planning view of one live Pather port.
+
+    `port` is a copy of the live port so failed route selection leaves Pather
+    state unchanged. `tool` is the already-resolved routing Tool for this
+    portspec.
+    """
+    portspec: str
+    """Live Pather port name being planned."""
+    port: Port
+    """Copied live port used as immutable route input."""
+    tool: Tool
+    """Resolved Tool for this port."""
+
+
+@dataclass(frozen=True, slots=True)
+class PreparedRouteAction:
+    """
+    Prepared mutation for one routed Pather port.
+
+    Pure selection has already completed, and the planner has materialized the
+    selected primitive offers into `render_steps` and computed the final live
+    port. `plug_into`, when set, names the destination port to consume after the
+    route endpoint is applied.
+    """
+    portspec: str
+    """Live Pather port name to update."""
+    render_steps: tuple[RenderStep, ...]
+    """Committed route steps to append to Pather's pending render queue."""
+    final_port: Port
+    """Final live port value after all route steps."""
+    plug_into: str | None = None
+    """Optional destination port to consume after the final port is applied."""
+
+
+@dataclass(frozen=True, slots=True)
+class PreparedRouteResult:
+    """
+    Complete prepared result for one Pather routing operation.
+
+    `actions` contain materialized, committed render data and are applied first.
+    `renames` are deferred until after all route actions so trace-into/thru
+    behavior can be represented without exposing the solver's selected
+    primitive sequence to Pather.
+    """
+    actions: tuple[PreparedRouteAction, ...]
+    """Prepared per-port route mutations."""
+    renames: tuple[tuple[str, str], ...] = ()
+    """Deferred `(old_name, new_name)` port renames applied after actions."""

masque/builder/renderpather.py

@@ -1,646 +0,0 @@
-"""
-Pather with batched (multi-step) rendering
-"""
-from typing import Self
-from collections.abc import Sequence, Mapping, MutableMapping, Iterable
-import copy
-import logging
-from collections import defaultdict
-from functools import wraps
-from pprint import pformat
-
-from numpy import pi
-from numpy.typing import ArrayLike
-
-from ..pattern import Pattern
-from ..library import ILibrary, TreeView
-from ..error import BuildError
-from ..ports import PortList, Port
-from ..abstract import Abstract
-from ..utils import SupportsBool
-from .tools import Tool, RenderStep
-from .pather_mixin import PatherMixin
-
-
-logger = logging.getLogger(__name__)
-
-
-class RenderPather(PatherMixin):
-    """
-      `RenderPather` is an alternative to `Pather` which uses the `path`/`path_to`/`mpath`
-    functions to plan out wire paths without incrementally generating the layout. Instead,
-    it waits until `render` is called, at which point it draws all the planned segments
-    simultaneously. This allows it to e.g. draw each wire using a single `Path` or
-    `Polygon` shape instead of multiple rectangles.
-
-      `RenderPather` calls out to `Tool.planL` and `Tool.render` to provide tool-specific
-    dimensions and build the final geometry for each wire. `Tool.planL` provides the
-    output port data (relative to the input) for each segment. The tool, input and output
-    ports are placed into a `RenderStep`, and a sequence of `RenderStep`s is stored for
-    each port. When `render` is called, it bundles `RenderStep`s into batches which use
-    the same `Tool`, and passes each batch to the relevant tool's `Tool.render` to build
-    the geometry.
-
-    See `Pather` for routing examples. After routing is complete, `render` must be called
-    to generate the final geometry.
-    """
-    __slots__ = ('pattern', 'library', 'paths', 'tools', '_dead', )
-
-    pattern: Pattern
-    """ Layout of this device """
-
-    library: ILibrary
-    """ Library from which patterns should be referenced """
-
-    _dead: bool
-    """ If True, plug()/place() are skipped (for debugging) """
-
-    paths: defaultdict[str, list[RenderStep]]
-    """ Per-port list of operations, to be used by `render` """
-
-    tools: dict[str | None, Tool]
-    """
-    Tool objects are used to dynamically generate new single-use Devices
-    (e.g wires or waveguides) to be plugged into this device.
-    """
-
-    @property
-    def ports(self) -> dict[str, Port]:
-        return self.pattern.ports
-
-    @ports.setter
-    def ports(self, value: dict[str, Port]) -> None:
-        self.pattern.ports = value
-
-    def __init__(
-            self,
-            library: ILibrary,
-            *,
-            pattern: Pattern | None = None,
-            ports: str | Mapping[str, Port] | None = None,
-            tools: Tool | MutableMapping[str | None, Tool] | None = None,
-            name: str | None = None,
-            ) -> None:
-        """
-        Args:
-            library: The library from which referenced patterns will be taken,
-                and where new patterns (e.g. generated by the `tools`) will be placed.
-            pattern: The pattern which will be modified by subsequent operations.
-                If `None` (default), a new pattern is created.
-            ports: Allows specifying the initial set of ports, if `pattern` does
-                not already have any ports (or is not provided). May be a string,
-                in which case it is interpreted as a name in `library`.
-                Default `None` (no ports).
-            tools: A mapping of {port: tool} which specifies what `Tool` should be used
-                to generate waveguide or wire segments when `path`/`path_to`/`mpath`
-                are called. Relies on `Tool.planL` and `Tool.render` implementations.
-            name: If specified, `library[name]` is set to `self.pattern`.
-        """
-        self._dead = False
-        self.paths = defaultdict(list)
-        self.library = library
-        if pattern is not None:
-            self.pattern = pattern
-        else:
-            self.pattern = Pattern()
-
-        if ports is not None:
-            if self.pattern.ports:
-                raise BuildError('Ports supplied for pattern with pre-existing ports!')
-            if isinstance(ports, str):
-                ports = library.abstract(ports).ports
-
-            self.pattern.ports.update(copy.deepcopy(dict(ports)))
-
-        if name is not None:
-            library[name] = self.pattern
-
-        if tools is None:
-            self.tools = {}
-        elif isinstance(tools, Tool):
-            self.tools = {None: tools}
-        else:
-            self.tools = dict(tools)
-
-    @classmethod
-    def interface(
-            cls: type['RenderPather'],
-            source: PortList | Mapping[str, Port] | str,
-            *,
-            library: ILibrary | None = None,
-            tools: Tool | MutableMapping[str | None, Tool] | None = None,
-            in_prefix: str = 'in_',
-            out_prefix: str = '',
-            port_map: dict[str, str] | Sequence[str] | None = None,
-            name: str | None = None,
-            ) -> 'RenderPather':
-        """
-        Wrapper for `Pattern.interface()`, which returns a RenderPather instead.
-
-        Args:
-            source: A collection of ports (e.g. Pattern, Builder, or dict)
-                from which to create the interface. May be a pattern name if
-                `library` is provided.
-            library: Library from which existing patterns should be referenced,
-                and to which the new one should be added (if named). If not provided,
-                `source.library` must exist and will be used.
-            tools: `Tool`s which will be used by the pather for generating new wires
-                or waveguides (via `path`/`path_to`/`mpath`).
-            in_prefix: Prepended to port names for newly-created ports with
-                reversed directions compared to the current device.
-            out_prefix: Prepended to port names for ports which are directly
-                copied from the current device.
-            port_map: Specification for ports to copy into the new device:
-                - If `None`, all ports are copied.
-                - If a sequence, only the listed ports are copied
-                - If a mapping, the listed ports (keys) are copied and
-                    renamed (to the values).
-
-        Returns:
-            The new `RenderPather`, with an empty pattern and 2x as many ports as
-              listed in port_map.
-
-        Raises:
-            `PortError` if `port_map` contains port names not present in the
-                current device.
-            `PortError` if applying the prefixes results in duplicate port
-                names.
-        """
-        if library is None:
-            if hasattr(source, 'library') and isinstance(source.library, ILibrary):
-                library = source.library
-            else:
-                raise BuildError('No library provided (and not present in `source.library`')
-
-        if tools is None and hasattr(source, 'tools') and isinstance(source.tools, dict):
-            tools = source.tools
-
-        if isinstance(source, str):
-            source = library.abstract(source).ports
-
-        pat = Pattern.interface(source, in_prefix=in_prefix, out_prefix=out_prefix, port_map=port_map)
-        new = RenderPather(library=library, pattern=pat, name=name, tools=tools)
-        return new
-
-    def __repr__(self) -> str:
-        s = f'<RenderPather {self.pattern} L({len(self.library)}) {pformat(self.tools)}>'
-        return s
-
-    def plug(
-            self,
-            other: Abstract | str | Pattern | TreeView,
-            map_in: dict[str, str],
-            map_out: dict[str, str | None] | None = None,
-            *,
-            mirrored: bool = False,
-            thru: bool | str = True,
-            set_rotation: bool | None = None,
-            append: bool = False,
-            ok_connections: Iterable[tuple[str, str]] = (),
-            ) -> Self:
-        """
-          Wrapper for `Pattern.plug` which adds a `RenderStep` with opcode 'P'
-        for any affected ports. This separates any future `RenderStep`s on the
-        same port into a new batch, since the plugged device interferes with drawing.
-
-        Args:
-            other: An `Abstract`, string, or `Pattern` describing the device to be instatiated.
-            map_in: dict of `{'self_port': 'other_port'}` mappings, specifying
-                port connections between the two devices.
-            map_out: dict of `{'old_name': 'new_name'}` mappings, specifying
-                new names for ports in `other`.
-            mirrored: Enables mirroring `other` across the x axis prior to
-                connecting any ports.
-            thru: If map_in specifies only a single port, `thru` provides a mechainsm
-                to avoid repeating the port name. Eg, for `map_in={'myport': 'A'}`,
-                - If True (default), and `other` has only two ports total, and map_out
-                doesn't specify a name for the other port, its name is set to the key
-                in `map_in`, i.e. 'myport'.
-                - If a string, `map_out[thru]` is set to the key in `map_in` (i.e. 'myport').
-                An error is raised if that entry already exists.
-
-                This makes it easy to extend a pattern with simple 2-port devices
-                (e.g. wires) without providing `map_out` each time `plug` is
-                called. See "Examples" above for more info. Default `True`.
-            set_rotation: If the necessary rotation cannot be determined from
-                the ports being connected (i.e. all pairs have at least one
-                port with `rotation=None`), `set_rotation` must be provided
-                to indicate how much `other` should be rotated. Otherwise,
-                `set_rotation` must remain `None`.
-            append: If `True`, `other` is appended instead of being referenced.
-                Note that this does not flatten  `other`, so its refs will still
-                be refs (now inside `self`).
-            ok_connections: Set of "allowed" ptype combinations. Identical
-                ptypes are always allowed to connect, as is `'unk'` with
-                any other ptypte. Non-allowed ptype connections will emit a
-                warning. Order is ignored, i.e. `(a, b)` is equivalent to
-                `(b, a)`.
-
-
-        Returns:
-            self
-
-        Raises:
-            `PortError` if any ports specified in `map_in` or `map_out` do not
-                exist in `self.ports` or `other_names`.
-            `PortError` if there are any duplicate names after `map_in` and `map_out`
-                are applied.
-            `PortError` if the specified port mapping is not achieveable (the ports
-                do not line up)
-        """
-        if self._dead:
-            logger.error('Skipping plug() since device is dead')
-            return self
-
-        other_tgt: Pattern | Abstract
-        if isinstance(other, str):
-            other_tgt = self.library.abstract(other)
-        if append and isinstance(other, Abstract):
-            other_tgt = self.library[other.name]
-
-        # get rid of plugged ports
-        for kk in map_in:
-            if kk in self.paths:
-                self.paths[kk].append(RenderStep('P', None, self.ports[kk].copy(), self.ports[kk].copy(), None))
-
-        plugged = map_in.values()
-        for name, port in other_tgt.ports.items():
-            if name in plugged:
-                continue
-            new_name = map_out.get(name, name) if map_out is not None else name
-            if new_name is not None and new_name in self.paths:
-                self.paths[new_name].append(RenderStep('P', None, port.copy(), port.copy(), None))
-
-        self.pattern.plug(
-            other = other_tgt,
-            map_in = map_in,
-            map_out = map_out,
-            mirrored = mirrored,
-            thru = thru,
-            set_rotation = set_rotation,
-            append = append,
-            ok_connections = ok_connections,
-            )
-
-        return self
-
-    def place(
-            self,
-            other: Abstract | str,
-            *,
-            offset: ArrayLike = (0, 0),
-            rotation: float = 0,
-            pivot: ArrayLike = (0, 0),
-            mirrored: bool = False,
-            port_map: dict[str, str | None] | None = None,
-            skip_port_check: bool = False,
-            append: bool = False,
-            ) -> Self:
-        """
-          Wrapper for `Pattern.place` which adds a `RenderStep` with opcode 'P'
-        for any affected ports. This separates any future `RenderStep`s on the
-        same port into a new batch, since the placed device interferes with drawing.
-
-        Note that mirroring is applied before rotation; translation (`offset`) is applied last.
-
-        Args:
-            other: An `Abstract` or `Pattern` describing the device to be instatiated.
-            offset: Offset at which to place the instance. Default (0, 0).
-            rotation: Rotation applied to the instance before placement. Default 0.
-            pivot: Rotation is applied around this pivot point (default (0, 0)).
-                Rotation is applied prior to translation (`offset`).
-            mirrored: Whether theinstance should be mirrored across the x axis.
-                Mirroring is applied before translation and rotation.
-            port_map: dict of `{'old_name': 'new_name'}` mappings, specifying
-                new names for ports in the instantiated pattern. New names can be
-                `None`, which will delete those ports.
-            skip_port_check: Can be used to skip the internal call to `check_ports`,
-                in case it has already been performed elsewhere.
-            append: If `True`, `other` is appended instead of being referenced.
-                Note that this does not flatten  `other`, so its refs will still
-                be refs (now inside `self`).
-
-        Returns:
-            self
-
-        Raises:
-            `PortError` if any ports specified in `map_in` or `map_out` do not
-                exist in `self.ports` or `other.ports`.
-            `PortError` if there are any duplicate names after `map_in` and `map_out`
-                are applied.
-        """
-        if self._dead:
-            logger.error('Skipping place() since device is dead')
-            return self
-
-        other_tgt: Pattern | Abstract
-        if isinstance(other, str):
-            other_tgt = self.library.abstract(other)
-        if append and isinstance(other, Abstract):
-            other_tgt = self.library[other.name]
-
-        for name, port in other_tgt.ports.items():
-            new_name = port_map.get(name, name) if port_map is not None else name
-            if new_name is not None and new_name in self.paths:
-                self.paths[new_name].append(RenderStep('P', None, port.copy(), port.copy(), None))
-
-        self.pattern.place(
-            other = other_tgt,
-            offset = offset,
-            rotation = rotation,
-            pivot = pivot,
-            mirrored = mirrored,
-            port_map = port_map,
-            skip_port_check = skip_port_check,
-            append = append,
-            )
-
-        return self
-
-    def plugged(
-            self,
-            connections: dict[str, str],
-            ) -> Self:
-        for aa, bb in connections.items():
-            porta = self.ports[aa]
-            portb = self.ports[bb]
-            self.paths[aa].append(RenderStep('P', None, porta.copy(), porta.copy(), None))
-            self.paths[bb].append(RenderStep('P', None, portb.copy(), portb.copy(), None))
-        PortList.plugged(self, connections)
-        return self
-
-    def path(
-            self,
-            portspec: str,
-            ccw: SupportsBool | None,
-            length: float,
-            *,
-            plug_into: str | None = None,
-            **kwargs,
-            ) -> Self:
-        """
-        Plan a "wire"/"waveguide" extending from the port `portspec`, with the aim
-        of traveling exactly `length` distance.
-
-        The wire will travel `length` distance along the port's axis, an an unspecified
-        (tool-dependent) distance in the perpendicular direction. The output port will
-        be rotated (or not) based on the `ccw` parameter.
-
-        `RenderPather.render` must be called after all paths have been fully planned.
-
-        Args:
-            portspec: The name of the port into which the wire will be plugged.
-            ccw: If `None`, the output should be along the same axis as the input.
-                Otherwise, cast to bool and turn counterclockwise if True
-                and clockwise otherwise.
-            length: The total distance from input to output, along the input's axis only.
-                (There may be a tool-dependent offset along the other axis.)
-            plug_into: If not None, attempts to plug the wire's output port into the provided
-                port on `self`.
-
-        Returns:
-            self
-
-        Raises:
-            BuildError if `distance` is too small to fit the bend (if a bend is present).
-            LibraryError if no valid name could be picked for the pattern.
-        """
-        if self._dead:
-            logger.error('Skipping path() since device is dead')
-            return self
-
-        port = self.pattern[portspec]
-        in_ptype = port.ptype
-        port_rot = port.rotation
-        assert port_rot is not None         # TODO allow manually setting rotation for RenderPather.path()?
-
-        tool = self.tools.get(portspec, self.tools[None])
-        # ask the tool for bend size (fill missing dx or dy), check feasibility, and get out_ptype
-        out_port, data = tool.planL(ccw, length, in_ptype=in_ptype, **kwargs)
-
-        # Update port
-        out_port.rotate_around((0, 0), pi + port_rot)
-        out_port.translate(port.offset)
-
-        step = RenderStep('L', tool, port.copy(), out_port.copy(), data)
-        self.paths[portspec].append(step)
-
-        self.pattern.ports[portspec] = out_port.copy()
-
-        if plug_into is not None:
-            self.plugged({portspec: plug_into})
-
-        return self
-
-    def pathS(
-            self,
-            portspec: str,
-            length: float,
-            jog: float,
-            *,
-            plug_into: str | None = None,
-            **kwargs,
-            ) -> Self:
-        """
-        Create an S-shaped "wire"/"waveguide" and `plug` it into the port `portspec`, with the aim
-        of traveling exactly `length` distance with an offset `jog` along the other axis (+ve jog is
-        left of direction of travel).
-
-        The output port will have the same orientation as the source port (`portspec`).
-
-        `RenderPather.render` must be called after all paths have been fully planned.
-
-        This function attempts to use `tool.planS()`, but falls back to `tool.planL()` if the former
-        raises a NotImplementedError.
-
-        Args:
-            portspec: The name of the port into which the wire will be plugged.
-            jog: Total manhattan distance perpendicular to the direction of travel.
-                Positive values are to the left of the direction of travel.
-            length: The total manhattan distance from input to output, along the input's axis only.
-                (There may be a tool-dependent offset along the other axis.)
-            plug_into: If not None, attempts to plug the wire's output port into the provided
-                port on `self`.
-
-        Returns:
-            self
-
-        Raises:
-            BuildError if `distance` is too small to fit the s-bend (for nonzero jog).
-            LibraryError if no valid name could be picked for the pattern.
-        """
-        if self._dead:
-            logger.error('Skipping pathS() since device is dead')
-            return self
-
-        port = self.pattern[portspec]
-        in_ptype = port.ptype
-        port_rot = port.rotation
-        assert port_rot is not None         # TODO allow manually setting rotation for RenderPather.path()?
-
-        tool = self.tools.get(portspec, self.tools[None])
-
-        # check feasibility, get output port and data
-        try:
-            out_port, data = tool.planS(length, jog, in_ptype=in_ptype, **kwargs)
-        except NotImplementedError:
-            # Fall back to drawing two L-bends
-            ccw0 = jog > 0
-            kwargs_no_out = (kwargs | {'out_ptype': None})
-            t_port0, _ = tool.planL(    ccw0, length / 2, in_ptype=in_ptype, **kwargs_no_out)       # TODO length/2 may fail with asymmetric ptypes
-            jog0 = Port((0, 0), 0).measure_travel(t_port0)[0][1]
-            t_port1, _ = tool.planL(not ccw0, abs(jog - jog0), in_ptype=t_port0.ptype, **kwargs)
-            jog1 = Port((0, 0), 0).measure_travel(t_port1)[0][1]
-
-            kwargs_plug = kwargs | {'plug_into': plug_into}
-            self.path(portspec,     ccw0, length - abs(jog1), **kwargs_no_out)
-            self.path(portspec, not ccw0,    abs(jog - jog0), **kwargs_plug)
-            return self
-
-        out_port.rotate_around((0, 0), pi + port_rot)
-        out_port.translate(port.offset)
-        step = RenderStep('S', tool, port.copy(), out_port.copy(), data)
-        self.paths[portspec].append(step)
-        self.pattern.ports[portspec] = out_port.copy()
-
-        if plug_into is not None:
-            self.plugged({portspec: plug_into})
-        return self
-
-
-    def render(
-            self,
-            append: bool = True,
-            ) -> Self:
-        """
-        Generate the geometry which has been planned out with `path`/`path_to`/etc.
-
-        Args:
-            append: If `True`, the rendered geometry will be directly appended to
-                `self.pattern`. Note that it will not be flattened, so if only one
-                layer of hierarchy is eliminated.
-
-        Returns:
-            self
-        """
-        lib = self.library
-        tool_port_names = ('A', 'B')
-        pat = Pattern()
-
-        def render_batch(portspec: str, batch: list[RenderStep], append: bool) -> None:
-            assert batch[0].tool is not None
-            name = lib << batch[0].tool.render(batch, port_names=tool_port_names)
-            pat.ports[portspec] = batch[0].start_port.copy()
-            if append:
-                pat.plug(lib[name], {portspec: tool_port_names[0]}, append=append)
-                del lib[name]       # NOTE if the rendered pattern has refs, those are now in `pat` but not flattened
-            else:
-                pat.plug(lib.abstract(name), {portspec: tool_port_names[0]}, append=append)
-
-        for portspec, steps in self.paths.items():
-            batch: list[RenderStep] = []
-            for step in steps:
-                appendable_op = step.opcode in ('L', 'S', 'U')
-                same_tool = batch and step.tool == batch[0].tool
-
-                # If we can't continue a batch, render it
-                if batch and (not appendable_op or not same_tool):
-                    render_batch(portspec, batch, append)
-                    batch = []
-
-                # batch is emptied already if we couldn't continue it
-                if appendable_op:
-                    batch.append(step)
-
-                # Opcodes which break the batch go below this line
-                if not appendable_op and portspec in pat.ports:
-                    del pat.ports[portspec]
-
-            #If the last batch didn't end yet
-            if batch:
-                render_batch(portspec, batch, append)
-
-        self.paths.clear()
-        pat.ports.clear()
-        self.pattern.append(pat)
-
-        return self
-
-    def translate(self, offset: ArrayLike) -> Self:
-        """
-        Translate the pattern and all ports.
-
-        Args:
-            offset: (x, y) distance to translate by
-
-        Returns:
-            self
-        """
-        self.pattern.translate_elements(offset)
-        return self
-
-    def rotate_around(self, pivot: ArrayLike, angle: float) -> Self:
-        """
-        Rotate the pattern and all ports.
-
-        Args:
-            angle: angle (radians, counterclockwise) to rotate by
-            pivot: location to rotate around
-
-        Returns:
-            self
-        """
-        self.pattern.rotate_around(pivot, angle)
-        return self
-
-    def mirror(self, axis: int) -> Self:
-        """
-        Mirror the pattern and all ports across the specified axis.
-
-        Args:
-            axis: Axis to mirror across (x=0, y=1)
-
-        Returns:
-            self
-        """
-        self.pattern.mirror(axis)
-        return self
-
-    def set_dead(self) -> Self:
-        """
-        Disallows further changes through `plug()` or `place()`.
-        This is meant for debugging:
-        ```
-            dev.plug(a, ...)
-            dev.set_dead()      # added for debug purposes
-            dev.plug(b, ...)    # usually raises an error, but now skipped
-            dev.plug(c, ...)    # also skipped
-            dev.pattern.visualize()     # shows the device as of the set_dead() call
-        ```
-
-        Returns:
-            self
-        """
-        self._dead = True
-        return self
-
-    @wraps(Pattern.label)
-    def label(self, *args, **kwargs) -> Self:
-        self.pattern.label(*args, **kwargs)
-        return self
-
-    @wraps(Pattern.ref)
-    def ref(self, *args, **kwargs) -> Self:
-        self.pattern.ref(*args, **kwargs)
-        return self
-
-    @wraps(Pattern.polygon)
-    def polygon(self, *args, **kwargs) -> Self:
-        self.pattern.polygon(*args, **kwargs)
-        return self
-
-    @wraps(Pattern.rect)
-    def rect(self, *args, **kwargs) -> Self:
-        self.pattern.rect(*args, **kwargs)
-        return self
-

masque/builder/tool_testing.py

@@ -0,0 +1,368 @@
+"""Pytest-independent contract checks for custom routing Tools."""
+from __future__ import annotations
+
+from copy import deepcopy
+from dataclasses import dataclass, field
+from math import isfinite
+from types import MappingProxyType
+from typing import TYPE_CHECKING, Any
+
+import numpy
+from numpy import pi
+
+from ..library import ILibrary, SINGLE_USE_PREFIX
+from ..ports import Port
+from ..utils import ptypes_compatible
+from ._tolerances import angles_equal, array_close, scalar_close
+from .error import ToolContractError
+from .tools import (
+    BendOffer, PrimitiveKind, PrimitiveOffer, RenderStep, SOffer, StraightOffer, Tool, UOffer,
+    )
+
+if TYPE_CHECKING:
+    from collections.abc import Mapping, Sequence
+
+
+_RESERVED_OPTION_KEYS = frozenset(('kind', 'in_ptype', 'out_ptype', 'ccw'))
+
+
+@dataclass(frozen=True, slots=True)
+class ToolContractCase:
+    """One primitive-discovery query to exercise against a custom Tool."""
+
+    kind: PrimitiveKind
+    in_ptype: str | None = None
+    out_ptype: str | None = None
+    ccw: bool | None = None
+    tool_options: Mapping[str, Any] = field(default_factory=lambda: MappingProxyType({}))
+    probe_parameters: tuple[float, ...] = ()
+    require_offers: bool = True
+    check_bbox: bool = False
+    label: str | None = None
+
+    def __post_init__(self) -> None:
+        if self.kind not in ('straight', 'bend', 's', 'u'):
+            raise ValueError(f'Unrecognized primitive kind {self.kind!r}')
+        if self.kind == 'bend':
+            if self.ccw is None:
+                raise ValueError('Bend ToolContractCase requires ccw')
+        elif self.ccw is not None:
+            raise ValueError('ccw is only valid for bend ToolContractCase')
+
+        try:
+            options = deepcopy(dict(self.tool_options))
+        except Exception as err:
+            raise ValueError('ToolContractCase.tool_options must be a deep-copyable mapping') from err
+        nonstring = [key for key in options if not isinstance(key, str)]
+        if nonstring:
+            raise ValueError(f'ToolContractCase.tool_options keys must be strings; got {nonstring!r}')
+        collisions = sorted(_RESERVED_OPTION_KEYS & options.keys())
+        if collisions:
+            raise ValueError(f'ToolContractCase.tool_options contains reserved keys: {", ".join(collisions)}')
+
+        try:
+            probes = tuple(float(value) for value in self.probe_parameters)
+        except (TypeError, ValueError, OverflowError) as err:
+            raise ValueError('ToolContractCase.probe_parameters must contain numeric scalars') from err
+        if not all(isfinite(value) for value in probes):
+            raise ValueError('ToolContractCase.probe_parameters must be finite')
+
+        object.__setattr__(self, 'ccw', None if self.ccw is None else bool(self.ccw))
+        object.__setattr__(self, 'tool_options', MappingProxyType(options))
+        object.__setattr__(self, 'probe_parameters', probes)
+
+
+def _automatic_probes(offer: PrimitiveOffer) -> tuple[float, ...]:
+    """Choose deterministic representative parameters inside one offer domain."""
+    lower, upper = (float(value) for value in offer.parameter_domain)
+    if lower == upper:
+        return (lower,)
+    if numpy.isfinite(lower) and numpy.isfinite(upper):
+        midpoint = lower / 2 + upper / 2
+        if midpoint == upper:
+            midpoint = float(numpy.nextafter(upper, lower))
+        return (lower, midpoint)
+    if numpy.isfinite(lower):
+        step = max(1.0, abs(lower) * 0.1)
+        return (lower, lower + step)
+    if numpy.isfinite(upper):
+        step = max(1.0, abs(upper) * 0.1)
+        return (upper - step, upper - 2 * step)
+    return (-1.0, 1.0)
+
+
+def _offer_probes(offer: PrimitiveOffer, extras: Sequence[float]) -> tuple[float, ...]:
+    """Combine automatic and applicable explicit probes without duplicates."""
+    probes: list[float] = []
+    for parameter in (*_automatic_probes(offer), *extras):
+        try:
+            selected = offer.canonicalize_parameter(parameter)
+        except Exception:
+            continue
+        if not any(scalar_close(selected, previous) for previous in probes):
+            probes.append(selected)
+    return tuple(probes)
+
+
+def _offer_metadata(offer: PrimitiveOffer) -> tuple[Any, ...]:
+    """Return discovery metadata that must remain stable across repeated queries."""
+    cost_policy: tuple[str, Any]
+    if callable(offer.cost):
+        cost_policy = ('callable', type(offer.cost).__qualname__)
+    else:
+        cost_policy = ('factor', float(offer.cost))
+    return (
+        type(offer),
+        offer.kind,
+        offer.in_ptype,
+        offer.out_ptype,
+        tuple(float(value) for value in offer.parameter_domain),
+        getattr(offer, 'ccw', None),
+        cost_policy,
+        )
+
+
+def _evaluated_cost(offer: PrimitiveOffer, parameter: float, endpoint: Port) -> float:
+    """Mirror the solver's one-endpoint base-cost path while honoring overrides."""
+    if type(offer).cost_at is PrimitiveOffer.cost_at:
+        return PrimitiveOffer._cost_for_endpoint(offer, parameter, endpoint)
+    return float(offer.cost_at(parameter))
+
+
+def validate_tool_contract(tool: Tool, cases: Sequence[ToolContractCase]) -> None:
+    """Validate Tool discovery, offer callbacks, and one-step rendering.
+
+    All independent violations are collected and raised as one
+    `ExceptionGroup` containing contextual `ToolContractError` instances.
+    """
+    cases = tuple(cases)
+    if not cases:
+        raise ValueError('validate_tool_contract() requires at least one case')
+
+    errors: list[ToolContractError] = []
+
+    def violation(context: str, message: str, cause: Exception | None = None) -> None:
+        err = ToolContractError(f'{context}: {message}')
+        if cause is not None:
+            err.__cause__ = cause
+        errors.append(err)
+
+    def discover(case: ToolContractCase, context: str, repetition: str) -> tuple[PrimitiveOffer, ...] | None:
+        expected_offer_type = {
+            'straight': StraightOffer,
+            'bend': BendOffer,
+            's': SOffer,
+            'u': UOffer,
+            }[case.kind]
+        try:
+            kwargs = deepcopy(dict(case.tool_options))
+            if case.kind == 'bend':
+                kwargs['ccw'] = case.ccw
+            offers = tool.primitive_offers(
+                case.kind,
+                in_ptype=case.in_ptype,
+                out_ptype=case.out_ptype,
+                **kwargs,
+                )
+        except Exception as err:
+            violation(context, f'{repetition} discovery raised {type(err).__name__}: {err}', err)
+            return None
+
+        if not isinstance(offers, tuple):
+            violation(context, f'{repetition} discovery returned {type(offers).__name__}, expected tuple')
+            return None
+        valid = True
+        for offer_index, offer in enumerate(offers):
+            if not isinstance(offer, PrimitiveOffer):
+                violation(
+                    context,
+                    f'{repetition} discovery item {offer_index} is {type(offer).__name__}, expected PrimitiveOffer',
+                    )
+                valid = False
+            elif offer.kind != case.kind:
+                violation(
+                    context,
+                    f'{repetition} discovery item {offer_index} has kind {offer.kind!r}, expected {case.kind!r}',
+                    )
+                valid = False
+            elif not isinstance(offer, expected_offer_type):
+                violation(
+                    context,
+                    f'{repetition} discovery item {offer_index} is {type(offer).__name__}, '
+                    f'expected {expected_offer_type.__name__}',
+                    )
+                valid = False
+        return offers if valid else None
+
+    for case_index, case in enumerate(cases):
+        context = case.label or f'case {case_index} ({case.kind})'
+        first = discover(case, context, 'first')
+        second = discover(case, context, 'repeated')
+        if first is None or second is None:
+            continue
+        if case.require_offers and not first:
+            violation(context, 'discovery returned no offers')
+        if len(first) != len(second):
+            violation(context, f'discovery count changed from {len(first)} to {len(second)}')
+
+        matched_explicit = [False] * len(case.probe_parameters)
+        for offer_index, offer in enumerate(first):
+            offer_context = f'{context}, offer {offer_index}'
+            repeated = second[offer_index] if offer_index < len(second) else None
+            if repeated is not None and _offer_metadata(offer) != _offer_metadata(repeated):
+                violation(offer_context, 'discovery metadata changed between repeated queries')
+
+            probes = _offer_probes(offer, case.probe_parameters)
+            for explicit_index, parameter in enumerate(case.probe_parameters):
+                try:
+                    offer.canonicalize_parameter(parameter)
+                except Exception:
+                    continue
+                matched_explicit[explicit_index] = True
+
+            stable_ptype: str | None = None
+            stable_rotation: float | None = None
+            has_stable_endpoint = False
+            for parameter in probes:
+                probe_context = f'{offer_context}, parameter {parameter:g}'
+                try:
+                    endpoint = offer.endpoint_at(parameter)
+                except Exception as err:
+                    violation(probe_context, f'endpoint_at() raised {type(err).__name__}: {err}', err)
+                    continue
+                if not isinstance(endpoint, Port):
+                    violation(probe_context, f'endpoint_at() returned {type(endpoint).__name__}, expected Port')
+                    continue
+                if not numpy.all(numpy.isfinite(endpoint.offset)):
+                    violation(probe_context, 'endpoint offset must be finite')
+                if endpoint.rotation is None or not numpy.isfinite(endpoint.rotation):
+                    violation(probe_context, 'endpoint rotation must be finite and specified')
+                if not ptypes_compatible(endpoint.ptype, offer.out_ptype):
+                    violation(probe_context, 'endpoint ptype does not match declared out_ptype')
+
+                if offer.kind in ('straight', 'bend') and not scalar_close(endpoint.x, parameter):
+                    violation(probe_context, 'straight/bend endpoint x must equal its parameter')
+                if offer.kind in ('s', 'u') and not scalar_close(endpoint.y, parameter):
+                    violation(probe_context, 'S/U endpoint y must equal its parameter')
+                expected_rotation = {
+                    'straight': pi,
+                    'bend': -pi / 2 if isinstance(offer, BendOffer) and offer.ccw else pi / 2,
+                    's': pi,
+                    'u': 0.0,
+                    }[offer.kind]
+                if endpoint.rotation is not None and not angles_equal(endpoint.rotation, expected_rotation):
+                    violation(
+                        probe_context,
+                        f'endpoint rotation does not match {offer.kind!r} geometry',
+                        )
+
+                if has_stable_endpoint:
+                    if endpoint.ptype != stable_ptype:
+                        violation(probe_context, 'endpoint ptype changes across the offer domain')
+                    if (
+                            endpoint.rotation is None
+                            or stable_rotation is None
+                            or not angles_equal(endpoint.rotation, stable_rotation)
+                            ):
+                        violation(probe_context, 'endpoint rotation changes across the offer domain')
+                else:
+                    stable_ptype = endpoint.ptype
+                    stable_rotation = endpoint.rotation
+                    has_stable_endpoint = True
+
+                try:
+                    cost = float(_evaluated_cost(offer, parameter, endpoint))
+                    if not numpy.isfinite(cost) or cost < 0:
+                        violation(probe_context, f'cost must be finite and nonnegative, got {cost!r}')
+                except Exception as err:
+                    violation(probe_context, f'cost_at() raised {type(err).__name__}: {err}', err)
+                    cost = None
+
+                if repeated is not None:
+                    try:
+                        repeated_endpoint = repeated.endpoint_at(parameter)
+                        repeated_cost = float(_evaluated_cost(repeated, parameter, repeated_endpoint))
+                        if (
+                                not isinstance(repeated_endpoint, Port)
+                                or not array_close(repeated_endpoint.offset, endpoint.offset)
+                                or repeated_endpoint.ptype != endpoint.ptype
+                                or repeated_endpoint.rotation is None
+                                or endpoint.rotation is None
+                                or not angles_equal(repeated_endpoint.rotation, endpoint.rotation)
+                                ):
+                            violation(probe_context, 'endpoint result changed after repeated discovery')
+                        if cost is not None and not scalar_close(repeated_cost, cost):
+                            violation(probe_context, 'cost result changed after repeated discovery')
+                    except Exception as err:
+                        violation(
+                            probe_context,
+                            f'repeated offer evaluation raised {type(err).__name__}: {err}',
+                            err,
+                            )
+
+                if case.check_bbox:
+                    try:
+                        offer.bbox_at(parameter)
+                    except Exception as err:
+                        violation(probe_context, f'bbox_at() raised {type(err).__name__}: {err}', err)
+
+                try:
+                    data = offer.commit(parameter)
+                except Exception as err:
+                    violation(probe_context, f'commit() raised {type(err).__name__}: {err}', err)
+                    continue
+
+                try:
+                    start = Port((0, 0), rotation=pi, ptype=offer.in_ptype or 'unk')
+                    tree = tool.render((RenderStep(offer.kind, tool, start, endpoint.copy(), data),))
+                except Exception as err:
+                    violation(probe_context, f'render() raised {type(err).__name__}: {err}', err)
+                    continue
+                if not isinstance(tree, ILibrary):
+                    violation(probe_context, f'render() returned {type(tree).__name__}, expected ILibrary')
+                    continue
+                try:
+                    top_name = tree.top()
+                    pattern = tree.top_pattern()
+                except Exception as err:
+                    violation(probe_context, f'rendered tree has no valid top cell: {err}', err)
+                    continue
+                missing = sorted(
+                    name
+                    for name in tree.dangling_refs(top_name)
+                    if isinstance(name, str) and name.startswith(SINGLE_USE_PREFIX)
+                    )
+                if missing:
+                    violation(probe_context, f'rendered tree has missing single-use refs: {missing}')
+                missing_ports = [name for name in ('A', 'B') if name not in pattern.ports]
+                if missing_ports:
+                    violation(probe_context, f'rendered top cell is missing ports: {missing_ports}')
+                    continue
+                input_port, output_port = pattern.ports['A'], pattern.ports['B']
+                if not ptypes_compatible(input_port.ptype, offer.in_ptype):
+                    violation(probe_context, 'rendered input ptype does not match offer in_ptype')
+                try:
+                    rendered_offset, rendered_rotation = input_port.measure_travel(output_port)
+                except Exception as err:
+                    violation(probe_context, f'unable to measure rendered endpoint: {err}', err)
+                    continue
+                if not array_close(rendered_offset, endpoint.offset):
+                    violation(probe_context, 'rendered output offset does not match planned endpoint')
+                if (
+                        rendered_rotation is None
+                        or endpoint.rotation is None
+                        or not angles_equal(rendered_rotation, endpoint.rotation)
+                        ):
+                    violation(probe_context, 'rendered output rotation does not match planned endpoint')
+                if not ptypes_compatible(output_port.ptype, endpoint.ptype):
+                    violation(probe_context, 'rendered output ptype does not match planned endpoint')
+
+        for parameter, matched in zip(case.probe_parameters, matched_explicit, strict=True):
+            if not matched:
+                violation(context, f'explicit probe {parameter:g} is outside every discovered offer domain')
+
+    if errors:
+        raise ExceptionGroup(
+            f'{type(tool).__name__} failed Tool contract validation with {len(errors)} violation(s)',
+            errors,
+            )

masque/builder/utils.py

@@ -1,5 +1,5 @@
-from typing import SupportsFloat, cast, TYPE_CHECKING
-from collections.abc import Mapping, Sequence
+from typing import TYPE_CHECKING
+from collections.abc import Mapping
 from pprint import pformat
 
 import numpy
@@ -8,11 +8,23 @@ from numpy.typing import ArrayLike, NDArray
 
 from ..utils import rotation_matrix_2d, SupportsBool
 from ..error import BuildError
+from ._tolerances import manhattan_axis
 
 if TYPE_CHECKING:
     from ..ports import Port
 
 
+_EXTENSION_BOUND_TYPES = (
+    'emin', 'min_extension',
+    'emax', 'max_extension',
+    'min_past_furthest',
+    )
+_POSITION_MIN_BOUND_TYPES = ('pmin', 'min_position', 'xmin', 'ymin')
+_POSITION_MAX_BOUND_TYPES = ('pmax', 'max_position', 'xmax', 'ymax')
+_POSITION_BOUND_TYPES = _POSITION_MIN_BOUND_TYPES + _POSITION_MAX_BOUND_TYPES
+_BOUND_TYPES = _EXTENSION_BOUND_TYPES + _POSITION_BOUND_TYPES
+
+
 def ell(
         ports: Mapping[str, 'Port'],
         ccw: SupportsBool | None,
@@ -46,7 +58,7 @@ def ell(
         ccw: Turn direction. `True` means counterclockwise, `False` means clockwise,
             and `None` means no bend. If `None`, spacing must remain `None` or `0` (default),
             Otherwise, spacing must be set to a non-`None` value.
-        bound_method: Method used for determining the travel distance; see diagram above.
+        bound_type: Method used for determining the travel distance; see diagram above.
             Valid values are:
             - 'min_extension' or 'emin':
                 The total extension value for the furthest-out port (B in the diagram).
@@ -64,7 +76,7 @@ def ell(
                 the x- and y- axes. If specifying a position, it is projected onto
                 the extension direction.
 
-        bound_value: Value associated with `bound_type`, see above.
+        bound: Value associated with `bound_type`, see above.
         spacing: Distance between adjacent channels. Can be scalar, resulting in evenly
             spaced channels, or a vector with length one less than `ports`, allowing
             non-uniform spacing.
@@ -82,9 +94,21 @@ def ell(
     """
     if not ports:
         raise BuildError('Empty port list passed to `ell()`')
+    if bound_type not in _BOUND_TYPES:
+        raise BuildError(f'Invalid bound type {bound_type!r}; expected one of {_BOUND_TYPES}')
+
+    try:
+        bound_arr = numpy.asarray(bound, dtype=float)
+    except (TypeError, ValueError) as err:
+        raise BuildError('bound must be a numeric scalar or length-2 vector') from err
+    if bound_arr.size not in (1, 2):
+        raise BuildError(f'bound must be scalar or have length 2; got {bound_arr.size} values')
+    if not numpy.all(numpy.isfinite(bound_arr)):
+        raise BuildError('bound must contain only finite values')
+    bound_values = bound_arr.reshape(-1)
 
     if ccw is None:
-        if spacing is not None and not numpy.isclose(spacing, 0):
+        if spacing is not None and not numpy.allclose(spacing, 0):
             raise BuildError('Spacing must be 0 or None when ccw=None')
         spacing = 0
     elif spacing is None:
@@ -106,11 +130,19 @@ def ell(
             raise BuildError('Asked to find aggregation for ports that face in different directions:\n'
                              + pformat(port_rotations))
     else:
-        if set_rotation is not None:
+        if set_rotation is None:
             raise BuildError('set_rotation must be specified if no ports have rotations!')
+        if not numpy.isfinite(set_rotation):
+            raise BuildError('set_rotation must be finite')
         rotations = numpy.full_like(has_rotation, set_rotation, dtype=float)
 
-    is_horizontal = numpy.isclose(rotations[0] % pi, 0)
+    axis = manhattan_axis(float(rotations[0]))
+    if bound_type in _POSITION_BOUND_TYPES and axis is None:
+        raise BuildError(
+            'Positional bounds require a nearly Manhattan port direction; '
+            f'got rotation {rotations[0]:g}'
+            )
+    is_horizontal = axis == 0
     if bound_type in ('ymin', 'ymax') and is_horizontal:
         raise BuildError(f'Asked for {bound_type} position but ports are pointing along the x-axis!')
     if bound_type in ('xmin', 'xmax') and not is_horizontal:
@@ -132,8 +164,21 @@ def ell(
     if spacing is None:
         ch_offsets = numpy.zeros_like(y_order)
     else:
-        steps = numpy.zeros_like(y_order)
-        steps[1:] = spacing
+        spacing_arr = numpy.asarray(spacing, dtype=float).reshape(-1)
+        if not numpy.all(numpy.isfinite(spacing_arr)):
+            raise BuildError('spacing must contain only finite values')
+        if numpy.any(spacing_arr < 0):
+            raise BuildError('spacing must be nonnegative')
+        steps: NDArray[numpy.float64] = numpy.zeros(len(y_order), dtype=float)
+        if spacing_arr.size == 1:
+            steps[1:] = spacing_arr[0]
+        elif spacing_arr.size == len(ports) - 1:
+            steps[1:] = spacing_arr
+        else:
+            raise BuildError(
+                f'spacing must be scalar or have length {len(ports) - 1} for {len(ports)} ports; '
+                f'got length {spacing_arr.size}'
+                )
         ch_offsets = numpy.cumsum(steps)[y_ind]
 
     x_start = rot_offsets[:, 0]
@@ -164,38 +209,34 @@ def ell(
         travel = d_to_align - (ch_offsets.max() - ch_offsets)
         offsets = travel - travel.min().clip(max=0)
 
-    rot_bound: SupportsFloat
-    if bound_type in ('emin', 'min_extension',
-                      'emax', 'max_extension',
-                      'min_past_furthest',):
-        if numpy.size(bound) == 2:
-            bound = cast('Sequence[float]', bound)
-            rot_bound = (rot_matrix @ ((bound[0], 0),
-                                       (0, bound[1])))[0, :]
-        else:
-            bound = cast('float', bound)
-            rot_bound = numpy.array(bound)
+    if bound_type in _EXTENSION_BOUND_TYPES:
+        if numpy.any(bound_values < 0):
+            raise BuildError(f'Got negative bound for extension: {bound_values}')
 
-        if rot_bound < 0:
-            raise BuildError(f'Got negative bound for extension: {rot_bound}')
+        if bound_values.size == 2:
+            horizontal_weight = abs(float(numpy.cos(direction)))
+            vertical_weight = abs(float(numpy.sin(direction)))
+            use_x = horizontal_weight > vertical_weight or numpy.isclose(horizontal_weight, vertical_weight)
+            rot_bound = float(bound_values[0 if use_x else 1])
+        else:
+            rot_bound = float(bound_values[0])
 
         if bound_type in ('emin', 'min_extension', 'min_past_furthest'):
-            offsets += rot_bound.max()
+            offsets += rot_bound
         elif bound_type in ('emax', 'max_extension'):
-            offsets += rot_bound.min() - offsets.max()
+            offsets += rot_bound - offsets.max()
     else:
-        if numpy.size(bound) == 2:
-            bound = cast('Sequence[float]', bound)
-            rot_bound = (rot_matrix @ bound)[0]
+        if bound_values.size == 2:
+            rot_bound = float((rot_matrix @ bound_values)[0])
         else:
-            bound = cast('float', bound)
             neg = (direction + pi / 4) % (2 * pi) > pi
-            rot_bound = -bound if neg else bound
+            bound_scalar = float(bound_values[0])
+            rot_bound = -bound_scalar if neg else bound_scalar
 
         min_possible = x_start + offsets
-        if bound_type in ('pmax', 'max_position', 'xmax', 'ymax'):
+        if bound_type in _POSITION_MAX_BOUND_TYPES:
             extension = rot_bound - min_possible.max()
-        elif bound_type in ('pmin', 'min_position', 'xmin', 'ymin'):
+        else:
             extension = rot_bound - min_possible.min()
 
         offsets += extension

masque/file/dxf.py

@@ -16,7 +16,7 @@ import gzip
 import numpy
 import ezdxf
 from ezdxf.enums import TextEntityAlignment
-from ezdxf.entities import LWPolyline, Polyline, Text, Insert
+from ezdxf.entities import LWPolyline, Polyline, Text, Insert, Solid, Trace
 
 from .utils import is_gzipped, tmpfile
 from .. import Pattern, Ref, PatternError, Label
@@ -55,8 +55,7 @@ def write(
         tuple: (1, 2) -> '1.2'
         str: '1.2' -> '1.2' (no change)
 
-    DXF does not support shape repetition (only block repeptition). Please call
-    library.wrap_repeated_shapes() before writing to file.
+    Shape repetitions are expanded into individual DXF entities.
 
     Other functions you may want to call:
         - `masque.file.oasis.check_valid_names(library.keys())` to check for invalid names
@@ -193,8 +192,37 @@ def read(
 
     top_name, top_pat = _read_block(msp)
     mlib = Library({top_name: top_pat})
+
+    blocks_by_name = {
+        bb.name: bb
+        for bb in lib.blocks
+        if not bb.is_any_layout
+    }
+
+    referenced: set[str] = set()
+    pending = [msp]
+    seen_blocks: set[str] = set()
+    while pending:
+        block = pending.pop()
+        block_name = getattr(block, 'name', None)
+        if block_name is not None and block_name in seen_blocks:
+            continue
+        if block_name is not None:
+            seen_blocks.add(block_name)
+        for element in block:
+            if not isinstance(element, Insert):
+                continue
+            target = element.dxfattribs().get('name')
+            if target is None or target in referenced:
+                continue
+            referenced.add(target)
+            if target in blocks_by_name:
+                pending.append(blocks_by_name[target])
+
     for bb in lib.blocks:
-        if bb.name == '*Model_Space':
+        if bb.is_any_layout:
+            continue
+        if bb.name.startswith('_') and bb.name not in referenced:
             continue
         name, pat = _read_block(bb)
         mlib[name] = pat
@@ -213,32 +241,60 @@ def _read_block(block: ezdxf.layouts.BlockLayout | ezdxf.layouts.Modelspace) ->
         if isinstance(element, LWPolyline | Polyline):
             if isinstance(element, LWPolyline):
                 points = numpy.asarray(element.get_points())
-            elif isinstance(element, Polyline):
+                is_closed = element.closed
+            else:
                 points = numpy.asarray([pp.xyz for pp in element.points()])
+                is_closed = element.is_closed
             attr = element.dxfattribs()
             layer = attr.get('layer', DEFAULT_LAYER)
 
-            if points.shape[1] == 2:
-                raise PatternError('Invalid or unimplemented polygon?')
-
-            if points.shape[1] > 2:
-                if (points[0, 2] != points[:, 2]).any():
-                    raise PatternError('PolyLine has non-constant width (not yet representable in masque!)')
-                if points.shape[1] == 4 and (points[:, 3] != 0).any():
-                    raise PatternError('LWPolyLine has bulge (not yet representable in masque!)')
-
+            width = 0
+            if isinstance(element, LWPolyline):
+                # ezdxf 1.4+ get_points() returns (x, y, start_width, end_width, bulge)
+                if points.shape[1] >= 5:
+                    if (points[:, 4] != 0).any():
+                        raise PatternError('LWPolyline has bulge (not yet representable in masque!)')
+                    if (points[:, 2] != points[:, 3]).any() or (points[:, 2] != points[0, 2]).any():
+                        raise PatternError('LWPolyline has non-constant width (not yet representable in masque!)')
                     width = points[0, 2]
+                elif points.shape[1] == 3:
+                    # width used to be in column 2
+                    width = points[0, 2]
+
             if width == 0:
                 width = attr.get('const_width', 0)
 
+            verts = points[:, :2]
+            if is_closed and (len(verts) < 2 or not numpy.allclose(verts[0], verts[-1])):
+                verts = numpy.vstack((verts, verts[0]))
+
             shape: Path | Polygon
-                if width == 0 and len(points) > 2 and numpy.array_equal(points[0], points[-1]):
-                    shape = Polygon(vertices=points[:-1, :2])
+            if width == 0 and is_closed:
+                # Use Polygon if it has at least 3 unique vertices
+                shape_verts = verts[:-1] if len(verts) > 1 else verts
+                if len(shape_verts) >= 3:
+                    shape = Polygon(vertices=shape_verts)
                 else:
-                    shape = Path(width=width, vertices=points[:, :2])
+                    shape = Path(width=width, vertices=verts)
+            else:
+                shape = Path(width=width, vertices=verts)
 
             pat.shapes[layer].append(shape)
-
+        elif isinstance(element, Solid | Trace):
+            attr = element.dxfattribs()
+            layer = attr.get('layer', DEFAULT_LAYER)
+            points = numpy.array([element.get_dxf_attrib(f'vtx{i}') for i in range(4)
+                                  if element.has_dxf_attrib(f'vtx{i}')])
+            if len(points) >= 3:
+                # If vtx2 == vtx3, it's a triangle. ezdxf handles this.
+                if len(points) == 4 and numpy.allclose(points[2], points[3]):
+                    verts = points[:3, :2]
+                # DXF Solid/Trace uses 0-1-3-2 vertex order for quadrilaterals!
+                elif len(points) == 4:
+                    verts = points[[0, 1, 3, 2], :2]
+                else:
+                    verts = points[:, :2]
+                pat.shapes[layer].append(Polygon(vertices=verts))
         elif isinstance(element, Text):
             args = dict(
                 offset=numpy.asarray(element.get_placement()[1])[:2],
@@ -273,12 +329,57 @@ def _read_block(block: ezdxf.layouts.BlockLayout | ezdxf.layouts.Modelspace) ->
                 )
 
             if 'column_count' in attr:
-                args['repetition'] = Grid(
-                    a_vector=(attr['column_spacing'], 0),
-                    b_vector=(0, attr['row_spacing']),
-                    a_count=attr['column_count'],
-                    b_count=attr['row_count'],
+                col_spacing = attr['column_spacing']
+                row_spacing = attr['row_spacing']
+                col_count = attr['column_count']
+                row_count = attr['row_count']
+                local_x = numpy.array((col_spacing, 0.0))
+                local_y = numpy.array((0.0, row_spacing))
+                inv_rot = rotation_matrix_2d(-rotation)
+
+                candidates = (
+                    (inv_rot @ local_x, inv_rot @ local_y, col_count, row_count),
+                    (inv_rot @ local_y, inv_rot @ local_x, row_count, col_count),
                     )
+                repetition = None
+                for a_vector, b_vector, a_count, b_count in candidates:
+                    rotated_a = rotation_matrix_2d(rotation) @ a_vector
+                    rotated_b = rotation_matrix_2d(rotation) @ b_vector
+                    if (numpy.isclose(rotated_a[1], 0, atol=1e-8)
+                            and numpy.isclose(rotated_b[0], 0, atol=1e-8)
+                            and numpy.isclose(rotated_a[0], col_spacing, atol=1e-8)
+                            and numpy.isclose(rotated_b[1], row_spacing, atol=1e-8)
+                            and a_count == col_count
+                            and b_count == row_count):
+                        repetition = Grid(
+                            a_vector=a_vector,
+                            b_vector=b_vector,
+                            a_count=a_count,
+                            b_count=b_count,
+                            )
+                        break
+                    if (numpy.isclose(rotated_a[0], 0, atol=1e-8)
+                            and numpy.isclose(rotated_b[1], 0, atol=1e-8)
+                            and numpy.isclose(rotated_b[0], col_spacing, atol=1e-8)
+                            and numpy.isclose(rotated_a[1], row_spacing, atol=1e-8)
+                            and b_count == col_count
+                            and a_count == row_count):
+                        repetition = Grid(
+                            a_vector=a_vector,
+                            b_vector=b_vector,
+                            a_count=a_count,
+                            b_count=b_count,
+                            )
+                        break
+
+                if repetition is None:
+                    repetition = Grid(
+                        a_vector=inv_rot @ local_x,
+                        b_vector=inv_rot @ local_y,
+                        a_count=col_count,
+                        b_count=row_count,
+                        )
+                args['repetition'] = repetition
             pat.ref(**args)
         else:
             logger.warning(f'Ignoring DXF element {element.dxftype()} (not implemented).')
@@ -303,15 +404,23 @@ def _mrefs_to_drefs(
         elif isinstance(rep, Grid):
             a = rep.a_vector
             b = rep.b_vector if rep.b_vector is not None else numpy.zeros(2)
-            rotated_a = rotation_matrix_2d(-ref.rotation) @ a
-            rotated_b = rotation_matrix_2d(-ref.rotation) @ b
-            if rotated_a[1] == 0 and rotated_b[0] == 0:
+            # In masque, the grid basis vectors are NOT rotated by the reference's rotation.
+            # In DXF, the grid basis vectors are [column_spacing, 0] and [0, row_spacing],
+            # which ARE then rotated by the block reference's rotation.
+            # Therefore, we can only use a DXF array if ref.rotation is 0 (or a multiple of 90)
+            # AND the grid is already manhattan.
+
+            # Rotate basis vectors by the reference rotation to see where they end up in the DXF frame
+            rotated_a = rotation_matrix_2d(ref.rotation) @ a
+            rotated_b = rotation_matrix_2d(ref.rotation) @ b
+
+            if numpy.isclose(rotated_a[1], 0, atol=1e-8) and numpy.isclose(rotated_b[0], 0, atol=1e-8):
                 attribs['column_count'] = rep.a_count
                 attribs['row_count'] = rep.b_count
                 attribs['column_spacing'] = rotated_a[0]
                 attribs['row_spacing'] = rotated_b[1]
                 block.add_blockref(encoded_name, ref.offset, dxfattribs=attribs)
-            elif rotated_a[0] == 0 and rotated_b[1] == 0:
+            elif numpy.isclose(rotated_a[0], 0, atol=1e-8) and numpy.isclose(rotated_b[1], 0, atol=1e-8):
                 attribs['column_count'] = rep.b_count
                 attribs['row_count'] = rep.a_count
                 attribs['column_spacing'] = rotated_b[0]
@@ -344,16 +453,23 @@ def _shapes_to_elements(
     for layer, sseq in shapes.items():
         attribs = dict(layer=_mlayer2dxf(layer))
         for shape in sseq:
+            displacements = [numpy.zeros(2)]
             if shape.repetition is not None:
-                raise PatternError(
-                    'Shape repetitions are not supported by DXF.'
-                    ' Please call library.wrap_repeated_shapes() before writing to file.'
-                    )
+                displacements = shape.repetition.displacements
 
+            for dd in displacements:
+                if isinstance(shape, Path):
+                    # preserve path.
+                    # Note: DXF paths don't support endcaps well, so this is still a bit limited.
+                    xy = shape.vertices + dd
+                    attribs_path = {**attribs}
+                    if shape.width > 0:
+                        attribs_path['const_width'] = shape.width
+                    block.add_lwpolyline(xy, dxfattribs=attribs_path)
+                else:
                     for polygon in shape.to_polygons():
-                xy_open = polygon.vertices
-                xy_closed = numpy.vstack((xy_open, xy_open[0, :]))
-                block.add_lwpolyline(xy_closed, dxfattribs=attribs)
+                        xy_open = polygon.vertices + dd
+                        block.add_lwpolyline(xy_open, close=True, dxfattribs=attribs)
 
 
 def _labels_to_texts(
@@ -363,11 +479,17 @@ def _labels_to_texts(
     for layer, lseq in labels.items():
         attribs = dict(layer=_mlayer2dxf(layer))
         for label in lseq:
-            xy = label.offset
+            if label.repetition is None:
                 block.add_text(
                     label.string,
                     dxfattribs=attribs
-                ).set_placement(xy, align=TextEntityAlignment.BOTTOM_LEFT)
+                    ).set_placement(label.offset, align=TextEntityAlignment.BOTTOM_LEFT)
+            else:
+                for dd in label.repetition.displacements:
+                    block.add_text(
+                        label.string,
+                        dxfattribs=attribs
+                        ).set_placement(label.offset + dd, align=TextEntityAlignment.BOTTOM_LEFT)
 
 
 def _mlayer2dxf(layer: layer_t) -> str:

masque/file/gdsii/__init__.py

@@ -0,0 +1,8 @@
+"""
+GDSII file format readers and writers.
+"""
+from .klamath import check_valid_names as check_valid_names
+from .klamath import read as read
+from .klamath import readfile as readfile
+from .writer import write as write
+from .writer import writefile as writefile

masque/file/gdsii/arrow.py

@@ -0,0 +1,840 @@
+# ruff: noqa: ARG001
+"""
+GDSII file format readers and writers using the `TODO` library.
+
+Note that GDSII references follow the same convention as `masque`,
+  with this order of operations:
+   1. Mirroring
+   2. Rotation
+   3. Scaling
+   4. Offset and array expansion (no mirroring/rotation/scaling applied to offsets)
+
+  Scaling, rotation, and mirroring apply to individual instances, not grid
+   vectors or offsets.
+
+Notes:
+ * absolute positioning is not supported
+ * PLEX is not supported
+ * ELFLAGS are not supported
+ * GDS does not support library- or structure-level annotations
+ * GDS creation/modification/access times are set to 1900-01-01 for reproducibility.
+ * Gzip modification time is set to 0 (start of current epoch, usually 1970-01-01)
+
+ TODO writing
+ TODO warn on boxes, nodes
+"""
+from __future__ import annotations
+
+from typing import TYPE_CHECKING, Any
+from functools import cache
+from importlib.machinery import EXTENSION_SUFFIXES
+import importlib.util
+import logging
+import os
+import pathlib
+import gzip
+import sys
+import tempfile
+
+from klamath.basic import KlamathError
+import numpy
+import pyarrow
+from pyarrow.cffi import ffi
+
+from ..utils import is_gzipped
+from ... import Pattern, Ref, PatternError, Label
+from ...shapes import Polygon, Path, PolyCollection, RectCollection
+from ...repetition import Grid
+from ...library import Library
+
+if TYPE_CHECKING:
+    from collections.abc import Callable
+    import mmap
+
+    from numpy.typing import NDArray
+
+    from ...utils import annotations_t
+
+
+logger = logging.getLogger(__name__)
+
+ffi.cdef(
+    """
+    const char* last_error_message(void);
+    int read_path(const char* path, struct ArrowArray* array, struct ArrowSchema* schema);
+    int scan_bytes(uint8_t* data, size_t size, struct ArrowArray* array, struct ArrowSchema* schema);
+    int read_cells_bytes(
+        uint8_t* data,
+        size_t size,
+        uint64_t* ranges,
+        size_t range_count,
+        struct ArrowArray* array,
+        struct ArrowSchema* schema
+    );
+    """
+)
+
+_PATH_CAP_MAP = {
+    0: Path.Cap.Flush,
+    1: Path.Cap.Circle,
+    2: Path.Cap.Square,
+    4: Path.Cap.SquareCustom,
+    }
+
+
+def _packed_layer_u32_to_pairs(values: NDArray[numpy.unsignedinteger[Any]]) -> NDArray[numpy.int16]:
+    layer = (values >> numpy.uint32(16)).astype(numpy.uint16).view(numpy.int16)
+    dtype = (values & numpy.uint32(0xffff)).astype(numpy.uint16).view(numpy.int16)
+    return numpy.stack((layer, dtype), axis=-1)
+
+
+def _packed_counts_u32_to_pairs(values: NDArray[numpy.unsignedinteger[Any]]) -> NDArray[numpy.int64]:
+    a_count = (values >> numpy.uint32(16)).astype(numpy.uint16).astype(numpy.int64)
+    b_count = (values & numpy.uint32(0xffff)).astype(numpy.uint16).astype(numpy.int64)
+    return numpy.stack((a_count, b_count), axis=-1)
+
+
+def _packed_xy_u64_to_pairs(values: NDArray[numpy.unsignedinteger[Any]]) -> NDArray[numpy.int32]:
+    xx = (values >> numpy.uint64(32)).astype(numpy.uint32).view(numpy.int32)
+    yy = (values & numpy.uint64(0xffff_ffff)).astype(numpy.uint32).view(numpy.int32)
+    return numpy.stack((xx, yy), axis=-1)
+
+
+def _local_library_filename() -> str:
+    if sys.platform.startswith('linux'):
+        return 'libklamath_rs_ext.so'
+    if sys.platform == 'darwin':
+        return 'libklamath_rs_ext.dylib'
+    if sys.platform == 'win32':
+        return 'klamath_rs_ext.dll'
+    raise OSError(f'Unsupported platform for klamath_rs_ext: {sys.platform!r}')
+
+
+def _installed_library_candidates() -> list[pathlib.Path]:
+    candidates: list[pathlib.Path] = []
+
+    try:
+        spec = importlib.util.find_spec('klamath_rs_ext.klamath_rs_ext')
+    except ModuleNotFoundError:
+        spec = None
+    if spec is not None and spec.origin is not None:
+        candidates.append(pathlib.Path(spec.origin))
+
+    try:
+        pkg_spec = importlib.util.find_spec('klamath_rs_ext')
+    except ModuleNotFoundError:
+        pkg_spec = None
+    if pkg_spec is not None and pkg_spec.submodule_search_locations is not None:
+        for location in pkg_spec.submodule_search_locations:
+            pkg_dir = pathlib.Path(location)
+            for suffix in EXTENSION_SUFFIXES:
+                candidates.extend(sorted(pkg_dir.glob(f'klamath_rs_ext*{suffix}')))
+
+    return candidates
+
+
+def _repo_library_candidates() -> list[pathlib.Path]:
+    repo_root = pathlib.Path(__file__).resolve().parents[3]
+    library_name = _local_library_filename()
+    return [
+        repo_root / 'klamath-rs' / 'target' / 'release' / library_name,
+        repo_root / 'klamath-rs' / 'target' / 'debug' / library_name,
+        ]
+
+
+def _find_klamath_rs_library() -> pathlib.Path | None:
+    env_path = os.environ.get('KLAMATH_RS_EXT_LIB')
+    if env_path:
+        candidate = pathlib.Path(env_path).expanduser()
+        if candidate.exists():
+            return candidate.resolve()
+
+    seen: set[pathlib.Path] = set()
+    for candidate in _installed_library_candidates() + _repo_library_candidates():
+        resolved = candidate.expanduser()
+        if resolved in seen:
+            continue
+        seen.add(resolved)
+        if resolved.exists():
+            return resolved.resolve()
+    return None
+
+
+def is_available() -> bool:
+    return _find_klamath_rs_library() is not None
+
+
+@cache
+def _get_clib() -> Any:
+    lib_path = _find_klamath_rs_library()
+    if lib_path is None:
+        raise ImportError(
+            'Could not locate klamath_rs_ext shared library. '
+            'Build klamath-rs with `cargo build --release --manifest-path klamath-rs/Cargo.toml` '
+            'or set KLAMATH_RS_EXT_LIB to the built library path.'
+            )
+    return ffi.dlopen(str(lib_path))
+
+
+def _read_annotations(
+        prop_offs: NDArray[numpy.integer[Any]],
+        prop_key: NDArray[numpy.integer[Any]],
+        prop_val: list[str],
+        ee: int,
+        ) -> annotations_t:
+    prop_ii, prop_ff = prop_offs[ee], prop_offs[ee + 1]
+    if prop_ii >= prop_ff:
+        return None
+    return {str(prop_key[off]): [prop_val[off]] for off in range(prop_ii, prop_ff)}
+
+
+def _read_to_arrow(
+        filename: str | pathlib.Path,
+        ) -> pyarrow.Array:
+    path = pathlib.Path(filename).expanduser().resolve()
+    ptr_array = ffi.new('struct ArrowArray[]', 1)
+    ptr_schema = ffi.new('struct ArrowSchema[]', 1)
+    if is_gzipped(path):
+        with gzip.open(path, mode='rb') as src:
+            data = src.read()
+        with tempfile.NamedTemporaryFile(suffix='.gds', delete=False) as tmp_stream:
+            tmp_stream.write(data)
+            tmp_name = tmp_stream.name
+        try:
+            _call_native(_get_clib().read_path(tmp_name.encode(), ptr_array, ptr_schema), 'read_path')
+        finally:
+            pathlib.Path(tmp_name).unlink(missing_ok=True)
+    else:
+        _call_native(_get_clib().read_path(str(path).encode(), ptr_array, ptr_schema), 'read_path')
+    return _import_arrow_array(ptr_array, ptr_schema)
+
+
+def _import_arrow_array(ptr_array: Any, ptr_schema: Any) -> pyarrow.Array:
+    iptr_schema = int(ffi.cast('uintptr_t', ptr_schema))
+    iptr_array = int(ffi.cast('uintptr_t', ptr_array))
+    return pyarrow.Array._import_from_c(iptr_array, iptr_schema)
+
+
+def _call_native(status: int, action: str) -> None:
+    if status == 0:
+        return
+
+    err_ptr = _get_clib().last_error_message()
+    if err_ptr == ffi.NULL:
+        raise KlamathError(f'{action} failed')
+
+    message = ffi.string(err_ptr).decode(errors='replace')
+    raise KlamathError(message)
+
+
+def _scan_buffer_to_arrow(buffer: bytes | mmap.mmap | memoryview) -> pyarrow.Array:
+    ptr_array = ffi.new('struct ArrowArray[]', 1)
+    ptr_schema = ffi.new('struct ArrowSchema[]', 1)
+    buf_view = memoryview(buffer)
+    cbuf = ffi.from_buffer('uint8_t[]', buf_view)
+    _call_native(_get_clib().scan_bytes(cbuf, len(buf_view), ptr_array, ptr_schema), 'scan_bytes')
+    return _import_arrow_array(ptr_array, ptr_schema)
+
+
+def _read_selected_cells_to_arrow(
+        buffer: bytes | mmap.mmap | memoryview,
+        ranges: NDArray[numpy.uint64],
+        ) -> pyarrow.Array:
+    ptr_array = ffi.new('struct ArrowArray[]', 1)
+    ptr_schema = ffi.new('struct ArrowSchema[]', 1)
+    buf_view = memoryview(buffer)
+    cbuf = ffi.from_buffer('uint8_t[]', buf_view)
+    flat_ranges = numpy.require(ranges, dtype=numpy.uint64, requirements=('C_CONTIGUOUS', 'ALIGNED'))
+    cranges = ffi.from_buffer('uint64_t[]', flat_ranges)
+    _call_native(
+        _get_clib().read_cells_bytes(cbuf, len(buf_view), cranges, int(flat_ranges.shape[0]), ptr_array, ptr_schema),
+        'read_cells_bytes',
+    )
+    return _import_arrow_array(ptr_array, ptr_schema)
+
+
+def readfile(
+        filename: str | pathlib.Path,
+        ) -> tuple[Library, dict[str, Any]]:
+    """
+    Read a GDSII file from a path into `masque.Library` / `Pattern` objects.
+
+    Will automatically decompress gzipped files.
+
+    Args:
+        filename: Filename to read.
+
+    For callers that can consume Arrow directly, prefer `readfile_arrow()`
+    to skip Python `Pattern` construction entirely.
+    """
+    arrow_arr = _read_to_arrow(filename)
+    assert len(arrow_arr) == 1
+
+    results = read_arrow(arrow_arr[0])
+
+    return results
+
+
+def readfile_arrow(
+        filename: str | pathlib.Path,
+        ) -> tuple[pyarrow.StructScalar, dict[str, Any]]:
+    """
+    Read a GDSII file into the native Arrow representation without converting
+    it into `masque.Library` / `Pattern` objects.
+
+    This is the lowest-overhead public read path exposed by this module.
+
+    Args:
+        filename: Filename to read.
+
+    Returns:
+        - Arrow struct scalar for the library payload
+        - dict of GDSII library info
+    """
+    arrow_arr = _read_to_arrow(filename)
+    assert len(arrow_arr) == 1
+    libarr = arrow_arr[0]
+    return libarr, _read_header(libarr)
+
+
+def read_arrow(
+        libarr: pyarrow.Array,
+        ) -> tuple[Library, dict[str, Any]]:
+    """
+    # TODO check GDSII file for cycles!
+    Read a gdsii file and translate it into a dict of Pattern objects. GDSII structures are
+     translated into Pattern objects; boundaries are translated into polygons, and srefs and arefs
+     are translated into Ref objects.
+
+    Additional library info is returned in a dict, containing:
+      'name': name of the library
+      'meters_per_unit': number of meters per database unit (all values are in database units)
+      'logical_units_per_unit': number of "logical" units displayed by layout tools (typically microns)
+                                per database unit
+
+    Args:
+        libarr: Arrow library payload as returned by `readfile_arrow()`.
+
+    Returns:
+        - dict of pattern_name:Patterns generated from GDSII structures
+        - dict of GDSII library info
+    """
+    library_info = _read_header(libarr)
+
+    layer_names_np = _packed_layer_u32_to_pairs(libarr['layers'].values.to_numpy())
+    layer_tups = [(int(pair[0]), int(pair[1])) for pair in layer_names_np]
+
+    cell_ids = libarr['cells'].values.field('id').to_numpy()
+    cell_names = libarr['cell_names'].as_py()
+
+    def get_geom(libarr: pyarrow.Array, geom_type: str) -> dict[str, Any]:
+        el = libarr['cells'].values.field(geom_type)
+        elem = dict(
+            offsets = el.offsets.to_numpy(),
+            xy_arr = el.values.field('xy').values.to_numpy().reshape((-1, 2)),
+            xy_off = el.values.field('xy').offsets.to_numpy() // 2,
+            layer_inds = el.values.field('layer').to_numpy(),
+            prop_off = el.values.field('properties').offsets.to_numpy(),
+            prop_key = el.values.field('properties').values.field('key').to_numpy(),
+            prop_val = el.values.field('properties').values.field('value').to_pylist(),
+            )
+        return elem
+
+    def get_boundary_batches(libarr: pyarrow.Array) -> dict[str, Any]:
+        batches = libarr['cells'].values.field('boundary_batches')
+        return dict(
+            offsets = batches.offsets.to_numpy(),
+            layer_inds = batches.values.field('layer').to_numpy(),
+            vert_arr = batches.values.field('vertices').values.to_numpy().reshape((-1, 2)),
+            vert_off = batches.values.field('vertices').offsets.to_numpy() // 2,
+            poly_off = batches.values.field('vertex_offsets').offsets.to_numpy(),
+            poly_offsets = batches.values.field('vertex_offsets').values.to_numpy(),
+            )
+
+    def get_rect_batches(libarr: pyarrow.Array) -> dict[str, Any]:
+        batches = libarr['cells'].values.field('rect_batches')
+        return dict(
+            offsets = batches.offsets.to_numpy(),
+            layer_inds = batches.values.field('layer').to_numpy(),
+            rect_arr = batches.values.field('rects').values.to_numpy().reshape((-1, 4)),
+            rect_off = batches.values.field('rects').offsets.to_numpy() // 4,
+            )
+
+    def get_boundary_props(libarr: pyarrow.Array) -> dict[str, Any]:
+        boundaries = libarr['cells'].values.field('boundary_props')
+        return dict(
+            offsets = boundaries.offsets.to_numpy(),
+            layer_inds = boundaries.values.field('layer').to_numpy(),
+            vert_arr = boundaries.values.field('vertices').values.to_numpy().reshape((-1, 2)),
+            vert_off = boundaries.values.field('vertices').offsets.to_numpy() // 2,
+            prop_off = boundaries.values.field('properties').offsets.to_numpy(),
+            prop_key = boundaries.values.field('properties').values.field('key').to_numpy(),
+            prop_val = boundaries.values.field('properties').values.field('value').to_pylist(),
+            )
+
+    def get_refs(libarr: pyarrow.Array, geom_type: str, has_repetition: bool) -> dict[str, Any]:
+        refs = libarr['cells'].values.field(geom_type)
+        values = refs.values
+        elem = dict(
+            offsets = refs.offsets.to_numpy(),
+            targets = values.field('target').to_numpy(),
+            xy = _packed_xy_u64_to_pairs(values.field('xy').to_numpy()),
+            invert_y = values.field('invert_y').to_numpy(zero_copy_only=False),
+            angle_rad = values.field('angle_rad').to_numpy(),
+            scale = values.field('scale').to_numpy(),
+            )
+        if has_repetition:
+            elem.update(dict(
+                xy0 = _packed_xy_u64_to_pairs(values.field('xy0').to_numpy()),
+                xy1 = _packed_xy_u64_to_pairs(values.field('xy1').to_numpy()),
+                counts = _packed_counts_u32_to_pairs(values.field('counts').to_numpy()),
+                ))
+        return elem
+
+    def get_ref_props(libarr: pyarrow.Array, geom_type: str, has_repetition: bool) -> dict[str, Any]:
+        refs = libarr['cells'].values.field(geom_type)
+        values = refs.values
+        elem = dict(
+            offsets = refs.offsets.to_numpy(),
+            targets = values.field('target').to_numpy(),
+            xy = _packed_xy_u64_to_pairs(values.field('xy').to_numpy()),
+            invert_y = values.field('invert_y').to_numpy(zero_copy_only=False),
+            angle_rad = values.field('angle_rad').to_numpy(),
+            scale = values.field('scale').to_numpy(),
+            prop_off = values.field('properties').offsets.to_numpy(),
+            prop_key = values.field('properties').values.field('key').to_numpy(),
+            prop_val = values.field('properties').values.field('value').to_pylist(),
+            )
+        if has_repetition:
+            elem.update(dict(
+                xy0 = _packed_xy_u64_to_pairs(values.field('xy0').to_numpy()),
+                xy1 = _packed_xy_u64_to_pairs(values.field('xy1').to_numpy()),
+                counts = _packed_counts_u32_to_pairs(values.field('counts').to_numpy()),
+                ))
+        return elem
+
+    txt = libarr['cells'].values.field('texts')
+    texts = dict(
+        offsets = txt.offsets.to_numpy(),
+        layer_inds = txt.values.field('layer').to_numpy(),
+        xy = _packed_xy_u64_to_pairs(txt.values.field('xy').to_numpy()),
+        string = txt.values.field('string').to_pylist(),
+        prop_off = txt.values.field('properties').offsets.to_numpy(),
+        prop_key = txt.values.field('properties').values.field('key').to_numpy(),
+        prop_val = txt.values.field('properties').values.field('value').to_pylist(),
+        )
+
+    elements = dict(
+        srefs = get_refs(libarr, 'srefs', has_repetition=False),
+        arefs = get_refs(libarr, 'arefs', has_repetition=True),
+        sref_props = get_ref_props(libarr, 'sref_props', has_repetition=False),
+        aref_props = get_ref_props(libarr, 'aref_props', has_repetition=True),
+        rect_batches = get_rect_batches(libarr),
+        boundary_batches = get_boundary_batches(libarr),
+        boundary_props = get_boundary_props(libarr),
+        paths = get_geom(libarr, 'paths'),
+        texts = texts,
+        )
+
+    paths = libarr['cells'].values.field('paths')
+    elements['paths'].update(dict(
+        width = paths.values.field('width').fill_null(0).to_numpy(),
+        path_type = paths.values.field('path_type').fill_null(0).to_numpy(),
+        extensions = numpy.stack((
+            paths.values.field('extension_start').fill_null(0).to_numpy(),
+            paths.values.field('extension_end').fill_null(0).to_numpy(),
+            ), axis=-1),
+        ))
+
+    global_args = dict(
+        cell_names = cell_names,
+        layer_tups = layer_tups,
+        )
+
+    mlib = Library()
+    for cc in range(len(libarr['cells'])):
+        name = cell_names[int(cell_ids[cc])]
+        pat = Pattern()
+        _rect_batches_to_rectcollections(pat, global_args, elements['rect_batches'], cc)
+        _boundary_batches_to_polygons(pat, global_args, elements['boundary_batches'], cc)
+        _boundary_props_to_polygons(pat, global_args, elements['boundary_props'], cc)
+        _gpaths_to_mpaths(pat, global_args, elements['paths'], cc)
+        _srefs_to_mrefs(pat, global_args, elements['srefs'], cc)
+        _arefs_to_mrefs(pat, global_args, elements['arefs'], cc)
+        _sref_props_to_mrefs(pat, global_args, elements['sref_props'], cc)
+        _aref_props_to_mrefs(pat, global_args, elements['aref_props'], cc)
+        _texts_to_labels(pat, global_args, elements['texts'], cc)
+        mlib[name] = pat
+
+    return mlib, library_info
+
+
+def _read_header(libarr: pyarrow.Array) -> dict[str, Any]:
+    """
+    Read the file header and create the library_info dict.
+    """
+    library_info = dict(
+        name = libarr['lib_name'].as_py(),
+        meters_per_unit = libarr['meters_per_db_unit'].as_py(),
+        logical_units_per_unit = libarr['user_units_per_db_unit'].as_py(),
+        )
+    return library_info
+
+
+def _srefs_to_mrefs(
+        pat: Pattern,
+        global_args: dict[str, Any],
+        elem: dict[str, Any],
+        cc: int,
+        ) -> None:
+    cell_names = global_args['cell_names']
+    elem_off = elem['offsets']
+    elem_count = elem_off[cc + 1] - elem_off[cc]
+    if elem_count == 0:
+        return
+
+    start = elem_off[cc]
+    stop = elem_off[cc + 1]
+    elem_targets = elem['targets'][start:stop]
+    elem_xy = elem['xy'][start:stop]
+    elem_invert_y = elem['invert_y'][start:stop]
+    elem_angle_rad = elem['angle_rad'][start:stop]
+    elem_scale = elem['scale'][start:stop]
+
+    _append_plain_refs_sorted(
+        pat=pat,
+        cell_names=cell_names,
+        elem_targets=elem_targets,
+        elem_xy=elem_xy,
+        elem_invert_y=elem_invert_y,
+        elem_angle_rad=elem_angle_rad,
+        elem_scale=elem_scale,
+        )
+
+
+def _append_plain_refs_sorted(
+        *,
+        pat: Pattern,
+        cell_names: list[str],
+        elem_targets: NDArray[numpy.integer[Any]],
+        elem_xy: NDArray[numpy.integer[Any]],
+        elem_invert_y: NDArray[numpy.bool_ | numpy.bool],
+        elem_angle_rad: NDArray[numpy.floating[Any]],
+        elem_scale: NDArray[numpy.floating[Any]],
+        ) -> None:
+    elem_count = len(elem_targets)
+    if elem_count == 0:
+        return
+
+    target_start = 0
+    while target_start < elem_count:
+        target_id = int(elem_targets[target_start])
+        target_stop = target_start + 1
+        while target_stop < elem_count and elem_targets[target_stop] == target_id:
+            target_stop += 1
+
+        append_refs = pat.refs[cell_names[target_id]].extend
+        append_refs(
+            Ref._from_raw(
+                offset=elem_xy[ee],
+                mirrored=elem_invert_y[ee],
+                rotation=elem_angle_rad[ee],
+                scale=elem_scale[ee],
+                repetition=None,
+                annotations=None,
+                )
+            for ee in range(target_start, target_stop)
+            )
+
+        target_start = target_stop
+
+
+def _arefs_to_mrefs(
+        pat: Pattern,
+        global_args: dict[str, Any],
+        elem: dict[str, Any],
+        cc: int,
+        ) -> None:
+    cell_names = global_args['cell_names']
+    elem_off = elem['offsets']
+    elem_count = elem_off[cc + 1] - elem_off[cc]
+    if elem_count == 0:
+        return
+
+    start = elem_off[cc]
+    stop = elem_off[cc + 1]
+    elem_targets = elem['targets'][start:stop]
+    elem_xy = elem['xy'][start:stop]
+    elem_invert_y = elem['invert_y'][start:stop]
+    elem_angle_rad = elem['angle_rad'][start:stop]
+    elem_scale = elem['scale'][start:stop]
+    elem_xy0 = elem['xy0'][start:stop]
+    elem_xy1 = elem['xy1'][start:stop]
+    elem_counts = elem['counts'][start:stop]
+
+    if len(elem_targets) == 0:
+        return
+
+    target = None
+    append_ref: Callable[[Ref], Any] | None = None
+    for ee in range(len(elem_targets)):
+        target_id = int(elem_targets[ee])
+        if target != target_id:
+            target = target_id
+            append_ref = pat.refs[cell_names[target_id]].append
+        assert append_ref is not None
+        a_count, b_count = elem_counts[ee]
+        append_ref(Ref._from_raw(
+            offset=elem_xy[ee],
+            mirrored=elem_invert_y[ee],
+            rotation=elem_angle_rad[ee],
+            scale=elem_scale[ee],
+            repetition=Grid._from_raw(a_vector=elem_xy0[ee], b_vector=elem_xy1[ee], a_count=a_count, b_count=b_count),
+            annotations=None,
+            ))
+
+
+def _sref_props_to_mrefs(
+        pat: Pattern,
+        global_args: dict[str, Any],
+        elem: dict[str, Any],
+        cc: int,
+        ) -> None:
+    cell_names = global_args['cell_names']
+    elem_off = elem['offsets']
+    prop_key = elem['prop_key']
+    prop_val = elem['prop_val']
+
+    elem_count = elem_off[cc + 1] - elem_off[cc]
+    if elem_count == 0:
+        return
+
+    elem_slc = slice(elem_off[cc], elem_off[cc] + elem_count + 1)
+    prop_offs = elem['prop_off'][elem_slc]
+    elem_targets = elem['targets'][elem_off[cc]:elem_off[cc + 1]]
+    elem_xy = elem['xy'][elem_off[cc]:elem_off[cc + 1]]
+    elem_invert_y = elem['invert_y'][elem_off[cc]:elem_off[cc + 1]]
+    elem_angle_rad = elem['angle_rad'][elem_off[cc]:elem_off[cc + 1]]
+    elem_scale = elem['scale'][elem_off[cc]:elem_off[cc + 1]]
+
+    for ee in range(elem_count):
+        annotations = _read_annotations(prop_offs, prop_key, prop_val, ee)
+        ref = Ref._from_raw(
+            offset=elem_xy[ee],
+            mirrored=elem_invert_y[ee],
+            rotation=elem_angle_rad[ee],
+            scale=elem_scale[ee],
+            repetition=None,
+            annotations=annotations,
+            )
+        pat.refs[cell_names[int(elem_targets[ee])]].append(ref)
+
+
+def _aref_props_to_mrefs(
+        pat: Pattern,
+        global_args: dict[str, Any],
+        elem: dict[str, Any],
+        cc: int,
+        ) -> None:
+    cell_names = global_args['cell_names']
+    elem_off = elem['offsets']
+    prop_key = elem['prop_key']
+    prop_val = elem['prop_val']
+
+    elem_count = elem_off[cc + 1] - elem_off[cc]
+    if elem_count == 0:
+        return
+
+    elem_slc = slice(elem_off[cc], elem_off[cc] + elem_count + 1)
+    prop_offs = elem['prop_off'][elem_slc]
+    elem_targets = elem['targets'][elem_off[cc]:elem_off[cc + 1]]
+    elem_xy = elem['xy'][elem_off[cc]:elem_off[cc + 1]]
+    elem_invert_y = elem['invert_y'][elem_off[cc]:elem_off[cc + 1]]
+    elem_angle_rad = elem['angle_rad'][elem_off[cc]:elem_off[cc + 1]]
+    elem_scale = elem['scale'][elem_off[cc]:elem_off[cc + 1]]
+    elem_xy0 = elem['xy0'][elem_off[cc]:elem_off[cc + 1]]
+    elem_xy1 = elem['xy1'][elem_off[cc]:elem_off[cc + 1]]
+    elem_counts = elem['counts'][elem_off[cc]:elem_off[cc + 1]]
+
+    for ee in range(elem_count):
+        a_count, b_count = elem_counts[ee]
+        annotations = _read_annotations(prop_offs, prop_key, prop_val, ee)
+        ref = Ref._from_raw(
+            offset=elem_xy[ee],
+            mirrored=elem_invert_y[ee],
+            rotation=elem_angle_rad[ee],
+            scale=elem_scale[ee],
+            repetition=Grid._from_raw(a_vector=elem_xy0[ee], b_vector=elem_xy1[ee], a_count=a_count, b_count=b_count),
+            annotations=annotations,
+            )
+        pat.refs[cell_names[int(elem_targets[ee])]].append(ref)
+
+
+def _texts_to_labels(
+        pat: Pattern,
+        global_args: dict[str, Any],
+        elem: dict[str, Any],
+        cc: int,
+        ) -> None:
+    elem_off = elem['offsets']      # which elements belong to each cell
+    xy = elem['xy']
+    layer_tups = global_args['layer_tups']
+    layer_inds = elem['layer_inds']
+    prop_key = elem['prop_key']
+    prop_val = elem['prop_val']
+
+    elem_count = elem_off[cc + 1] - elem_off[cc]
+    elem_slc = slice(elem_off[cc], elem_off[cc] + elem_count + 1)   # +1 to capture ending location for last elem
+    prop_offs = elem['prop_off'][elem_slc]  # which props belong to each element
+    elem_xy = xy[elem_slc][:elem_count]
+    elem_layer_inds = layer_inds[elem_slc][:elem_count]
+    elem_strings = elem['string'][elem_slc][:elem_count]
+
+    for ee in range(elem_count):
+        layer = layer_tups[int(elem_layer_inds[ee])]
+        offset = elem_xy[ee]
+        string = elem_strings[ee]
+
+        annotations = _read_annotations(prop_offs, prop_key, prop_val, ee)
+        mlabel = Label._from_raw(string=string, offset=offset, annotations=annotations)
+        pat.labels[layer].append(mlabel)
+
+
+def _gpaths_to_mpaths(
+        pat: Pattern,
+        global_args: dict[str, Any],
+        elem: dict[str, Any],
+        cc: int,
+        ) -> None:
+    elem_off = elem['offsets']      # which elements belong to each cell
+    xy_val = elem['xy_arr']
+    layer_tups = global_args['layer_tups']
+    layer_inds = elem['layer_inds']
+    prop_key = elem['prop_key']
+    prop_val = elem['prop_val']
+
+    elem_count = elem_off[cc + 1] - elem_off[cc]
+    elem_slc = slice(elem_off[cc], elem_off[cc] + elem_count + 1)   # +1 to capture ending location for last elem
+    xy_offs = elem['xy_off'][elem_slc]      # which xy coords belong to each element
+    prop_offs = elem['prop_off'][elem_slc]  # which props belong to each element
+    elem_layer_inds = layer_inds[elem_slc][:elem_count]
+    elem_widths = elem['width'][elem_slc][:elem_count]
+    elem_path_types = elem['path_type'][elem_slc][:elem_count]
+    elem_extensions = elem['extensions'][elem_slc][:elem_count]
+
+    for ee in range(elem_count):
+        layer = layer_tups[int(elem_layer_inds[ee])]
+        vertices = xy_val[xy_offs[ee]:xy_offs[ee + 1]]
+        width = elem_widths[ee]
+        cap_int = int(elem_path_types[ee])
+        if cap_int not in _PATH_CAP_MAP:
+            raise PatternError(f'Unrecognized path type: {cap_int}')
+        cap = _PATH_CAP_MAP[cap_int]
+        if cap_int == 4:
+            cap_extensions = elem_extensions[ee]
+        else:
+            cap_extensions = None
+
+        annotations = _read_annotations(prop_offs, prop_key, prop_val, ee)
+        path = Path._from_raw(
+            vertices=vertices,
+            width=width,
+            cap=cap,
+            cap_extensions=cap_extensions,
+            annotations=annotations,
+            )
+        pat.shapes[layer].append(path)
+
+
+def _boundary_batches_to_polygons(
+        pat: Pattern,
+        global_args: dict[str, Any],
+        elem: dict[str, Any],
+        cc: int,
+        ) -> None:
+    elem_off = elem['offsets']      # which elements belong to each cell
+    vert_arr = elem['vert_arr']
+    vert_off = elem['vert_off']
+    layer_inds = elem['layer_inds']
+    layer_tups = global_args['layer_tups']
+    poly_off = elem['poly_off']
+    poly_offsets = elem['poly_offsets']
+
+    batch_count = elem_off[cc + 1] - elem_off[cc]
+    if batch_count == 0:
+        return
+
+    elem_slc = slice(elem_off[cc], elem_off[cc] + batch_count + 1)   # +1 to capture ending location for last elem
+    elem_vert_off = vert_off[elem_slc]
+    elem_poly_off = poly_off[elem_slc]
+    elem_layer_inds = layer_inds[elem_slc][:batch_count]
+
+    for bb in range(batch_count):
+        layer = layer_tups[int(elem_layer_inds[bb])]
+        vertices = vert_arr[elem_vert_off[bb]:elem_vert_off[bb + 1]]
+        vertex_offsets = poly_offsets[elem_poly_off[bb]:elem_poly_off[bb + 1]]
+
+        if vertex_offsets.size == 1:
+            poly = Polygon._from_raw(vertices=vertices, annotations=None)
+            pat.shapes[layer].append(poly)
+        else:
+            polys = PolyCollection._from_raw(vertex_lists=vertices, vertex_offsets=vertex_offsets, annotations=None)
+            pat.shapes[layer].append(polys)
+
+
+def _rect_batches_to_rectcollections(
+        pat: Pattern,
+        global_args: dict[str, Any],
+        elem: dict[str, Any],
+        cc: int,
+        ) -> None:
+    elem_off = elem['offsets']
+    rect_arr = elem['rect_arr']
+    rect_off = elem['rect_off']
+    layer_inds = elem['layer_inds']
+    layer_tups = global_args['layer_tups']
+
+    batch_count = elem_off[cc + 1] - elem_off[cc]
+    if batch_count == 0:
+        return
+
+    elem_slc = slice(elem_off[cc], elem_off[cc] + batch_count + 1)
+    elem_rect_off = rect_off[elem_slc]
+    elem_layer_inds = layer_inds[elem_slc][:batch_count]
+
+    for bb in range(batch_count):
+        layer = layer_tups[int(elem_layer_inds[bb])]
+        rects = rect_arr[elem_rect_off[bb]:elem_rect_off[bb + 1]]
+        rect_collection = RectCollection._from_raw(rects=rects, annotations=None)
+        pat.shapes[layer].append(rect_collection)
+
+
+def _boundary_props_to_polygons(
+        pat: Pattern,
+        global_args: dict[str, Any],
+        elem: dict[str, Any],
+        cc: int,
+        ) -> None:
+    elem_off = elem['offsets']
+    vert_arr = elem['vert_arr']
+    vert_off = elem['vert_off']
+    layer_inds = elem['layer_inds']
+    layer_tups = global_args['layer_tups']
+    prop_key = elem['prop_key']
+    prop_val = elem['prop_val']
+
+    elem_count = elem_off[cc + 1] - elem_off[cc]
+    if elem_count == 0:
+        return
+
+    elem_slc = slice(elem_off[cc], elem_off[cc] + elem_count + 1)
+    elem_vert_off = vert_off[elem_slc]
+    prop_offs = elem['prop_off'][elem_slc]
+    elem_layer_inds = layer_inds[elem_slc][:elem_count]
+
+    for ee in range(elem_count):
+        layer = layer_tups[int(elem_layer_inds[ee])]
+        vertices = vert_arr[elem_vert_off[ee]:elem_vert_off[ee + 1]]
+        annotations = _read_annotations(prop_offs, prop_key, prop_val, ee)
+        poly = Polygon._from_raw(vertices=vertices, annotations=annotations)
+        pat.shapes[layer].append(poly)

masque/file/gdsii/klamath.py

@@ -19,11 +19,9 @@ Notes:
  * GDS creation/modification/access times are set to 1900-01-01 for reproducibility.
  * Gzip modification time is set to 0 (start of current epoch, usually 1970-01-01)
 """
-from typing import IO, cast, Any
+from typing import IO, Any
 from collections.abc import Iterable, Mapping, Callable
 from types import MappingProxyType
-import io
-import mmap
 import logging
 import pathlib
 import gzip
@@ -35,79 +33,37 @@ from numpy.typing import ArrayLike, NDArray
 import klamath
 from klamath import records
 
-from .utils import is_gzipped, tmpfile
-from .. import Pattern, Ref, PatternError, LibraryError, Label, Shape
-from ..shapes import Polygon, Path
-from ..repetition import Grid
-from ..utils import layer_t, annotations_t
-from ..library import LazyLibrary, Library, ILibrary, ILibraryView
+from ..utils import is_gzipped
+from ... import Pattern, Ref, PatternError, LibraryError, Label, Shape
+from ...shapes import Polygon, Path, RectCollection
+from ...repetition import Grid
+from ...utils import layer_t, annotations_t
+from ...library import Library
 
 
 logger = logging.getLogger(__name__)
 
 
-path_cap_map = {
+_PATH_CAP_MAP = {
     0: Path.Cap.Flush,
     1: Path.Cap.Circle,
     2: Path.Cap.Square,
     4: Path.Cap.SquareCustom,
     }
 
-RO_EMPTY_DICT: Mapping[int, bytes] = MappingProxyType({})
+_EMPTY_PROPERTIES: Mapping[int, bytes] = MappingProxyType({})
 
 
-def rint_cast(val: ArrayLike) -> NDArray[numpy.int32]:
+def _rint_cast(val: ArrayLike) -> NDArray[numpy.int32]:
     return numpy.rint(val).astype(numpy.int32)
 
 
-def write(
-        library: Mapping[str, Pattern],
+def _write_header(
         stream: IO[bytes],
         meters_per_unit: float,
-        logical_units_per_unit: float = 1,
-        library_name: str = 'masque-klamath',
+        logical_units_per_unit: float,
+        library_name: str,
         ) -> None:
-    """
-    Convert a library to a GDSII stream, mapping data as follows:
-         Pattern -> GDSII structure
-         Ref -> GDSII SREF or AREF
-         Path -> GSDII path
-         Shape (other than path) -> GDSII boundary/ies
-         Label -> GDSII text
-         annnotations -> properties, where possible
-
-     For each shape,
-        layer is chosen to be equal to `shape.layer` if it is an int,
-            or `shape.layer[0]` if it is a tuple
-        datatype is chosen to be `shape.layer[1]` if available,
-            otherwise `0`
-
-    GDS does not support shape repetition (only cell repeptition). Please call
-    `library.wrap_repeated_shapes()` before writing to file.
-
-    Other functions you may want to call:
-        - `masque.file.gdsii.check_valid_names(library.keys())` to check for invalid names
-        - `library.dangling_refs()` to check for references to missing patterns
-        - `pattern.polygonize()` for any patterns with shapes other
-            than `masque.shapes.Polygon` or `masque.shapes.Path`
-
-    Args:
-        library: A {name: Pattern} mapping of patterns to write.
-        meters_per_unit: Written into the GDSII file, meters per (database) length unit.
-            All distances are assumed to be an integer multiple of this unit, and are stored as such.
-        logical_units_per_unit: Written into the GDSII file. Allows the GDSII to specify a
-            "logical" unit which is different from the "database" unit, for display purposes.
-            Default `1`.
-        library_name: Library name written into the GDSII file.
-            Default 'masque-klamath'.
-    """
-    if not isinstance(library, ILibrary):
-        if isinstance(library, dict):
-            library = Library(library)
-        else:
-            library = Library(dict(library))
-
-    # Create library
     header = klamath.library.FileHeader(
         name=library_name.encode('ASCII'),
         user_units_per_db_unit=logical_units_per_unit,
@@ -115,51 +71,19 @@ def write(
         )
     header.write(stream)
 
-    # Now create a structure for each pattern, and add in any Boundary and SREF elements
-    for name, pat in library.items():
+
+def _write_pattern_struct(stream: IO[bytes], name: str, pat: Pattern) -> None:
     elements: list[klamath.elements.Element] = []
     elements += _shapes_to_elements(pat.shapes)
     elements += _labels_to_texts(pat.labels)
     elements += _mrefs_to_grefs(pat.refs)
-
     klamath.library.write_struct(stream, name=name.encode('ASCII'), elements=elements)
+
+
+def _write_footer(stream: IO[bytes]) -> None:
     records.ENDLIB.write(stream, None)
 
 
-def writefile(
-        library: Mapping[str, Pattern],
-        filename: str | pathlib.Path,
-        *args,
-        **kwargs,
-        ) -> None:
-    """
-    Wrapper for `write()` that takes a filename or path instead of a stream.
-
-    Will automatically compress the file if it has a .gz suffix.
-
-    Args:
-        library: {name: Pattern} pairs to save.
-        filename: Filename to save to.
-        *args: passed to `write()`
-        **kwargs: passed to `write()`
-    """
-    path = pathlib.Path(filename)
-
-    with tmpfile(path) as base_stream:
-        streams: tuple[Any, ...] = (base_stream,)
-        if path.suffix == '.gz':
-            stream = cast('IO[bytes]', gzip.GzipFile(filename='', mtime=0, fileobj=base_stream, mode='wb', compresslevel=6))
-            streams = (stream,) + streams
-        else:
-            stream = base_stream
-
-        try:
-            write(library, stream, *args, **kwargs)
-        finally:
-            for ss in streams:
-                ss.close()
-
-
 def readfile(
         filename: str | pathlib.Path,
         *args,
@@ -216,7 +140,7 @@ def read(
     found_struct = records.BGNSTR.skip_past(stream)
     while found_struct:
         name = records.STRNAME.skip_and_read(stream)
-        pat = read_elements(stream, raw_mode=raw_mode)
+        pat = _read_elements(stream, raw_mode=raw_mode)
         mlib[name.decode('ASCII')] = pat
         found_struct = records.BGNSTR.skip_past(stream)
 
@@ -236,7 +160,7 @@ def _read_header(stream: IO[bytes]) -> dict[str, Any]:
     return library_info
 
 
-def read_elements(
+def _read_elements(
         stream: IO[bytes],
         raw_mode: bool = True,
         ) -> Pattern:
@@ -318,31 +242,45 @@ def _gref_to_mref(ref: klamath.library.Reference) -> tuple[str, Ref]:
 
 
 def _gpath_to_mpath(gpath: klamath.library.Path, raw_mode: bool) -> tuple[layer_t, Path]:
-    if gpath.path_type in path_cap_map:
-        cap = path_cap_map[gpath.path_type]
+    if gpath.path_type in _PATH_CAP_MAP:
+        cap = _PATH_CAP_MAP[gpath.path_type]
     else:
         raise PatternError(f'Unrecognized path type: {gpath.path_type}')
 
-    mpath = Path(
-        vertices=gpath.xy.astype(float),
+    vertices = gpath.xy.astype(float)
+    annotations = _properties_to_annotations(gpath.properties)
+    cap_extensions = None
+    if cap == Path.Cap.SquareCustom:
+        cap_extensions = numpy.asarray(gpath.extension, dtype=float)
+
+    if raw_mode:
+        mpath = Path._from_raw(
+            vertices=vertices,
             width=gpath.width,
             cap=cap,
+            cap_extensions=cap_extensions,
+            annotations=annotations,
+            )
+    else:
+        mpath = Path(
+            vertices=vertices,
+            width=gpath.width,
+            cap=cap,
+            cap_extensions=cap_extensions,
             offset=numpy.zeros(2),
-        annotations=_properties_to_annotations(gpath.properties),
-        raw=raw_mode,
+            annotations=annotations,
             )
-    if cap == Path.Cap.SquareCustom:
-        mpath.cap_extensions = gpath.extension
     return gpath.layer, mpath
 
 
 def _boundary_to_polygon(boundary: klamath.library.Boundary, raw_mode: bool) -> tuple[layer_t, Polygon]:
-    return boundary.layer, Polygon(
-        vertices=boundary.xy[:-1].astype(float),
-        offset=numpy.zeros(2),
-        annotations=_properties_to_annotations(boundary.properties),
-        raw=raw_mode,
-        )
+    vertices = boundary.xy[:-1].astype(float)
+    annotations = _properties_to_annotations(boundary.properties)
+    if raw_mode:
+        poly = Polygon._from_raw(vertices=vertices, annotations=annotations)
+    else:
+        poly = Polygon(vertices=vertices, offset=numpy.zeros(2), annotations=annotations)
+    return boundary.layer, poly
 
 
 def _mrefs_to_grefs(refs: dict[str | None, list[Ref]]) -> list[klamath.library.Reference]:
@@ -367,7 +305,7 @@ def _mrefs_to_grefs(refs: dict[str | None, list[Ref]]) -> list[klamath.library.R
                     ])
                 aref = klamath.library.Reference(
                     struct_name=encoded_name,
-                    xy=rint_cast(xy),
+                    xy=_rint_cast(xy),
                     colrow=(numpy.rint(rep.a_count), numpy.rint(rep.b_count)),
                     angle_deg=angle_deg,
                     invert_y=ref.mirrored,
@@ -378,7 +316,7 @@ def _mrefs_to_grefs(refs: dict[str | None, list[Ref]]) -> list[klamath.library.R
             elif rep is None:
                 sref = klamath.library.Reference(
                     struct_name=encoded_name,
-                    xy=rint_cast([ref.offset]),
+                    xy=_rint_cast([ref.offset]),
                     colrow=None,
                     angle_deg=angle_deg,
                     invert_y=ref.mirrored,
@@ -390,7 +328,7 @@ def _mrefs_to_grefs(refs: dict[str | None, list[Ref]]) -> list[klamath.library.R
                 new_srefs = [
                     klamath.library.Reference(
                         struct_name=encoded_name,
-                        xy=rint_cast([ref.offset + dd]),
+                        xy=_rint_cast([ref.offset + dd]),
                         colrow=None,
                         angle_deg=angle_deg,
                         invert_y=ref.mirrored,
@@ -410,7 +348,7 @@ def _properties_to_annotations(properties: Mapping[int, bytes]) -> annotations_t
 
 def _annotations_to_properties(annotations: annotations_t, max_len: int = 126) -> Mapping[int, bytes]:
     if annotations is None:
-        return RO_EMPTY_DICT
+        return _EMPTY_PROPERTIES
     cum_len = 0
     props = {}
     for key, vals in annotations.items():
@@ -447,13 +385,13 @@ def _shapes_to_elements(
 
             properties = _annotations_to_properties(shape.annotations, 128)
             if isinstance(shape, Path) and not polygonize_paths:
-                xy = rint_cast(shape.vertices + shape.offset)
-                width = rint_cast(shape.width)
-                path_type = next(k for k, v in path_cap_map.items() if v == shape.cap)    # reverse lookup
+                xy = _rint_cast(shape.vertices + shape.offset)
+                width = _rint_cast(shape.width)
+                path_type = next(k for k, v in _PATH_CAP_MAP.items() if v == shape.cap)    # reverse lookup
 
                 extension: tuple[int, int]
                 if shape.cap == Path.Cap.SquareCustom and shape.cap_extensions is not None:
-                    extension = tuple(shape.cap_extensions)     # type: ignore
+                    extension = tuple(_rint_cast(shape.cap_extensions))
                 else:
                     extension = (0, 0)
 
@@ -466,6 +404,20 @@ def _shapes_to_elements(
                     properties=properties,
                     )
                 elements.append(path)
+            elif isinstance(shape, RectCollection):
+                for rect in shape.rects:
+                    xy_closed = numpy.empty((5, 2), dtype=numpy.int32)
+                    xy_closed[0] = _rint_cast((rect[0], rect[1]))
+                    xy_closed[1] = _rint_cast((rect[0], rect[3]))
+                    xy_closed[2] = _rint_cast((rect[2], rect[3]))
+                    xy_closed[3] = _rint_cast((rect[2], rect[1]))
+                    xy_closed[4] = xy_closed[0]
+                    boundary = klamath.elements.Boundary(
+                        layer=(layer, data_type),
+                        xy=xy_closed,
+                        properties=properties,
+                        )
+                    elements.append(boundary)
             elif isinstance(shape, Polygon):
                 polygon = shape
                 xy_closed = numpy.empty((polygon.vertices.shape[0] + 1, 2), dtype=numpy.int32)
@@ -497,7 +449,7 @@ def _labels_to_texts(labels: dict[layer_t, list[Label]]) -> list[klamath.element
         layer, text_type = _mlayer2gds(mlayer)
         for label in lseq:
             properties = _annotations_to_properties(label.annotations, 128)
-            xy = rint_cast([label.offset])
+            xy = _rint_cast([label.offset])
             text = klamath.elements.Text(
                 layer=(layer, text_type),
                 xy=xy,
@@ -514,112 +466,6 @@ def _labels_to_texts(labels: dict[layer_t, list[Label]]) -> list[klamath.element
     return texts
 
 
-def load_library(
-        stream: IO[bytes],
-        *,
-        full_load: bool = False,
-        postprocess: Callable[[ILibraryView, str, Pattern], Pattern] | None = None
-        ) -> tuple[LazyLibrary, dict[str, Any]]:
-    """
-    Scan a GDSII stream to determine what structures are present, and create
-        a library from them. This enables deferred reading of structures
-        on an as-needed basis.
-    All structures are loaded as secondary
-
-    Args:
-        stream: Seekable stream. Position 0 should be the start of the file.
-            The caller should leave the stream open while the library
-            is still in use, since the library will need to access it
-            in order to read the structure contents.
-        full_load: If True, force all structures to be read immediately rather
-            than as-needed. Since data is read sequentially from the file, this
-            will be faster than using the resulting library's `precache` method.
-        postprocess: If given, this function is used to post-process each
-            pattern *upon first load only*.
-
-    Returns:
-        LazyLibrary object, allowing for deferred load of structures.
-        Additional library info (dict, same format as from `read`).
-    """
-    stream.seek(0)
-    lib = LazyLibrary()
-
-    if full_load:
-        # Full load approach (immediately load everything)
-        patterns, library_info = read(stream)
-        for name, pattern in patterns.items():
-            if postprocess is not None:
-                lib[name] = postprocess(lib, name, pattern)
-            else:
-                lib[name] = pattern
-        return lib, library_info
-
-    # Normal approach (scan and defer load)
-    library_info = _read_header(stream)
-    structs = klamath.library.scan_structs(stream)
-
-    for name_bytes, pos in structs.items():
-        name = name_bytes.decode('ASCII')
-
-        def mkstruct(pos: int = pos, name: str = name) -> Pattern:
-            stream.seek(pos)
-            pat = read_elements(stream, raw_mode=True)
-            if postprocess is not None:
-                pat = postprocess(lib, name, pat)
-            return pat
-
-        lib[name] = mkstruct
-
-    return lib, library_info
-
-
-def load_libraryfile(
-        filename: str | pathlib.Path,
-        *,
-        use_mmap: bool = True,
-        full_load: bool = False,
-        postprocess: Callable[[ILibraryView, str, Pattern], Pattern] | None = None
-        ) -> tuple[LazyLibrary, dict[str, Any]]:
-    """
-    Wrapper for `load_library()` that takes a filename or path instead of a stream.
-
-    Will automatically decompress the file if it is gzipped.
-
-    NOTE that any streams/mmaps opened will remain open until ALL of the
-     `PatternGenerator` objects in the library are garbage collected.
-
-    Args:
-        path: filename or path to read from
-        use_mmap: If `True`, will attempt to memory-map the file instead
-                  of buffering. In the case of gzipped files, the file
-                  is decompressed into a python `bytes` object in memory
-                  and reopened as an `io.BytesIO` stream.
-        full_load: If `True`, immediately loads all data. See `load_library`.
-        postprocess: Passed to `load_library`
-
-    Returns:
-        LazyLibrary object, allowing for deferred load of structures.
-        Additional library info (dict, same format as from `read`).
-    """
-    path = pathlib.Path(filename)
-    stream: IO[bytes]
-    if is_gzipped(path):
-        if use_mmap:
-            logger.info('Asked to mmap a gzipped file, reading into memory instead...')
-            gz_stream = gzip.open(path, mode='rb')      # noqa: SIM115
-            stream = io.BytesIO(gz_stream.read())       # type: ignore
-        else:
-            gz_stream = gzip.open(path, mode='rb')      # noqa: SIM115
-            stream = io.BufferedReader(gz_stream)       # type: ignore
-    else:       # noqa: PLR5501
-        if use_mmap:
-            base_stream = path.open(mode='rb', buffering=0)                         # noqa: SIM115
-            stream = mmap.mmap(base_stream.fileno(), 0, access=mmap.ACCESS_READ)    # type: ignore
-        else:
-            stream = path.open(mode='rb')          # noqa: SIM115
-    return load_library(stream, full_load=full_load, postprocess=postprocess)
-
-
 def check_valid_names(
         names: Iterable[str],
         max_length: int = 32,
@@ -632,6 +478,7 @@ def check_valid_names(
         max_length: Max allowed length
 
     """
+    names = tuple(names)
     allowed_chars = set(string.ascii_letters + string.digits + '_?$')
 
     bad_chars = [
@@ -648,7 +495,7 @@ def check_valid_names(
         logger.error('Names contain invalid characters:\n' + pformat(bad_chars))
 
     if bad_lengths:
-        logger.error(f'Names too long (>{max_length}:\n' + pformat(bad_chars))
+        logger.error(f'Names too long (>{max_length}):\n' + pformat(bad_lengths))
 
     if bad_chars or bad_lengths:
         raise LibraryError('Library contains invalid names, see log above')

masque/file/gdsii/lazy.py

@@ -0,0 +1,288 @@
+"""
+Classic source-backed lazy GDSII reader built on the pure-python klamath path.
+
+This module provides the non-Arrow half of Masque's lazy GDS architecture:
+
+- `GdsLibrarySource` scans a GDS stream once to discover library metadata,
+  struct order, and child edges without materializing every cell.
+- cells are materialized on demand through the classic `gdsii` decoder
+  whenever a caller indexes the lazy view
+- untouched cells can be copied directly to another GDS file without
+  materializing them
+- the source can be wrapped in `PortLoadView` or merged through
+  `OverlayLibrary`
+
+The public surface intentionally parallels `gdsii.lazy_arrow` closely so that
+callers can swap between the classic and Arrow-backed implementations with
+minimal changes.
+"""
+from __future__ import annotations
+
+from dataclasses import dataclass
+from typing import IO, TYPE_CHECKING, Any, cast
+import gzip
+import io
+import logging
+import mmap
+import pathlib
+
+import klamath
+from klamath import records
+
+from . import klamath as gdsii_klamath
+from ..utils import is_gzipped
+from ...error import LibraryError
+from ...library import (
+    ILibraryView,
+    IMaterializable,
+    LibraryView,
+)
+
+if TYPE_CHECKING:
+    from collections.abc import Iterator, Sequence
+
+    import numpy
+    from numpy.typing import NDArray
+
+    from ...pattern import Pattern
+
+
+logger = logging.getLogger(__name__)
+
+
+@dataclass
+class _SourceHandle:
+    """ Owns the underlying stream and any companion file handle for a source. """
+    path: pathlib.Path | None
+    stream: IO[bytes]
+    handle: IO[bytes] | None = None
+
+    def close(self) -> None:
+        self.stream.close()
+        if self.handle is not None and self.handle is not self.stream:
+            self.handle.close()
+            self.handle = None
+
+
+@dataclass(frozen=True)
+class _CellScan:
+    """ Scan-time metadata for one cell in the source stream. """
+    offset: int
+    struct_start: int
+    struct_end: int
+    children: set[str]
+
+
+def _open_source_stream(
+        filename: str | pathlib.Path,
+        *,
+        use_mmap: bool,
+        ) -> _SourceHandle:
+    path = pathlib.Path(filename).expanduser().resolve()
+    if is_gzipped(path):
+        if use_mmap:
+            logger.info('Asked to mmap a gzipped file, reading into memory instead...')
+            with gzip.open(path, mode='rb') as gzip_stream:
+                data = gzip_stream.read()
+            return _SourceHandle(path=path, stream=io.BytesIO(data))
+        source_stream = cast('IO[bytes]', gzip.open(path, mode='rb'))      # noqa: SIM115
+        return _SourceHandle(path=path, stream=source_stream)
+
+    if use_mmap:
+        handle = path.open(mode='rb', buffering=0)
+        mapped = cast('IO[bytes]', mmap.mmap(handle.fileno(), 0, access=mmap.ACCESS_READ))
+        return _SourceHandle(path=path, stream=mapped, handle=handle)
+
+    source_stream = path.open(mode='rb')
+    return _SourceHandle(path=path, stream=source_stream)
+
+
+def _scan_library(
+        stream: IO[bytes],
+        ) -> tuple[dict[str, Any], list[str], dict[str, _CellScan]]:
+    library_info = gdsii_klamath._read_header(stream)
+    order: list[str] = []
+    cells: dict[str, _CellScan] = {}
+
+    while True:
+        struct_start = stream.tell()
+        if not records.BGNSTR.skip_past(stream):
+            break
+        name = records.STRNAME.skip_and_read(stream).decode('ASCII')
+        offset = stream.tell()
+        elements = klamath.library.read_elements(stream)
+        struct_end = stream.tell()
+        children = {
+            element.struct_name.decode('ASCII')
+            for element in elements
+            if isinstance(element, klamath.elements.Reference)
+        }
+        order.append(name)
+        cells[name] = _CellScan(
+            offset=offset,
+            struct_start=struct_start,
+            struct_end=struct_end,
+            children=children,
+            )
+
+    return library_info, order, cells
+
+
+class GdsLibrarySource(ILibraryView, IMaterializable):
+    """
+    Read-only library backed by a seekable GDS stream.
+
+    Cells are scanned once up front to discover order, byte ranges, and child
+    edges. Untouched structures can be copied directly, while accessed cells
+    are materialized through the classic GDS decoder.
+
+    The source owns the stream lifetime, preserves on-disk ordering through
+    `source_order()`, and answers graph queries from scan metadata whenever
+    possible so callers can inspect hierarchy without forcing a full load.
+    """
+
+    def __init__(
+            self,
+            *,
+            source: _SourceHandle,
+            library_info: dict[str, Any],
+            cell_order: Sequence[str],
+            cells: dict[str, _CellScan],
+            ) -> None:
+        self.path = source.path
+        self.library_info = library_info
+        self._source = source
+        self._cell_order = tuple(cell_order)
+        self._cells = cells
+        self._cache: dict[str, Pattern] = {}
+        self._lookups_in_progress: list[str] = []
+
+    @classmethod
+    def from_file(
+            cls,
+            filename: str | pathlib.Path,
+            *,
+            use_mmap: bool = True,
+            ) -> GdsLibrarySource:
+        source = _open_source_stream(filename, use_mmap=use_mmap)
+        source.stream.seek(0)
+        library_info, cell_order, cells = _scan_library(source.stream)
+        return cls(source=source, library_info=library_info, cell_order=cell_order, cells=cells)
+
+    def __getitem__(self, key: str) -> Pattern:
+        return self.materialize(key, persist=True)
+
+    def __iter__(self) -> Iterator[str]:
+        return iter(self._cell_order)
+
+    def __len__(self) -> int:
+        return len(self._cell_order)
+
+    def __contains__(self, key: object) -> bool:
+        return key in self._cells
+
+    def source_order(self) -> tuple[str, ...]:
+        return self._cell_order
+
+    def can_copy_raw_struct(self, name: str) -> bool:
+        """Return whether `name` still matches its original GDS structure."""
+        return name in self._cells and name not in self._cache
+
+    def raw_struct_bytes(self, name: str) -> bytes:
+        """Read the original complete GDS structure for `name`."""
+        cell = self._cells[name]
+        stream = self._source.stream
+        stream.seek(cell.struct_start)
+        data = stream.read(cell.struct_end - cell.struct_start)
+        if len(data) != cell.struct_end - cell.struct_start:
+            raise LibraryError(f'Unexpected end of GDS source while copying structure {name!r}')
+        return data
+
+    def _decode_pattern(self, name: str) -> Pattern:
+        if name not in self._cells:
+            raise KeyError(name)
+
+        if name in self._lookups_in_progress:
+            chain = ' -> '.join(self._lookups_in_progress + [name])
+            raise LibraryError(
+                f'Detected circular reference or recursive lookup of "{name}".\n'
+                f'Lookup chain: {chain}\n'
+                'This may be caused by an invalid (cyclical) reference, or buggy code.\n'
+                'If you are lazy-loading a file, try a non-lazy load and check for reference cycles.'
+                )
+
+        self._lookups_in_progress.append(name)
+        try:
+            self._source.stream.seek(self._cells[name].offset)
+            pat = gdsii_klamath._read_elements(self._source.stream, raw_mode=True)
+        finally:
+            self._lookups_in_progress.pop()
+
+        return pat
+
+    def materialize(self, name: str, *, persist: bool = True) -> Pattern:
+        if name in self._cache:
+            return self._cache[name]
+
+        pat = self._decode_pattern(name)
+
+        if persist:
+            self._cache[name] = pat
+        return pat
+
+    def materialize_detached(self, name: str) -> Pattern:
+        if name in self._cache:
+            return self._cache[name].deepcopy()
+        return self._decode_pattern(name)
+
+    def materialize_many_detached(
+            self,
+            names: Sequence[str],
+            ) -> LibraryView:
+        return LibraryView({
+            name: self.materialize_detached(name)
+            for name in dict.fromkeys(names)
+            })
+
+    def _raw_children(self, name: str) -> set[str]:
+        if name in self._cache:
+            return super()._raw_children(name)
+        return set(self._cells[name].children)
+
+    def _raw_ref_transforms(
+            self,
+            parent: str,
+            target: str,
+            ) -> list[NDArray[numpy.float64]]:
+        if parent in self._cache:
+            return super()._raw_ref_transforms(parent, target)
+        pat = self.materialize(parent, persist=False)
+        return [ref.as_transforms() for ref in pat.refs.get(target, ())]
+
+    def close(self) -> None:
+        self._source.close()
+
+    def __enter__(self) -> GdsLibrarySource:
+        return self
+
+    def __exit__(self, *_args: object) -> None:
+        self.close()
+
+
+def read(
+        stream: IO[bytes],
+        ) -> tuple[GdsLibrarySource, dict[str, Any]]:
+    source = _SourceHandle(path=None, stream=stream)
+    stream.seek(0)
+    library_info, cell_order, cells = _scan_library(stream)
+    lib = GdsLibrarySource(source=source, library_info=library_info, cell_order=cell_order, cells=cells)
+    return lib, library_info
+
+
+def readfile(
+        filename: str | pathlib.Path,
+        *,
+        use_mmap: bool = True,
+        ) -> tuple[GdsLibrarySource, dict[str, Any]]:
+    lib = GdsLibrarySource.from_file(filename, use_mmap=use_mmap)
+    return lib, lib.library_info

masque/file/gdsii/lazy_arrow.py

@@ -0,0 +1,381 @@
+"""
+Lazy GDSII readers and writers backed by native Arrow scan/materialize paths.
+
+This module is intentionally separate from `gdsii.arrow` so the eager read path
+keeps its current behavior and performance profile.
+"""
+from __future__ import annotations
+
+from dataclasses import dataclass
+from typing import IO, TYPE_CHECKING, Any
+import gzip
+import logging
+import mmap
+import pathlib
+
+import numpy
+
+from . import arrow
+from ..utils import is_gzipped
+from ...library import (
+    ILibraryView,
+    IMaterializable,
+    LibraryView,
+)
+
+if TYPE_CHECKING:
+    from collections.abc import Iterator, Sequence
+
+    from numpy.typing import NDArray
+    import pyarrow
+
+    from ...pattern import Pattern
+
+
+logger = logging.getLogger(__name__)
+
+
+@dataclass(frozen=True)
+class _StructRange:
+    start: int
+    end: int
+
+
+@dataclass
+class _SourceBuffer:
+    path: pathlib.Path
+    data: bytes | mmap.mmap
+    handle: IO[bytes] | None = None
+
+    def raw_slice(self, start: int, end: int) -> bytes:
+        return self.data[start:end]
+
+
+@dataclass
+class _ScanRefs:
+    offsets: NDArray[numpy.integer[Any]]
+    targets: NDArray[numpy.integer[Any]]
+    xy: NDArray[numpy.int32]
+    xy0: NDArray[numpy.int32]
+    xy1: NDArray[numpy.int32]
+    counts: NDArray[numpy.int64]
+    invert_y: NDArray[numpy.bool_ | numpy.bool]
+    angle_rad: NDArray[numpy.floating[Any]]
+    scale: NDArray[numpy.floating[Any]]
+
+
+@dataclass(frozen=True)
+class _CellScan:
+    cell_id: int
+    struct_range: _StructRange
+    ref_start: int
+    ref_stop: int
+    children: set[str]
+
+
+@dataclass
+class _ScanPayload:
+    libarr: pyarrow.StructScalar
+    library_info: dict[str, Any]
+    cell_names: list[str]
+    cell_order: list[str]
+    cells: dict[str, _CellScan]
+    refs: _ScanRefs
+
+def _open_source_buffer(path: pathlib.Path) -> _SourceBuffer:
+    if is_gzipped(path):
+        with gzip.open(path, mode='rb') as stream:
+            data = stream.read()
+        return _SourceBuffer(path=path, data=data)
+
+    handle = path.open(mode='rb', buffering=0)
+    mapped = mmap.mmap(handle.fileno(), 0, access=mmap.ACCESS_READ)
+    return _SourceBuffer(path=path, data=mapped, handle=handle)
+
+
+def _extract_scan_payload(libarr: pyarrow.StructScalar) -> _ScanPayload:
+    library_info = arrow._read_header(libarr)
+    cell_names = libarr['cell_names'].as_py()
+
+    cells = libarr['cells']
+    cell_values = cells.values
+    cell_ids = cell_values.field('id').to_numpy()
+    struct_starts = cell_values.field('struct_start_offset').to_numpy()
+    struct_ends = cell_values.field('struct_end_offset').to_numpy()
+
+    refs = cell_values.field('refs')
+    ref_values = refs.values
+    ref_offsets = refs.offsets.to_numpy()
+    targets = ref_values.field('target').to_numpy()
+    xy = arrow._packed_xy_u64_to_pairs(ref_values.field('xy').to_numpy())
+    xy0 = arrow._packed_xy_u64_to_pairs(ref_values.field('xy0').to_numpy())
+    xy1 = arrow._packed_xy_u64_to_pairs(ref_values.field('xy1').to_numpy())
+    counts = arrow._packed_counts_u32_to_pairs(ref_values.field('counts').to_numpy())
+    invert_y = ref_values.field('invert_y').to_numpy(zero_copy_only=False)
+    angle_rad = ref_values.field('angle_rad').to_numpy()
+    scale = ref_values.field('scale').to_numpy()
+
+    ref_payload = _ScanRefs(
+        offsets=ref_offsets,
+        targets=targets,
+        xy=xy,
+        xy0=xy0,
+        xy1=xy1,
+        counts=counts,
+        invert_y=invert_y,
+        angle_rad=angle_rad,
+        scale=scale,
+    )
+
+    cell_order = [cell_names[int(cell_id)] for cell_id in cell_ids]
+    cell_scan: dict[str, _CellScan] = {}
+    for cc, name in enumerate(cell_order):
+        ref_start = int(ref_offsets[cc])
+        ref_stop = int(ref_offsets[cc + 1])
+        children = {
+            cell_names[int(target)]
+            for target in targets[ref_start:ref_stop]
+        }
+        cell_scan[name] = _CellScan(
+            cell_id=int(cell_ids[cc]),
+            struct_range=_StructRange(int(struct_starts[cc]), int(struct_ends[cc])),
+            ref_start=ref_start,
+            ref_stop=ref_stop,
+            children=children,
+        )
+
+    return _ScanPayload(
+        libarr=libarr,
+        library_info=library_info,
+        cell_names=cell_names,
+        cell_order=cell_order,
+        cells=cell_scan,
+        refs=ref_payload,
+    )
+
+def _make_ref_rows(
+        xy: NDArray[numpy.integer[Any]],
+        angle_rad: NDArray[numpy.floating[Any]],
+        invert_y: NDArray[numpy.bool_ | numpy.bool],
+        scale: NDArray[numpy.floating[Any]],
+        ) -> NDArray[numpy.float64]:
+    rows = numpy.empty((len(xy), 5), dtype=float)
+    rows[:, :2] = xy
+    rows[:, 2] = angle_rad
+    rows[:, 3] = invert_y.astype(float)
+    rows[:, 4] = scale
+    return rows
+
+
+def _expand_aref_row(
+        xy: NDArray[numpy.integer[Any]],
+        xy0: NDArray[numpy.integer[Any]],
+        xy1: NDArray[numpy.integer[Any]],
+        counts: NDArray[numpy.integer[Any]],
+        angle_rad: float,
+        invert_y: bool,
+        scale: float,
+        ) -> NDArray[numpy.float64]:
+    a_count = int(counts[0])
+    b_count = int(counts[1])
+    aa, bb = numpy.meshgrid(numpy.arange(a_count), numpy.arange(b_count), indexing='ij')
+    displacements = aa.reshape(-1, 1) * xy0[None, :] + bb.reshape(-1, 1) * xy1[None, :]
+    rows = numpy.empty((displacements.shape[0], 5), dtype=float)
+    rows[:, :2] = xy + displacements
+    rows[:, 2] = angle_rad
+    rows[:, 3] = float(invert_y)
+    rows[:, 4] = scale
+    return rows
+
+
+class ArrowLibrary(ILibraryView, IMaterializable):
+    """
+    Read-only library backed by the native lazy Arrow scan schema.
+
+    Materializing a cell via `__getitem__` caches a real `Pattern` for that cell.
+    Cached cells are treated as edited for future writes from this module.
+    """
+
+    path: pathlib.Path
+    library_info: dict[str, Any]
+
+    def __init__(
+            self,
+            *,
+            path: pathlib.Path,
+            payload: _ScanPayload,
+            source: _SourceBuffer,
+            ) -> None:
+        self.path = path
+        self.library_info = payload.library_info
+        self._payload = payload
+        self._source = source
+        self._cache: dict[str, Pattern] = {}
+
+    @classmethod
+    def from_file(cls, filename: str | pathlib.Path) -> ArrowLibrary:
+        path = pathlib.Path(filename).expanduser().resolve()
+        source = _open_source_buffer(path)
+        scan_arr = arrow._scan_buffer_to_arrow(source.data)
+        assert len(scan_arr) == 1
+        payload = _extract_scan_payload(scan_arr[0])
+        return cls(path=path, payload=payload, source=source)
+
+    def __getitem__(self, key: str) -> Pattern:
+        return self.materialize(key, persist=True)
+
+    def __iter__(self) -> Iterator[str]:
+        return iter(self._payload.cell_order)
+
+    def __len__(self) -> int:
+        return len(self._payload.cell_order)
+
+    def __contains__(self, key: object) -> bool:
+        return key in self._payload.cells
+
+    def source_order(self) -> tuple[str, ...]:
+        return tuple(self._payload.cell_order)
+
+    def raw_struct_bytes(self, name: str) -> bytes:
+        struct_range = self._payload.cells[name].struct_range
+        return self._source.raw_slice(struct_range.start, struct_range.end)
+
+    def can_copy_raw_struct(self, name: str) -> bool:
+        return name not in self._cache
+
+    def materialize_many(
+            self,
+            names: Sequence[str],
+            *,
+            persist: bool = True,
+            ) -> LibraryView:
+        mats = self._materialize_patterns(names, persist=persist, detached=False)
+        return LibraryView(mats)
+
+    def materialize_many_detached(
+            self,
+            names: Sequence[str],
+            ) -> LibraryView:
+        mats = self._materialize_patterns(names, persist=False, detached=True)
+        return LibraryView(mats)
+
+    def _materialize_patterns(
+            self,
+            names: Sequence[str],
+            *,
+            persist: bool,
+            detached: bool,
+            ) -> dict[str, Pattern]:
+        ordered_names = list(dict.fromkeys(names))
+        missing = [name for name in ordered_names if name not in self._payload.cells]
+        if missing:
+            raise KeyError(missing[0])
+
+        materialized: dict[str, Pattern] = {}
+        uncached = [name for name in ordered_names if name not in self._cache]
+        if uncached:
+            ranges = numpy.asarray(
+                [
+                    [
+                        self._payload.cells[name].struct_range.start,
+                        self._payload.cells[name].struct_range.end,
+                    ]
+                    for name in uncached
+                ],
+                dtype=numpy.uint64,
+            )
+            arrow_arr = arrow._read_selected_cells_to_arrow(self._source.data, ranges)
+            assert len(arrow_arr) == 1
+            selected_lib, _info = arrow.read_arrow(arrow_arr[0])
+            for name in uncached:
+                pat = selected_lib[name]
+                materialized[name] = pat
+                if persist:
+                    self._cache[name] = pat
+
+        for name in ordered_names:
+            if name not in materialized:
+                cached = self._cache[name]
+                materialized[name] = cached.deepcopy() if detached else cached
+        return materialized
+
+    def materialize(self, name: str, *, persist: bool = True) -> Pattern:
+        return self._materialize_patterns((name,), persist=persist, detached=False)[name]
+
+    def materialize_detached(self, name: str) -> Pattern:
+        return self._materialize_patterns((name,), persist=False, detached=True)[name]
+
+    def _raw_children(self, name: str) -> set[str]:
+        if name in self._cache:
+            return super()._raw_children(name)
+        return set(self._payload.cells[name].children)
+
+    def _collect_raw_transforms(self, cell: _CellScan, target_id: int) -> list[NDArray[numpy.float64]]:
+        refs = self._payload.refs
+        start = cell.ref_start
+        stop = cell.ref_stop
+        if stop <= start:
+            return []
+
+        targets = refs.targets[start:stop]
+        mask = targets == target_id
+        if not mask.any():
+            return []
+
+        rows: list[NDArray[numpy.float64]] = []
+        counts = refs.counts[start:stop]
+        unit_mask = mask & (counts[:, 0] == 1) & (counts[:, 1] == 1)
+        if unit_mask.any():
+            rows.append(_make_ref_rows(
+                refs.xy[start:stop][unit_mask],
+                refs.angle_rad[start:stop][unit_mask],
+                refs.invert_y[start:stop][unit_mask],
+                refs.scale[start:stop][unit_mask],
+            ))
+
+        aref_indices = numpy.nonzero(mask & ~unit_mask)[0]
+        for idx in aref_indices:
+            abs_idx = start + int(idx)
+            rows.append(_expand_aref_row(
+                xy=refs.xy[abs_idx],
+                xy0=refs.xy0[abs_idx],
+                xy1=refs.xy1[abs_idx],
+                counts=refs.counts[abs_idx],
+                angle_rad=float(refs.angle_rad[abs_idx]),
+                invert_y=bool(refs.invert_y[abs_idx]),
+                scale=float(refs.scale[abs_idx]),
+            ))
+        return rows
+
+    def close(self) -> None:
+        data = self._source.data
+        if isinstance(data, mmap.mmap):
+            data.close()
+        if self._source.handle is not None:
+            self._source.handle.close()
+            self._source.handle = None
+
+    def __enter__(self) -> ArrowLibrary:
+        return self
+
+    def __exit__(self, *_args: object) -> None:
+        self.close()
+
+    def _raw_ref_transforms(
+            self,
+            parent: str,
+            target: str,
+            ) -> list[NDArray[numpy.float64]]:
+        if parent in self._cache:
+            return super()._raw_ref_transforms(parent, target)
+        target_cell = self._payload.cells.get(target)
+        if target_cell is None or parent not in self._payload.cells:
+            return []
+        return self._collect_raw_transforms(self._payload.cells[parent], target_cell.cell_id)
+
+
+def readfile(
+        filename: str | pathlib.Path,
+        ) -> tuple[ArrowLibrary, dict[str, Any]]:
+    lib = ArrowLibrary.from_file(filename)
+    return lib, lib.library_info

masque/file/gdsii/writer.py

@@ -0,0 +1,174 @@
+"""
+GDSII writer for eager and source-backed libraries.
+
+The generic mutable overlay and ports-importing view live in `masque.library`.
+This module preserves source-backed GDS copy-through behavior where possible,
+falling back to normal pattern serialization when a cell has been materialized
+or remapped.
+"""
+from __future__ import annotations
+
+from typing import IO, TYPE_CHECKING, Any, Protocol, cast, runtime_checkable
+import gzip
+import logging
+import pathlib
+
+from . import klamath
+from ..utils import tmpfile
+from ...error import LibraryError
+from ...library import IBorrowing, ILibraryView, IMaterializable
+
+if TYPE_CHECKING:
+    from collections.abc import Mapping
+
+    from ...pattern import Pattern
+
+
+logger = logging.getLogger(__name__)
+
+
+@runtime_checkable
+class _GdsInfoSource(Protocol):
+    """Structural capability for propagating GDS header metadata."""
+    library_info: dict[str, Any]
+
+
+@runtime_checkable
+class _GdsRawCellSource(Protocol):
+    """GDS-specific raw-structure copy-through capability."""
+
+    def can_copy_raw_struct(self, name: str) -> bool: ...
+
+    def raw_struct_bytes(self, name: str) -> bytes: ...
+
+
+def _resolve_raw_struct(
+        library: ILibraryView,
+        name: str,
+        ) -> tuple[_GdsRawCellSource, str] | None:
+    """Resolve an unchanged visible cell to a copyable raw GDS structure."""
+    current = library
+    current_name = name
+    seen: set[tuple[int, str]] = set()
+    while True:
+        key = (id(current), current_name)
+        if key in seen:
+            return None
+        seen.add(key)
+
+        if isinstance(current, _GdsRawCellSource):
+            if current.can_copy_raw_struct(current_name):
+                return current, current_name
+            return None
+
+        if not isinstance(current, IBorrowing):
+            return None
+        source_cell = current.source_cell(current_name)
+        if source_cell is None:
+            return None
+        source, source_name = source_cell
+        if source_name != current_name:
+            return None
+        current = source
+        current_name = source_name
+
+
+def _get_write_info(
+        library: Mapping[str, Pattern] | ILibraryView,
+        *,
+        meters_per_unit: float | None,
+        logical_units_per_unit: float | None,
+        library_name: str | None,
+        ) -> tuple[float, float, str]:
+    if meters_per_unit is not None and logical_units_per_unit is not None and library_name is not None:
+        return meters_per_unit, logical_units_per_unit, library_name
+
+    infos: list[dict[str, Any]] = []
+    stack: list[Mapping[str, Pattern] | ILibraryView] = [library]
+    seen: set[int] = set()
+    while stack:
+        current = stack.pop()
+        if id(current) in seen:
+            continue
+        seen.add(id(current))
+        if isinstance(current, _GdsInfoSource) and isinstance(current.library_info, dict):
+            infos.append(current.library_info)
+        if isinstance(current, IBorrowing):
+            stack.extend(reversed(current.borrowed_sources()))
+
+    if infos:
+        unit_pairs = {(info['meters_per_unit'], info['logical_units_per_unit']) for info in infos}
+        if len(unit_pairs) > 1:
+            raise LibraryError('Merged lazy GDS sources must have identical units before writing')
+        info = infos[0]
+        meters = info['meters_per_unit'] if meters_per_unit is None else meters_per_unit
+        logical = info['logical_units_per_unit'] if logical_units_per_unit is None else logical_units_per_unit
+        name = info['name'] if library_name is None else library_name
+        return meters, logical, name
+
+    if meters_per_unit is None:
+        raise LibraryError('meters_per_unit is required when writing a library without GDS metadata')
+    logical = 1 if logical_units_per_unit is None else logical_units_per_unit
+    name = 'masque-klamath' if library_name is None else library_name
+    return meters_per_unit, logical, name
+
+
+def write(
+        library: Mapping[str, Pattern] | ILibraryView,
+        stream: IO[bytes],
+        meters_per_unit: float | None = None,
+        logical_units_per_unit: float | None = None,
+        library_name: str | None = None,
+        ) -> None:
+    """Write an eager or source-backed library to a GDSII stream."""
+    meters_per_unit, logical_units_per_unit, library_name = _get_write_info(
+        library,
+        meters_per_unit=meters_per_unit,
+        logical_units_per_unit=logical_units_per_unit,
+        library_name=library_name,
+    )
+
+    klamath._write_header(stream, meters_per_unit, logical_units_per_unit, library_name)
+
+    names = library.source_order() if isinstance(library, ILibraryView) else tuple(library)
+    for name in names:
+        if isinstance(library, ILibraryView):
+            raw_struct = _resolve_raw_struct(library, name)
+            if raw_struct is not None:
+                raw_source, source_name = raw_struct
+                stream.write(raw_source.raw_struct_bytes(source_name))
+                continue
+
+        if isinstance(library, IMaterializable):
+            pat = library.materialize(name, persist=False)
+        else:
+            pat = library[name]
+        klamath._write_pattern_struct(stream, name, pat)
+
+    klamath._write_footer(stream)
+
+
+def writefile(
+        library: Mapping[str, Pattern] | ILibraryView,
+        filename: str | pathlib.Path,
+        meters_per_unit: float | None = None,
+        logical_units_per_unit: float | None = None,
+        library_name: str | None = None,
+        ) -> None:
+    """Write an eager or source-backed library to a path, compressing `.gz` files."""
+    path = pathlib.Path(filename)
+    with tmpfile(path) as base_stream:
+        if path.suffix == '.gz':
+            stream = cast('IO[bytes]', gzip.GzipFile(
+                filename='',
+                mtime=0,
+                fileobj=base_stream,
+                mode='wb',
+                compresslevel=6,
+                ))
+            try:
+                write(library, stream, meters_per_unit, logical_units_per_unit, library_name)
+            finally:
+                stream.close()
+        else:
+            write(library, base_stream, meters_per_unit, logical_units_per_unit, library_name)

masque/file/oasis.py

@@ -182,8 +182,8 @@ def writefile(
     Args:
         library: A {name: Pattern} mapping of patterns to write.
         filename: Filename to save to.
-        *args: passed to `oasis.write`
-        **kwargs: passed to `oasis.write`
+        *args: passed to `oasis.build()`
+        **kwargs: passed to `oasis.build()`
     """
     path = pathlib.Path(filename)
 
@@ -213,9 +213,9 @@ def readfile(
     Will automatically decompress gzipped files.
 
     Args:
-        filename: Filename to save to.
-        *args: passed to `oasis.read`
-        **kwargs: passed to `oasis.read`
+        filename: Filename to load from.
+        *args: passed to `oasis.read()`
+        **kwargs: passed to `oasis.read()`
     """
     path = pathlib.Path(filename)
     if is_gzipped(path):
@@ -562,7 +562,9 @@ def _shapes_to_elements(
                 xy = rint_cast(shape.offset + shape.vertices[0] + rep_offset)
                 deltas = rint_cast(numpy.diff(shape.vertices, axis=0))
                 half_width = rint_cast(shape.width / 2)
-                path_type = next(k for k, v in path_cap_map.items() if v == shape.cap)    # reverse lookup
+                path_type = next((k for k, v in path_cap_map.items() if v == shape.cap), None)    # reverse lookup
+                if path_type is None:
+                    raise PatternError(f'OASIS writer does not support path cap {shape.cap}')
                 extension_start = (path_type, shape.cap_extensions[0] if shape.cap_extensions is not None else None)
                 extension_end = (path_type, shape.cap_extensions[1] if shape.cap_extensions is not None else None)
                 path = fatrec.Path(
@@ -622,10 +624,12 @@ def repetition_fata2masq(
         ) -> Repetition | None:
     mrep: Repetition | None
     if isinstance(rep, fatamorgana.GridRepetition):
-        mrep = Grid(a_vector=rep.a_vector,
+        mrep = Grid(
+            a_vector = rep.a_vector,
             b_vector = rep.b_vector,
             a_count = rep.a_count,
-                    b_count=rep.b_count)
+            b_count = rep.b_count,
+            )
     elif isinstance(rep, fatamorgana.ArbitraryRepetition):
         displacements = numpy.cumsum(numpy.column_stack((
             rep.x_displacements,
@@ -647,14 +651,19 @@ def repetition_masq2fata(
     frep: fatamorgana.GridRepetition | fatamorgana.ArbitraryRepetition | None
     if isinstance(rep, Grid):
         a_vector = rint_cast(rep.a_vector)
-        b_vector = rint_cast(rep.b_vector) if rep.b_vector is not None else None
-        a_count = rint_cast(rep.a_count)
-        b_count = rint_cast(rep.b_count) if rep.b_count is not None else None
+        a_count = int(rep.a_count)
+        if rep.b_count > 1:
+            b_vector = rint_cast(rep.b_vector)
+            b_count = int(rep.b_count)
+        else:
+            b_vector = None
+            b_count = None
+
         frep = fatamorgana.GridRepetition(
-            a_vector=cast('list[int]', a_vector),
-            b_vector=cast('list[int] | None', b_vector),
-            a_count=cast('int', a_count),
-            b_count=cast('int | None', b_count),
+            a_vector = a_vector,
+            b_vector = b_vector,
+            a_count = a_count,
+            b_count = b_count,
             )
         offset = (0, 0)
     elif isinstance(rep, Arbitrary):
@@ -707,13 +716,9 @@ def properties_to_annotations(
                 string = repr(value)
                 logger.warning(f'Converting property value for key ({key}) to string ({string})')
                 values.append(string)
-        annotations[key] = values
+        annotations.setdefault(key, []).extend(values)
     return annotations
 
-    properties = [fatrec.Property(key, vals, is_standard=False)
-                  for key, vals in annotations.items()]
-    return properties
-
 
 def check_valid_names(
         names: Iterable[str],

masque/file/svg.py

@@ -9,26 +9,64 @@ from numpy.typing import ArrayLike
 import svgwrite     # type: ignore
 
 from .utils import mangle_name
-from .. import Pattern
+from .. import Pattern, Ref
+from ..library import IMaterializable
+from ..utils import rotation_matrix_2d
 
 
 logger = logging.getLogger(__name__)
 
 
+def _ref_to_svg_transform(ref: Ref) -> str:
+    linear = rotation_matrix_2d(ref.rotation) * ref.scale
+    if ref.mirrored:
+        linear = linear @ numpy.diag((1.0, -1.0))
+
+    a = linear[0, 0]
+    b = linear[1, 0]
+    c = linear[0, 1]
+    d = linear[1, 1]
+    e = ref.offset[0]
+    f = ref.offset[1]
+    return f'matrix({a:g} {b:g} {c:g} {d:g} {e:g} {f:g})'
+
+
+def _make_svg_ids(names: Mapping[str, Pattern]) -> dict[str, str]:
+    svg_ids: dict[str, str] = {}
+    seen_ids: set[str] = set()
+    for name in names:
+        base_id = mangle_name(name)
+        svg_id = base_id
+        suffix = 1
+        while svg_id in seen_ids:
+            suffix += 1
+            svg_id = f'{base_id}_{suffix}'
+        seen_ids.add(svg_id)
+        svg_ids[name] = svg_id
+    return svg_ids
+
+
+def _detached_library(library: Mapping[str, Pattern]) -> dict[str, Pattern]:
+    if isinstance(library, IMaterializable):
+        detached = library.materialize_many_detached(tuple(library))
+        return dict(detached.items())
+    return {name: pat.deepcopy() for name, pat in library.items()}
+
+
 def writefile(
         library: Mapping[str, Pattern],
         top: str,
         filename: str,
         custom_attributes: bool = False,
+        annotate_ports: bool = False,
         ) -> None:
     """
-    Write a Pattern to an SVG file, by first calling .polygonize() on it
+    Write a Pattern to an SVG file, by first calling .polygonize() on a detached
+     materialized copy
      to change the shapes into polygons, and then writing patterns as SVG
      groups (<g>, inside <defs>), polygons as paths (<path>), and refs
      as <use> elements.
 
-    Note that this function modifies the Pattern.
-
     If `custom_attributes` is `True`, a non-standard `pattern_layer` attribute
      is written to the relevant elements.
 
@@ -40,17 +78,21 @@ def writefile(
      prior to calling this function.
 
     Args:
-        pattern: Pattern to write to file. Modified by this function.
+        library: Mapping of pattern names to patterns.
+        top: Name of the top-level pattern to render.
         filename: Filename to write to.
         custom_attributes: Whether to write non-standard `pattern_layer` attribute to the
             SVG elements.
+        annotate_ports: If True, draw an arrow for each port (similar to
+            `Pattern.visualize(..., ports=True)`).
     """
-    pattern = library[top]
+    detached = _detached_library(library)
+    pattern = detached[top]
 
     # Polygonize pattern
     pattern.polygonize()
 
-    bounds = pattern.get_bounds(library=library)
+    bounds = pattern.get_bounds(library=detached)
     if bounds is None:
         bounds_min, bounds_max = numpy.array([[-1, -1], [1, 1]])
         logger.warning('Pattern had no bounds (empty?); setting arbitrary viewbox', stacklevel=1)
@@ -63,10 +105,11 @@ def writefile(
     # Create file
     svg = svgwrite.Drawing(filename, profile='full', viewBox=viewbox_string,
                            debug=(not custom_attributes))
+    svg_ids = _make_svg_ids(detached)
 
     # Now create a group for each pattern and add in any Boundary and Use elements
-    for name, pat in library.items():
-        svg_group = svg.g(id=mangle_name(name), fill='blue', stroke='red')
+    for name, pat in detached.items():
+        svg_group = svg.g(id=svg_ids[name], fill='blue', stroke='red')
 
         for layer, shapes in pat.shapes.items():
             for shape in shapes:
@@ -79,16 +122,37 @@ def writefile(
 
                     svg_group.add(path)
 
+        if annotate_ports:
+            # Draw arrows for the ports, pointing into the device (per port definition)
+            for port_name, port in pat.ports.items():
+                if port.rotation is not None:
+                    p1 = port.offset
+                    angle = port.rotation
+                    size = 1.0  # arrow size
+                    p2 = p1 + size * numpy.array([numpy.cos(angle), numpy.sin(angle)])
+
+                    # head
+                    head_angle = 0.5
+                    h1 = p1 + 0.7 * size * numpy.array([numpy.cos(angle + head_angle), numpy.sin(angle + head_angle)])
+                    h2 = p1 + 0.7 * size * numpy.array([numpy.cos(angle - head_angle), numpy.sin(angle - head_angle)])
+
+                    line = svg.line(start=p1, end=p2, stroke='green', stroke_width=0.2)
+                    head = svg.polyline(points=[h1, p1, h2], fill='none', stroke='green', stroke_width=0.2)
+
+                    svg_group.add(line)
+                    svg_group.add(head)
+                    svg_group.add(svg.text(port_name, insert=p2, font_size=0.5, fill='green'))
+
         for target, refs in pat.refs.items():
             if target is None:
                 continue
             for ref in refs:
-                transform = f'scale({ref.scale:g}) rotate({ref.rotation:g}) translate({ref.offset[0]:g},{ref.offset[1]:g})'
-                use = svg.use(href='#' + mangle_name(target), transform=transform)
+                transform = _ref_to_svg_transform(ref)
+                use = svg.use(href='#' + svg_ids[target], transform=transform)
                 svg_group.add(use)
 
         svg.defs.add(svg_group)
-    svg.add(svg.use(href='#' + mangle_name(top)))
+    svg.add(svg.use(href='#' + svg_ids[top]))
     svg.save()
 
 
@@ -103,21 +167,21 @@ def writefile_inverted(
      box and drawing the polygons with reverse vertex order inside it, all within
      one `<path>` element.
 
-    Note that this function modifies the Pattern.
-
     If you want pattern polygonized with non-default arguments, just call `pattern.polygonize()`
      prior to calling this function.
 
     Args:
-        pattern: Pattern to write to file. Modified by this function.
+        library: Mapping of pattern names to patterns.
+        top: Name of the top-level pattern to render.
         filename: Filename to write to.
     """
-    pattern = library[top]
+    detached = _detached_library(library)
+    pattern = detached[top]
 
     # Polygonize and flatten pattern
-    pattern.polygonize().flatten(library)
+    pattern.polygonize().flatten(detached)
 
-    bounds = pattern.get_bounds(library=library)
+    bounds = pattern.get_bounds(library=detached)
     if bounds is None:
         bounds_min, bounds_max = numpy.array([[-1, -1], [1, 1]])
         logger.warning('Pattern had no bounds (empty?); setting arbitrary viewbox', stacklevel=1)

masque/file/utils.py

@@ -14,12 +14,188 @@ from pprint import pformat
 from itertools import chain
 
 from .. import Pattern, PatternError, Library, LibraryError
+from ..library import (
+    IBorrowing, ILibraryView, OverlayLibrary, SINGLE_USE_PREFIX,
+    dangling_mode_t,
+    )
 from ..shapes import Polygon, Path
 
 
 logger = logging.getLogger(__name__)
 
 
+def _has_source_provenance(library: ILibraryView, name: str) -> bool:
+    """Return whether `name` has an uninterrupted borrowing provenance chain."""
+    current = library
+    current_name = name
+    seen: set[tuple[int, str]] = set()
+    followed_source = False
+    while isinstance(current, IBorrowing):
+        key = (id(current), current_name)
+        if key in seen:
+            return False
+        seen.add(key)
+        source_cell = current.source_cell(current_name)
+        if source_cell is None:
+            return False
+        followed_source = True
+        current, current_name = source_cell
+    return followed_source
+
+
+def _prune_checked_empty(
+        library: OverlayLibrary,
+        checked_names: set[str],
+        *,
+        dangling: dangling_mode_t,
+        ) -> set[str]:
+    """Prune checked empty cells without modifying source-backed parents."""
+    parent_graph = library.parent_graph(dangling=dangling)
+    source_backed = set(library) - checked_names
+
+    def safely_empty(name: str) -> bool:
+        return (
+            name in library
+            and name in checked_names
+            and not (parent_graph.get(name, set()) & source_backed)
+            and library[name].is_empty()
+            )
+
+    empty = {name for name in checked_names if safely_empty(name)}
+    pruned: set[str] = set()
+    while empty:
+        parents: set[str] = set()
+        for name in empty:
+            name_parents = parent_graph.get(name, set())
+            del library[name]
+            checked_names.discard(name)
+            for parent in name_parents & checked_names:
+                if parent in library and name in library[parent].refs:
+                    del library[parent].refs[name]
+            parents |= name_parents
+        pruned |= empty
+        empty = {parent for parent in parents if safely_empty(parent)}
+    return pruned
+
+
+def _wrap_checked_repeated_shapes(
+        library: OverlayLibrary,
+        checked_names: set[str],
+        ) -> None:
+    """Wrap repetitions in checked cells while leaving source-backed cells untouched."""
+    for pattern_name in tuple(checked_names):
+        if pattern_name not in library:
+            continue
+        pattern = library[pattern_name]
+        for layer in pattern.shapes:
+            new_shapes = []
+            for shape in pattern.shapes[layer]:
+                if shape.repetition is None:
+                    new_shapes.append(shape)
+                    continue
+                name = library.get_name(SINGLE_USE_PREFIX + 'rep')
+                library[name] = Pattern(shapes={layer: [shape]})
+                checked_names.add(name)
+                pattern.ref(name, repetition=shape.repetition)
+                shape.repetition = None
+            pattern.shapes[layer] = new_shapes
+
+        for layer in pattern.labels:
+            new_labels = []
+            for label in pattern.labels[layer]:
+                if label.repetition is None:
+                    new_labels.append(label)
+                    continue
+                name = library.get_name(SINGLE_USE_PREFIX + 'rep')
+                library[name] = Pattern(labels={layer: [label]})
+                checked_names.add(name)
+                pattern.ref(name, repetition=label.repetition)
+                label.repetition = None
+            pattern.labels[layer] = new_labels
+
+
+def preflight_source_aware(
+        lib: ILibraryView,
+        sort: bool = True,
+        sort_elements: bool = False,
+        allow_dangling_refs: bool | None = None,
+        allow_named_layers: bool = True,
+        prune_empty_patterns: bool = False,
+        wrap_repeated_shapes: bool = False,
+        ) -> OverlayLibrary:
+    """
+    Preflight cells without reusable source provenance.
+
+    Returns a borrowing `OverlayLibrary`. Cells with uninterrupted
+    `IBorrowing.source_cell()` provenance remain source-backed and receive no
+    per-pattern checks. Other cells are detached into the overlay and checked.
+    Keep `lib` and its borrowed sources open for the result's lifetime.
+
+    Args:
+        sort: Whether to sort checked pattern contents. Library name order is
+            retained because sorting source-backed cells would require loading them.
+        sort_elements: Whether to sort elements within checked patterns.
+        allow_dangling_refs: If `None` (default), warns about any refs to patterns that are not
+            in the provided library. If `True`, no check is performed; if `False`, a `LibraryError`
+            is raised instead.
+        allow_named_layers: If `False`, raises a `PatternError` if any layer is referred to by
+            a string in a checked pattern instead of a number (or tuple).
+        prune_empty_patterns: Recursively delete checked empty patterns when
+            doing so does not require modifying a source-backed parent.
+        wrap_repeated_shapes: Turn repeated shapes in checked patterns into
+            repeated refs containing non-repeated shapes.
+
+    Returns:
+        A borrowing overlay containing checked patterns and source-backed cells.
+    """
+    checked_names = {
+        name
+        for name in lib
+        if not _has_source_provenance(lib, name)
+        }
+    overlay = OverlayLibrary()
+    overlay.add_source(lib)
+
+    if sort:
+        for name in sorted(checked_names):
+            overlay[name].sort(sort_elements=sort_elements)
+
+    if not allow_dangling_refs:
+        refs = overlay.referenced_patterns()
+        dangling = refs - set(overlay.keys())
+        if dangling:
+            msg = 'Dangling refs found: ' + pformat(dangling)
+            if allow_dangling_refs is None:
+                logger.warning(msg)
+            else:
+                raise LibraryError(msg)
+
+    if not allow_named_layers:
+        checked_named_layers: Mapping[str, set] = defaultdict(set)
+        for name in checked_names:
+            pattern = overlay[name]
+            for layer in chain(pattern.shapes.keys(), pattern.labels.keys()):
+                if isinstance(layer, str):
+                    checked_named_layers[name].add(layer)
+        checked_named_layers = dict(checked_named_layers)
+        if checked_named_layers:
+            raise PatternError('Non-numeric layers found:' + pformat(checked_named_layers))
+
+    if prune_empty_patterns:
+        prune_dangling: dangling_mode_t = 'error' if allow_dangling_refs is False else 'ignore'
+        pruned = _prune_checked_empty(overlay, checked_names, dangling=prune_dangling)
+        if pruned:
+            logger.info(f'Preflight pruned {len(pruned)} checked empty patterns')
+            logger.debug('Pruned: ' + pformat(pruned))
+        else:
+            logger.debug('Preflight found no safely prunable checked patterns')
+
+    if wrap_repeated_shapes:
+        _wrap_checked_repeated_shapes(overlay, checked_names)
+
+    return overlay
+
+
 def preflight(
         lib: Library,
         sort: bool = True,
@@ -30,33 +206,35 @@ def preflight(
         wrap_repeated_shapes: bool = False,
         ) -> Library:
     """
-    Run a standard set of useful operations and checks, usually done immediately prior
-    to writing to a file (or immediately after reading).
+    Run a standard set of useful operations and checks on an entire library.
+
+    This helper is not copy-isolating. When `sort=True`, it constructs a new
+    `Library` wrapper around the same `Pattern` objects after sorting them in
+    place. Later mutating steps may still mutate caller-owned patterns. Deep-copy
+    the library first when isolation is required.
 
     Args:
-        sort: Whether to sort the patterns based on their names, and optionaly sort the pattern contents.
-            Default True. Useful for reproducible builds.
-        sort_elements: Whether to sort the pattern contents. Requires sort=True to run.
-        allow_dangling_refs: If `None` (default), warns about any refs to patterns that are not
-            in the provided library. If `True`, no check is performed; if `False`, a `LibraryError`
-            is raised instead.
-        allow_named_layers: If `False`, raises a `PatternError` if any layer is referred to by
-            a string instead of a number (or tuple).
-        prune_empty_patterns: Runs `Library.prune_empty()`, recursively deleting any empty patterns.
-        wrap_repeated_shapes: Runs `Library.wrap_repeated_shapes()`, turning repeated shapes into
-            repeated refs containing non-repeated shapes.
+        sort: Whether to sort patterns by name and sort each pattern's contents.
+        sort_elements: Whether to sort elements within each pattern. Requires
+            `sort=True`.
+        allow_dangling_refs: If `None`, warn about missing targets. If `True`,
+            skip the check. If `False`, raise `LibraryError`.
+        allow_named_layers: If `False`, raise `PatternError` for string layers.
+        prune_empty_patterns: Recursively delete empty patterns.
+        wrap_repeated_shapes: Move shape and label repetitions onto wrapping refs.
 
     Returns:
-        `lib` or an equivalent sorted library
+        `lib`, or an equivalent name-sorted `Library` when `sort=True`.
     """
+    mutable_lib = lib
     if sort:
-        lib = Library(dict(sorted(
-            (nn, pp.sort(sort_elements=sort_elements)) for nn, pp in lib.items()
+        mutable_lib = Library(dict(sorted(
+            (nn, pp.sort(sort_elements=sort_elements)) for nn, pp in mutable_lib.items()
             )))
 
     if not allow_dangling_refs:
-        refs = lib.referenced_patterns()
-        dangling = refs - set(lib.keys())
+        refs = mutable_lib.referenced_patterns()
+        dangling = refs - set(mutable_lib.keys())
         if dangling:
             msg = 'Dangling refs found: ' + pformat(dangling)
             if allow_dangling_refs is None:
@@ -66,7 +244,7 @@ def preflight(
 
     if not allow_named_layers:
         named_layers: Mapping[str, set] = defaultdict(set)
-        for name, pat in lib.items():
+        for name, pat in mutable_lib.items():
             for layer in chain(pat.shapes.keys(), pat.labels.keys()):
                 if isinstance(layer, str):
                     named_layers[name].add(layer)
@@ -75,7 +253,8 @@ def preflight(
             raise PatternError('Non-numeric layers found:' + pformat(named_layers))
 
     if prune_empty_patterns:
-        pruned = lib.prune_empty()
+        prune_dangling: dangling_mode_t = 'error' if allow_dangling_refs is False else 'ignore'
+        pruned = mutable_lib.prune_empty(dangling=prune_dangling)
         if pruned:
             logger.info(f'Preflight pruned {len(pruned)} empty patterns')
             logger.debug('Pruned: ' + pformat(pruned))
@@ -83,9 +262,9 @@ def preflight(
             logger.debug('Preflight found no empty patterns')
 
     if wrap_repeated_shapes:
-        lib.wrap_repeated_shapes()
+        mutable_lib.wrap_repeated_shapes()
 
-    return lib
+    return mutable_lib
 
 
 def mangle_name(name: str) -> str:
@@ -144,7 +323,11 @@ def tmpfile(path: str | pathlib.Path) -> Iterator[IO[bytes]]:
     path = pathlib.Path(path)
     suffixes = ''.join(path.suffixes)
     with tempfile.NamedTemporaryFile(suffix=suffixes, delete=False) as tmp_stream:
+        try:
             yield tmp_stream
+        except Exception:
+            pathlib.Path(tmp_stream.name).unlink(missing_ok=True)
+            raise
 
     try:
         shutil.move(tmp_stream.name, path)

masque/label.py

@@ -7,12 +7,12 @@ from numpy.typing import ArrayLike, NDArray
 
 from .repetition import Repetition
 from .utils import rotation_matrix_2d, annotations_t, annotations_eq, annotations_lt, rep2key
-from .traits import PositionableImpl, Copyable, Pivotable, RepeatableImpl, Bounded
+from .traits import PositionableImpl, Copyable, Pivotable, RepeatableImpl, Bounded, Flippable
 from .traits import AnnotatableImpl
 
 
 @functools.total_ordering
-class Label(PositionableImpl, RepeatableImpl, AnnotatableImpl, Bounded, Pivotable, Copyable):
+class Label(PositionableImpl, RepeatableImpl, AnnotatableImpl, Bounded, Pivotable, Copyable, Flippable):
     """
     A text annotation with a position (but no size; it is not drawn)
     """
@@ -53,17 +53,36 @@ class Label(PositionableImpl, RepeatableImpl, AnnotatableImpl, Bounded, Pivotabl
         self.repetition = repetition
         self.annotations = annotations if annotations is not None else {}
 
+    @classmethod
+    def _from_raw(
+            cls,
+            string: str,
+            *,
+            offset: NDArray[numpy.float64],
+            repetition: Repetition | None = None,
+            annotations: annotations_t | None = None,
+            ) -> Self:
+        new = cls.__new__(cls)
+        new._string = string
+        new._offset = offset
+        new._repetition = repetition
+        new._annotations = annotations
+        return new
+
     def __copy__(self) -> Self:
         return type(self)(
             string=self.string,
             offset=self.offset.copy(),
             repetition=self.repetition,
+            annotations=copy.copy(self.annotations),
             )
 
     def __deepcopy__(self, memo: dict | None = None) -> Self:
         memo = {} if memo is None else memo
         new = copy.copy(self)
         new._offset = self._offset.copy()
+        new._repetition = copy.deepcopy(self._repetition, memo)
+        new._annotations = copy.deepcopy(self._annotations, memo)
         return new
 
     def __lt__(self, other: 'Label') -> bool:
@@ -76,6 +95,8 @@ class Label(PositionableImpl, RepeatableImpl, AnnotatableImpl, Bounded, Pivotabl
         return annotations_lt(self.annotations, other.annotations)
 
     def __eq__(self, other: Any) -> bool:
+        if type(self) is not type(other):
+            return False
         return (
             self.string == other.string
             and numpy.array_equal(self.offset, other.offset)
@@ -96,10 +117,34 @@ class Label(PositionableImpl, RepeatableImpl, AnnotatableImpl, Bounded, Pivotabl
         """
         pivot = numpy.asarray(pivot, dtype=float)
         self.translate(-pivot)
+        if self.repetition is not None:
+            self.repetition.rotate(rotation)
         self.offset = numpy.dot(rotation_matrix_2d(rotation), self.offset)
         self.translate(+pivot)
         return self
 
+    def flip_across(self, axis: int | None = None, *, x: float | None = None, y: float | None = None) -> Self:
+        """
+        Extrinsic transformation: Flip the label across a line in the pattern's
+        coordinate system. This affects both the label's offset and its
+        repetition grid.
+
+        Args:
+            axis: Axis to mirror across. 0: x-axis (flip y), 1: y-axis (flip x).
+            x: Vertical line x=val to mirror across.
+            y: Horizontal line y=val to mirror across.
+
+        Returns:
+            self
+        """
+        axis, pivot = self._check_flip_args(axis=axis, x=x, y=y)
+        self.translate(-pivot)
+        if self.repetition is not None:
+            self.repetition.mirror(axis)
+        self.offset[1 - axis] *= -1
+        self.translate(+pivot)
+        return self
+
     def get_bounds_single(self) -> NDArray[numpy.float64]:
         """
         Return the bounds of the label.

masque/library/__init__.py

@@ -0,0 +1,35 @@
+"""Library classes for managing name-to-pattern mappings."""
+from .utils import (
+    INameView as INameView,
+    SINGLE_USE_PREFIX as SINGLE_USE_PREFIX,
+    Tree as Tree,
+    TreeView as TreeView,
+    b64suffix as b64suffix,
+    dangling_mode_t as dangling_mode_t,
+    visitor_function_t as visitor_function_t,
+)
+from .base import (
+    AbstractView as AbstractView,
+    ILibrary as ILibrary,
+    ILibraryView as ILibraryView,
+)
+from .capabilities import (
+    IBorrowing as IBorrowing,
+    IMaterializable as IMaterializable,
+)
+from .mapping import (
+    Library as Library,
+    LibraryView as LibraryView,
+)
+from .overlay import (
+    OverlayLibrary as OverlayLibrary,
+    PortLoadView as PortLoadView,
+    LayerMappedView as LayerMappedView,
+)
+from .build import (
+    LibraryBuilder as LibraryBuilder,
+    BuildReport as BuildReport,
+    CellProvenance as CellProvenance,
+    cell as cell,
+)
+from .lazy import LazyLibrary as LazyLibrary

masque/library/capabilities.py

@@ -0,0 +1,72 @@
+"""Optional capabilities implemented by lazy and borrowing libraries."""
+from __future__ import annotations
+
+from abc import ABC, abstractmethod
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from collections.abc import Sequence
+
+    from ..pattern import Pattern
+    from .base import ILibraryView
+    from .mapping import LibraryView
+
+
+class IMaterializable(ABC):
+    """Capability for libraries which support explicit pattern materialization."""
+
+    @abstractmethod
+    def materialize(self, name: str, *, persist: bool = True) -> Pattern:
+        """Materialize one pattern, optionally retaining it in the library's cache."""
+
+    def materialize_many(
+            self,
+            names: Sequence[str],
+            *,
+            persist: bool = True,
+            ) -> LibraryView:
+        """Materialize a de-duplicated sequence into a plain read-only view."""
+        from .mapping import LibraryView        # noqa: PLC0415
+
+        return LibraryView({
+            name: self.materialize(name, persist=persist)
+            for name in dict.fromkeys(names)
+            })
+
+    def materialize_detached(self, name: str) -> Pattern:
+        """Materialize a caller-owned pattern which is safe to mutate."""
+        return self.materialize(name, persist=False).deepcopy()
+
+    def materialize_many_detached(
+            self,
+            names: Sequence[str],
+            ) -> LibraryView:
+        """Materialize caller-owned patterns without retaining them in this library."""
+        from .mapping import LibraryView        # noqa: PLC0415
+
+        materialized = self.materialize_many(names, persist=False)
+        return LibraryView({
+            name: materialized[name].deepcopy()
+            for name in dict.fromkeys(names)
+            })
+
+
+class IBorrowing(ABC):
+    """Capability for library views which directly borrow other libraries."""
+
+    @abstractmethod
+    def borrowed_sources(self) -> tuple[ILibraryView, ...]:
+        """Return the source views directly borrowed by this library."""
+
+    def source_cell(self, name: str) -> tuple[ILibraryView, str] | None:       # noqa: ARG002
+        """
+        Return a direct source cell with unchanged layout data, if available.
+
+        The source may use a different name, which is returned alongside it.
+        Port metadata may differ because ports are not layout-file content.
+        The result is not recursively resolved: consumers must follow further
+        borrowing views themselves and enforce format-specific constraints such
+        as whether the visible and source names must match. `None` means the
+        source cannot be reused safely or no source provenance is available.
+        """
+        return None

masque/library/lazy.py

@@ -0,0 +1,183 @@
+"""Closure-backed lazy library implementation."""
+from __future__ import annotations
+
+from pprint import pformat
+from typing import TYPE_CHECKING, Self, cast
+import logging
+
+from ..error import LibraryError
+from .base import ILibrary
+from .capabilities import IMaterializable
+
+if TYPE_CHECKING:
+    from collections.abc import Callable, Iterator, Mapping, Sequence
+
+    from ..pattern import Pattern
+
+
+logger = logging.getLogger(__name__)
+
+
+class LazyLibrary(ILibrary, IMaterializable):
+    """
+    This class is usually used to create a library of Patterns by mapping names to
+     functions which generate or load the relevant `Pattern` object as-needed.
+
+    TODO: lots of stuff causes recursive loads (e.g. data_to_ports?). What should you avoid?
+    """
+    mapping: dict[str, Callable[[], Pattern]]
+    cache: dict[str, Pattern]
+    _lookups_in_progress: list[str]
+
+    def __init__(self) -> None:
+        self.mapping = {}
+        self.cache = {}
+        self._lookups_in_progress = []
+
+    def __setitem__(
+            self,
+            key: str,
+            value: Pattern | Callable[[], Pattern],
+            ) -> None:
+        if key in self.mapping:
+            raise LibraryError(f'"{key}" already exists in the library. Overwriting is not allowed!')
+
+        if callable(value):
+            value_func = value
+        else:
+            value_func = lambda: cast('Pattern', value)      # noqa: E731
+
+        self.mapping[key] = value_func
+        if key in self.cache:
+            del self.cache[key]
+
+    def __delitem__(self, key: str) -> None:
+        del self.mapping[key]
+        if key in self.cache:
+            del self.cache[key]
+
+    def __getitem__(self, key: str) -> Pattern:
+        return self.materialize(key, persist=True)
+
+    def materialize(self, key: str, *, persist: bool = True) -> Pattern:
+        logger.debug(f'loading {key}')
+        if key in self.cache:
+            logger.debug(f'found {key} in cache')
+            return self.cache[key]
+
+        if key in self._lookups_in_progress:
+            chain = ' -> '.join(self._lookups_in_progress + [key])
+            raise LibraryError(
+                f'Detected circular reference or recursive lookup of "{key}".\n'
+                f'Lookup chain: {chain}\n'
+                'This may be caused by an invalid (cyclical) reference, or buggy code.\n'
+                'If you are lazy-loading a file, try a non-lazy load and check for reference cycles.'
+                )
+
+        self._lookups_in_progress.append(key)
+        try:
+            func = self.mapping[key]
+            pat = func()
+        finally:
+            self._lookups_in_progress.pop()
+        if persist:
+            self.cache[key] = pat
+        return pat
+
+    def __iter__(self) -> Iterator[str]:
+        return iter(self.mapping)
+
+    def __len__(self) -> int:
+        return len(self.mapping)
+
+    def __contains__(self, key: object) -> bool:
+        return key in self.mapping
+
+    def referenced_patterns(
+            self,
+            tops: str | Sequence[str] | None = None,
+            skip: set[str] | None = None,
+            ) -> set[str]:
+        # Closure-backed cells do not have hierarchy metadata. Preserve laziness
+        # by loading only patterns reached from the requested roots.
+        return self._referenced_patterns_by_lookup(tops=tops, skip=skip)
+
+    def _merge(self, key_self: str, other: Mapping[str, Pattern], key_other: str) -> None:
+        if isinstance(other, LazyLibrary):
+            self.mapping[key_self] = other.mapping[key_other]
+            if key_other in other.cache:
+                self.cache[key_self] = other.cache[key_other]
+        else:
+            self[key_self] = other[key_other]
+
+    def __repr__(self) -> str:
+        return '<LazyLibrary with keys\n' + pformat(list(self.keys())) + '>'
+
+    def rename(
+            self,
+            old_name: str,
+            new_name: str,
+            move_references: bool = False,
+            ) -> Self:
+        """
+        Rename a pattern.
+
+        Args:
+            old_name: Current name for the pattern
+            new_name: New name for the pattern
+            move_references: Whether to scan all refs in the pattern and
+                move them to point to `new_name` as necessary.
+                Default `False`.
+
+        Returns:
+            self
+        """
+        if old_name not in self.mapping:
+            raise LibraryError(f'"{old_name}" does not exist in the library.')
+        if old_name == new_name:
+            return self
+
+        self[new_name] = self.mapping[old_name]        # copy over function
+        if old_name in self.cache:
+            self.cache[new_name] = self.cache[old_name]
+        del self[old_name]
+
+        if move_references:
+            self.move_references(old_name, new_name)
+
+        return self
+
+    def move_references(self, old_target: str, new_target: str) -> Self:
+        """
+        Change all references pointing at `old_target` into references pointing at `new_target`.
+
+        Args:
+            old_target: Current reference target
+            new_target: New target for the reference
+
+        Returns:
+            self
+        """
+        if old_target == new_target:
+            return self
+
+        self.precache()
+        for pattern in self.cache.values():
+            if old_target in pattern.refs:
+                pattern.refs[new_target].extend(pattern.refs[old_target])
+                del pattern.refs[old_target]
+        return self
+
+    def precache(self) -> Self:
+        """
+        Force all patterns into the cache
+
+        Returns:
+            self
+        """
+        for key in self.mapping:
+            _ = self[key]       # want to trigger our own __getitem__
+        return self
+
+    def __deepcopy__(self, memo: dict | None = None) -> LazyLibrary:
+        raise LibraryError('LazyLibrary cannot be deepcopied (deepcopy doesn\'t descend into closures)')

masque/library/mapping.py

@@ -0,0 +1,225 @@
+"""Concrete mapping-backed library implementations."""
+from __future__ import annotations
+
+from pprint import pformat
+from typing import TYPE_CHECKING, Self
+
+from ..error import LibraryError
+from .base import ILibrary, ILibraryView
+from .capabilities import IBorrowing, IMaterializable
+from .utils import dangling_mode_t, _validate_dangling_mode
+
+if TYPE_CHECKING:
+    from collections.abc import Callable, Iterator, Mapping, MutableMapping, Sequence
+
+    import numpy
+    from numpy.typing import NDArray
+
+    from ..pattern import Pattern
+
+
+class LibraryView(ILibraryView):
+    """
+    Default implementation for a read-only library.
+
+    A library is a mapping from unique names (str) to collections of geometry (`Pattern`).
+    This library is backed by an arbitrary python object which implements the `Mapping` interface.
+    """
+    mapping: Mapping[str, Pattern]
+
+    def __init__(
+            self,
+            mapping: Mapping[str, Pattern],
+            ) -> None:
+        self.mapping = mapping
+
+    def __getitem__(self, key: str) -> Pattern:
+        return self.mapping[key]
+
+    def __iter__(self) -> Iterator[str]:
+        return iter(self.mapping)
+
+    def __len__(self) -> int:
+        return len(self.mapping)
+
+    def __contains__(self, key: object) -> bool:
+        return key in self.mapping
+
+    def __repr__(self) -> str:
+        return f'<LibraryView ({type(self.mapping)}) with keys\n' + pformat(list(self.keys())) + '>'
+
+
+class _SubtreeLibraryView(ILibraryView, IMaterializable, IBorrowing):
+    """Borrowed subtree view with snapshotted membership and hierarchy."""
+
+    def __init__(
+            self,
+            source: ILibraryView,
+            *,
+            names: set[str],
+            child_graph: Mapping[str, set[str]],
+            ) -> None:
+        self._source = source
+        source_order = source.source_order()
+        ordered = list(dict.fromkeys(name for name in source_order if name in names))
+        seen = set(ordered)
+        ordered.extend(name for name in source if name in names and name not in seen)
+        self._order = tuple(ordered)
+        self._names = frozenset(self._order)
+        self._child_graph = {
+            name: set(child_graph.get(name, set()))
+            for name in self._order
+            }
+
+    def __getitem__(self, key: str) -> Pattern:
+        if key not in self._names:
+            raise KeyError(key)
+        return self._source[key]
+
+    def __iter__(self) -> Iterator[str]:
+        return iter(self._order)
+
+    def __len__(self) -> int:
+        return len(self._order)
+
+    def __contains__(self, key: object) -> bool:
+        return key in self._names
+
+    def borrowed_sources(self) -> tuple[ILibraryView, ...]:
+        return (self._source,)
+
+    def source_cell(self, name: str) -> tuple[ILibraryView, str] | None:
+        if name not in self._names:
+            return None
+        return self._source, name
+
+    def source_order(self) -> tuple[str, ...]:
+        return self._order
+
+    def materialize(self, name: str, *, persist: bool = True) -> Pattern:
+        if name not in self._names:
+            raise KeyError(name)
+        if isinstance(self._source, IMaterializable):
+            return self._source.materialize(name, persist=persist)
+        return self._source[name]
+
+    def materialize_detached(self, name: str) -> Pattern:
+        if name not in self._names:
+            raise KeyError(name)
+        if isinstance(self._source, IMaterializable):
+            return self._source.materialize_detached(name)
+        return self._source[name].deepcopy()
+
+    def materialize_many_detached(
+            self,
+            names: Sequence[str],
+            ) -> LibraryView:
+        ordered_names = tuple(dict.fromkeys(names))
+        missing = next((name for name in ordered_names if name not in self._names), None)
+        if missing is not None:
+            raise KeyError(missing)
+        if isinstance(self._source, IMaterializable):
+            return self._source.materialize_many_detached(ordered_names)
+        return LibraryView({name: self._source[name].deepcopy() for name in ordered_names})
+
+    def child_graph(
+            self,
+            dangling: dangling_mode_t = 'error',
+            ) -> dict[str, set[str]]:
+        _validate_dangling_mode(dangling)
+        graph = {name: set(children) for name, children in self._child_graph.items()}
+        existing = set(graph)
+        dangling_refs = set().union(*(children - existing for children in graph.values())) if graph else set()
+        if dangling == 'error':
+            if dangling_refs:
+                raise self._dangling_refs_error(dangling_refs, 'building child graph')
+            return graph
+        if dangling == 'ignore':
+            return {
+                name: {child for child in children if child in existing}
+                for name, children in graph.items()
+                }
+        for target in dangling_refs:
+            graph.setdefault(target, set())
+        return graph
+
+    def find_refs_local(
+            self,
+            name: str,
+            parent_graph: dict[str, set[str]] | None = None,
+            dangling: dangling_mode_t = 'error',
+            ) -> dict[str, list[NDArray[numpy.float64]]]:
+        _validate_dangling_mode(dangling)
+        if parent_graph is None:
+            graph_mode: dangling_mode_t = 'ignore' if dangling == 'ignore' else 'include'
+            parent_graph = self.parent_graph(dangling=graph_mode)
+        refs = self._source.find_refs_local(name, parent_graph=parent_graph, dangling=dangling)
+        return {parent: transforms for parent, transforms in refs.items() if parent in self._names}
+
+
+class Library(ILibrary):
+    """
+    Default implementation for a writeable library.
+
+    A library is a mapping from unique names (str) to collections of geometry (`Pattern`).
+    This library is backed by an arbitrary python object which implements the `MutableMapping` interface.
+    """
+    mapping: MutableMapping[str, Pattern]
+
+    def __init__(
+            self,
+            mapping: MutableMapping[str, Pattern] | None = None,
+            ) -> None:
+        if mapping is None:
+            self.mapping = {}
+        else:
+            self.mapping = mapping
+
+    def __getitem__(self, key: str) -> Pattern:
+        return self.mapping[key]
+
+    def __iter__(self) -> Iterator[str]:
+        return iter(self.mapping)
+
+    def __len__(self) -> int:
+        return len(self.mapping)
+
+    def __contains__(self, key: object) -> bool:
+        return key in self.mapping
+
+    def __setitem__(
+            self,
+            key: str,
+            value: Pattern | Callable[[], Pattern],
+            ) -> None:
+        if key in self.mapping:
+            raise LibraryError(f'"{key}" already exists in the library. Overwriting is not allowed!')
+
+        value = value() if callable(value) else value
+        self.mapping[key] = value
+
+    def __delitem__(self, key: str) -> None:
+        del self.mapping[key]
+
+    def _merge(self, key_self: str, other: Mapping[str, Pattern], key_other: str) -> None:
+        self[key_self] = other[key_other]
+
+    def __repr__(self) -> str:
+        return f'<Library ({type(self.mapping)}) with keys\n' + pformat(list(self.keys())) + '>'
+
+    @classmethod
+    def mktree(cls: type[Self], name: str) -> tuple[Self, Pattern]:
+        """
+        Create a new Library and immediately add a pattern
+
+        Args:
+            name: The name for the new pattern (usually the name of the topcell).
+
+        Returns:
+            The newly created `Library` and the newly created `Pattern`
+        """
+        from ..pattern import Pattern        # noqa: PLC0415
+        tree = cls()
+        pat = Pattern()
+        tree[name] = pat
+        return tree, pat

masque/library/overlay.py

@@ -0,0 +1,574 @@
+"""Overlay and lazily processed library views."""
+from __future__ import annotations
+
+from collections import defaultdict
+from dataclasses import dataclass
+from typing import TYPE_CHECKING, Literal, Self, cast
+import copy
+
+from ..error import LibraryError
+from ..pattern import Pattern, map_layers, map_targets
+from .base import ILibrary, ILibraryView
+from .capabilities import IBorrowing, IMaterializable
+from .utils import (
+    INameView,
+    dangling_mode_t,
+    _plan_source_names,
+    _rename_patterns,
+    _source_rename_map,
+    _validate_dangling_mode,
+    )
+from .mapping import LibraryView
+
+if TYPE_CHECKING:
+    from collections.abc import Callable, Iterator, Mapping, Sequence
+
+    import numpy
+    from numpy.typing import NDArray
+
+    from ..ports import Port
+    from ..utils import layer_t
+
+
+@dataclass
+class _SourceLayer:
+    """ One imported source layer tracked by an `OverlayLibrary`. """
+    library: ILibraryView
+    source_target_map: dict[str, str]
+    child_graph: dict[str, set[str]]
+
+
+@dataclass(frozen=True)
+class _SourceEntry:
+    """ Reference to a single visible source-backed cell in an overlay. """
+    layer_index: int
+    source_name: str
+
+
+def _materialize_detached_pattern(view: ILibraryView, name: str) -> Pattern:
+    if isinstance(view, IMaterializable):
+        return view.materialize_detached(name)
+    return view[name].deepcopy()
+
+
+class _ProcessedLibraryView(ILibraryView, IMaterializable, IBorrowing):
+    """Shared detached-materialization behavior for read-only processing views."""
+
+    def __init__(
+            self,
+            source: ILibraryView,
+            *,
+            copy_through: bool,
+            ) -> None:
+        self._source = source
+        self._copy_through = copy_through
+        self._cache: dict[str, Pattern] = {}
+        self._lookups_in_progress: list[str] = []
+
+    def __getitem__(self, key: str) -> Pattern:
+        return self.materialize(key, persist=True)
+
+    def __iter__(self) -> Iterator[str]:
+        return iter(self._source)
+
+    def __len__(self) -> int:
+        return len(self._source)
+
+    def __contains__(self, key: object) -> bool:
+        return key in self._source
+
+    def _process_pattern(self, name: str, pattern: Pattern) -> Pattern:
+        """Apply this view's processing to one detached source pattern."""
+        raise NotImplementedError
+
+    def _materialize_uncached_detached(self, name: str) -> Pattern:
+        if name in self._lookups_in_progress:
+            chain = ' -> '.join(self._lookups_in_progress + [name])
+            raise LibraryError(
+                f'Detected circular reference or recursive lookup of "{name}".\n'
+                f'Lookup chain: {chain}\n'
+                'This may be caused by an invalid (cyclical) reference, or buggy code.'
+                )
+
+        self._lookups_in_progress.append(name)
+        try:
+            pattern = _materialize_detached_pattern(self._source, name)
+            pattern = self._process_pattern(name, pattern)
+        finally:
+            self._lookups_in_progress.pop()
+
+        return pattern
+
+    def materialize(self, name: str, *, persist: bool = True) -> Pattern:
+        if name in self._cache:
+            return self._cache[name]
+
+        pattern = self._materialize_uncached_detached(name)
+
+        if persist:
+            self._cache[name] = pattern
+        return pattern
+
+    def materialize_detached(self, name: str) -> Pattern:
+        if name in self._cache:
+            return self._cache[name].deepcopy()
+        return self._materialize_uncached_detached(name)
+
+    def materialize_many_detached(
+            self,
+            names: Sequence[str],
+            ) -> LibraryView:
+        ordered_names = tuple(dict.fromkeys(names))
+        result: dict[str, Pattern] = {}
+        uncached = [name for name in ordered_names if name not in self._cache]
+
+        for name in ordered_names:
+            if name in self._cache:
+                result[name] = self._cache[name].deepcopy()
+
+        if uncached:
+            if isinstance(self._source, IMaterializable):
+                source_patterns = self._source.materialize_many_detached(uncached)
+            else:
+                source_patterns = LibraryView({name: self._source[name].deepcopy() for name in uncached})
+            for name in uncached:
+                if name in self._lookups_in_progress:
+                    chain = ' -> '.join(self._lookups_in_progress + [name])
+                    raise LibraryError(f'Detected circular reference or recursive lookup of "{name}".\nLookup chain: {chain}')
+                self._lookups_in_progress.append(name)
+                try:
+                    result[name] = self._process_pattern(name, source_patterns[name])
+                finally:
+                    self._lookups_in_progress.pop()
+
+        return LibraryView({name: result[name] for name in ordered_names})
+
+    def source_order(self) -> tuple[str, ...]:
+        return self._source.source_order()
+
+    def borrowed_sources(self) -> tuple[ILibraryView, ...]:
+        return (self._source,)
+
+    def source_cell(self, name: str) -> tuple[ILibraryView, str] | None:
+        if not self._copy_through or name not in self._source or name in self._cache:
+            return None
+        return self._source, name
+
+    def child_graph(
+            self,
+            dangling: dangling_mode_t = 'error',
+            ) -> dict[str, set[str]]:
+        _validate_dangling_mode(dangling)
+        return self._source.child_graph(dangling=dangling)
+
+    def find_refs_local(
+            self,
+            name: str,
+            parent_graph: dict[str, set[str]] | None = None,
+            dangling: dangling_mode_t = 'error',
+            ) -> dict[str, list[NDArray[numpy.float64]]]:
+        _validate_dangling_mode(dangling)
+        finder = getattr(self._source, 'find_refs_local', None)
+        if callable(finder):
+            return cast('dict[str, list[NDArray[numpy.float64]]]', finder(name, parent_graph=parent_graph, dangling=dangling))
+        return super().find_refs_local(name, parent_graph=parent_graph, dangling=dangling)
+
+
+class PortLoadView(_ProcessedLibraryView):
+    """
+    Read-only view which loads or applies ports on first materialization.
+
+    The wrapped source remains untouched; this view owns a separate processed
+    cache so direct-copy workflows can continue to use the raw source view.
+    The view borrows its source: callers must keep the source open for the
+    lifetime of the view and close the source themselves.
+
+    Graph queries and source ordering are delegated to the wrapped source,
+    while `source_cell()` exposes unchanged layout provenance and `__getitem__`
+    and `materialize_many()` return port-imported patterns.
+    """
+
+    def __init__(
+            self,
+            source: ILibraryView,
+            *,
+            layers: Sequence[layer_t] = (),
+            max_depth: int = 0,
+            skip_subcells: bool = True,
+            ports: Mapping[str, Mapping[str, Port]] | None = None,
+            replace: bool = False,
+            ) -> None:
+        super().__init__(source, copy_through=True)
+        self._layers = tuple(layers)
+        self._max_depth = max_depth
+        self._skip_subcells = skip_subcells
+        self._ports = {
+            name: copy.deepcopy(dict(cell_ports))
+            for name, cell_ports in (ports or {}).items()
+        }
+        self._replace = replace
+
+    def _process_pattern(self, name: str, pattern: Pattern) -> Pattern:
+        from ..utils.ports2data import data_to_ports        # noqa: PLC0415
+
+        if self._layers:
+            pattern = data_to_ports(
+                layers=self._layers,
+                library=self,
+                pattern=pattern,
+                name=name,
+                max_depth=self._max_depth,
+                skip_subcells=self._skip_subcells,
+                )
+        if name in self._ports:
+            ports = copy.deepcopy(self._ports[name])
+            if self._replace:
+                pattern.ports = ports
+            else:
+                pattern.ports.update(ports)
+        return pattern
+
+
+class LayerMappedView(_ProcessedLibraryView):
+    """
+    Read-only view which remaps shape and label layers on materialization.
+
+    The wrapped source remains untouched. By default, source-aware writers
+    must materialize and serialize every mapped cell. With `copy_through=True`,
+    unmaterialized cells may instead be copied unchanged from their source;
+    persistent access maps and caches a cell, disabling copy-through for it.
+    """
+
+    def __init__(
+            self,
+            source: ILibraryView,
+            map_layer: Callable[[layer_t], layer_t],
+            *,
+            copy_through: bool = False,
+            ) -> None:
+        super().__init__(source, copy_through=copy_through)
+        self._map_layer = map_layer
+
+    def _process_pattern(self, name: str, pattern: Pattern) -> Pattern:
+        _ = name
+        pattern.shapes = map_layers(pattern.shapes, self._map_layer)
+        pattern.labels = map_layers(pattern.labels, self._map_layer)
+        return pattern
+
+
+class OverlayLibrary(ILibrary, IMaterializable, IBorrowing):
+    """
+    Mutable overlay over one or more source libraries.
+
+    Source-backed cells remain lazy until accessed through `__getitem__`, which
+    persistently materializes a detached, overlay-owned `Pattern`.
+
+    Source libraries must remain open and must not be mutated after they are
+    added. The overlay borrows each source and snapshots its names, hierarchy,
+    and initial visible-name mapping while retaining the source itself for lazy
+    pattern materialization.
+    """
+
+    def __init__(self) -> None:
+        self._layers: list[_SourceLayer] = []
+        self._entries: dict[str, Pattern | _SourceEntry] = {}
+        self._order: list[str] = []
+        self._target_remap: dict[str, str] = {}
+
+    def __iter__(self) -> Iterator[str]:
+        return (name for name in self._order if name in self._entries)
+
+    def __len__(self) -> int:
+        return len(self._entries)
+
+    def __contains__(self, key: object) -> bool:
+        return key in self._entries
+
+    def __getitem__(self, key: str) -> Pattern:
+        return self.materialize(key, persist=True)
+
+    def __setitem__(
+            self,
+            key: str,
+            value: Pattern | Callable[[], Pattern],
+            ) -> None:
+        if key in self._entries:
+            raise LibraryError(f'"{key}" already exists in the library. Overwriting is not allowed!')
+        pattern = value() if callable(value) else value
+        self._entries[key] = pattern
+        if key not in self._order:
+            self._order.append(key)
+
+    def __delitem__(self, key: str) -> None:
+        if key not in self._entries:
+            raise KeyError(key)
+        del self._entries[key]
+
+    def _merge(self, key_self: str, other: Mapping[str, Pattern], key_other: str) -> None:
+        self[key_self] = copy.deepcopy(other[key_other])
+
+    def add_source(
+            self,
+            source: Mapping[str, Pattern] | ILibraryView,
+            *,
+            rename_theirs: Callable[[INameView, str], str] | None = _rename_patterns,
+            rename_when: Literal['conflict', 'always'] = 'conflict',
+            ) -> dict[str, str]:
+        """
+        Add a source-backed library layer.
+
+        The source must remain open, and its names, hierarchy, and pattern
+        contents must remain unchanged for the lifetime of this overlay.
+
+        Args:
+            rename_theirs: Function used to choose visible names for imported
+                source cells. Its `INameView` argument contains existing and
+                previously reserved names, but does not support pattern lookup.
+                By default, conflicting single-use names are made unique;
+                pass `None` to reject every conflict.
+            rename_when: If `'conflict'`, only conflicting names are renamed.
+                If `'always'`, every imported source name is passed through
+                `rename_theirs`.
+        """
+        view = source if isinstance(source, ILibraryView) else LibraryView(source)
+        source_order = list(view.source_order())
+        child_graph = view.child_graph(dangling='include')
+
+        source_to_visible = _plan_source_names(
+            self,
+            source_order,
+            rename_theirs = rename_theirs,
+            rename_when = rename_when,
+            )
+        layer = _SourceLayer(
+            library=view,
+            source_target_map=dict(source_to_visible),
+            child_graph=child_graph,
+        )
+        layer_index = len(self._layers)
+        self._layers.append(layer)
+
+        for source_name, visible_name in source_to_visible.items():
+            self._entries[visible_name] = _SourceEntry(layer_index=layer_index, source_name=source_name)
+            if visible_name not in self._order:
+                self._order.append(visible_name)
+
+        return _source_rename_map(source_to_visible)
+
+    def rename(
+            self,
+            old_name: str,
+            new_name: str,
+            move_references: bool = False,
+            ) -> OverlayLibrary:
+        if old_name not in self._entries:
+            raise LibraryError(f'"{old_name}" does not exist in the library.')
+        if old_name == new_name:
+            return self
+        if new_name in self._entries:
+            raise LibraryError(f'"{new_name}" already exists in the library.')
+
+        entry = self._entries.pop(old_name)
+        self._entries[new_name] = entry
+
+        idx = self._order.index(old_name)
+        self._order[idx] = new_name
+
+        if move_references:
+            self.move_references(old_name, new_name)
+        return self
+
+    def _resolve_target(self, target: str) -> str:
+        seen: set[str] = set()
+        current = target
+        while current in self._target_remap:
+            if current in seen:
+                raise LibraryError(f'Cycle encountered while resolving target remap for {target!r}')
+            seen.add(current)
+            current = self._target_remap[current]
+        return current
+
+    def _set_target_remap(self, old_target: str, new_target: str) -> None:
+        resolved_new = self._resolve_target(new_target)
+        if resolved_new == old_target:
+            raise LibraryError(f'Ref target remap would create a cycle: {old_target!r} -> {new_target!r}')
+        self._target_remap[old_target] = resolved_new
+        for key in list(self._target_remap):
+            self._target_remap[key] = self._resolve_target(self._target_remap[key])
+
+    def move_references(self, old_target: str, new_target: str) -> OverlayLibrary:
+        if old_target == new_target:
+            return self
+        self._set_target_remap(old_target, new_target)
+        for entry in list(self._entries.values()):
+            if isinstance(entry, Pattern) and old_target in entry.refs:
+                entry.refs[new_target].extend(entry.refs[old_target])
+                del entry.refs[old_target]
+        return self
+
+    def _effective_target(self, layer: _SourceLayer, target: str) -> str:
+        visible = layer.source_target_map.get(target, target)
+        return self._resolve_target(visible)
+
+    def _remap_source_pattern(self, layer: _SourceLayer, source_pat: Pattern) -> Pattern:
+        def remap(target: str | None) -> str | None:
+            return None if target is None else self._effective_target(layer, target)
+
+        if source_pat.refs:
+            source_pat.refs = map_targets(source_pat.refs, remap)
+        return source_pat
+
+    def materialize(self, name: str, *, persist: bool = True) -> Pattern:
+        if name not in self._entries:
+            raise KeyError(name)
+        entry = self._entries[name]
+        if isinstance(entry, Pattern):
+            return entry
+
+        layer = self._layers[entry.layer_index]
+        source_pat = _materialize_detached_pattern(layer.library, entry.source_name)
+        pat = self._remap_source_pattern(layer, source_pat)
+        if persist:
+            self._entries[name] = pat
+        return pat
+
+    def materialize_detached(self, name: str) -> Pattern:
+        if name not in self._entries:
+            raise KeyError(name)
+        entry = self._entries[name]
+        if isinstance(entry, Pattern):
+            return entry.deepcopy()
+        layer = self._layers[entry.layer_index]
+        source_pat = _materialize_detached_pattern(layer.library, entry.source_name)
+        return self._remap_source_pattern(layer, source_pat)
+
+    def materialize_many_detached(
+            self,
+            names: Sequence[str],
+            ) -> LibraryView:
+        ordered_names = tuple(dict.fromkeys(names))
+        missing = next((name for name in ordered_names if name not in self._entries), None)
+        if missing is not None:
+            raise KeyError(missing)
+
+        result: dict[str, Pattern] = {}
+        grouped: dict[int, list[tuple[str, str]]] = defaultdict(list)
+        for name in ordered_names:
+            entry = self._entries[name]
+            if isinstance(entry, Pattern):
+                result[name] = entry.deepcopy()
+            else:
+                grouped[entry.layer_index].append((name, entry.source_name))
+
+        for layer_index, cells in grouped.items():
+            layer = self._layers[layer_index]
+            source_names = [source_name for _name, source_name in cells]
+            if isinstance(layer.library, IMaterializable):
+                source_patterns = layer.library.materialize_many_detached(source_names)
+            else:
+                source_patterns = LibraryView({
+                    source_name: layer.library[source_name].deepcopy()
+                    for source_name in source_names
+                    })
+            for name, source_name in cells:
+                result[name] = self._remap_source_pattern(layer, source_patterns[source_name])
+
+        return LibraryView({name: result[name] for name in ordered_names})
+
+    def child_graph(
+            self,
+            dangling: dangling_mode_t = 'error',
+            ) -> dict[str, set[str]]:
+        _validate_dangling_mode(dangling)
+        graph: dict[str, set[str]] = {}
+        for name in self._order:
+            if name not in self._entries:
+                continue
+            entry = self._entries[name]
+            if isinstance(entry, Pattern):
+                graph[name] = {child for child, refs in entry.refs.items() if child is not None and refs}
+                continue
+            layer = self._layers[entry.layer_index]
+            children = {self._effective_target(layer, child) for child in layer.child_graph.get(entry.source_name, set())}
+            graph[name] = children
+
+        existing = set(graph)
+        dangling_refs = set().union(*(children - existing for children in graph.values()))
+        if dangling == 'error':
+            if dangling_refs:
+                raise self._dangling_refs_error(cast('set[str]', dangling_refs), 'building child graph')
+            return graph
+        if dangling == 'ignore':
+            return {name: {child for child in children if child in existing} for name, children in graph.items()}
+
+        for child in dangling_refs:
+            graph.setdefault(cast('str', child), set())
+        return graph
+
+    def subtree(
+            self,
+            tops: str | Sequence[str],
+            ) -> Self:
+        if isinstance(tops, str):
+            tops = (tops,)
+
+        graph = self.child_graph(dangling='include')
+        keep = self._referenced_patterns_from_graph(graph, tops=tops)
+        keep &= set(self)
+        keep |= set(tops)
+
+        new = type(self)()
+        new._layers = [
+            _SourceLayer(
+                library=layer.library,
+                source_target_map=dict(layer.source_target_map),
+                child_graph={name: set(children) for name, children in layer.child_graph.items()},
+                )
+            for layer in self._layers
+            ]
+        new._order = [name for name in self._order if name in keep and name in self._entries]
+        new._entries = {name: self._entries[name] for name in new._order}
+        new._target_remap = dict(self._target_remap)
+        return new
+
+    def find_refs_local(
+            self,
+            name: str,
+            parent_graph: dict[str, set[str]] | None = None,
+            dangling: dangling_mode_t = 'error',
+            ) -> dict[str, list[NDArray[numpy.float64]]]:
+        _validate_dangling_mode(dangling)
+        instances: dict[str, list[NDArray[numpy.float64]]] = defaultdict(list)
+        if parent_graph is None:
+            graph_mode = 'ignore' if dangling == 'ignore' else 'include'
+            parent_graph = self.parent_graph(dangling=graph_mode)
+
+        if name not in self:
+            if name not in parent_graph:
+                return instances
+            if dangling == 'error':
+                raise self._dangling_refs_error({name}, f'finding local refs for {name!r}')
+            if dangling == 'ignore':
+                return instances
+
+        for parent in parent_graph.get(name, set()):
+            pat = self.materialize(parent, persist=False)
+            for ref in pat.refs.get(name, []):
+                instances[parent].append(ref.as_transforms())
+        return instances
+
+    def source_order(self) -> tuple[str, ...]:
+        return tuple(name for name in self._order if name in self._entries)
+
+    def borrowed_sources(self) -> tuple[ILibraryView, ...]:
+        return tuple(layer.library for layer in self._layers)
+
+    def source_cell(self, name: str) -> tuple[ILibraryView, str] | None:
+        entry = self._entries.get(name)
+        if not isinstance(entry, _SourceEntry):
+            return None
+        layer = self._layers[entry.layer_index]
+        children = layer.child_graph.get(entry.source_name, set())
+        if any(self._effective_target(layer, child) != child for child in children):
+            return None
+        return layer.library, entry.source_name

masque/library/utils.py

@@ -0,0 +1,223 @@
+"""Shared types and helpers for library implementations."""
+from __future__ import annotations
+
+from abc import ABC
+from typing import TYPE_CHECKING, Literal, Protocol, TypeAlias
+from collections.abc import Callable, Collection, Iterator, Mapping, MutableMapping, Sequence
+import logging
+import re
+
+from ..error import LibraryError
+
+if TYPE_CHECKING:
+    import numpy
+    from numpy.typing import NDArray
+
+    from ..pattern import Pattern
+
+
+logger = logging.getLogger(__name__)
+
+SINGLE_USE_PREFIX = '_'
+"""
+Names starting with this prefix are assumed to refer to single-use patterns,
+which may be renamed automatically by `ILibrary.add()` (via
+`rename_theirs=_rename_patterns()` )
+"""
+# TODO what are the consequences of making '_' special?  maybe we can make this decision everywhere?
+
+
+class INameView(Collection[str], ABC):
+    """
+    Read-only collection of reserved names with a shared name allocator.
+
+    Name views support membership, iteration, `len()`, and `get_name()`. They
+    do not provide pattern lookup or the other operations of a library mapping.
+    """
+
+    def get_name(
+            self,
+            name: str = SINGLE_USE_PREFIX * 2,
+            sanitize: bool = True,
+            max_length: int = 32,
+            quiet: bool | None = None,
+            ) -> str:
+        """
+        Find a unique name.
+
+        This function may be overridden in a subclass or monkey-patched to fit
+        the caller's requirements.
+
+        Args:
+            name: Preferred name. Default is `SINGLE_USE_PREFIX * 2`.
+            sanitize: Allow only alphanumeric characters and _?$, replacing
+                invalid characters with underscores.
+            max_length: Truncate names longer than this.
+            quiet: Suppress log messages when `True`. The default suppresses
+                messages only when `name` starts with `SINGLE_USE_PREFIX`.
+
+        Returns:
+            A name unique within this view.
+        """
+        if quiet is None:
+            quiet = name.startswith(SINGLE_USE_PREFIX)
+
+        if sanitize:
+            sanitized_name = re.compile(r'[^A-Za-z0-9_\?\$]').sub('_', name)
+        else:
+            sanitized_name = name
+
+        suffixed_name = sanitized_name
+        if sanitized_name in self:
+            ii = sum(1 for nn in self if nn.startswith(sanitized_name))
+        else:
+            ii = 0
+        while suffixed_name in self or suffixed_name == '':
+            suffixed_name = sanitized_name + b64suffix(ii)
+            ii += 1
+
+        if len(suffixed_name) > max_length:
+            if name == '':
+                raise LibraryError(f'No valid pattern names remaining within the specified {max_length=}')
+
+            cropped_name = self.get_name(sanitized_name[:-1], sanitize=sanitize, max_length=max_length, quiet=True)
+        else:
+            cropped_name = suffixed_name
+
+        if not quiet:
+            logger.info(f'Requested name "{name}" changed to "{cropped_name}"')
+
+        return cropped_name
+
+
+class visitor_function_t(Protocol):
+    """ Signature for `Library.dfs()` visitor functions. """
+    def __call__(
+            self,
+            pattern: Pattern,
+            hierarchy: tuple[str | None, ...],
+            memo: dict,
+            transform: NDArray[numpy.float64] | Literal[False],
+            ) -> Pattern:
+        ...
+
+
+TreeView: TypeAlias = Mapping[str, 'Pattern']
+""" A name-to-`Pattern` mapping which is expected to have only one top-level cell """
+
+Tree: TypeAlias = MutableMapping[str, 'Pattern']
+""" A mutable name-to-`Pattern` mapping which is expected to have only one top-level cell """
+
+dangling_mode_t: TypeAlias = Literal['error', 'ignore', 'include']
+""" How helpers should handle refs whose targets are not present in the library. """
+
+
+def _rename_patterns(lib: INameView, name: str) -> str:
+    """
+    The default `rename_theirs` function for `ILibrary.add`.
+
+      Treats names starting with `SINGLE_USE_PREFIX` (default: one underscore) as
+    "one-offs" for which name conflicts should be automatically resolved.
+    Conflicts are resolved by calling `lib.get_name(SINGLE_USE_PREFIX + stem)`
+    where `stem = name.removeprefix(SINGLE_USE_PREFIX).split('$')[0]`.
+    Names lacking the prefix are directly returned (not renamed).
+
+    Args:
+        lib: The library into which `name` is to be added (but is presumed to conflict)
+        name: The original name, to be modified
+
+    Returns:
+        The new name, not guaranteed to be conflict-free!
+    """
+    if not name.startswith(SINGLE_USE_PREFIX):
+        return name
+
+    stem = name.removeprefix(SINGLE_USE_PREFIX).split('$')[0]
+    return lib.get_name(SINGLE_USE_PREFIX + stem)
+
+
+def _validate_dangling_mode(dangling: dangling_mode_t) -> None:
+    if dangling not in ('error', 'ignore', 'include'):
+        raise ValueError(
+            f'Unknown dangling-reference mode {dangling!r}; '
+            'expected one of "error", "ignore", or "include"'
+            )
+
+
+class _ProspectiveNames(INameView):
+    """Target names plus names reserved earlier in an addition plan."""
+
+    def __init__(
+            self,
+            target: INameView,
+            reserved: set[str],
+            ) -> None:
+        self._target = target
+        self._reserved = reserved
+
+    def __iter__(self) -> Iterator[str]:
+        yield from self._target
+        yield from self._reserved
+
+    def __len__(self) -> int:
+        return len(self._target) + len(self._reserved)
+
+    def __contains__(self, key: object) -> bool:
+        return key in self._reserved or key in self._target
+
+
+def _plan_source_names(
+        target: INameView,
+        source_order: Sequence[str],
+        *,
+        rename_theirs: Callable[[INameView, str], str] | None = None,
+        rename_when: Literal['conflict', 'always'] = 'conflict',
+        ) -> dict[str, str]:
+    if rename_when not in ('conflict', 'always'):
+        raise ValueError(f'Unknown source rename mode: {rename_when!r}')
+    if rename_when == 'always' and rename_theirs is None:
+        raise TypeError('rename_theirs is required when rename_when="always"')
+
+    source_to_visible: dict[str, str] = {}
+    reserved: set[str] = set()
+    prospective = _ProspectiveNames(target, reserved)
+
+    for name in source_order:
+        visible = name
+        if rename_when == 'always':
+            assert rename_theirs is not None
+            visible = rename_theirs(prospective, name)
+        elif visible in prospective:
+            if rename_theirs is None:
+                raise LibraryError(f'Conflicting name while adding source: {name!r}')
+            visible = rename_theirs(prospective, name)
+        if visible in prospective:
+            raise LibraryError(f'Unresolved duplicate key encountered while adding source: {name!r} -> {visible!r}')
+        source_to_visible[name] = visible
+        reserved.add(visible)
+
+    return source_to_visible
+
+
+def _source_rename_map(source_to_visible: Mapping[str, str]) -> dict[str, str]:
+    return {
+        source_name: visible_name
+        for source_name, visible_name in source_to_visible.items()
+        if source_name != visible_name
+        }
+
+def b64suffix(ii: int) -> str:
+    """
+    Turn an integer into a base64-equivalent suffix.
+
+    This could be done with base64.b64encode, but this way is faster for many small `ii`.
+    """
+    def i2a(nn: int) -> str:
+        return 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789$?'[nn]
+
+    parts = ['$', i2a(ii % 64)]
+    ii >>= 6
+    while ii:
+        parts.append(i2a(ii % 64))
+        ii >>= 6
+    return ''.join(parts)

masque/pattern.py

@@ -26,9 +26,45 @@ from .traits import AnnotatableImpl, Scalable, Mirrorable, Rotatable, Positionab
 from .ports import Port, PortList
 
 
+
 logger = logging.getLogger(__name__)
 
 
+def _check_ref_cycles(
+        pattern: 'Pattern',
+        library: Mapping[str, 'Pattern'],
+        *,
+        operation: str,
+        ) -> None:
+    visited: set[str] = set()
+    active: list[str] = []
+    active_set: set[str] = set()
+
+    def visit(current: 'Pattern') -> None:
+        for target, refs in current.refs.items():
+            if target is None or not refs:
+                continue
+            if target in active_set:
+                cycle_start = active.index(target)
+                cycle = active[cycle_start:] + [target]
+                raise PatternError(
+                    f'Circular reference while {operation}: {" -> ".join(cycle)}'
+                    )
+            if target in visited:
+                continue
+
+            active.append(target)
+            active_set.add(target)
+            try:
+                visit(library[target])
+            finally:
+                active.pop()
+                active_set.remove(target)
+            visited.add(target)
+
+    visit(pattern)
+
+
 @functools.total_ordering
 class Pattern(PortList, AnnotatableImpl, Mirrorable):
     """
@@ -37,8 +73,8 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
     or provide equivalent functions.
 
     `Pattern` also stores a dict of `Port`s, which can be used to "snap" together points.
-    See `Pattern.plug()` and `Pattern.place()`, as well as the helper classes
-    `builder.Builder`, `builder.Pather`, `builder.RenderPather`, and `ports.PortsList`.
+    See `Pattern.plug()` and `Pattern.place()`, as well as `builder.Pather`
+    and `ports.PortsList`.
 
     For convenience, ports can be read out using square brackets:
     - `pattern['A'] == Port((0, 0), 0)`
@@ -171,7 +207,8 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
         return s
 
     def __copy__(self) -> 'Pattern':
-        logger.warning('Making a shallow copy of a Pattern... old shapes are re-referenced!')
+        logger.warning('Making a shallow copy of a Pattern... old shapes/refs/labels are re-referenced! '
+                       'Consider using .deepcopy() if this was not intended.')
         new = Pattern(
             annotations=copy.deepcopy(self.annotations),
             ports=copy.deepcopy(self.ports),
@@ -198,7 +235,7 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
 
     def __lt__(self, other: 'Pattern') -> bool:
         self_nonempty_targets = [target for target, reflist in self.refs.items() if reflist]
-        other_nonempty_targets = [target for target, reflist in self.refs.items() if reflist]
+        other_nonempty_targets = [target for target, reflist in other.refs.items() if reflist]
         self_tgtkeys = tuple(sorted((target is None, target) for target in self_nonempty_targets))
         other_tgtkeys = tuple(sorted((target is None, target) for target in other_nonempty_targets))
 
@@ -212,7 +249,7 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
                 return refs_ours < refs_theirs
 
         self_nonempty_layers = [ll for ll, elems in self.shapes.items() if elems]
-        other_nonempty_layers = [ll for ll, elems in self.shapes.items() if elems]
+        other_nonempty_layers = [ll for ll, elems in other.shapes.items() if elems]
         self_layerkeys = tuple(sorted(layer2key(ll) for ll in self_nonempty_layers))
         other_layerkeys = tuple(sorted(layer2key(ll) for ll in other_nonempty_layers))
 
@@ -221,21 +258,21 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
 
         for _, _, layer in self_layerkeys:
             shapes_ours = tuple(sorted(self.shapes[layer]))
-            shapes_theirs = tuple(sorted(self.shapes[layer]))
+            shapes_theirs = tuple(sorted(other.shapes[layer]))
             if shapes_ours != shapes_theirs:
                 return shapes_ours < shapes_theirs
 
         self_nonempty_txtlayers = [ll for ll, elems in self.labels.items() if elems]
-        other_nonempty_txtlayers = [ll for ll, elems in self.labels.items() if elems]
+        other_nonempty_txtlayers = [ll for ll, elems in other.labels.items() if elems]
         self_txtlayerkeys = tuple(sorted(layer2key(ll) for ll in self_nonempty_txtlayers))
         other_txtlayerkeys = tuple(sorted(layer2key(ll) for ll in other_nonempty_txtlayers))
 
         if self_txtlayerkeys != other_txtlayerkeys:
             return self_txtlayerkeys < other_txtlayerkeys
 
-        for _, _, layer in self_layerkeys:
+        for _, _, layer in self_txtlayerkeys:
             labels_ours = tuple(sorted(self.labels[layer]))
-            labels_theirs = tuple(sorted(self.labels[layer]))
+            labels_theirs = tuple(sorted(other.labels[layer]))
             if labels_ours != labels_theirs:
                 return labels_ours < labels_theirs
 
@@ -252,7 +289,7 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
             return False
 
         self_nonempty_targets = [target for target, reflist in self.refs.items() if reflist]
-        other_nonempty_targets = [target for target, reflist in self.refs.items() if reflist]
+        other_nonempty_targets = [target for target, reflist in other.refs.items() if reflist]
         self_tgtkeys = tuple(sorted((target is None, target) for target in self_nonempty_targets))
         other_tgtkeys = tuple(sorted((target is None, target) for target in other_nonempty_targets))
 
@@ -266,7 +303,7 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
                 return False
 
         self_nonempty_layers = [ll for ll, elems in self.shapes.items() if elems]
-        other_nonempty_layers = [ll for ll, elems in self.shapes.items() if elems]
+        other_nonempty_layers = [ll for ll, elems in other.shapes.items() if elems]
         self_layerkeys = tuple(sorted(layer2key(ll) for ll in self_nonempty_layers))
         other_layerkeys = tuple(sorted(layer2key(ll) for ll in other_nonempty_layers))
 
@@ -275,21 +312,21 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
 
         for _, _, layer in self_layerkeys:
             shapes_ours = tuple(sorted(self.shapes[layer]))
-            shapes_theirs = tuple(sorted(self.shapes[layer]))
+            shapes_theirs = tuple(sorted(other.shapes[layer]))
             if shapes_ours != shapes_theirs:
                 return False
 
         self_nonempty_txtlayers = [ll for ll, elems in self.labels.items() if elems]
-        other_nonempty_txtlayers = [ll for ll, elems in self.labels.items() if elems]
+        other_nonempty_txtlayers = [ll for ll, elems in other.labels.items() if elems]
         self_txtlayerkeys = tuple(sorted(layer2key(ll) for ll in self_nonempty_txtlayers))
         other_txtlayerkeys = tuple(sorted(layer2key(ll) for ll in other_nonempty_txtlayers))
 
         if self_txtlayerkeys != other_txtlayerkeys:
             return False
 
-        for _, _, layer in self_layerkeys:
+        for _, _, layer in self_txtlayerkeys:
             labels_ours = tuple(sorted(self.labels[layer]))
-            labels_theirs = tuple(sorted(self.labels[layer]))
+            labels_theirs = tuple(sorted(other.labels[layer]))
             if labels_ours != labels_theirs:
                 return False
 
@@ -347,6 +384,16 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
         Returns:
             self
         """
+        annotation_conflicts: set[str] = set()
+        if other_pattern.annotations is not None and self.annotations is not None:
+            annotation_conflicts = set(self.annotations.keys()) & set(other_pattern.annotations.keys())
+            if annotation_conflicts:
+                raise PatternError(f'Annotation keys overlap: {annotation_conflicts}')
+
+        port_conflicts = set(self.ports.keys()) & set(other_pattern.ports.keys())
+        if port_conflicts:
+            raise PatternError(f'Port names overlap: {port_conflicts}')
+
         for target, rseq in other_pattern.refs.items():
             self.refs[target].extend(rseq)
         for layer, sseq in other_pattern.shapes.items():
@@ -357,14 +404,7 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
         if other_pattern.annotations is not None:
             if self.annotations is None:
                 self.annotations = {}
-            annotation_conflicts = set(self.annotations.keys()) & set(other_pattern.annotations.keys())
-            if annotation_conflicts:
-                raise PatternError(f'Annotation keys overlap: {annotation_conflicts}')
             self.annotations.update(other_pattern.annotations)
-
-        port_conflicts = set(self.ports.keys()) & set(other_pattern.ports.keys())
-        if port_conflicts:
-            raise PatternError(f'Port names overlap: {port_conflicts}')
         self.ports.update(other_pattern.ports)
 
         return self
@@ -499,6 +539,74 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
             ]
         return polys
 
+    def layer_as_polygons(
+            self,
+            layer: layer_t,
+            flatten: bool = True,
+            library: Mapping[str, 'Pattern'] | None = None,
+            *,
+            _cycle_checked: bool = False,
+            ) -> list[Polygon]:
+        """
+        Collect all geometry effectively on a given layer as a list of polygons.
+
+        If `flatten=True`, it recursively gathers shapes on `layer` from all `self.refs`.
+        `Repetition` objects are expanded, and non-polygon shapes are converted
+        to `Polygon` approximations.
+
+        Args:
+            layer: The layer to collect geometry from.
+            flatten: If `True`, include geometry from referenced patterns.
+            library: Required if `flatten=True` to resolve references.
+
+        Returns:
+            A list of `Polygon` objects.
+
+        Raises:
+            PatternError: If `flatten=True` and the referenced hierarchy contains a cycle.
+        """
+        if flatten and self.has_refs() and library is None:
+            raise PatternError("Must provide a library to layer_as_polygons() when flatten=True")
+        if flatten and self.has_refs() and not _cycle_checked:
+            assert library is not None
+            _check_ref_cycles(self, library, operation='collecting layer polygons')
+
+        polys: list[Polygon] = []
+
+        # Local shapes
+        for shape in self.shapes.get(layer, []):
+            for p in shape.to_polygons():
+                # expand repetitions
+                if p.repetition is not None:
+                    for offset in p.repetition.displacements:
+                        polys.append(p.deepcopy().translate(offset).set_repetition(None))
+                else:
+                    polys.append(p.deepcopy())
+
+        if flatten and self.has_refs():
+            assert library is not None
+            for target, refs in self.refs.items():
+                if target is None or not refs:
+                    continue
+                target_pat = library[target]
+                for ref in refs:
+                    # Get polygons from target pattern on the same layer
+                    ref_polys = target_pat.layer_as_polygons(
+                        layer,
+                        flatten=True,
+                        library=library,
+                        _cycle_checked=True,
+                        )
+                    # Apply ref transformations
+                    for p in ref_polys:
+                        p_pat = ref.as_pattern(Pattern(shapes={layer: [p]}))
+                        # as_pattern expands repetition of the ref itself
+                        # but we need to pull the polygons back out
+                        for p_transformed in p_pat.shapes[layer]:
+                            polys.append(cast('Polygon', p_transformed))
+
+        return polys
+
     def referenced_patterns(self) -> set[str | None]:
         """
         Get all pattern namers referenced by this pattern. Non-recursive.
@@ -506,13 +614,15 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
         Returns:
             A set of all pattern names referenced by this pattern.
         """
-        return set(self.refs.keys())
+        return {target for target, refs in self.refs.items() if refs}
 
     def get_bounds(
             self,
             library: Mapping[str, 'Pattern'] | None = None,
             recurse: bool = True,
             cache: MutableMapping[str, NDArray[numpy.float64] | None] | None = None,
+            *,
+            _cycle_checked: bool = False,
             ) -> NDArray[numpy.float64] | None:
         """
         Return a `numpy.ndarray` containing `[[x_min, y_min], [x_max, y_max]]`, corresponding to the
@@ -529,7 +639,13 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
 
         Returns:
             `[[x_min, y_min], [x_max, y_max]]` or `None`
+
+        Raises:
+            PatternError: If recursive bounds are requested for a cyclic hierarchy.
         """
+        if recurse and self.has_refs() and library is not None and not _cycle_checked:
+            _check_ref_cycles(self, library, operation='calculating bounds')
+
         if self.is_empty():
             return None
 
@@ -568,7 +684,12 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
                 if target in cache:
                     unrot_bounds = cache[target]
                 elif any(numpy.isclose(ref.rotation % (pi / 2), 0) for ref in refs):
-                    unrot_bounds = library[target].get_bounds(library=library, recurse=recurse, cache=cache)
+                    unrot_bounds = library[target].get_bounds(
+                        library=library,
+                        recurse=recurse,
+                        cache=cache,
+                        _cycle_checked=True,
+                        )
                     cache[target] = unrot_bounds
 
                 for ref in refs:
@@ -635,6 +756,7 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
         """
         for entry in chain(chain_elements(self.shapes, self.labels, self.refs), self.ports.values()):
             cast('Positionable', entry).translate(offset)
+        self._log_bulk_update(f"translate({offset!r})")
         return self
 
     def scale_elements(self, c: float) -> Self:
@@ -688,7 +810,9 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
 
     def rotate_around(self, pivot: ArrayLike, rotation: float) -> Self:
         """
-        Rotate the Pattern around the a location.
+        Extrinsic transformation: Rotate the Pattern around the a location in the
+        container's coordinate system. This affects all elements' offsets and
+        their repetition grids.
 
         Args:
             pivot: (x, y) location to rotate around
@@ -702,11 +826,14 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
         self.rotate_elements(rotation)
         self.rotate_element_centers(rotation)
         self.translate_elements(+pivot)
+        self._log_bulk_update(f"rotate_around({pivot}, {rotation})")
         return self
 
     def rotate_element_centers(self, rotation: float) -> Self:
         """
-        Rotate the offsets of all shapes, labels, refs, and ports around (0, 0)
+        Extrinsic transformation part: Rotate the offsets and repetition grids of all
+        shapes, labels, refs, and ports around (0, 0) in the container's
+        coordinate system.
 
         Args:
             rotation: Angle to rotate by (counter-clockwise, radians)
@@ -717,11 +844,15 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
         for entry in chain(chain_elements(self.shapes, self.refs, self.labels), self.ports.values()):
             old_offset = cast('Positionable', entry).offset
             cast('Positionable', entry).offset = numpy.dot(rotation_matrix_2d(rotation), old_offset)
+            if isinstance(entry, Repeatable) and entry.repetition is not None:
+                entry.repetition.rotate(rotation)
         return self
 
     def rotate_elements(self, rotation: float) -> Self:
         """
-        Rotate each shape, ref, and port around its origin (offset)
+        Intrinsic transformation part: Rotate each shape, ref, label, and port around its
+        origin (offset) in the container's coordinate system. This does NOT
+        affect their repetition grids.
 
         Args:
             rotation: Angle to rotate by (counter-clockwise, radians)
@@ -729,54 +860,61 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
         Returns:
             self
         """
-        for entry in chain(chain_elements(self.shapes, self.refs), self.ports.values()):
-            cast('Rotatable', entry).rotate(rotation)
+        for entry in chain(chain_elements(self.shapes, self.refs, self.labels), self.ports.values()):
+            if isinstance(entry, Rotatable):
+                entry.rotate(rotation)
         return self
 
-    def mirror_element_centers(self, across_axis: int = 0) -> Self:
+    def mirror_element_centers(self, axis: int = 0) -> Self:
         """
-        Mirror the offsets of all shapes, labels, and refs across an axis
+        Extrinsic transformation part: Mirror the offsets and repetition grids of all
+        shapes, labels, refs, and ports relative to the container's origin.
 
         Args:
-            across_axis: Axis to mirror across
-                (0: mirror across x axis, 1: mirror across y axis)
+            axis: Axis to mirror across (0: x-axis, 1: y-axis)
 
         Returns:
             self
         """
         for entry in chain(chain_elements(self.shapes, self.refs, self.labels), self.ports.values()):
-            cast('Positionable', entry).offset[1 - across_axis] *= -1
+            cast('Positionable', entry).offset[1 - axis] *= -1
+            if isinstance(entry, Repeatable) and entry.repetition is not None:
+                entry.repetition.mirror(axis)
         return self
 
-    def mirror_elements(self, across_axis: int = 0) -> Self:
+    def mirror_elements(self, axis: int = 0) -> Self:
         """
-        Mirror each shape, ref, and pattern across an axis, relative
-          to its offset
+        Intrinsic transformation part: Mirror each shape, ref, label, and port relative
+        to its offset. This does NOT affect their repetition grids.
 
         Args:
-            across_axis: Axis to mirror across
-                (0: mirror across x axis, 1: mirror across y axis)
+            axis: Axis to mirror across
+                0: mirror across x axis (flip y),
+                1: mirror across y axis (flip x)
 
         Returns:
             self
         """
-        for entry in chain(chain_elements(self.shapes, self.refs), self.ports.values()):
-            cast('Mirrorable', entry).mirror(across_axis)
+        for entry in chain(chain_elements(self.shapes, self.refs, self.labels), self.ports.values()):
+            if isinstance(entry, Mirrorable):
+                entry.mirror(axis=axis)
+        self._log_bulk_update(f"mirror_elements({axis})")
         return self
 
-    def mirror(self, across_axis: int = 0) -> Self:
+    def mirror(self, axis: int = 0) -> Self:
         """
-        Mirror the Pattern across an axis
+        Extrinsic transformation: Mirror the Pattern across an axis through its origin.
+        This affects all elements' offsets and their internal orientations.
 
         Args:
-            across_axis: Axis to mirror across
-                (0: mirror across x axis, 1: mirror across y axis)
+            axis: Axis to mirror across (0: x-axis, 1: y-axis).
 
         Returns:
             self
         """
-        self.mirror_elements(across_axis)
-        self.mirror_element_centers(across_axis)
+        self.mirror_elements(axis=axis)
+        self.mirror_element_centers(axis=axis)
+        self._log_bulk_update(f"mirror({axis})")
         return self
 
     def copy(self) -> Self:
@@ -787,7 +925,7 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
         Returns:
             A deep copy of the current Pattern.
         """
-        return copy.deepcopy(self)
+        return self.deepcopy()
 
     def deepcopy(self) -> Self:
         """
@@ -930,6 +1068,28 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
                 del self.labels[layer]
         return self
 
+    def resolve_repeated_refs(self) -> Self:
+        """
+        Expand all repeated references into multiple individual references.
+        Alters the current pattern in-place.
+
+        Returns:
+            self
+        """
+        new_refs: defaultdict[str | None, list[Ref]] = defaultdict(list)
+        for target, rseq in self.refs.items():
+            for ref in rseq:
+                if ref.repetition is None:
+                    new_refs[target].append(ref)
+                else:
+                    for dd in ref.repetition.displacements:
+                        new_ref = ref.deepcopy()
+                        new_ref.offset = ref.offset + dd
+                        new_ref.repetition = None
+                        new_refs[target].append(new_ref)
+        self.refs = new_refs
+        return self
+
     def prune_refs(self) -> Self:
         """
         Remove empty ref lists in `self.refs`.
@@ -981,10 +1141,16 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
 
                 if target_pat is None:
                     raise PatternError(f'Circular reference in {name} to {target}')
-                if target_pat.is_empty():        # avoid some extra allocations
+                ports_only = flatten_ports and bool(target_pat.ports)
+                if target_pat.is_empty() and not ports_only:        # avoid some extra allocations
                     continue
 
                 for ref in refs:
+                    if flatten_ports and ref.repetition is not None and target_pat.ports:
+                        raise PatternError(
+                            f'Cannot flatten ports from repeated ref to {target!r}; '
+                            'flatten with flatten_ports=False or expand/rename the ports manually first.'
+                            )
                     p = ref.as_pattern(pattern=target_pat)
                     if not flatten_ports:
                         p.ports.clear()
@@ -1003,6 +1169,8 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
             line_color: str = 'k',
             fill_color: str = 'none',
             overdraw: bool = False,
+            filename: str | None = None,
+            ports: bool = False,
             ) -> None:
         """
         Draw a picture of the Pattern and wait for the user to inspect it
@@ -1013,65 +1181,181 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
          klayout or a different GDS viewer!
 
         Args:
-            offset: Coordinates to offset by before drawing
-            line_color: Outlines are drawn with this color (passed to `matplotlib.collections.PolyCollection`)
-            fill_color: Interiors are drawn with this color (passed to `matplotlib.collections.PolyCollection`)
-            overdraw: Whether to create a new figure or draw on a pre-existing one
+            library: Mapping of {name: Pattern} for resolving references. Required if `self.has_refs()`.
+            offset: Coordinates to offset by before drawing.
+            line_color: Outlines are drawn with this color.
+            fill_color: Interiors are drawn with this color.
+            overdraw: Whether to create a new figure or draw on a pre-existing one.
+            filename: If provided, save the figure to this file instead of showing it.
+            ports: If True, annotate the plot with arrows representing the ports.
+
+        Raises:
+            PatternError: If the referenced hierarchy contains a cycle.
         """
         # TODO: add text labels to visualize()
+        if self.has_refs() and library is None:
+            raise PatternError('Must provide a library when visualizing a pattern with refs')
+        if self.has_refs():
+            assert library is not None
+            _check_ref_cycles(self, library, operation='visualizing pattern hierarchy')
+
         try:
-            from matplotlib import pyplot       # type: ignore
-            import matplotlib.collections       # type: ignore
+            from matplotlib import pyplot       # type: ignore  #noqa: PLC0415
+            import matplotlib.collections       # type: ignore  #noqa: PLC0415
         except ImportError:
             logger.exception('Pattern.visualize() depends on matplotlib!\n'
                 + 'Make sure to install masque with the [visualize] option to pull in the needed dependencies.')
             raise
 
-        if self.has_refs() and library is None:
-            raise PatternError('Must provide a library when visualizing a pattern with refs')
+        # Cache for {Pattern object ID: List of local polygon vertex arrays}
+        # Polygons are stored relative to the pattern's origin (offset included)
+        poly_cache: dict[int, list[NDArray[numpy.float64]]] = {}
 
-        offset = numpy.asarray(offset, dtype=float)
+        def get_local_polys(pat: 'Pattern') -> list[NDArray[numpy.float64]]:
+            pid = id(pat)
+            if pid not in poly_cache:
+                polys = []
+                for shape in chain.from_iterable(pat.shapes.values()):
+                    for ss in shape.to_polygons():
+                        # Shape.to_polygons() returns Polygons with their own offsets and vertices.
+                        # We need to expand any shape-level repetition here.
+                        v_base = ss.vertices + ss.offset
+                        if ss.repetition is not None:
+                            for disp in ss.repetition.displacements:
+                                polys.append(v_base + disp)
+                        else:
+                            polys.append(v_base)
+                poly_cache[pid] = polys
+            return poly_cache[pid]
 
+        all_polygons: list[NDArray[numpy.float64]] = []
+        port_info: list[tuple[str, NDArray[numpy.float64], float]] = []
+
+        def collect_polys_recursive(
+                pat: 'Pattern',
+                c_offset: NDArray[numpy.float64],
+                c_rotation: float,
+                c_mirrored: bool,
+                c_scale: float,
+                ) -> None:
+            # Current transform: T(c_offset) * R(c_rotation) * M(c_mirrored) * S(c_scale)
+
+            # 1. Transform and collect local polygons
+            local_polys = get_local_polys(pat)
+            if local_polys:
+                rot_mat = rotation_matrix_2d(c_rotation)
+                for v in local_polys:
+                    vt = v * c_scale
+                    if c_mirrored:
+                        vt = vt.copy()
+                        vt[:, 1] *= -1
+                    vt = (rot_mat @ vt.T).T + c_offset
+                    all_polygons.append(vt)
+
+            # 2. Collect ports if requested
+            if ports:
+                for name, p in pat.ports.items():
+                    pt_v = p.offset * c_scale
+                    if c_mirrored:
+                        pt_v = pt_v.copy()
+                        pt_v[1] *= -1
+                    pt_v = rotation_matrix_2d(c_rotation) @ pt_v + c_offset
+
+                    if p.rotation is not None:
+                        pt_rot = p.rotation
+                        if c_mirrored:
+                            pt_rot = -pt_rot
+                        pt_rot += c_rotation
+                        port_info.append((name, pt_v, pt_rot))
+
+            # 3. Recurse into refs
+            for target, refs in pat.refs.items():
+                if target is None or not refs:
+                    continue
+                assert library is not None
+                target_pat = library[target]
+                for ref in refs:
+                    # Ref order of operations: mirror, rotate, scale, translate, repeat
+
+                    # Combined scale and mirror
+                    r_scale = c_scale * ref.scale
+                    r_mirrored = c_mirrored ^ ref.mirrored
+
+                    # Combined rotation: push c_mirrored and c_rotation through ref.rotation
+                    r_rot_relative = -ref.rotation if c_mirrored else ref.rotation
+                    r_rotation = c_rotation + r_rot_relative
+
+                    # Offset composition helper
+                    def get_full_offset(rel_offset: NDArray[numpy.float64]) -> NDArray[numpy.float64]:
+                        o = rel_offset * c_scale
+                        if c_mirrored:
+                            o = o.copy()
+                            o[1] *= -1
+                        return rotation_matrix_2d(c_rotation) @ o + c_offset
+
+                    if ref.repetition is not None:
+                        for disp in ref.repetition.displacements:
+                            collect_polys_recursive(
+                                target_pat,
+                                get_full_offset(ref.offset + disp),
+                                r_rotation,
+                                r_mirrored,
+                                r_scale
+                                )
+                    else:
+                        collect_polys_recursive(
+                            target_pat,
+                            get_full_offset(ref.offset),
+                            r_rotation,
+                            r_mirrored,
+                            r_scale
+                            )
+
+        # Start recursive collection
+        collect_polys_recursive(self, numpy.asarray(offset, dtype=float), 0.0, False, 1.0)
+
+        # Plotting
         if not overdraw:
             figure = pyplot.figure()
-            pyplot.axis('equal')
         else:
             figure = pyplot.gcf()
 
         axes = figure.gca()
 
-        polygons = []
-        for shape in chain.from_iterable(self.shapes.values()):
-            polygons += [offset + s.offset + s.vertices for s in shape.to_polygons()]
-
+        if all_polygons:
             mpl_poly_collection = matplotlib.collections.PolyCollection(
-            polygons,
+                all_polygons,
                 facecolors = fill_color,
                 edgecolors = line_color,
                 )
             axes.add_collection(mpl_poly_collection)
-        pyplot.axis('equal')
 
-        for target, refs in self.refs.items():
-            if target is None:
-                continue
-            if not refs:
-                continue
-            assert library is not None
-            target_pat = library[target]
-            for ref in refs:
-                ref.as_pattern(target_pat).visualize(
-                    library=library,
-                    offset=offset,
-                    overdraw=True,
-                    line_color=line_color,
-                    fill_color=fill_color,
+        if ports:
+            for port_name, pt_v, pt_rot in port_info:
+                p1 = pt_v
+                angle = pt_rot
+                size = 1.0  # arrow size
+                p2 = p1 + size * numpy.array([numpy.cos(angle), numpy.sin(angle)])
+
+                axes.annotate(
+                    port_name,
+                    xy = tuple(p1),
+                    xytext = tuple(p2),
+                    arrowprops = dict(arrowstyle="->", color='g', linewidth=1),
+                    color = 'g',
+                    fontsize = 8,
                     )
 
+        axes.autoscale_view()
+        axes.set_aspect('equal')
+
         if not overdraw:
-            pyplot.xlabel('x')
-            pyplot.ylabel('y')
-            pyplot.show()
+            axes.set_xlabel('x')
+            axes.set_ylabel('y')
+            if filename:
+                figure.savefig(filename)
+            else:
+                figure.show()
 
 #    @overload
 #    def place(
@@ -1114,6 +1398,7 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
             port_map: dict[str, str | None] | None = None,
             skip_port_check: bool = False,
             append: bool = False,
+            skip_geometry: bool = False,
             ) -> Self:
         """
         Instantiate or append the pattern `other` into the current pattern, adding its
@@ -1145,6 +1430,10 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
             append: If `True`, `other` is appended instead of being referenced.
                 Note that this does not flatten  `other`, so its refs will still
                 be refs (now inside `self`).
+            skip_geometry: If `True`, the operation only updates the port list and
+                skips adding any geometry (shapes, labels, or references). This
+                allows the pattern assembly to proceed for port-tracking purposes
+                even when layout generation is suppressed.
 
         Returns:
             self
@@ -1159,7 +1448,26 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
             port_map = {}
 
         if not skip_port_check:
-            self.check_ports(other.ports.keys(), map_in=None, map_out=port_map)
+            port_map, overwrite_targets = self._resolve_insert_mapping(
+                other.ports.keys(),
+                map_in=None,
+                map_out=port_map,
+                allow_conflicts=skip_geometry,
+                )
+            for target in overwrite_targets:
+                self.ports.pop(target, None)
+
+        if not skip_geometry:
+            if append:
+                if isinstance(other, Abstract):
+                    raise PatternError('Must provide a full `Pattern` (not an `Abstract`) when appending!')
+                if other.annotations is not None and self.annotations is not None:
+                    annotation_conflicts = set(self.annotations.keys()) & set(other.annotations.keys())
+                    if annotation_conflicts:
+                        raise PatternError(f'Annotation keys overlap: {annotation_conflicts}')
+            elif isinstance(other, Pattern):
+                raise PatternError('Must provide an `Abstract` (not a `Pattern`) when creating a reference. '
+                                   'Use `append=True` if you intended to append the full geometry.')
 
         ports = {}
         for name, port in other.ports.items():
@@ -1176,10 +1484,12 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
             pp.rotate_around(pivot, rotation)
             pp.translate(offset)
             self.ports[name] = pp
+            self._log_port_update(name)
+
+        if skip_geometry:
+            return self
 
         if append:
-            if isinstance(other, Abstract):
-                raise PatternError('Must provide a full `Pattern` (not an `Abstract`) when appending!')
             other_copy = other.deepcopy()
             other_copy.ports.clear()
             if mirrored:
@@ -1188,7 +1498,6 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
             other_copy.translate_elements(offset)
             self.append(other_copy)
         else:
-            assert not isinstance(other, Pattern)
             ref = Ref(mirrored=mirrored)
             ref.rotate_around(pivot, rotation)
             ref.translate(offset)
@@ -1234,6 +1543,7 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
             set_rotation: bool | None = None,
             append: bool = False,
             ok_connections: Iterable[tuple[str, str]] = (),
+            skip_geometry: bool = False,
             ) -> Self:
         """
         Instantiate or append a pattern into the current pattern, connecting
@@ -1283,11 +1593,15 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
             append: If `True`, `other` is appended instead of being referenced.
                 Note that this does not flatten  `other`, so its refs will still
                 be refs (now inside `self`).
-            ok_connections: Set of "allowed" ptype combinations. Identical
-                ptypes are always allowed to connect, as is `'unk'` with
-                any other ptypte. Non-allowed ptype connections will emit a
-                warning. Order is ignored, i.e. `(a, b)` is equivalent to
-                `(b, a)`.
+            ok_connections: Set of additional allowed ptype combinations.
+                Ptypes accepted by the shared compatibility policy are always
+                allowed. Non-allowed ptype connections will emit a warning.
+                Order is ignored, i.e. `(a, b)` is equivalent to `(b, a)`.
+            skip_geometry: If `True`, only ports are updated and geometry is
+                skipped. If a valid transform cannot be found (e.g. due to
+                misaligned ports), a 'best-effort' dummy transform is used
+                to ensure new ports are still added at approximate locations,
+                allowing downstream routing to continue.
 
         Returns:
             self
@@ -1319,7 +1633,24 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
             out_port_name = next(iter(set(other.ports.keys()) - set(map_in.values())))
             map_out = {out_port_name: next(iter(map_in.keys()))}
 
-        self.check_ports(other.ports.keys(), map_in, map_out)
+        map_out, overwrite_targets = self._resolve_insert_mapping(
+            other.ports.keys(),
+            map_in,
+            map_out,
+            allow_conflicts=skip_geometry,
+            )
+        if not skip_geometry:
+            if append:
+                if isinstance(other, Abstract):
+                    raise PatternError('Must provide a full `Pattern` (not an `Abstract`) when appending!')
+                if other.annotations is not None and self.annotations is not None:
+                    annotation_conflicts = set(self.annotations.keys()) & set(other.annotations.keys())
+                    if annotation_conflicts:
+                        raise PatternError(f'Annotation keys overlap: {annotation_conflicts}')
+            elif isinstance(other, Pattern):
+                raise PatternError('Must provide an `Abstract` (not a `Pattern`) when creating a reference. '
+                                   'Use `append=True` if you intended to append the full geometry.')
+        try:
             translation, rotation, pivot = self.find_transform(
                 other,
                 map_in,
@@ -1327,15 +1658,34 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
                 set_rotation = set_rotation,
                 ok_connections = ok_connections,
                 )
+        except PortError:
+            if not skip_geometry:
+                raise
+            logger.warning("Port transform failed for dead device. Using dummy transform.")
+            if map_in:
+                ki, vi = next(iter(map_in.items()))
+                s_port = self.ports[ki]
+                o_port = other.ports[vi].deepcopy()
+                if mirrored:
+                    o_port.mirror()
+                    o_port.offset[1] *= -1
+                translation = s_port.offset - o_port.offset
+                rotation = (s_port.rotation - o_port.rotation - pi) if (s_port.rotation is not None and o_port.rotation is not None) else 0
+                pivot = o_port.offset
+            else:
+                translation = numpy.zeros(2)
+                rotation = 0.0
+                pivot = numpy.zeros(2)
+
+        for target in overwrite_targets:
+            self.ports.pop(target, None)
 
         # get rid of plugged ports
         for ki, vi in map_in.items():
             del self.ports[ki]
+            self._log_port_removal(ki)
             map_out[vi] = None
 
-        if isinstance(other, Pattern):
-            assert append, 'Got a name (not an abstract) but was asked to reference (not append)'
-
         self.place(
             other,
             offset = translation,
@@ -1345,6 +1695,7 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
             port_map = map_out,
             skip_port_check = True,
             append = append,
+            skip_geometry = skip_geometry,
             )
         return self
 
@@ -1378,7 +1729,7 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
           current device.
 
         Args:
-            source: A collection of ports (e.g. Pattern, Builder, or dict)
+            source: A collection of ports (e.g. Pattern, Pather, or dict)
                 from which to create the interface.
             in_prefix: Prepended to port names for newly-created ports with
                 reversed directions compared to the current device.
@@ -1406,9 +1757,13 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
         else:
             raise PatternError(f'Unable to get ports from {type(source)}: {source}')
 
-        if port_map:
+        if port_map is not None:
             if isinstance(port_map, dict):
                 missing_inkeys = set(port_map.keys()) - set(orig_ports.keys())
+                port_targets = list(port_map.values())
+                duplicate_targets = {vv for vv in port_targets if port_targets.count(vv) > 1}
+                if duplicate_targets:
+                    raise PortError(f'Duplicate targets in `port_map`: {duplicate_targets}')
                 mapped_ports = {port_map[k]: v for k, v in orig_ports.items() if k in port_map}
             else:
                 port_set = set(port_map)
@@ -1474,6 +1829,8 @@ def map_layers(
     new_elements: defaultdict[layer_t, list[TT]] = defaultdict(list)
     for old_layer, seq in elements.items():
         new_layer = map_layer(old_layer)
+        if new_layer is None:
+            raise PatternError(f'Layer mapping returned None for source layer {old_layer!r}')
         new_elements[new_layer].extend(seq)
     return new_elements
 

masque/ports.py

@@ -2,6 +2,7 @@ from typing import overload, Self, NoReturn, Any
 from collections.abc import Iterable, KeysView, ValuesView, Mapping
 import logging
 import functools
+import copy
 from collections import Counter
 from abc import ABCMeta, abstractmethod
 from itertools import chain
@@ -10,16 +11,17 @@ import numpy
 from numpy import pi
 from numpy.typing import ArrayLike, NDArray
 
-from .traits import PositionableImpl, Rotatable, PivotableImpl, Copyable, Mirrorable
-from .utils import rotate_offsets_around, rotation_matrix_2d
+from .traits import PositionableImpl, PivotableImpl, Copyable, Mirrorable, Flippable
+from .utils import ptypes_compatible, rotate_offsets_around, rotation_matrix_2d
 from .error import PortError, format_stacktrace
 
 
 logger = logging.getLogger(__name__)
+port_logger = logging.getLogger('masque.ports')
 
 
 @functools.total_ordering
-class Port(PositionableImpl, Rotatable, PivotableImpl, Copyable, Mirrorable):
+class Port(PivotableImpl, PositionableImpl, Mirrorable, Flippable, Copyable):
     """
     A point at which a `Device` can be snapped to another `Device`.
 
@@ -91,6 +93,12 @@ class Port(PositionableImpl, Rotatable, PivotableImpl, Copyable, Mirrorable):
     def copy(self) -> Self:
         return self.deepcopy()
 
+    def __deepcopy__(self, memo: dict | None = None) -> Self:
+        memo = {} if memo is None else memo
+        new = copy.copy(self)
+        new._offset = self._offset.copy()
+        return new
+
     def get_bounds(self) -> NDArray[numpy.float64]:
         return numpy.vstack((self.offset, self.offset))
 
@@ -99,6 +107,27 @@ class Port(PositionableImpl, Rotatable, PivotableImpl, Copyable, Mirrorable):
         self.ptype = ptype
         return self
 
+    def flip_across(self, axis: int | None = None, *, x: float | None = None, y: float | None = None) -> Self:
+        """
+        Mirror the object across a line in the container's coordinate system.
+
+        Note this operation is performed relative to the pattern's origin and modifies the port's offset.
+
+        Args:
+            axis: Axis to mirror across. 0 mirrors across y=0. 1 mirrors across x=0.
+            x: Vertical line x=val to mirror across.
+            y: Horizontal line y=val to mirror across.
+
+        Returns:
+            self
+        """
+        axis, pivot = self._check_flip_args(axis=axis, x=x, y=y)
+        self.translate(-pivot)
+        self.mirror(axis)
+        self.offset[1 - axis] *= -1
+        self.translate(+pivot)
+        return self
+
     def mirror(self, axis: int = 0) -> Self:
         if self.rotation is not None:
             self.rotation *= -1
@@ -114,6 +143,34 @@ class Port(PositionableImpl, Rotatable, PivotableImpl, Copyable, Mirrorable):
         self.rotation = rotation
         return self
 
+    def describe(self) -> str:
+        """
+        Returns a human-readable description of the port's state including cardinal directions.
+        """
+        deg = numpy.rad2deg(self.rotation) if self.rotation is not None else None
+
+        cardinal = ""
+        travel_dir = ""
+
+        if self.rotation is not None:
+            dirs = {0: "East (+x)", 90: "North (+y)", 180: "West (-x)", 270: "South (-y)"}
+            # normalize to [0, 360)
+            deg_norm = deg % 360
+
+            # Find closest cardinal
+            closest = min(dirs.keys(), key=lambda x: abs((deg_norm - x + 180) % 360 - 180))
+            if numpy.isclose((deg_norm - closest + 180) % 360 - 180, 0, atol=1e-3):
+                cardinal = f" ({dirs[closest]})"
+
+            # Travel direction (rotation + 180)
+            t_deg = (deg_norm + 180) % 360
+            closest_t = min(dirs.keys(), key=lambda x: abs((t_deg - x + 180) % 360 - 180))
+            if numpy.isclose((t_deg - closest_t + 180) % 360 - 180, 0, atol=1e-3):
+                travel_dir = f" (Travel -> {dirs[closest_t]})"
+
+        deg_text = 'any' if deg is None else f'{deg:g}'
+        return f"pos=({self.x:g}, {self.y:g}), rot={deg_text}{cardinal}{travel_dir}"
+
     def __repr__(self) -> str:
         if self.rotation is None:
             rot = 'any'
@@ -179,6 +236,19 @@ class PortList(metaclass=ABCMeta):
     def ports(self, value: dict[str, Port]) -> None:
         pass
 
+    def _log_port_update(self, name: str) -> None:
+        """ Log the current state of the named port """
+        port_logger.debug("Port %s: %s", name, self.ports[name].describe())
+
+    def _log_port_removal(self, name: str) -> None:
+        """ Log that the named port has been removed """
+        port_logger.debug("Port %s: removed", name)
+
+    def _log_bulk_update(self, label: str) -> None:
+        """ Log all current ports at DEBUG level """
+        for name, port in self.ports.items():
+            port_logger.debug("%s: Port %s: %s", label, name, port)
+
     @overload
     def __getitem__(self, key: str) -> Port:
         pass
@@ -203,6 +273,12 @@ class PortList(metaclass=ABCMeta):
         else:                                       # noqa: RET505
             return {k: self.ports[k] for k in key}
 
+    def measure_travel(self, src: str, dst: str) -> tuple[NDArray[numpy.float64], float | None]:
+        """
+        Convenience wrapper for measuring travel between two named ports.
+        """
+        return self[src].measure_travel(self[dst])
+
     def __contains__(self, key: str) -> NoReturn:
         raise NotImplementedError('PortsList.__contains__ is left unimplemented. Use `key in container.ports` instead.')
 
@@ -232,6 +308,7 @@ class PortList(metaclass=ABCMeta):
             raise PortError(f'Port {name} already exists.')
         assert name not in self.ports
         self.ports[name] = value
+        self._log_port_update(name)
         return self
 
     def rename_ports(
@@ -253,17 +330,147 @@ class PortList(metaclass=ABCMeta):
         Returns:
             self
         """
+        self._rename_ports_impl(mapping, overwrite=overwrite)
+        return self
+
+    @staticmethod
+    def _normalize_target_mapping(
+            ordered_targets: Iterable[tuple[str, str | None]],
+            explicit_map: Mapping[str, str | None] | None = None,
+            ) -> dict[str, str | None]:
+        ordered_targets = list(ordered_targets)
+        normalized = {} if explicit_map is None else copy.deepcopy(dict(explicit_map))
+        winners = {
+            target: source
+            for source, target in ordered_targets
+            if target is not None
+            }
+        for source, target in ordered_targets:
+            if target is not None and winners[target] != source:
+                normalized[source] = None
+        return normalized
+
+    def _resolve_insert_mapping(
+            self,
+            other_names: Iterable[str],
+            map_in: Mapping[str, str] | None = None,
+            map_out: Mapping[str, str | None] | None = None,
+            *,
+            allow_conflicts: bool = False,
+            ) -> tuple[dict[str, str | None], set[str]]:
+        if map_in is None:
+            map_in = {}
+
+        normalized_map_out = {} if map_out is None else copy.deepcopy(dict(map_out))
+        other_names = list(other_names)
+        other = set(other_names)
+
+        missing_inkeys = set(map_in.keys()) - set(self.ports.keys())
+        if missing_inkeys:
+            raise PortError(f'`map_in` keys not present in device: {missing_inkeys}')
+
+        missing_invals = set(map_in.values()) - other
+        if missing_invals:
+            raise PortError(f'`map_in` values not present in other device: {missing_invals}')
+
+        map_in_counts = Counter(map_in.values())
+        conflicts_in = {kk for kk, vv in map_in_counts.items() if vv > 1}
+        if conflicts_in:
+            raise PortError(f'Duplicate values in `map_in`: {conflicts_in}')
+
+        missing_outkeys = set(normalized_map_out.keys()) - other
+        if missing_outkeys:
+            raise PortError(f'`map_out` keys not present in other device: {missing_outkeys}')
+
+        connected_outkeys = set(normalized_map_out.keys()) & set(map_in.values())
+        if connected_outkeys:
+            raise PortError(f'`map_out` keys conflict with connected ports: {connected_outkeys}')
+
+        orig_remaining = set(self.ports.keys()) - set(map_in.keys())
+        connected = set(map_in.values())
+        if allow_conflicts:
+            ordered_targets = [
+                (name, normalized_map_out.get(name, name))
+                for name in other_names
+                if name not in connected
+                ]
+            normalized_map_out = self._normalize_target_mapping(ordered_targets, normalized_map_out)
+            final_targets = {
+                normalized_map_out.get(name, name)
+                for name in other_names
+                if name not in connected and normalized_map_out.get(name, name) is not None
+                }
+            overwrite_targets = {target for target in final_targets if target in orig_remaining}
+            return normalized_map_out, overwrite_targets
+
+        other_remaining = other - set(normalized_map_out.keys()) - connected
+        mapped_vals = set(normalized_map_out.values())
+        mapped_vals.discard(None)
+
+        conflicts_final = orig_remaining & (other_remaining | mapped_vals)
+        if conflicts_final:
+            raise PortError(f'Device ports conflict with existing ports: {conflicts_final}')
+
+        conflicts_partial = other_remaining & mapped_vals
+        if conflicts_partial:
+            raise PortError(f'`map_out` targets conflict with non-mapped outputs: {conflicts_partial}')
+
+        map_out_counts = Counter(normalized_map_out.values())
+        map_out_counts[None] = 0
+        conflicts_out = {kk for kk, vv in map_out_counts.items() if vv > 1}
+        if conflicts_out:
+            raise PortError(f'Duplicate targets in `map_out`: {conflicts_out}')
+        return normalized_map_out, set()
+
+    def _rename_ports_impl(
+            self,
+            mapping: Mapping[str, str | None],
+            *,
+            overwrite: bool = False,
+            allow_collisions: bool = False,
+            ) -> dict[str, str]:
         if not overwrite:
             duplicates = (set(self.ports.keys()) - set(mapping.keys())) & set(mapping.values())
             if duplicates:
                 raise PortError(f'Unrenamed ports would be overwritten: {duplicates}')
+        missing = set(mapping) - set(self.ports)
+        if missing:
+            raise PortError(f'Ports to rename were not found: {missing}')
+        renamed_targets = [vv for vv in mapping.values() if vv is not None]
+        if not allow_collisions:
+            duplicate_targets = {vv for vv in renamed_targets if renamed_targets.count(vv) > 1}
+            if duplicate_targets:
+                raise PortError(f'Renamed ports would collide: {duplicate_targets}')
 
-        renamed = {vv: self.ports.pop(kk) for kk, vv in mapping.items()}
-        if None in renamed:
-            del renamed[None]
+        winners = {
+            target: source
+            for source, target in mapping.items()
+            if target is not None
+            }
+        overwritten = {
+            target
+            for target, source in winners.items()
+            if target in self.ports and target not in mapping and target != source
+            }
 
+        for kk, vv in mapping.items():
+            if vv is None or vv != kk:
+                self._log_port_removal(kk)
+
+        source_ports = {kk: self.ports.pop(kk) for kk in mapping}
+        for target in overwritten:
+            self.ports.pop(target, None)
+
+        renamed = {
+            vv: source_ports[kk]
+            for kk, vv in mapping.items()
+            if vv is not None and winners[vv] == kk
+            }
         self.ports.update(renamed)      # type: ignore
-        return self
+
+        for vv in winners:
+            self._log_port_update(vv)
+        return winners
 
     def add_port_pair(
             self,
@@ -285,12 +492,16 @@ class PortList(metaclass=ABCMeta):
         Returns:
             self
         """
+        if names[0] == names[1]:
+            raise PortError(f'Port names must be distinct: {names[0]!r}')
         new_ports = {
             names[0]: Port(offset, rotation=rotation, ptype=ptype),
             names[1]: Port(offset, rotation=rotation + pi, ptype=ptype),
             }
         self.check_ports(names)
         self.ports.update(new_ports)
+        self._log_port_update(names[0])
+        self._log_port_update(names[1])
         return self
 
     def plugged(
@@ -313,13 +524,25 @@ class PortList(metaclass=ABCMeta):
         Raises:
             `PortError` if the ports are not properly aligned.
         """
+        if not connections:
+            raise PortError('Must provide at least one port connection')
+        missing_a = set(connections) - set(self.ports)
+        if missing_a:
+            raise PortError(f'Connection source ports were not found: {missing_a}')
+        missing_b = set(connections.values()) - set(self.ports)
+        if missing_b:
+            raise PortError(f'Connection destination ports were not found: {missing_b}')
         a_names, b_names = list(zip(*connections.items(), strict=True))
+        used_names = list(chain(a_names, b_names))
+        duplicate_names = {name for name in used_names if used_names.count(name) > 1}
+        if duplicate_names:
+            raise PortError(f'Each port may appear in at most one connection: {duplicate_names}')
         a_ports = [self.ports[pp] for pp in a_names]
         b_ports = [self.ports[pp] for pp in b_names]
 
         a_types = [pp.ptype for pp in a_ports]
         b_types = [pp.ptype for pp in b_ports]
-        type_conflicts = numpy.array([at != bt and 'unk' not in (at, bt)
+        type_conflicts = numpy.array([not ptypes_compatible(at, bt)
                                       for at, bt in zip(a_types, b_types, strict=True)])
 
         if type_conflicts.any():
@@ -351,15 +574,16 @@ class PortList(metaclass=ABCMeta):
                 raise PortError(msg)
 
         translations = a_offsets - b_offsets
-        if not numpy.allclose(translations, 0):
+        if not numpy.allclose(a_offsets, b_offsets):
             msg = 'Port translations do not match:\n'
             for nn, (kk, vv) in enumerate(connections.items()):
-                if not numpy.allclose(translations[nn], 0):
+                if not numpy.allclose(a_offsets[nn], b_offsets[nn]):
                     msg += f'{kk} | {translations[nn]} | {vv}\n'
             raise PortError(msg)
 
         for pp in chain(a_names, b_names):
             del self.ports[pp]
+            self._log_port_removal(pp)
         return self
 
     def check_ports(
@@ -390,45 +614,7 @@ class PortList(metaclass=ABCMeta):
             `PortError` if there are any duplicate names after `map_in` and `map_out`
                 are applied.
         """
-        if map_in is None:
-            map_in = {}
-
-        if map_out is None:
-            map_out = {}
-
-        other = set(other_names)
-
-        missing_inkeys = set(map_in.keys()) - set(self.ports.keys())
-        if missing_inkeys:
-            raise PortError(f'`map_in` keys not present in device: {missing_inkeys}')
-
-        missing_invals = set(map_in.values()) - other
-        if missing_invals:
-            raise PortError(f'`map_in` values not present in other device: {missing_invals}')
-
-        missing_outkeys = set(map_out.keys()) - other
-        if missing_outkeys:
-            raise PortError(f'`map_out` keys not present in other device: {missing_outkeys}')
-
-        orig_remaining = set(self.ports.keys()) - set(map_in.keys())
-        other_remaining = other - set(map_out.keys()) - set(map_in.values())
-        mapped_vals = set(map_out.values())
-        mapped_vals.discard(None)
-
-        conflicts_final = orig_remaining & (other_remaining | mapped_vals)
-        if conflicts_final:
-            raise PortError(f'Device ports conflict with existing ports: {conflicts_final}')
-
-        conflicts_partial = other_remaining & mapped_vals
-        if conflicts_partial:
-            raise PortError(f'`map_out` targets conflict with non-mapped outputs: {conflicts_partial}')
-
-        map_out_counts = Counter(map_out.values())
-        map_out_counts[None] = 0
-        conflicts_out = {kk for kk, vv in map_out_counts.items() if vv > 1}
-        if conflicts_out:
-            raise PortError(f'Duplicate targets in `map_out`: {conflicts_out}')
-
+        self._resolve_insert_mapping(other_names, map_in, map_out)
         return self
 
     def find_transform(
@@ -455,11 +641,10 @@ class PortList(metaclass=ABCMeta):
                 port with `rotation=None`), `set_rotation` must be provided
                 to indicate how much `other` should be rotated. Otherwise,
                 `set_rotation` must remain `None`.
-            ok_connections: Set of "allowed" ptype combinations. Identical
-                ptypes are always allowed to connect, as is `'unk'` with
-                any other ptypte. Non-allowed ptype connections will log a
-                warning. Order is ignored, i.e. `(a, b)` is equivalent to
-                `(b, a)`.
+            ok_connections: Set of additional allowed ptype combinations.
+                Ptypes accepted by the shared compatibility policy are always
+                allowed. Non-allowed ptype connections will log a warning.
+                Order is ignored, i.e. `(a, b)` is equivalent to `(b, a)`.
 
         Returns:
             - The (x, y) translation (performed last)
@@ -468,6 +653,8 @@ class PortList(metaclass=ABCMeta):
 
             The rotation should be performed before the translation.
         """
+        if not map_in:
+            raise PortError('Must provide at least one port connection')
         s_ports = self[map_in.keys()]
         o_ports = other[map_in.values()]
         return self.find_port_transform(
@@ -506,11 +693,10 @@ class PortList(metaclass=ABCMeta):
                 port with `rotation=None`), `set_rotation` must be provided
                 to indicate how much `o_ports` should be rotated. Otherwise,
                 `set_rotation` must remain `None`.
-            ok_connections: Set of "allowed" ptype combinations. Identical
-                ptypes are always allowed to connect, as is `'unk'` with
-                any other ptypte. Non-allowed ptype connections will log a
-                warning. Order is ignored, i.e. `(a, b)` is equivalent to
-                `(b, a)`.
+            ok_connections: Set of additional allowed ptype combinations.
+                Ptypes accepted by the shared compatibility policy are always
+                allowed. Non-allowed ptype connections will log a warning.
+                Order is ignored, i.e. `(a, b)` is equivalent to `(b, a)`.
 
         Returns:
             - The (x, y) translation (performed last)
@@ -519,6 +705,8 @@ class PortList(metaclass=ABCMeta):
 
             The rotation should be performed before the translation.
         """
+        if not map_in:
+            raise PortError('Must provide at least one port connection')
         s_offsets = numpy.array([p.offset for p in s_ports.values()])
         o_offsets = numpy.array([p.offset for p in o_ports.values()])
         s_types = [p.ptype for p in s_ports.values()]
@@ -535,8 +723,10 @@ class PortList(metaclass=ABCMeta):
             o_rotations *= -1
 
         ok_pairs = {tuple(sorted(pair)) for pair in ok_connections if pair[0] != pair[1]}
-        type_conflicts = numpy.array([(st != ot) and ('unk' not in (st, ot)) and (tuple(sorted((st, ot))) not in ok_pairs)
-                                      for st, ot in zip(s_types, o_types, strict=True)])
+        type_conflicts = numpy.array([
+            not ptypes_compatible(st, ot) and tuple(sorted((st, ot))) not in ok_pairs
+            for st, ot in zip(s_types, o_types, strict=True)
+            ])
         if type_conflicts.any():
             msg = 'Ports have conflicting types:\n'
             for nn, (kk, vv) in enumerate(map_in.items()):
@@ -548,7 +738,7 @@ class PortList(metaclass=ABCMeta):
         rotations = numpy.mod(s_rotations - o_rotations - pi, 2 * pi)
         if not has_rot.any():
             if set_rotation is None:
-                PortError('Must provide set_rotation if rotation is indeterminate')
+                raise PortError('Must provide set_rotation if rotation is indeterminate')
             rotations[:] = set_rotation
         else:
             rotations[~has_rot] = rotations[has_rot][0]
@@ -573,4 +763,3 @@ class PortList(metaclass=ABCMeta):
             raise PortError(msg)
 
         return translations[0], rotations[0], o_offsets[0]
-

masque/ref.py

@@ -15,7 +15,8 @@ from .utils import annotations_t, rotation_matrix_2d, annotations_eq, annotation
 from .repetition import Repetition
 from .traits import (
     PositionableImpl, RotatableImpl, ScalableImpl,
-    Mirrorable, PivotableImpl, Copyable, RepeatableImpl, AnnotatableImpl,
+    PivotableImpl, Copyable, RepeatableImpl, AnnotatableImpl,
+    FlippableImpl,
     )
 
 
@@ -25,8 +26,9 @@ if TYPE_CHECKING:
 
 @functools.total_ordering
 class Ref(
-        PositionableImpl, RotatableImpl, ScalableImpl, Mirrorable,
-        PivotableImpl, Copyable, RepeatableImpl, AnnotatableImpl,
+        FlippableImpl, PivotableImpl, RepeatableImpl, AnnotatableImpl,
+        PositionableImpl, RotatableImpl, ScalableImpl,
+        Copyable,
         ):
     """
     `Ref` provides basic support for nesting Pattern objects within each other.
@@ -42,7 +44,7 @@ class Ref(
     __slots__ = (
         '_mirrored',
         # inherited
-        '_offset', '_rotation', 'scale', '_repetition', '_annotations',
+        '_offset', '_rotation', '_scale', '_repetition', '_annotations',
         )
 
     _mirrored: bool
@@ -84,24 +86,48 @@ class Ref(
         self.repetition = repetition
         self.annotations = annotations if annotations is not None else {}
 
+    @classmethod
+    def _from_raw(
+            cls,
+            *,
+            offset: NDArray[numpy.float64],
+            rotation: float,
+            mirrored: bool,
+            scale: float,
+            repetition: Repetition | None,
+            annotations: annotations_t | None,
+            ) -> Self:
+        new = cls.__new__(cls)
+        new._offset = offset
+        new._rotation = rotation % (2 * pi)
+        new._scale = scale
+        new._mirrored = mirrored
+        new._repetition = repetition
+        new._annotations = annotations
+        return new
+
     def __copy__(self) -> 'Ref':
         new = Ref(
             offset=self.offset.copy(),
             rotation=self.rotation,
             scale=self.scale,
             mirrored=self.mirrored,
-            repetition=copy.deepcopy(self.repetition),
-            annotations=copy.deepcopy(self.annotations),
+            repetition=self.repetition,
+            annotations=self.annotations,
             )
         return new
 
     def __deepcopy__(self, memo: dict | None = None) -> 'Ref':
         memo = {} if memo is None else memo
         new = copy.copy(self)
-        #new.repetition = copy.deepcopy(self.repetition, memo)
-        #new.annotations = copy.deepcopy(self.annotations, memo)
+        new._offset = self._offset.copy()
+        new.repetition = copy.deepcopy(self.repetition, memo)
+        new.annotations = copy.deepcopy(self.annotations, memo)
         return new
 
+    def copy(self) -> 'Ref':
+        return self.deepcopy()
+
     def __lt__(self, other: 'Ref') -> bool:
         if (self.offset != other.offset).any():
             return tuple(self.offset) < tuple(other.offset)
@@ -116,6 +142,8 @@ class Ref(
         return annotations_lt(self.annotations, other.annotations)
 
     def __eq__(self, other: Any) -> bool:
+        if type(self) is not type(other):
+            return False
         return (
             numpy.array_equal(self.offset, other.offset)
             and self.mirrored == other.mirrored
@@ -160,16 +188,16 @@ class Ref(
         return pattern
 
     def rotate(self, rotation: float) -> Self:
+        """
+        Intrinsic transformation: Rotate the target pattern relative to this Ref's
+        origin. This does NOT affect the repetition grid.
+        """
         self.rotation += rotation
-        if self.repetition is not None:
-            self.repetition.rotate(rotation)
         return self
 
     def mirror(self, axis: int = 0) -> Self:
         self.mirror_target(axis)
         self.rotation *= -1
-        if self.repetition is not None:
-            self.repetition.mirror(axis)
         return self
 
     def mirror_target(self, axis: int = 0) -> Self:
@@ -187,10 +215,11 @@ class Ref(
         xys = self.offset[None, :]
         if self.repetition is not None:
             xys = xys + self.repetition.displacements
-        transforms = numpy.empty((xys.shape[0], 4))
+        transforms = numpy.empty((xys.shape[0], 5))
         transforms[:, :2] = xys
         transforms[:, 2] = self.rotation
         transforms[:, 3] = self.mirrored
+        transforms[:, 4] = self.scale
         return transforms
 
     def get_bounds_single(
@@ -227,7 +256,10 @@ class Ref(
             bounds = numpy.vstack((numpy.min(corners, axis=0),
                                    numpy.max(corners, axis=0))) * self.scale + [self.offset]
             return bounds
-        return self.as_pattern(pattern=pattern).get_bounds(library)
+
+        single_ref = self.deepcopy()
+        single_ref.repetition = None
+        return single_ref.as_pattern(pattern=pattern).get_bounds(library)
 
     def __repr__(self) -> str:
         rotation = f' r{numpy.rad2deg(self.rotation):g}' if self.rotation != 0 else ''

masque/repetition.py

@@ -34,7 +34,7 @@ class Repetition(Copyable, Rotatable, Mirrorable, Scalable, Bounded, metaclass=A
         pass
 
     @abstractmethod
-    def __le__(self, other: 'Repetition') -> bool:
+    def __lt__(self, other: 'Repetition') -> bool:
         pass
 
     @abstractmethod
@@ -64,7 +64,7 @@ class Grid(Repetition):
     _a_count: int
     """ Number of instances along the direction specified by the `a_vector` """
 
-    _b_vector: NDArray[numpy.float64] | None
+    _b_vector: NDArray[numpy.float64]
     """ Vector `[x, y]` specifying a second lattice vector for the grid.
         Specifies center-to-center spacing between adjacent elements.
         Can be `None` for a 1D array.
@@ -113,6 +113,22 @@ class Grid(Repetition):
         self.a_count = a_count
         self.b_count = b_count
 
+    @classmethod
+    def _from_raw(
+            cls: type[GG],
+            *,
+            a_vector: NDArray[numpy.float64],
+            a_count: int,
+            b_vector: NDArray[numpy.float64],
+            b_count: int,
+            ) -> GG:
+        new = cls.__new__(cls)
+        new._a_vector = a_vector
+        new._b_vector = b_vector
+        new._a_count = int(a_count)
+        new._b_count = int(b_count)
+        return new
+
     @classmethod
     def aligned(
             cls: type[GG],
@@ -184,6 +200,8 @@ class Grid(Repetition):
     def a_count(self, val: int) -> None:
         if val != int(val):
             raise PatternError('a_count must be convertable to an int!')
+        if int(val) < 1:
+            raise PatternError(f'Repetition has too-small a_count: {val}')
         self._a_count = int(val)
 
     # b_count property
@@ -195,13 +213,12 @@ class Grid(Repetition):
     def b_count(self, val: int) -> None:
         if val != int(val):
             raise PatternError('b_count must be convertable to an int!')
+        if int(val) < 1:
+            raise PatternError(f'Repetition has too-small b_count: {val}')
         self._b_count = int(val)
 
     @property
     def displacements(self) -> NDArray[numpy.float64]:
-        if self.b_vector is None:
-            return numpy.arange(self.a_count)[:, None] * self.a_vector[None, :]
-
         aa, bb = numpy.meshgrid(numpy.arange(self.a_count), numpy.arange(self.b_count), indexing='ij')
         return (aa.flatten()[:, None] * self.a_vector[None, :]
               + bb.flatten()[:, None] * self.b_vector[None, :])             # noqa
@@ -291,7 +308,7 @@ class Grid(Repetition):
             return False
         return True
 
-    def __le__(self, other: Repetition) -> bool:
+    def __lt__(self, other: Repetition) -> bool:
         if type(self) is not type(other):
             return repr(type(self)) < repr(type(other))
         other = cast('Grid', other)
@@ -301,12 +318,8 @@ class Grid(Repetition):
             return self.b_count < other.b_count
         if not numpy.array_equal(self.a_vector, other.a_vector):
             return tuple(self.a_vector) < tuple(other.a_vector)
-        if self.b_vector is None:
-            return other.b_vector is not None
-        if other.b_vector is None:
-            return False
         if not numpy.array_equal(self.b_vector, other.b_vector):
-            return tuple(self.a_vector) < tuple(other.a_vector)
+            return tuple(self.b_vector) < tuple(other.b_vector)
         return False
 
 
@@ -332,7 +345,22 @@ class Arbitrary(Repetition):
 
     @displacements.setter
     def displacements(self, val: ArrayLike) -> None:
+        try:
             vala = numpy.array(val, dtype=float)
+        except (TypeError, ValueError) as exc:
+            raise PatternError('displacements must be convertible to an Nx2 ndarray') from exc
+
+        if vala.size == 0:
+            self._displacements = numpy.empty((0, 2), dtype=float)
+            return
+
+        if vala.ndim == 1:
+            if vala.size != 2:
+                raise PatternError('displacements must be convertible to an Nx2 ndarray')
+            vala = vala.reshape(1, 2)
+        elif vala.ndim != 2 or vala.shape[1] != 2:
+            raise PatternError('displacements must be convertible to an Nx2 ndarray')
+
         order = numpy.lexsort(vala.T[::-1])     # sortrows
         self._displacements = vala[order]
 
@@ -350,11 +378,11 @@ class Arbitrary(Repetition):
         return (f'<Arbitrary {len(self.displacements)}pts >')
 
     def __eq__(self, other: Any) -> bool:
-        if not type(other) is not type(self):
+        if type(other) is not type(self):
             return False
         return numpy.array_equal(self.displacements, other.displacements)
 
-    def __le__(self, other: Repetition) -> bool:
+    def __lt__(self, other: Repetition) -> bool:
         if type(self) is not type(other):
             return repr(type(self)) < repr(type(other))
         other = cast('Arbitrary', other)
@@ -391,7 +419,9 @@ class Arbitrary(Repetition):
         Returns:
             self
         """
-        self.displacements[1 - axis] *= -1
+        new_displacements = self.displacements.copy()
+        new_displacements[:, 1 - axis] *= -1
+        self.displacements = new_displacements
         return self
 
     def get_bounds(self) -> NDArray[numpy.float64] | None:
@@ -402,6 +432,8 @@ class Arbitrary(Repetition):
         Returns:
             `[[x_min, y_min], [x_max, y_max]]` or `None`
         """
+        if self.displacements.size == 0:
+            return None
         xy_min = numpy.min(self.displacements, axis=0)
         xy_max = numpy.max(self.displacements, axis=0)
         return numpy.array((xy_min, xy_max))
@@ -416,6 +448,5 @@ class Arbitrary(Repetition):
         Returns:
             self
         """
-        self.displacements *= c
+        self.displacements = self.displacements * c
         return self
-

masque/shapes/__init__.py

@@ -11,6 +11,7 @@ from .shape import (
 
 from .polygon import Polygon as Polygon
 from .poly_collection import PolyCollection as PolyCollection
+from .rect_collection import RectCollection as RectCollection
 from .circle import Circle as Circle
 from .ellipse import Ellipse as Ellipse
 from .arc import Arc as Arc

masque/shapes/arc.py

@@ -1,6 +1,7 @@
 from typing import Any, cast
 import copy
 import functools
+from enum import Enum
 
 import numpy
 from numpy import pi
@@ -13,18 +14,37 @@ from ..utils import is_scalar, annotations_t, annotations_lt, annotations_eq, re
 from ..traits import PositionableImpl
 
 
+@functools.total_ordering
+class ArcAngleRef(Enum):
+    Center = 'center'
+    FocusPos = 'focus_pos'
+    FocusNeg = 'focus_neg'
+
+    def __lt__(self, other: Any) -> bool:
+        if self.__class__ is not other.__class__:
+            return self.__class__.__name__ < other.__class__.__name__
+        order = {
+            ArcAngleRef.Center: 0,
+            ArcAngleRef.FocusPos: 1,
+            ArcAngleRef.FocusNeg: 2,
+        }
+        return order[self] < order[other]
+
+
 @functools.total_ordering
 class Arc(PositionableImpl, Shape):
     """
-    An elliptical arc, formed by cutting off an elliptical ring with two rays which exit from its
-     center. It has a position, two radii, a start and stop angle, a rotation, and a width.
+    An elliptical arc, formed by cutting off an elliptical ring with two rays.
+    By default the rays exit from its center, but they can optionally exit from one of the
+     foci of the nominal ellipse. It has a position, two radii, a start and stop angle,
+     a rotation, and a width.
 
     The radii define an ellipse; the ring is formed with radii +/- width/2.
     The rotation gives the angle from x-axis, counterclockwise, to the first (x) radius.
     The start and stop angle are measured counterclockwise from the first (x) radius.
     """
     __slots__ = (
-        '_radii', '_angles', '_width', '_rotation',
+        '_radii', '_angles', '_width', '_rotation', '_angle_ref',
         # Inherited
         '_offset', '_repetition', '_annotations',
         )
@@ -41,6 +61,11 @@ class Arc(PositionableImpl, Shape):
     _width: float
     """ Width of the arc """
 
+    _angle_ref: ArcAngleRef
+    """ Origin used by start/stop rays """
+
+    AngleRef = ArcAngleRef
+
     # radius properties
     @property
     def radii(self) -> NDArray[numpy.float64]:
@@ -54,8 +79,8 @@ class Arc(PositionableImpl, Shape):
         val = numpy.array(val, dtype=float).flatten()
         if not val.size == 2:
             raise PatternError('Radii must have length 2')
-        if not val.min() >= 0:
-            raise PatternError('Radii must be non-negative')
+        if not val.min() > 0:
+            raise PatternError('Radii must be positive')
         self._radii = val
 
     @property
@@ -64,8 +89,8 @@ class Arc(PositionableImpl, Shape):
 
     @radius_x.setter
     def radius_x(self, val: float) -> None:
-        if not val >= 0:
-            raise PatternError('Radius must be non-negative')
+        if not val > 0:
+            raise PatternError('Radius must be positive')
         self._radii[0] = val
 
     @property
@@ -74,8 +99,8 @@ class Arc(PositionableImpl, Shape):
 
     @radius_y.setter
     def radius_y(self, val: float) -> None:
-        if not val >= 0:
-            raise PatternError('Radius must be non-negative')
+        if not val > 0:
+            raise PatternError('Radius must be positive')
         self._radii[1] = val
 
     # arc start/stop angle properties
@@ -113,6 +138,18 @@ class Arc(PositionableImpl, Shape):
     def stop_angle(self, val: float) -> None:
         self.angles = (self.angles[0], val)
 
+    # Angle reference property
+    @property
+    def angle_ref(self) -> ArcAngleRef:
+        """
+        Origin used to interpret start and stop angle rays.
+        """
+        return self._angle_ref
+
+    @angle_ref.setter
+    def angle_ref(self, val: ArcAngleRef | str) -> None:
+        self._angle_ref = ArcAngleRef(val)
+
     # Rotation property
     @property
     def rotation(self) -> float:
@@ -159,34 +196,48 @@ class Arc(PositionableImpl, Shape):
             rotation: float = 0,
             repetition: Repetition | None = None,
             annotations: annotations_t = None,
-            raw: bool = False,
+            angle_ref: ArcAngleRef | str = ArcAngleRef.Center,
             ) -> None:
-        if raw:
-            assert isinstance(radii, numpy.ndarray)
-            assert isinstance(angles, numpy.ndarray)
-            assert isinstance(offset, numpy.ndarray)
-            self._radii = radii
-            self._angles = angles
-            self._width = width
-            self._offset = offset
-            self._rotation = rotation
-            self._repetition = repetition
-            self._annotations = annotations
-        else:
         self.radii = radii
         self.angles = angles
         self.width = width
         self.offset = offset
         self.rotation = rotation
+        self.angle_ref = angle_ref
         self.repetition = repetition
         self.annotations = annotations
 
+    @classmethod
+    def _from_raw(
+            cls,
+            *,
+            radii: NDArray[numpy.float64],
+            angles: NDArray[numpy.float64],
+            width: float,
+            offset: NDArray[numpy.float64],
+            rotation: float,
+            annotations: annotations_t = None,
+            repetition: Repetition | None = None,
+            angle_ref: ArcAngleRef | str = ArcAngleRef.Center,
+            ) -> 'Arc':
+        new = cls.__new__(cls)
+        new._radii = radii
+        new._angles = angles
+        new._width = width
+        new._offset = offset
+        new._rotation = rotation % (2 * pi)
+        new._angle_ref = ArcAngleRef(angle_ref)
+        new._repetition = repetition
+        new._annotations = annotations
+        return new
+
     def __deepcopy__(self, memo: dict | None = None) -> 'Arc':
         memo = {} if memo is None else memo
         new = copy.copy(self)
         new._offset = self._offset.copy()
         new._radii = self._radii.copy()
         new._angles = self._angles.copy()
+        new._repetition = copy.deepcopy(self._repetition, memo)
         new._annotations = copy.deepcopy(self._annotations)
         return new
 
@@ -198,6 +249,7 @@ class Arc(PositionableImpl, Shape):
             and numpy.array_equal(self.angles, other.angles)
             and self.width == other.width
             and self.rotation == other.rotation
+            and self.angle_ref == other.angle_ref
             and self.repetition == other.repetition
             and annotations_eq(self.annotations, other.annotations)
             )
@@ -214,6 +266,8 @@ class Arc(PositionableImpl, Shape):
             return tuple(self.radii) < tuple(other.radii)
         if not numpy.array_equal(self.angles, other.angles):
             return tuple(self.angles) < tuple(other.angles)
+        if self.angle_ref != other.angle_ref:
+            return self.angle_ref < other.angle_ref
         if not numpy.array_equal(self.offset, other.offset):
             return tuple(self.offset) < tuple(other.offset)
         if self.rotation != other.rotation:
@@ -230,6 +284,8 @@ class Arc(PositionableImpl, Shape):
         if (num_vertices is None) and (max_arclen is None):
             raise PatternError('Max number of points and arclength left unspecified'
                                + ' (default was also overridden)')
+        if max_arclen is not None and (numpy.isnan(max_arclen) or max_arclen <= 0):
+            raise PatternError('Max arclength must be positive and not NaN')
 
         r0, r1 = self.radii
 
@@ -256,29 +312,38 @@ class Arc(PositionableImpl, Shape):
             return arc_lengths, tt
 
         wh = self.width / 2.0
+        arclen_limits: list[float] = []
+        if max_arclen is not None:
+            arclen_limits.append(max_arclen)
         if num_vertices is not None:
             n_pts = numpy.ceil(max(self.radii + wh) / min(self.radii) * num_vertices * 100).astype(int)
             perimeter_inner = get_arclens(n_pts, *a_ranges[0], dr=-wh)[0].sum()
             perimeter_outer = get_arclens(n_pts, *a_ranges[1], dr= wh)[0].sum()
             implied_arclen = (perimeter_outer + perimeter_inner + self.width * 2) / num_vertices
-            max_arclen = min(implied_arclen, max_arclen if max_arclen is not None else numpy.inf)
-        assert max_arclen is not None
+            if not (numpy.isnan(implied_arclen) or implied_arclen <= 0):
+                arclen_limits.append(implied_arclen)
+        if not arclen_limits:
+            raise PatternError('Arc polygonization could not determine a valid max_arclen')
+        max_arclen = min(arclen_limits)
 
         def get_thetas(inner: bool) -> NDArray[numpy.float64]:
             """ Figure out the parameter values at which we should place vertices to meet the arclength constraint"""
             dr = -wh if inner else wh
 
-            n_pts = numpy.ceil(2 * pi * max(self.radii + dr) / max_arclen).astype(int)
+            n_pts = max(2, int(numpy.ceil(2 * pi * max(self.radii + dr) / max_arclen)))
             arc_lengths, thetas = get_arclens(n_pts, *a_ranges[0 if inner else 1], dr=dr)
 
             keep = [0]
-            removable = (numpy.cumsum(arc_lengths) <= max_arclen)
-            start = 1
+            start = 0
             while start < arc_lengths.size:
-                next_to_keep = start + numpy.where(removable)[0][-1]    # TODO: any chance we haven't sampled finely enough?
+                removable = (numpy.cumsum(arc_lengths[start:]) <= max_arclen)
+                if not removable.any():
+                    next_to_keep = start + 1
+                else:
+                    next_to_keep = start + numpy.where(removable)[0][-1] + 1
                 keep.append(next_to_keep)
-                removable = (numpy.cumsum(arc_lengths[next_to_keep + 1:]) <= max_arclen)
-                start = next_to_keep + 1
+                start = next_to_keep
+
             if keep[-1] != thetas.size - 1:
                 keep.append(thetas.size - 1)
 
@@ -310,81 +375,59 @@ class Arc(PositionableImpl, Shape):
         return [poly]
 
     def get_bounds_single(self) -> NDArray[numpy.float64]:
-        """
-        Equation for rotated ellipse is
-            `x = x0 + a * cos(t) * cos(rot) - b * sin(t) * sin(phi)`
-            `y = y0 + a * cos(t) * sin(rot) + b * sin(t) * cos(rot)`
-          where `t` is our parameter.
-
-        Differentiating and solving for 0 slope wrt. `t`, we find
-            `tan(t) = -+ b/a cot(phi)`
-          where -+ is for x, y cases, so that's where the extrema are.
-
-        If the extrema are innaccessible due to arc constraints, check the arc endpoints instead.
-        """
         a_ranges = cast('_array2x2_t', self._angles_to_parameters())
+        sin_r = numpy.sin(self.rotation)
+        cos_r = numpy.cos(self.rotation)
 
-        mins = []
-        maxs = []
+        def point(rx: float, ry: float, tt: float) -> NDArray[numpy.float64]:
+            return numpy.array((
+                rx * numpy.cos(tt) * cos_r - ry * numpy.sin(tt) * sin_r,
+                rx * numpy.cos(tt) * sin_r + ry * numpy.sin(tt) * cos_r,
+                ))
+
+        def points_in_interval(rx: float, ry: float, a0: float, a1: float) -> list[NDArray[numpy.float64]]:
+            candidates = [a0, a1]
+            if rx != 0 and ry != 0:
+                tx = numpy.arctan2(-ry * sin_r, rx * cos_r)
+                ty = numpy.arctan2(ry * cos_r, rx * sin_r)
+                candidates.extend((tx, tx + pi, ty, ty + pi))
+
+            lo = min(a0, a1)
+            hi = max(a0, a1)
+            pts = []
+            for base in candidates:
+                k_min = int(numpy.floor((lo - base) / (2 * pi))) - 1
+                k_max = int(numpy.ceil((hi - base) / (2 * pi))) + 1
+                for kk in range(k_min, k_max + 1):
+                    tt = base + kk * 2 * pi
+                    if lo <= tt <= hi:
+                        pts.append(point(rx, ry, tt))
+            return pts
+
+        pts = []
         for aa, sgn in zip(a_ranges, (-1, +1), strict=True):
             wh = sgn * self.width / 2
             rx = self.radius_x + wh
             ry = self.radius_y + wh
-
             if rx == 0 or ry == 0:
-                # Single point, at origin
-                mins.append([0, 0])
-                maxs.append([0, 0])
+                pts.append(numpy.zeros(2))
                 continue
+            pts.extend(points_in_interval(rx, ry, aa[0], aa[1]))
 
-            a0, a1 = aa
-            a0_offset = a0 - (a0 % (2 * pi))
-
-            sin_r = numpy.sin(self.rotation)
-            cos_r = numpy.cos(self.rotation)
-            sin_a = numpy.sin(aa)
-            cos_a = numpy.cos(aa)
-
-            # Cutoff angles
-            xpt = (-self.rotation) % (2 * pi) + a0_offset
-            ypt = (pi / 2 - self.rotation) % (2 * pi) + a0_offset
-            xnt = (xpt - pi) % (2 * pi) + a0_offset
-            ynt = (ypt - pi) % (2 * pi) + a0_offset
-
-            # Points along coordinate axes
-            rx2_inv = 1 / (rx * rx)
-            ry2_inv = 1 / (ry * ry)
-            xr = numpy.abs(cos_r * cos_r * rx2_inv + sin_r * sin_r * ry2_inv) ** -0.5
-            yr = numpy.abs(-sin_r * -sin_r * rx2_inv + cos_r * cos_r * ry2_inv) ** -0.5
-
-            # Arc endpoints
-            xn, xp = sorted(rx * cos_r * cos_a - ry * sin_r * sin_a)
-            yn, yp = sorted(rx * sin_r * cos_a + ry * cos_r * sin_a)
-
-            # If our arc subtends a coordinate axis, use the extremum along that axis
-            if a0 < xpt < a1 or a0 < xpt + 2 * pi < a1:
-                xp = xr
-
-            if a0 < xnt < a1 or a0 < xnt + 2 * pi < a1:
-                xn = -xr
-
-            if a0 < ypt < a1 or a0 < ypt + 2 * pi < a1:
-                yp = yr
-
-            if a0 < ynt < a1 or a0 < ynt + 2 * pi < a1:
-                yn = -yr
-
-            mins.append([xn, yn])
-            maxs.append([xp, yp])
-        return numpy.vstack((numpy.min(mins, axis=0) + self.offset,
-                             numpy.max(maxs, axis=0) + self.offset))
+        all_pts = numpy.asarray(pts) + self.offset
+        return numpy.vstack((numpy.min(all_pts, axis=0),
+                             numpy.max(all_pts, axis=0)))
 
     def rotate(self, theta: float) -> 'Arc':
         self.rotation += theta
         return self
 
     def mirror(self, axis: int = 0) -> 'Arc':
-        self.offset[axis - 1] *= -1
+        if self.angle_ref != ArcAngleRef.Center:
+            x_major = self.radius_x > self.radius_y
+            y_major = self.radius_y > self.radius_x
+            if (axis == 0 and y_major) or (axis == 1 and x_major):
+                self._swap_focus_ref()
         self.rotation *= -1
         self.rotation += axis * pi
         self.angles *= -1
@@ -396,6 +439,7 @@ class Arc(PositionableImpl, Shape):
         return self
 
     def normalized_form(self, norm_value: float) -> normalized_shape_tuple:
+        angle_ref = self.angle_ref
         if self.radius_x < self.radius_y:
             radii = self.radii / self.radius_x
             scale = self.radius_x
@@ -406,23 +450,26 @@ class Arc(PositionableImpl, Shape):
             scale = self.radius_y
             rotation = self.rotation + pi / 2
             angles = self.angles - pi / 2
+            angle_ref = _swapped_focus_ref(angle_ref)
 
         delta_angle = angles[1] - angles[0]
         start_angle = angles[0] % (2 * pi)
         if start_angle >= pi:
             start_angle -= pi
             rotation += pi
+            angle_ref = _swapped_focus_ref(angle_ref)
 
         norm_angles = (start_angle, start_angle + delta_angle)
         rotation %= 2 * pi
         width = self.width
 
-        return ((type(self), radii, norm_angles, width / norm_value),
+        return ((type(self), tuple(radii.tolist()), norm_angles, width / norm_value, angle_ref.value),
                 (self.offset, scale / norm_value, rotation, False),
                 lambda: Arc(
                     radii=radii * norm_value,
                     angles=norm_angles,
                     width=width * norm_value,
+                    angle_ref=angle_ref,
                     ))
 
     def get_cap_edges(self) -> NDArray[numpy.float64]:
@@ -433,27 +480,16 @@ class Arc(PositionableImpl, Shape):
              [[x2, y2], [x3, y3]]],    would create this arc from its corresponding ellipse.
             ```
         """
-        a_ranges = cast('_array2x2_t', self._angles_to_parameters())
+        a_ranges = self._angles_to_parameters()
 
-        mins = []
-        maxs = []
+        cuts = []
+        for index in range(2):
+            edge = []
             for aa, sgn in zip(a_ranges, (-1, +1), strict=True):
                 wh = sgn * self.width / 2
-            rx = self.radius_x + wh
-            ry = self.radius_y + wh
-
-            sin_r = numpy.sin(self.rotation)
-            cos_r = numpy.cos(self.rotation)
-            sin_a = numpy.sin(aa)
-            cos_a = numpy.cos(aa)
-
-            # arc endpoints
-            xn, xp = sorted(rx * cos_r * cos_a - ry * sin_r * sin_a)
-            yn, yp = sorted(rx * sin_r * cos_a + ry * cos_r * sin_a)
-
-            mins.append([xn, yn])
-            maxs.append([xp, yp])
-        return numpy.array([mins, maxs]) + self.offset
+                edge.append(self._point_on_edge(self.radius_x + wh, self.radius_y + wh, aa[index]))
+            cuts.append(edge)
+        return numpy.array(cuts) + self.offset
 
     def _angles_to_parameters(self) -> NDArray[numpy.float64]:
         """
@@ -464,22 +500,111 @@ class Arc(PositionableImpl, Shape):
                    `[[a_min_inner, a_max_inner], [a_min_outer, a_max_outer]]`
         """
         aa = []
+        d_angle = self.angles[1] - self.angles[0]
+        if abs(d_angle) >= 2 * pi:
+            # Full ring
+            return numpy.tile([0, 2 * pi], (2, 1)).astype(float)
+
         for sgn in (-1, +1):
             wh = sgn * self.width / 2.0
             rx = self.radius_x + wh
             ry = self.radius_y + wh
 
-            a0, a1 = (numpy.arctan2(rx * numpy.sin(ai), ry * numpy.cos(ai)) for ai in self.angles)
-            sign = numpy.sign(self.angles[1] - self.angles[0])
+            a0, a1 = (self._angle_to_parameter(ai, rx, ry) for ai in self.angles)
+            sign = numpy.sign(d_angle)
             if sign != numpy.sign(a1 - a0):
                 a1 += sign * 2 * pi
 
             aa.append((a0, a1))
         return numpy.array(aa, dtype=float)
 
+    def _angle_to_parameter(self, angle: float, rx: float, ry: float) -> float:
+        """
+        Convert an angle-reference ray to the ellipse parameter for one boundary edge.
+
+        Center-referenced arcs convert the ray angle from polar coordinates about the origin.
+        Focus-referenced arcs solve the forward ray/ellipse intersection from the selected
+        nominal focus and return the parameter `t` for `[rx*cos(t), ry*sin(t)]`.
+        """
+        if self.angle_ref == ArcAngleRef.Center:
+            return numpy.arctan2(rx * numpy.sin(angle), ry * numpy.cos(angle))
+
+        focus = self._focus_point()
+        if rx <= 0 or ry <= 0:
+            raise PatternError('Focus-referenced arc boundary radii must be positive')
+
+        fx, fy = focus
+        origin_position = fx * fx / (rx * rx) + fy * fy / (ry * ry)
+        if origin_position >= 1:
+            raise PatternError('Focus-referenced arc ray origin must be inside both arc boundary ellipses')
+
+        dx = numpy.cos(angle)
+        dy = numpy.sin(angle)
+        aa = dx * dx / (rx * rx) + dy * dy / (ry * ry)
+        bb = 2 * (fx * dx / (rx * rx) + fy * dy / (ry * ry))
+        cc = origin_position - 1
+        determinant = bb * bb - 4 * aa * cc
+        if determinant < 0:
+            raise PatternError('Focus-referenced arc ray does not intersect boundary ellipse')
+
+        roots = numpy.array((
+            (-bb - numpy.sqrt(determinant)) / (2 * aa),
+            (-bb + numpy.sqrt(determinant)) / (2 * aa),
+            ))
+        positive_roots = roots[roots > 0]
+        if positive_roots.size != 1:
+            raise PatternError('Focus-referenced arc ray must have exactly one forward boundary intersection')
+
+        point = focus + positive_roots[0] * numpy.array((dx, dy))
+        return numpy.arctan2(point[1] / ry, point[0] / rx)
+
+    def _focus_point(self) -> NDArray[numpy.float64]:
+        """
+        Return the selected nominal focus in the arc's unrotated local coordinates.
+
+        `FocusPos` and `FocusNeg` select opposite directions along the major axis. Circles
+        have coincident foci, so both focus modes intentionally collapse to the center.
+        """
+        if self.angle_ref == ArcAngleRef.Center or self.radius_x == self.radius_y:
+            return numpy.zeros(2)
+
+        sign = 1 if self.angle_ref == ArcAngleRef.FocusPos else -1
+        if self.radius_x > self.radius_y:
+            return numpy.array((sign * numpy.sqrt(self.radius_x * self.radius_x - self.radius_y * self.radius_y), 0.0))
+        return numpy.array((0.0, sign * numpy.sqrt(self.radius_y * self.radius_y - self.radius_x * self.radius_x)))
+
+    def _point_on_edge(self, rx: float, ry: float, tt: float) -> NDArray[numpy.float64]:
+        """
+        Return a rotated local-space point on a boundary ellipse, before applying offset.
+        """
+        sin_r = numpy.sin(self.rotation)
+        cos_r = numpy.cos(self.rotation)
+        return numpy.array((
+            rx * numpy.cos(tt) * cos_r - ry * numpy.sin(tt) * sin_r,
+            rx * numpy.cos(tt) * sin_r + ry * numpy.sin(tt) * cos_r,
+            ))
+
+    def _swap_focus_ref(self) -> None:
+        """
+        Swap `focus_pos` and `focus_neg`, leaving center-referenced arcs unchanged.
+        """
+        self.angle_ref = _swapped_focus_ref(self.angle_ref)
+
     def __repr__(self) -> str:
         angles = f' a°{numpy.rad2deg(self.angles)}'
         rotation = f' r°{numpy.rad2deg(self.rotation):g}' if self.rotation != 0 else ''
-        return f'<Arc o{self.offset} r{self.radii}{angles} w{self.width:g}{rotation}>'
+        angle_ref = f' ref={self.angle_ref.value}' if self.angle_ref != ArcAngleRef.Center else ''
+        return f'<Arc o{self.offset} r{self.radii}{angles} w{self.width:g}{rotation}{angle_ref}>'
+
+
+def _swapped_focus_ref(angle_ref: ArcAngleRef) -> ArcAngleRef:
+    """
+    Return the opposite focus reference, or center for center-referenced arcs.
+    """
+    if angle_ref == ArcAngleRef.FocusPos:
+        return ArcAngleRef.FocusNeg
+    if angle_ref == ArcAngleRef.FocusNeg:
+        return ArcAngleRef.FocusPos
+    return angle_ref
 
 _array2x2_t = tuple[tuple[float, float], tuple[float, float]]

masque/shapes/circle.py

@@ -50,24 +50,33 @@ class Circle(PositionableImpl, Shape):
             offset: ArrayLike = (0.0, 0.0),
             repetition: Repetition | None = None,
             annotations: annotations_t = None,
-            raw: bool = False,
             ) -> None:
-        if raw:
-            assert isinstance(offset, numpy.ndarray)
-            self._radius = radius
-            self._offset = offset
-            self._repetition = repetition
-            self._annotations = annotations
-        else:
         self.radius = radius
         self.offset = offset
         self.repetition = repetition
         self.annotations = annotations
 
+    @classmethod
+    def _from_raw(
+            cls,
+            *,
+            radius: float,
+            offset: NDArray[numpy.float64],
+            annotations: annotations_t = None,
+            repetition: Repetition | None = None,
+            ) -> 'Circle':
+        new = cls.__new__(cls)
+        new._radius = radius
+        new._offset = offset
+        new._repetition = repetition
+        new._annotations = annotations
+        return new
+
     def __deepcopy__(self, memo: dict | None = None) -> 'Circle':
         memo = {} if memo is None else memo
         new = copy.copy(self)
         new._offset = self._offset.copy()
+        new._repetition = copy.deepcopy(self._repetition, memo)
         new._annotations = copy.deepcopy(self._annotations)
         return new
 
@@ -108,7 +117,7 @@ class Circle(PositionableImpl, Shape):
             n += [num_vertices]
         if max_arclen is not None:
             n += [2 * pi * self.radius / max_arclen]
-        num_vertices = int(round(max(n)))
+        num_vertices = max(3, int(round(max(n))))
         thetas = numpy.linspace(2 * pi, 0, num_vertices, endpoint=False)
         xs = numpy.cos(thetas) * self.radius
         ys = numpy.sin(thetas) * self.radius
@@ -124,7 +133,6 @@ class Circle(PositionableImpl, Shape):
         return self
 
     def mirror(self, axis: int = 0) -> 'Circle':     # noqa: ARG002  (axis unused)
-        self.offset[axis - 1] *= -1
         return self
 
     def scale_by(self, c: float) -> 'Circle':

masque/shapes/ellipse.py

@@ -42,7 +42,7 @@ class Ellipse(PositionableImpl, Shape):
 
     @radii.setter
     def radii(self, val: ArrayLike) -> None:
-        val = numpy.array(val).flatten()
+        val = numpy.array(val, dtype=float).flatten()
         if not val.size == 2:
             raise PatternError('Radii must have length 2')
         if not val.min() >= 0:
@@ -95,28 +95,37 @@ class Ellipse(PositionableImpl, Shape):
             rotation: float = 0,
             repetition: Repetition | None = None,
             annotations: annotations_t = None,
-            raw: bool = False,
             ) -> None:
-        if raw:
-            assert isinstance(radii, numpy.ndarray)
-            assert isinstance(offset, numpy.ndarray)
-            self._radii = radii
-            self._offset = offset
-            self._rotation = rotation
-            self._repetition = repetition
-            self._annotations = annotations
-        else:
         self.radii = radii
         self.offset = offset
         self.rotation = rotation
         self.repetition = repetition
         self.annotations = annotations
 
+    @classmethod
+    def _from_raw(
+            cls,
+            *,
+            radii: NDArray[numpy.float64],
+            offset: NDArray[numpy.float64],
+            rotation: float,
+            annotations: annotations_t = None,
+            repetition: Repetition | None = None,
+            ) -> Self:
+        new = cls.__new__(cls)
+        new._radii = radii
+        new._offset = offset
+        new._rotation = rotation % pi
+        new._repetition = repetition
+        new._annotations = annotations
+        return new
+
     def __deepcopy__(self, memo: dict | None = None) -> Self:
         memo = {} if memo is None else memo
         new = copy.copy(self)
         new._offset = self._offset.copy()
         new._radii = self._radii.copy()
+        new._repetition = copy.deepcopy(self._repetition, memo)
         new._annotations = copy.deepcopy(self._annotations)
         return new
 
@@ -168,7 +177,7 @@ class Ellipse(PositionableImpl, Shape):
             n += [num_vertices]
         if max_arclen is not None:
             n += [perimeter / max_arclen]
-        num_vertices = int(round(max(n)))
+        num_vertices = max(3, int(round(max(n))))
         thetas = numpy.linspace(2 * pi, 0, num_vertices, endpoint=False)
 
         sin_th, cos_th = (numpy.sin(thetas), numpy.cos(thetas))
@@ -180,16 +189,19 @@ class Ellipse(PositionableImpl, Shape):
         return [poly]
 
     def get_bounds_single(self) -> NDArray[numpy.float64]:
-        rot_radii = numpy.dot(rotation_matrix_2d(self.rotation), self.radii)
-        return numpy.vstack((self.offset - rot_radii[0],
-                             self.offset + rot_radii[1]))
+        cos_r = numpy.cos(self.rotation)
+        sin_r = numpy.sin(self.rotation)
+        x_extent = numpy.sqrt((self.radius_x * cos_r) ** 2 + (self.radius_y * sin_r) ** 2)
+        y_extent = numpy.sqrt((self.radius_x * sin_r) ** 2 + (self.radius_y * cos_r) ** 2)
+        extents = numpy.array((x_extent, y_extent))
+        return numpy.vstack((self.offset - extents,
+                             self.offset + extents))
 
     def rotate(self, theta: float) -> Self:
         self.rotation += theta
         return self
 
     def mirror(self, axis: int = 0) -> Self:
-        self.offset[axis - 1] *= -1
         self.rotation *= -1
         self.rotation += axis * pi
         return self
@@ -207,7 +219,7 @@ class Ellipse(PositionableImpl, Shape):
             radii = self.radii[::-1] / self.radius_y
             scale = self.radius_y
             angle = (self.rotation + pi / 2) % pi
-        return ((type(self), radii),
+        return ((type(self), tuple(radii.tolist())),
                 (self.offset, scale / norm_value, angle, False),
                 lambda: Ellipse(radii=radii * norm_value))
 

masque/shapes/path.py

@@ -24,7 +24,16 @@ class PathCap(Enum):
 #                     #     defined by path.cap_extensions
 
     def __lt__(self, other: Any) -> bool:
-        return self.value == other.value
+        if self.__class__ is not other.__class__:
+            return self.__class__.__name__ < other.__class__.__name__
+        # Order: Flush, Square, Circle, SquareCustom
+        order = {
+            PathCap.Flush: 0,
+            PathCap.Square: 1,
+            PathCap.Circle: 2,
+            PathCap.SquareCustom: 3,
+        }
+        return order[self] < order[other]
 
 
 @functools.total_ordering
@@ -79,10 +88,10 @@ class Path(Shape):
     def cap(self, val: PathCap) -> None:
         self._cap = PathCap(val)
         if self.cap != PathCap.SquareCustom:
-            self.cap_extensions = None
-        elif self.cap_extensions is None:
+            self._cap_extensions = None
+        elif self._cap_extensions is None:
             # just got set to SquareCustom
-            self.cap_extensions = numpy.zeros(2)
+            self._cap_extensions = numpy.zeros(2)
 
     # cap_extensions property
     @property
@@ -192,37 +201,50 @@ class Path(Shape):
             rotation: float = 0,
             repetition: Repetition | None = None,
             annotations: annotations_t = None,
-            raw: bool = False,
             ) -> None:
         self._cap_extensions = None     # Since .cap setter might access it
 
-        if raw:
-            assert isinstance(vertices, numpy.ndarray)
-            assert isinstance(cap_extensions, numpy.ndarray) or cap_extensions is None
-            self._vertices = vertices
-            self._repetition = repetition
-            self._annotations = annotations
-            self._width = width
-            self._cap = cap
-            self._cap_extensions = cap_extensions
-        else:
         self.vertices = vertices
         self.repetition = repetition
         self.annotations = annotations
-            self.width = width
-            self.cap = cap
+        self._cap = cap
+        if cap == PathCap.SquareCustom and cap_extensions is None:
+            self._cap_extensions = numpy.zeros(2)
+        else:
             self.cap_extensions = cap_extensions
+        self.width = width
         if rotation:
             self.rotate(rotation)
         if numpy.any(offset):
             self.translate(offset)
 
+    @classmethod
+    def _from_raw(
+            cls,
+            *,
+            vertices: NDArray[numpy.float64],
+            width: float,
+            cap: PathCap,
+            cap_extensions: NDArray[numpy.float64] | None = None,
+            annotations: annotations_t = None,
+            repetition: Repetition | None = None,
+            ) -> Self:
+        new = cls.__new__(cls)
+        new._vertices = vertices
+        new._width = width
+        new._cap = cap
+        new._cap_extensions = cap_extensions
+        new._repetition = repetition
+        new._annotations = annotations
+        return new
+
     def __deepcopy__(self, memo: dict | None = None) -> 'Path':
         memo = {} if memo is None else memo
         new = copy.copy(self)
         new._vertices = self._vertices.copy()
         new._cap = copy.deepcopy(self._cap, memo)
         new._cap_extensions = copy.deepcopy(self._cap_extensions, memo)
+        new._repetition = copy.deepcopy(self._repetition, memo)
         new._annotations = copy.deepcopy(self._annotations)
         return new
 
@@ -253,6 +275,14 @@ class Path(Shape):
             if self.cap_extensions is None:
                 return True
             return tuple(self.cap_extensions) < tuple(other.cap_extensions)
+        if not numpy.array_equal(self.vertices, other.vertices):
+            min_len = min(self.vertices.shape[0], other.vertices.shape[0])
+            eq_mask = self.vertices[:min_len] != other.vertices[:min_len]
+            eq_lt = self.vertices[:min_len] < other.vertices[:min_len]
+            eq_lt_masked = eq_lt[eq_mask]
+            if eq_lt_masked.size > 0:
+                return eq_lt_masked.flat[0]
+            return self.vertices.shape[0] < other.vertices.shape[0]
         if self.repetition != other.repetition:
             return rep2key(self.repetition) < rep2key(other.repetition)
         return annotations_lt(self.annotations, other.annotations)
@@ -303,9 +333,30 @@ class Path(Shape):
             ) -> list['Polygon']:
         extensions = self._calculate_cap_extensions()
 
-        v = remove_colinear_vertices(self.vertices, closed_path=False)
+        v = remove_colinear_vertices(self.vertices, closed_path=False, preserve_uturns=True)
         dv = numpy.diff(v, axis=0)
-        dvdir = dv / numpy.sqrt((dv * dv).sum(axis=1))[:, None]
+        norms = numpy.sqrt((dv * dv).sum(axis=1))
+
+        # Filter out zero-length segments if any remained after remove_colinear_vertices
+        valid = (norms > 1e-18)
+        if not numpy.all(valid):
+            # This shouldn't happen much if remove_colinear_vertices is working
+            v = v[numpy.append(valid, True)]
+            dv = numpy.diff(v, axis=0)
+            norms = norms[valid]
+
+        if dv.shape[0] == 0:
+            # All vertices were the same. It's a point.
+            if self.width == 0:
+                return [Polygon(vertices=numpy.zeros((3, 2)))] # Area-less degenerate
+            if self.cap == PathCap.Circle:
+                return Circle(radius=self.width / 2, offset=v[0]).to_polygons(num_vertices=num_vertices, max_arclen=max_arclen)
+            if self.cap == PathCap.Square:
+                return [Polygon.square(side_length=self.width, offset=v[0])]
+            # Flush or CustomSquare
+            return [Polygon(vertices=numpy.zeros((3, 2)))]
+
+        dvdir = dv / norms[:, None]
 
         if self.width == 0:
             verts = numpy.vstack((v, v[::-1]))
@@ -324,11 +375,21 @@ class Path(Shape):
         bs = v[1:-1] - v[:-2] + perp[1:] - perp[:-1]
         ds = v[1:-1] - v[:-2] - perp[1:] + perp[:-1]
 
-        rp = numpy.linalg.solve(As, bs[:, :, None])[:, 0]
-        rn = numpy.linalg.solve(As, ds[:, :, None])[:, 0]
+        try:
+            # Vectorized solve for all intersections
+            # solve supports broadcasting: As (N-2, 2, 2), bs (N-2, 2, 1)
+            rp = numpy.linalg.solve(As, bs[:, :, None])[:, 0, 0]
+            rn = numpy.linalg.solve(As, ds[:, :, None])[:, 0, 0]
+        except numpy.linalg.LinAlgError:
+            # Fallback to slower lstsq if some segments are parallel (singular matrix)
+            rp = numpy.zeros(As.shape[0])
+            rn = numpy.zeros(As.shape[0])
+            for ii in range(As.shape[0]):
+                rp[ii] = numpy.linalg.lstsq(As[ii], bs[ii, :, None], rcond=1e-12)[0][0, 0]
+                rn[ii] = numpy.linalg.lstsq(As[ii], ds[ii, :, None], rcond=1e-12)[0][0, 0]
 
-        intersection_p = v[:-2] + rp * dv[:-1] + perp[:-1]
-        intersection_n = v[:-2] + rn * dv[:-1] - perp[:-1]
+        intersection_p = v[:-2] + rp[:, None] * dv[:-1] + perp[:-1]
+        intersection_n = v[:-2] + rn[:, None] * dv[:-1] - perp[:-1]
 
         towards_perp = (dv[1:] * perp[:-1]).sum(axis=1) > 0  # path bends towards previous perp?
 #       straight = (dv[1:] * perp[:-1]).sum(axis=1) == 0     # path is straight
@@ -396,12 +457,14 @@ class Path(Shape):
         return self
 
     def mirror(self, axis: int = 0) -> 'Path':
-        self.vertices[:, axis - 1] *= -1
+        self.vertices[:, 1 - axis] *= -1
         return self
 
     def scale_by(self, c: float) -> 'Path':
         self.vertices *= c
         self.width *= c
+        if self.cap_extensions is not None:
+            self.cap_extensions *= c
         return self
 
     def normalized_form(self, norm_value: float) -> normalized_shape_tuple:
@@ -418,21 +481,22 @@ class Path(Shape):
         rotated_vertices = numpy.vstack([numpy.dot(rotation_matrix_2d(-rotation), v)
                                         for v in normed_vertices])
 
-        # Reorder the vertices so that the one with lowest x, then y, comes first.
-        x_min = rotated_vertices[:, 0].argmin()
-        if not is_scalar(x_min):
-            y_min = rotated_vertices[x_min, 1].argmin()
-            x_min = cast('Sequence', x_min)[y_min]
-        reordered_vertices = numpy.roll(rotated_vertices, -x_min, axis=0)
+        # Canonical ordering for open paths: pick whichever of (v) or (v[::-1]) is smaller
+        if tuple(rotated_vertices.flat) > tuple(rotated_vertices[::-1].flat):
+            reordered_vertices = rotated_vertices[::-1]
+        else:
+            reordered_vertices = rotated_vertices
 
         width0 = self.width / norm_value
+        cap_extensions0 = None if self.cap_extensions is None else tuple(float(v) / norm_value for v in self.cap_extensions)
 
-        return ((type(self), reordered_vertices.data.tobytes(), width0, self.cap),
+        return ((type(self), reordered_vertices.data.tobytes(), width0, self.cap, cap_extensions0),
                 (offset, scale / norm_value, rotation, False),
                 lambda: Path(
                     reordered_vertices * norm_value,
-                    width=self.width * norm_value,
+                    width=width0 * norm_value,
                     cap=self.cap,
+                    cap_extensions=None if cap_extensions0 is None else tuple(v * norm_value for v in cap_extensions0),
                     ))
 
     def clean_vertices(self) -> 'Path':
@@ -462,7 +526,7 @@ class Path(Shape):
         Returns:
             self
         """
-        self.vertices = remove_colinear_vertices(self.vertices, closed_path=False)
+        self.vertices = remove_colinear_vertices(self.vertices, closed_path=False, preserve_uturns=True)
         return self
 
     def _calculate_cap_extensions(self) -> NDArray[numpy.float64]:

masque/shapes/poly_collection.py

@@ -34,7 +34,7 @@ class PolyCollection(Shape):
     _vertex_lists: NDArray[numpy.float64]
     """ 2D NDArray ((N+M+...) x 2)  of vertices `[[xa0, ya0], [xa1, ya1], ..., [xb0, yb0], [xb1, yb1], ... ]` """
 
-    _vertex_offsets: NDArray[numpy.intp]
+    _vertex_offsets: NDArray[numpy.integer[Any]]
     """ 1D NDArray specifying the starting offset for each polygon """
 
     @property
@@ -45,7 +45,7 @@ class PolyCollection(Shape):
         return self._vertex_lists
 
     @property
-    def vertex_offsets(self) -> NDArray[numpy.intp]:
+    def vertex_offsets(self) -> NDArray[numpy.integer[Any]]:
         """
         Starting offset (in `vertex_lists`) for each polygon
         """
@@ -56,12 +56,14 @@ class PolyCollection(Shape):
         """
         Iterator which provides slices which index vertex_lists
         """
+        if self._vertex_offsets.size == 0:
+            return
         for ii, ff in zip(
                 self._vertex_offsets,
-                chain(self._vertex_offsets, (self._vertex_lists.shape[0],)),
+                chain(self._vertex_offsets[1:], [self._vertex_lists.shape[0]]),
                 strict=True,
                 ):
-            yield slice(ii, ff)
+            yield slice(int(ii), int(ff))
 
     @property
     def polygon_vertices(self) -> Iterator[NDArray[numpy.float64]]:
@@ -82,7 +84,7 @@ class PolyCollection(Shape):
 
     def set_offset(self, val: ArrayLike) -> Self:
         if numpy.any(val):
-            raise PatternError('Path offset is forced to (0, 0)')
+            raise PatternError('PolyCollection offset is forced to (0, 0)')
         return self
 
     def translate(self, offset: ArrayLike) -> Self:
@@ -98,16 +100,7 @@ class PolyCollection(Shape):
             rotation: float = 0.0,
             repetition: Repetition | None = None,
             annotations: annotations_t = None,
-            raw: bool = False,
             ) -> None:
-        if raw:
-            assert isinstance(vertex_lists, numpy.ndarray)
-            assert isinstance(vertex_offsets, numpy.ndarray)
-            self._vertex_lists = vertex_lists
-            self._vertex_offsets = vertex_offsets
-            self._repetition = repetition
-            self._annotations = annotations
-        else:
         self._vertex_lists = numpy.asarray(vertex_lists, dtype=float)
         self._vertex_offsets = numpy.asarray(vertex_offsets, dtype=numpy.intp)
         self.repetition = repetition
@@ -117,11 +110,28 @@ class PolyCollection(Shape):
         if numpy.any(offset):
             self.translate(offset)
 
+    @classmethod
+    def _from_raw(
+            cls,
+            *,
+            vertex_lists: NDArray[numpy.float64],
+            vertex_offsets: NDArray[numpy.integer[Any]],
+            annotations: annotations_t = None,
+            repetition: Repetition | None = None,
+            ) -> Self:
+        new = cls.__new__(cls)
+        new._vertex_lists = vertex_lists
+        new._vertex_offsets = vertex_offsets
+        new._repetition = repetition
+        new._annotations = annotations
+        return new
+
     def __deepcopy__(self, memo: dict | None = None) -> Self:
         memo = {} if memo is None else memo
         new = copy.copy(self)
         new._vertex_lists = self._vertex_lists.copy()
         new._vertex_offsets = self._vertex_offsets.copy()
+        new._repetition = copy.deepcopy(self._repetition, memo)
         new._annotations = copy.deepcopy(self._annotations)
         return new
 
@@ -129,7 +139,7 @@ class PolyCollection(Shape):
         return (
             type(self) is type(other)
             and numpy.array_equal(self._vertex_lists, other._vertex_lists)
-            and numpy.array_equal(self._vertex_offsets, other._vertex_offsets)
+            and numpy.array_equal(self.vertex_offsets, other.vertex_offsets)
             and self.repetition == other.repetition
             and annotations_eq(self.annotations, other.annotations)
             )
@@ -168,7 +178,9 @@ class PolyCollection(Shape):
             annotations = copy.deepcopy(self.annotations),
             ) for vv in self.polygon_vertices]
 
-    def get_bounds_single(self) -> NDArray[numpy.float64]:         # TODO note shape get_bounds doesn't include repetition
+    def get_bounds_single(self) -> NDArray[numpy.float64] | None:         # TODO note shape get_bounds doesn't include repetition
+        if self._vertex_lists.size == 0:
+            return None
         return numpy.vstack((numpy.min(self._vertex_lists, axis=0),
                              numpy.max(self._vertex_lists, axis=0)))
 
@@ -179,7 +191,7 @@ class PolyCollection(Shape):
         return self
 
     def mirror(self, axis: int = 0) -> Self:
-        self._vertex_lists[:, axis - 1] *= -1
+        self._vertex_lists[:, 1 - axis] *= -1
         return self
 
     def scale_by(self, c: float) -> Self:
@@ -210,11 +222,11 @@ class PolyCollection(Shape):
 
         # TODO: normalize mirroring?
 
-        return ((type(self), rotated_vertices.data.tobytes() + self._vertex_offsets.tobytes()),
+        return ((type(self), rotated_vertices.data.tobytes() + self.vertex_offsets.tobytes()),
                 (offset, scale / norm_value, rotation, False),
                 lambda: PolyCollection(
                     vertex_lists=rotated_vertices * norm_value,
-                    vertex_offsets=self._vertex_offsets,
+                    vertex_offsets=self.vertex_offsets.copy(),
                     ),
                 )
 

masque/shapes/polygon.py

@@ -1,4 +1,4 @@
-from typing import Any, cast, TYPE_CHECKING, Self
+from typing import Any, cast, TYPE_CHECKING, Self, Literal
 import copy
 import functools
 
@@ -96,11 +96,11 @@ class Polygon(Shape):
     @offset.setter
     def offset(self, val: ArrayLike) -> None:
         if numpy.any(val):
-            raise PatternError('Path offset is forced to (0, 0)')
+            raise PatternError('Polygon offset is forced to (0, 0)')
 
     def set_offset(self, val: ArrayLike) -> Self:
         if numpy.any(val):
-            raise PatternError('Path offset is forced to (0, 0)')
+            raise PatternError('Polygon offset is forced to (0, 0)')
         return self
 
     def translate(self, offset: ArrayLike) -> Self:
@@ -115,14 +115,7 @@ class Polygon(Shape):
             rotation: float = 0.0,
             repetition: Repetition | None = None,
             annotations: annotations_t = None,
-            raw: bool = False,
             ) -> None:
-        if raw:
-            assert isinstance(vertices, numpy.ndarray)
-            self._vertices = vertices
-            self._repetition = repetition
-            self._annotations = annotations
-        else:
         self.vertices = vertices
         self.repetition = repetition
         self.annotations = annotations
@@ -131,10 +124,25 @@ class Polygon(Shape):
         if numpy.any(offset):
             self.translate(offset)
 
+    @classmethod
+    def _from_raw(
+            cls,
+            *,
+            vertices: NDArray[numpy.float64],
+            annotations: annotations_t = None,
+            repetition: Repetition | None = None,
+            ) -> Self:
+        new = cls.__new__(cls)
+        new._vertices = vertices
+        new._repetition = repetition
+        new._annotations = annotations
+        return new
+
     def __deepcopy__(self, memo: dict | None = None) -> 'Polygon':
         memo = {} if memo is None else memo
         new = copy.copy(self)
         new._vertices = self._vertices.copy()
+        new._repetition = copy.deepcopy(self._repetition, memo)
         new._annotations = copy.deepcopy(self._annotations)
         return new
 
@@ -321,7 +329,7 @@ class Polygon(Shape):
             else:
                 raise PatternError('Two of ymin, yctr, ymax, ly must be None!')
 
-        poly = Polygon.rectangle(lx, ly, offset=(xctr, yctr), repetition=repetition)
+        poly = Polygon.rectangle(abs(lx), abs(ly), offset=(xctr, yctr), repetition=repetition)
         return poly
 
     @staticmethod
@@ -394,7 +402,7 @@ class Polygon(Shape):
         return self
 
     def mirror(self, axis: int = 0) -> 'Polygon':
-        self.vertices[:, axis - 1] *= -1
+        self.vertices[:, 1 - axis] *= -1
         return self
 
     def scale_by(self, c: float) -> 'Polygon':
@@ -417,11 +425,15 @@ class Polygon(Shape):
                                         for v in normed_vertices])
 
         # Reorder the vertices so that the one with lowest x, then y, comes first.
-        x_min = rotated_vertices[:, 0].argmin()
-        if not is_scalar(x_min):
-            y_min = rotated_vertices[x_min, 1].argmin()
-            x_min = cast('Sequence', x_min)[y_min]
-        reordered_vertices = numpy.roll(rotated_vertices, -x_min, axis=0)
+        x_min_val = rotated_vertices[:, 0].min()
+        x_min_inds = numpy.where(rotated_vertices[:, 0] == x_min_val)[0]
+        if x_min_inds.size > 1:
+            y_min_val = rotated_vertices[x_min_inds, 1].min()
+            tie_breaker = numpy.where(rotated_vertices[x_min_inds, 1] == y_min_val)[0][0]
+            start_ind = x_min_inds[tie_breaker]
+        else:
+            start_ind = x_min_inds[0]
+        reordered_vertices = numpy.roll(rotated_vertices, -start_ind, axis=0)
 
         # TODO: normalize mirroring?
 
@@ -462,3 +474,23 @@ class Polygon(Shape):
     def __repr__(self) -> str:
         centroid = self.vertices.mean(axis=0)
         return f'<Polygon centroid {centroid} v{len(self.vertices)}>'
+
+    def boolean(
+            self,
+            other: Any,
+            operation: Literal['union', 'intersection', 'difference', 'xor'] = 'union',
+            scale: float = 1e6,
+            ) -> list['Polygon']:
+        """
+        Perform a boolean operation using this polygon as the subject.
+
+        Args:
+            other: Polygon, Iterable[Polygon], or raw vertices acting as the CLIP.
+            operation: 'union', 'intersection', 'difference', 'xor'.
+            scale: Scaling factor for integer conversion.
+
+        Returns:
+            A list of resulting Polygons.
+        """
+        from ..utils.boolean import boolean     #noqa: PLC0415
+        return boolean([self], other, operation=operation, scale=scale)

masque/shapes/rect_collection.py

@@ -0,0 +1,249 @@
+from typing import Any, cast, Self
+from collections.abc import Iterator
+import copy
+import functools
+
+import numpy
+from numpy import pi
+from numpy.typing import NDArray, ArrayLike
+
+from . import Shape, normalized_shape_tuple
+from .polygon import Polygon
+from ..error import PatternError
+from ..repetition import Repetition
+from ..utils import annotations_lt, annotations_eq, rep2key, annotations_t
+
+
+def _normalize_rects(rects: ArrayLike) -> NDArray[numpy.float64]:
+    arr = numpy.asarray(rects, dtype=float)
+    if arr.ndim != 2 or arr.shape[1] != 4:
+        raise PatternError('Rectangles must be an Nx4 array of [xmin, ymin, xmax, ymax]')
+    if numpy.any(arr[:, 0] > arr[:, 2]) or numpy.any(arr[:, 1] > arr[:, 3]):
+        raise PatternError('Rectangles must satisfy xmin <= xmax and ymin <= ymax')
+    if arr.shape[0] <= 1:
+        return arr
+    order = numpy.lexsort((arr[:, 3], arr[:, 2], arr[:, 1], arr[:, 0]))
+    return arr[order]
+
+
+def _renormalize_rects_in_place(rects: NDArray[numpy.float64]) -> None:
+    x0 = numpy.minimum(rects[:, 0], rects[:, 2])
+    x1 = numpy.maximum(rects[:, 0], rects[:, 2])
+    y0 = numpy.minimum(rects[:, 1], rects[:, 3])
+    y1 = numpy.maximum(rects[:, 1], rects[:, 3])
+    rects[:, 0] = x0
+    rects[:, 1] = y0
+    rects[:, 2] = x1
+    rects[:, 3] = y1
+
+
+@functools.total_ordering
+class RectCollection(Shape):
+    """
+    A collection of axis-aligned rectangles, stored as an Nx4 array of
+      `[xmin, ymin, xmax, ymax]` rows.
+    """
+    __slots__ = (
+        '_rects',
+        '_repetition', '_annotations',
+        )
+
+    _rects: NDArray[numpy.float64]
+
+    @property
+    def rects(self) -> NDArray[numpy.float64]:
+        return self._rects
+
+    @rects.setter
+    def rects(self, val: ArrayLike) -> None:
+        self._rects = _normalize_rects(val)
+
+    @property
+    def offset(self) -> NDArray[numpy.float64]:
+        return numpy.zeros(2)
+
+    @offset.setter
+    def offset(self, val: ArrayLike) -> None:
+        if numpy.any(val):
+            raise PatternError('RectCollection offset is forced to (0, 0)')
+
+    def set_offset(self, val: ArrayLike) -> Self:
+        if numpy.any(val):
+            raise PatternError('RectCollection offset is forced to (0, 0)')
+        return self
+
+    def translate(self, offset: ArrayLike) -> Self:
+        delta = numpy.asarray(offset, dtype=float).reshape(2)
+        self._rects[:, [0, 2]] += delta[0]
+        self._rects[:, [1, 3]] += delta[1]
+        return self
+
+    def __init__(
+            self,
+            rects: ArrayLike,
+            *,
+            offset: ArrayLike = (0.0, 0.0),
+            rotation: float = 0.0,
+            repetition: Repetition | None = None,
+            annotations: annotations_t = None,
+            ) -> None:
+        self.rects = rects
+        self.repetition = repetition
+        self.annotations = annotations
+        if rotation:
+            self.rotate(rotation)
+        if numpy.any(offset):
+            self.translate(offset)
+
+    @classmethod
+    def _from_raw(
+            cls,
+            *,
+            rects: NDArray[numpy.float64],
+            annotations: annotations_t = None,
+            repetition: Repetition | None = None,
+            ) -> Self:
+        new = cls.__new__(cls)
+        new._rects = rects
+        new._repetition = repetition
+        new._annotations = annotations
+        return new
+
+    @property
+    def polygon_vertices(self) -> Iterator[NDArray[numpy.float64]]:
+        for rect in self._rects:
+            xmin, ymin, xmax, ymax = rect
+            yield numpy.array([
+                [xmin, ymin],
+                [xmin, ymax],
+                [xmax, ymax],
+                [xmax, ymin],
+                ], dtype=float)
+
+    def __deepcopy__(self, memo: dict | None = None) -> Self:
+        memo = {} if memo is None else memo
+        new = copy.copy(self)
+        new._rects = self._rects.copy()
+        new._repetition = copy.deepcopy(self._repetition, memo)
+        new._annotations = copy.deepcopy(self._annotations)
+        return new
+
+    def _sorted_rects(self) -> NDArray[numpy.float64]:
+        if self._rects.shape[0] <= 1:
+            return self._rects
+        order = numpy.lexsort((self._rects[:, 3], self._rects[:, 2], self._rects[:, 1], self._rects[:, 0]))
+        return self._rects[order]
+
+    def __eq__(self, other: Any) -> bool:
+        return (
+            type(self) is type(other)
+            and numpy.array_equal(self._sorted_rects(), other._sorted_rects())
+            and self.repetition == other.repetition
+            and annotations_eq(self.annotations, other.annotations)
+            )
+
+    def __lt__(self, other: Shape) -> bool:
+        if type(self) is not type(other):
+            if repr(type(self)) != repr(type(other)):
+                return repr(type(self)) < repr(type(other))
+            return id(type(self)) < id(type(other))
+
+        other = cast('RectCollection', other)
+        self_rects = self._sorted_rects()
+        other_rects = other._sorted_rects()
+        if not numpy.array_equal(self_rects, other_rects):
+            min_len = min(self_rects.shape[0], other_rects.shape[0])
+            eq_mask = self_rects[:min_len] != other_rects[:min_len]
+            eq_lt = self_rects[:min_len] < other_rects[:min_len]
+            eq_lt_masked = eq_lt[eq_mask]
+            if eq_lt_masked.size > 0:
+                return bool(eq_lt_masked.flat[0])
+            return self_rects.shape[0] < other_rects.shape[0]
+        if self.repetition != other.repetition:
+            return rep2key(self.repetition) < rep2key(other.repetition)
+        return annotations_lt(self.annotations, other.annotations)
+
+    def to_polygons(
+            self,
+            num_vertices: int | None = None,      # unused  # noqa: ARG002
+            max_arclen: float | None = None,      # unused  # noqa: ARG002
+            ) -> list[Polygon]:
+        return [
+            Polygon(
+                vertices=vertices,
+                repetition=copy.deepcopy(self.repetition),
+                annotations=copy.deepcopy(self.annotations),
+                )
+            for vertices in self.polygon_vertices
+            ]
+
+    def get_bounds_single(self) -> NDArray[numpy.float64] | None:
+        if self._rects.size == 0:
+            return None
+        mins = self._rects[:, :2].min(axis=0)
+        maxs = self._rects[:, 2:].max(axis=0)
+        return numpy.vstack((mins, maxs))
+
+    def rotate(self, theta: float) -> Self:
+        quarter_turns = int(numpy.rint(theta / (pi / 2)))
+        if not numpy.isclose(theta, quarter_turns * (pi / 2)):
+            raise PatternError('RectCollection only supports Manhattan rotations')
+        turns = quarter_turns % 4
+        if turns == 0 or self._rects.size == 0:
+            return self
+
+        corners = numpy.stack((
+            self._rects[:, [0, 1]],
+            self._rects[:, [0, 3]],
+            self._rects[:, [2, 3]],
+            self._rects[:, [2, 1]],
+            ), axis=1)
+        flat = corners.reshape(-1, 2)
+        if turns == 1:
+            rotated = numpy.column_stack((-flat[:, 1], flat[:, 0]))
+        elif turns == 2:
+            rotated = -flat
+        else:
+            rotated = numpy.column_stack((flat[:, 1], -flat[:, 0]))
+        corners = rotated.reshape(corners.shape)
+        self._rects[:, 0] = corners[:, :, 0].min(axis=1)
+        self._rects[:, 1] = corners[:, :, 1].min(axis=1)
+        self._rects[:, 2] = corners[:, :, 0].max(axis=1)
+        self._rects[:, 3] = corners[:, :, 1].max(axis=1)
+        return self
+
+    def mirror(self, axis: int = 0) -> Self:
+        if axis not in (0, 1):
+            raise PatternError('Axis must be 0 or 1')
+        if axis == 0:
+            self._rects[:, [1, 3]] *= -1
+        else:
+            self._rects[:, [0, 2]] *= -1
+        _renormalize_rects_in_place(self._rects)
+        return self
+
+    def scale_by(self, c: float) -> Self:
+        self._rects *= c
+        _renormalize_rects_in_place(self._rects)
+        return self
+
+    def normalized_form(self, norm_value: float) -> normalized_shape_tuple:
+        rects = self._sorted_rects()
+        centers = 0.5 * (rects[:, :2] + rects[:, 2:])
+        offset = centers.mean(axis=0)
+        zeroed = rects.copy()
+        zeroed[:, [0, 2]] -= offset[0]
+        zeroed[:, [1, 3]] -= offset[1]
+        normed = zeroed / norm_value
+        return (
+            (type(self), normed.data.tobytes()),
+            (offset, 1.0, 0.0, False),
+            lambda: RectCollection(rects=normed * norm_value),
+            )
+
+    def __repr__(self) -> str:
+        if self._rects.size == 0:
+            return '<RectCollection r0>'
+        centers = 0.5 * (self._rects[:, :2] + self._rects[:, 2:])
+        centroid = centers.mean(axis=0)
+        return f'<RectCollection centroid {centroid} r{self._rects.shape[0]}>'

masque/shapes/shape.py

@@ -6,8 +6,8 @@ import numpy
 from numpy.typing import NDArray, ArrayLike
 
 from ..traits import (
-    Rotatable, Mirrorable, Copyable, Scalable,
-    Positionable, PivotableImpl, RepeatableImpl, AnnotatableImpl,
+    Copyable, Scalable, FlippableImpl,
+    PivotableImpl, RepeatableImpl, AnnotatableImpl,
     )
 
 if TYPE_CHECKING:
@@ -26,8 +26,9 @@ normalized_shape_tuple = tuple[
 DEFAULT_POLY_NUM_VERTICES = 24
 
 
-class Shape(Positionable, Rotatable, Mirrorable, Copyable, Scalable,
-            PivotableImpl, RepeatableImpl, AnnotatableImpl, metaclass=ABCMeta):
+class Shape(FlippableImpl, PivotableImpl, RepeatableImpl, AnnotatableImpl,
+            Copyable, Scalable,
+            metaclass=ABCMeta):
     """
     Class specifying functions common to all shapes.
     """
@@ -73,7 +74,7 @@ class Shape(Positionable, Rotatable, Mirrorable, Copyable, Scalable,
         pass
 
     @abstractmethod
-    def normalized_form(self, norm_value: int) -> normalized_shape_tuple:
+    def normalized_form(self, norm_value: float) -> normalized_shape_tuple:
         """
         Writes the shape in a standardized notation, with offset, scale, and rotation
          information separated out from the remaining values.
@@ -120,7 +121,7 @@ class Shape(Positionable, Rotatable, Mirrorable, Copyable, Scalable,
         Returns:
             List of `Polygon` objects with grid-aligned edges.
         """
-        from . import Polygon
+        from . import Polygon       #noqa: PLC0415
 
         gx = numpy.unique(grid_x)
         gy = numpy.unique(grid_y)
@@ -138,22 +139,24 @@ class Shape(Positionable, Rotatable, Mirrorable, Copyable, Scalable,
             for v, v_next in zip(p_verts, numpy.roll(p_verts, -1, axis=0), strict=True):
                 dv = v_next - v
 
-                # Find x-index bounds for the line      # TODO: fix this and err_xmin/xmax for grids smaller than the line / shape
+                # Find x-index bounds for the line
                 gxi_range = numpy.digitize([v[0], v_next[0]], gx)
-                gxi_min = numpy.min(gxi_range - 1).clip(0, len(gx) - 1)
-                gxi_max = numpy.max(gxi_range).clip(0, len(gx))
+                gxi_min = int(numpy.min(gxi_range - 1).clip(0, len(gx) - 1))
+                gxi_max = int(numpy.max(gxi_range).clip(0, len(gx)))
 
+                if gxi_min < len(gx) - 1:
                     err_xmin = (min(v[0], v_next[0]) - gx[gxi_min]) / (gx[gxi_min + 1] - gx[gxi_min])
-                err_xmax = (max(v[0], v_next[0]) - gx[gxi_max - 1]) / (gx[gxi_max] - gx[gxi_max - 1])
-
                     if err_xmin >= 0.5:
                         gxi_min += 1
+
+                if gxi_max > 0 and gxi_max < len(gx):
+                    err_xmax = (max(v[0], v_next[0]) - gx[gxi_max - 1]) / (gx[gxi_max] - gx[gxi_max - 1])
                     if err_xmax >= 0.5:
                         gxi_max += 1
 
                 if abs(dv[0]) < 1e-20:
                     # Vertical line, don't calculate slope
-                    xi = [gxi_min, gxi_max - 1]
+                    xi = [gxi_min, max(gxi_min, gxi_max - 1)]
                     ys = numpy.array([v[1], v_next[1]])
                     yi = numpy.digitize(ys, gy).clip(1, len(gy) - 1)
                     err_y = (ys - gy[yi]) / (gy[yi] - gy[yi - 1])
@@ -249,9 +252,9 @@ class Shape(Positionable, Rotatable, Mirrorable, Copyable, Scalable,
         Returns:
             List of `Polygon` objects with grid-aligned edges.
         """
-        from . import Polygon
-        import skimage.measure      # type: ignore
-        import float_raster
+        from . import Polygon   #noqa: PLC0415
+        import skimage.measure  #noqa: PLC0415
+        import float_raster     #noqa: PLC0415
 
         grx = numpy.unique(grid_x)
         gry = numpy.unique(grid_y)

masque/shapes/text.py

@@ -70,31 +70,48 @@ class Text(PositionableImpl, RotatableImpl, Shape):
             *,
             offset: ArrayLike = (0.0, 0.0),
             rotation: float = 0.0,
+            mirrored: bool = False,
             repetition: Repetition | None = None,
             annotations: annotations_t = None,
-            raw: bool = False,
             ) -> None:
-        if raw:
-            assert isinstance(offset, numpy.ndarray)
-            self._offset = offset
-            self._string = string
-            self._height = height
-            self._rotation = rotation
-            self._repetition = repetition
-            self._annotations = annotations
-        else:
         self.offset = offset
         self.string = string
         self.height = height
         self.rotation = rotation
+        self.mirrored = mirrored
         self.repetition = repetition
         self.annotations = annotations
         self.font_path = font_path
 
+    @classmethod
+    def _from_raw(
+            cls,
+            *,
+            string: str,
+            height: float,
+            font_path: str,
+            offset: NDArray[numpy.float64],
+            rotation: float,
+            mirrored: bool,
+            annotations: annotations_t = None,
+            repetition: Repetition | None = None,
+            ) -> Self:
+        new = cls.__new__(cls)
+        new._offset = offset
+        new._string = string
+        new._height = height
+        new._rotation = rotation % (2 * pi)
+        new._mirrored = mirrored
+        new._repetition = repetition
+        new._annotations = annotations
+        new.font_path = font_path
+        return new
+
     def __deepcopy__(self, memo: dict | None = None) -> Self:
         memo = {} if memo is None else memo
         new = copy.copy(self)
         new._offset = self._offset.copy()
+        new._repetition = copy.deepcopy(self._repetition, memo)
         new._annotations = copy.deepcopy(self._annotations)
         return new
 
@@ -105,6 +122,7 @@ class Text(PositionableImpl, RotatableImpl, Shape):
             and self.string == other.string
             and self.height == other.height
             and self.font_path == other.font_path
+            and self.mirrored == other.mirrored
             and self.rotation == other.rotation
             and self.repetition == other.repetition
             and annotations_eq(self.annotations, other.annotations)
@@ -124,6 +142,8 @@ class Text(PositionableImpl, RotatableImpl, Shape):
             return self.font_path < other.font_path
         if not numpy.array_equal(self.offset, other.offset):
             return tuple(self.offset) < tuple(other.offset)
+        if self.mirrored != other.mirrored:
+            return self.mirrored < other.mirrored
         if self.rotation != other.rotation:
             return self.rotation < other.rotation
         if self.repetition != other.repetition:
@@ -146,7 +166,7 @@ class Text(PositionableImpl, RotatableImpl, Shape):
                 if self.mirrored:
                     poly.mirror()
                 poly.scale_by(self.height)
-                poly.offset = self.offset + [total_advance, 0]
+                poly.translate(self.offset + [total_advance, 0])
                 poly.rotate_around(self.offset, self.rotation)
                 all_polygons += [poly]
 
@@ -171,22 +191,25 @@ class Text(PositionableImpl, RotatableImpl, Shape):
                 (self.offset, self.height / norm_value, rotation, bool(self.mirrored)),
                 lambda: Text(
                     string=self.string,
-                    height=self.height * norm_value,
+                    height=norm_value,
                     font_path=self.font_path,
                     rotation=rotation,
                     ).mirror2d(across_x=self.mirrored),
                 )
 
-    def get_bounds_single(self) -> NDArray[numpy.float64]:
+    def get_bounds_single(self) -> NDArray[numpy.float64] | None:
         # rotation makes this a huge pain when using slot.advance and glyph.bbox(), so
         #  just convert to polygons instead
         polys = self.to_polygons()
+        if not polys:
+            return None
+
         pbounds = numpy.full((len(polys), 2, 2), nan)
         for pp, poly in enumerate(polys):
             pbounds[pp] = poly.get_bounds_nonempty()
         bounds = numpy.vstack((
-            numpy.min(pbounds[: 0, :], axis=0),
-            numpy.max(pbounds[: 1, :], axis=0),
+            numpy.min(pbounds[:, 0, :], axis=0),
+            numpy.max(pbounds[:, 1, :], axis=0),
             ))
 
         return bounds
@@ -202,8 +225,8 @@ def get_char_as_polygons(
         char: str,
         resolution: float = 48 * 64,
         ) -> tuple[list[NDArray[numpy.float64]], float]:
-    from freetype import Face           # type: ignore
-    from matplotlib.path import Path    # type: ignore
+    from freetype import Face           # type: ignore  #noqa: PLC0415
+    from matplotlib.path import Path    # type: ignore  #noqa: PLC0415
 
     """
     Get a list of polygons representing a single character.

masque/test/__init__.py

@@ -0,0 +1,3 @@
+"""
+Tests (run with `python3 -m pytest -rxPXs | tee results.txt`)
+"""

masque/test/conftest.py

@@ -0,0 +1,13 @@
+"""
+
+Test fixtures
+
+"""
+
+# ruff: noqa: ARG001
+from typing import Any
+import numpy
+
+
+FixtureRequest = Any
+PRNG = numpy.random.RandomState(12345)

masque/test/helpers.py

@@ -0,0 +1,146 @@
+from typing import Any
+from collections.abc import Callable
+from copy import deepcopy
+
+import numpy
+from numpy.typing import ArrayLike, NDArray
+from numpy.testing import assert_allclose
+
+from masque import Pather, Port
+from masque.builder.tools import RenderStep
+
+
+def closed_edge_lengths(vertices: ArrayLike) -> NDArray[numpy.float64]:
+    """
+    Return lengths for each edge of an implicitly closed vertex loop.
+    """
+    vv = numpy.asarray(vertices, dtype=float)
+    return numpy.sqrt(numpy.sum(numpy.diff(vv, axis=0, append=vv[:1]) ** 2, axis=1))
+
+
+def assert_closed_edges_within(vertices: ArrayLike, max_len: float, *, atol: float = 1e-6) -> None:
+    """
+    Assert that every edge in an implicitly closed vertex loop is no longer than `max_len`.
+    """
+    assert numpy.all(closed_edge_lengths(vertices) <= max_len + atol)
+
+
+def assert_bounds_close(shape_or_polygon: Any, expected: ArrayLike, *, atol: float = 1e-10) -> None:
+    """
+    Assert that an object's single-shape bounds match `expected`.
+    """
+    assert_allclose(shape_or_polygon.get_bounds_single(), expected, atol=atol)
+
+
+def normalized_route_data(data: Any) -> Any:
+    """
+    Return a deterministic, comparison-friendly representation of route data.
+    """
+    if isinstance(data, dict):
+        return tuple((key, normalized_route_data(value)) for key, value in sorted(data.items(), key=lambda item: repr(item[0])))
+    if isinstance(data, list | tuple):
+        return tuple(normalized_route_data(value) for value in data)
+    if isinstance(data, numpy.ndarray):
+        return tuple(normalized_route_data(value) for value in data.tolist())
+    if isinstance(data, numpy.generic):
+        return data.item()
+    try:
+        hash(data)
+    except TypeError:
+        return repr(data)
+    return data
+
+
+def route_step_signature(step: RenderStep) -> tuple[Any, ...]:
+    """
+    Return the stable planning-relevant portion of one rendered route step.
+    """
+    return (
+        step.opcode,
+        tuple(round(float(value), 9) for value in step.start_port.offset),
+        None if step.start_port.rotation is None else round(float(step.start_port.rotation), 9),
+        step.start_port.ptype,
+        tuple(round(float(value), 9) for value in step.end_port.offset),
+        None if step.end_port.rotation is None else round(float(step.end_port.rotation), 9),
+        step.end_port.ptype,
+        normalized_route_data(step.data),
+        )
+
+
+def route_signature(pather: Pather, portspec: str) -> tuple[tuple[Any, ...], ...]:
+    """
+    Return a deterministic signature for a pather route.
+    """
+    return tuple(route_step_signature(step) for step in pather._paths[portspec])
+
+
+def route_endpoint(pather: Pather, portspec: str) -> Port:
+    """
+    Return the endpoint of a routed port, falling back to the live port for empty routes.
+    """
+    steps = pather._paths[portspec]
+    if not steps:
+        return pather.pattern[portspec]
+    return steps[-1].end_port
+
+
+def assert_route_endpoint(
+        pather: Pather,
+        portspec: str,
+        expected: Port,
+        *,
+        atol: float = 1e-8,
+        ) -> None:
+    """
+    Assert that a route endpoint matches an expected port pose and ptype.
+    """
+    actual = route_endpoint(pather, portspec)
+    assert_allclose(actual.offset, expected.offset, atol=atol)
+    if expected.rotation is None:
+        assert actual.rotation is None
+    else:
+        assert actual.rotation is not None
+        assert numpy.isclose(actual.rotation, expected.rotation, atol=atol)
+    assert actual.ptype == expected.ptype
+
+
+def assert_route_bend_budget(pather: Pather, portspec: str, max_bends: int) -> None:
+    """
+    Assert a simple render-step bend budget for route signatures.
+    """
+    bend_count = sum(1 for step in pather._paths[portspec] if step.kind == 'bend')
+    assert bend_count <= max_bends
+
+
+def assert_route_deterministic(
+        make_pather: Callable[[], Pather],
+        route: Callable[[Pather], None],
+        portspec: str,
+        ) -> None:
+    """
+    Assert that the same route operation produces the same route signature twice.
+    """
+    first = make_pather()
+    route(first)
+    first_signature = route_signature(first, portspec)
+
+    second = make_pather()
+    route(second)
+    assert route_signature(second, portspec) == first_signature
+
+
+def assert_route_failure_does_not_mutate(
+        pather: Pather,
+        route: Callable[[], None],
+        expected_exception: type[BaseException],
+        ) -> BaseException:
+    """
+    Assert that a failing route operation leaves pending route steps untouched.
+    """
+    before = deepcopy(dict(pather._paths))
+    try:
+        route()
+    except expected_exception as err:
+        assert dict(pather._paths) == before
+        return err
+    raise AssertionError(f'Expected {expected_exception.__name__}')

masque/test/test_abstract.py

@@ -0,0 +1,85 @@
+from numpy.testing import assert_allclose
+from numpy import pi
+
+from ..abstract import Abstract
+from ..ports import Port
+from ..ref import Ref
+
+
+def test_abstract_init() -> None:
+    ports = {"A": Port((0, 0), 0), "B": Port((10, 0), pi)}
+    abs_obj = Abstract("test", ports)
+    assert abs_obj.name == "test"
+    assert len(abs_obj.ports) == 2
+    assert abs_obj.ports["A"] is not ports["A"]  # Should be deepcopied
+
+
+def test_abstract_transform() -> None:
+    abs_obj = Abstract("test", {"A": Port((10, 0), 0)})
+    # Rotate 90 deg around (0,0)
+    abs_obj.rotate_around((0, 0), pi / 2)
+    # (10, 0) rot 0 -> (0, 10) rot pi/2
+    assert_allclose(abs_obj.ports["A"].offset, [0, 10], atol=1e-10)
+    assert abs_obj.ports["A"].rotation is not None
+    assert_allclose(abs_obj.ports["A"].rotation, pi / 2, atol=1e-10)
+
+    # Mirror across x axis (axis 0): flips y-offset
+    abs_obj.mirror(0)
+    # (0, 10) mirrored(0) -> (0, -10)
+    # rotation pi/2 mirrored(0) -> -pi/2 == 3pi/2
+    assert_allclose(abs_obj.ports["A"].offset, [0, -10], atol=1e-10)
+    assert abs_obj.ports["A"].rotation is not None
+    assert_allclose(abs_obj.ports["A"].rotation, 3 * pi / 2, atol=1e-10)
+
+
+def test_abstract_ref_transform() -> None:
+    abs_obj = Abstract("test", {"A": Port((10, 0), 0)})
+    ref = Ref(offset=(100, 100), rotation=pi / 2, mirrored=True)
+
+    # Apply ref transform
+    abs_obj.apply_ref_transform(ref)
+    # Ref order: mirror, rotate, scale, translate
+
+    # 1. mirror (across x: y -> -y)
+    # (10, 0) rot 0 -> (10, 0) rot 0
+
+    # 2. rotate pi/2 around (0,0)
+    # (10, 0) rot 0 -> (0, 10) rot pi/2
+
+    # 3. translate (100, 100)
+    # (0, 10) -> (100, 110)
+
+    assert_allclose(abs_obj.ports["A"].offset, [100, 110], atol=1e-10)
+    assert abs_obj.ports["A"].rotation is not None
+    assert_allclose(abs_obj.ports["A"].rotation, pi / 2, atol=1e-10)
+
+
+def test_abstract_ref_transform_scales_offsets() -> None:
+    abs_obj = Abstract("test", {"A": Port((10, 0), 0)})
+    ref = Ref(offset=(100, 100), rotation=pi / 2, mirrored=True, scale=2)
+
+    abs_obj.apply_ref_transform(ref)
+
+    assert_allclose(abs_obj.ports["A"].offset, [100, 120], atol=1e-10)
+    assert abs_obj.ports["A"].rotation is not None
+    assert_allclose(abs_obj.ports["A"].rotation, pi / 2, atol=1e-10)
+
+
+def test_abstract_undo_transform() -> None:
+    abs_obj = Abstract("test", {"A": Port((100, 110), pi / 2)})
+    ref = Ref(offset=(100, 100), rotation=pi / 2, mirrored=True)
+
+    abs_obj.undo_ref_transform(ref)
+    assert_allclose(abs_obj.ports["A"].offset, [10, 0], atol=1e-10)
+    assert abs_obj.ports["A"].rotation is not None
+    assert_allclose(abs_obj.ports["A"].rotation, 0, atol=1e-10)
+
+
+def test_abstract_undo_transform_scales_offsets() -> None:
+    abs_obj = Abstract("test", {"A": Port((100, 120), pi / 2)})
+    ref = Ref(offset=(100, 100), rotation=pi / 2, mirrored=True, scale=2)
+
+    abs_obj.undo_ref_transform(ref)
+    assert_allclose(abs_obj.ports["A"].offset, [10, 0], atol=1e-10)
+    assert abs_obj.ports["A"].rotation is not None
+    assert_allclose(abs_obj.ports["A"].rotation, 0, atol=1e-10)

masque/test/test_arc.py

@@ -0,0 +1,87 @@
+import pytest
+import numpy
+from numpy import pi
+from numpy.testing import assert_equal, assert_allclose
+
+from ..error import PatternError
+from ..shapes import Arc
+from .helpers import assert_closed_edges_within
+
+
+def test_arc_init() -> None:
+    a = Arc(radii=(10, 10), angles=(0, pi / 2), width=2, offset=(0, 0))
+    assert_equal(a.radii, [10, 10])
+    assert_equal(a.angles, [0, pi / 2])
+    assert a.width == 2
+
+def test_arc_to_polygons() -> None:
+    a = Arc(radii=(10, 10), angles=(0, pi / 2), width=2)
+    polys = a.to_polygons(num_vertices=32)
+    assert len(polys) == 1
+
+    # Quarter-circle ring section with outer radius 11 and inner radius 9.
+    bounds = polys[0].get_bounds_single()
+    assert_allclose(bounds, [[0, 0], [11, 11]], atol=1e-10)
+
+def test_arc_focus_to_polygons() -> None:
+    a = Arc(radii=(10, 6), angles=(-0.4, 0.7), width=1, angle_ref=Arc.AngleRef.FocusPos)
+    polys = a.to_polygons(num_vertices=32)
+    assert len(polys) == 1
+
+    focus = numpy.array([8.0, 0.0])
+    cuts = a.get_cap_edges()
+    for angle, cut in zip(a.angles, cuts, strict=True):
+        direction = numpy.array([numpy.cos(angle), numpy.sin(angle)])
+        for point in cut:
+            delta = point - focus
+            assert_allclose(direction[0] * delta[1] - direction[1] * delta[0], 0, atol=1e-10)
+            assert numpy.dot(direction, delta) > 0
+
+def test_arc_circle_focus_matches_center() -> None:
+    center = Arc(radii=(10, 10), angles=(0, pi / 2), width=2)
+    focus = Arc(radii=(10, 10), angles=(0, pi / 2), width=2, angle_ref=Arc.AngleRef.FocusPos)
+
+    assert_allclose(focus.to_polygons(num_vertices=32)[0].vertices,
+                    center.to_polygons(num_vertices=32)[0].vertices,
+                    atol=1e-10)
+
+def test_arc_edge_cases() -> None:
+    a = Arc(radii=(10, 10), angles=(0, 3 * pi), width=2)
+    a.to_polygons(num_vertices=64)
+    bounds = a.get_bounds_single()
+    assert_allclose(bounds, [[-11, -11], [11, 11]], atol=1e-10)
+
+def test_rotated_arc_bounds_match_polygonized_geometry() -> None:
+    arc = Arc(radii=(10, 20), angles=(0, pi), width=2, rotation=pi / 4, offset=(100, 200))
+    bounds = arc.get_bounds_single()
+    poly_bounds = arc.to_polygons(num_vertices=8192)[0].get_bounds_single()
+    assert_allclose(bounds, poly_bounds, atol=1e-3)
+
+def test_rotated_focus_arc_bounds_match_polygonized_geometry() -> None:
+    arc = Arc(radii=(10, 6), angles=(-0.25, 1.1), width=1, rotation=pi / 4,
+              offset=(100, 200), angle_ref=Arc.AngleRef.FocusPos)
+    bounds = arc.get_bounds_single()
+    poly_bounds = arc.to_polygons(num_vertices=8192)[0].get_bounds_single()
+    assert_allclose(bounds, poly_bounds, atol=1e-3)
+
+def test_arc_polygonization_rejects_nan_implied_arclen() -> None:
+    arc = Arc(radii=(10, 20), angles=(0, numpy.nan), width=2)
+    with pytest.raises(PatternError, match='valid max_arclen'):
+        arc.to_polygons(num_vertices=24)
+
+def test_focus_arc_rejects_focus_outside_inner_boundary() -> None:
+    arc = Arc(radii=(10, 5), angles=(0, 1), width=6, angle_ref=Arc.AngleRef.FocusPos)
+    with pytest.raises(PatternError, match='inside both arc boundary ellipses'):
+        arc.to_polygons(num_vertices=24)
+
+def test_focus_arc_max_arclen_limits_segments() -> None:
+    arc = Arc(radii=(10, 6), angles=(-0.25, 1.1), width=1, angle_ref=Arc.AngleRef.FocusNeg)
+    assert_closed_edges_within(arc.to_polygons(max_arclen=2)[0].vertices, 2)
+
+def test_arc_rejects_zero_radii_up_front() -> None:
+    with pytest.raises(PatternError, match='Radii must be positive'):
+        Arc(radii=(0, 5), angles=(0, 1), width=1)
+    with pytest.raises(PatternError, match='Radii must be positive'):
+        Arc(radii=(5, 0), angles=(0, 1), width=1)
+    with pytest.raises(PatternError, match='Radii must be positive'):
+        Arc(radii=(0, 0), angles=(0, 1), width=1)

masque/test/test_boolean.py

@@ -0,0 +1,242 @@
+# ruff: noqa: PLC0415
+import pytest
+import numpy
+from numpy.testing import assert_allclose
+from masque.pattern import Pattern
+from masque.shapes.polygon import Polygon
+from masque.repetition import Grid
+from masque.library import Library
+from masque.error import PatternError
+
+
+def _poly_area(poly: Polygon) -> float:
+    verts = poly.vertices
+    x = verts[:, 0]
+    y = verts[:, 1]
+    return 0.5 * abs(numpy.dot(x, numpy.roll(y, -1)) - numpy.dot(y, numpy.roll(x, -1)))
+
+def test_layer_as_polygons_basic() -> None:
+    pat = Pattern()
+    pat.polygon((1, 0), [[0, 0], [1, 0], [1, 1], [0, 1]])
+
+    polys = pat.layer_as_polygons((1, 0), flatten=False)
+    assert len(polys) == 1
+    assert isinstance(polys[0], Polygon)
+    assert_allclose(polys[0].vertices, [[0, 0], [1, 0], [1, 1], [0, 1]])
+
+def test_layer_as_polygons_repetition() -> None:
+    pat = Pattern()
+    rep = Grid(a_vector=(2, 0), a_count=2)
+    pat.polygon((1, 0), [[0, 0], [1, 0], [1, 1], [0, 1]], repetition=rep)
+
+    polys = pat.layer_as_polygons((1, 0), flatten=False)
+    assert len(polys) == 2
+    # First polygon at (0,0)
+    assert_allclose(polys[0].vertices, [[0, 0], [1, 0], [1, 1], [0, 1]])
+    # Second polygon at (2,0)
+    assert_allclose(polys[1].vertices, [[2, 0], [3, 0], [3, 1], [2, 1]])
+
+def test_layer_as_polygons_flatten() -> None:
+    lib = Library()
+
+    child = Pattern()
+    child.polygon((1, 0), [[0, 0], [1, 0], [1, 1]])
+    lib['child'] = child
+
+    parent = Pattern()
+    parent.ref('child', offset=(10, 10), rotation=numpy.pi/2)
+
+    polys = parent.layer_as_polygons((1, 0), flatten=True, library=lib)
+    assert len(polys) == 1
+    # Child vertices are rotated by the ref and then translated by the ref offset.
+    expected = numpy.array([[10, 10], [10, 11], [9, 11]])
+    assert_allclose(polys[0].vertices, expected, atol=1e-10)
+
+def test_boolean_import_error() -> None:
+    from masque import boolean
+    # If pyclipper is not installed, this should raise ImportError
+    try:
+        import pyclipper  # noqa: F401
+        pytest.skip("pyclipper is installed, cannot test ImportError")
+    except ImportError:
+        with pytest.raises(ImportError, match="Boolean operations require 'pyclipper'"):
+            boolean([], [], operation='union')
+
+def test_polygon_boolean_shortcut() -> None:
+    poly = Polygon([[0, 0], [1, 0], [1, 1]])
+    # This should also raise ImportError if pyclipper is missing
+    try:
+        import pyclipper  # noqa: F401
+        pytest.skip("pyclipper is installed")
+    except ImportError:
+        with pytest.raises(ImportError, match="Boolean operations require 'pyclipper'"):
+            poly.boolean(poly)
+
+
+def test_boolean_intersection_with_pyclipper() -> None:
+    pytest.importorskip("pyclipper")
+    from masque.utils.boolean import boolean
+
+    result = boolean(
+        [Polygon([[0, 0], [2, 0], [2, 2], [0, 2]])],
+        [Polygon([[1, 1], [3, 1], [3, 3], [1, 3]])],
+        operation='intersection',
+    )
+
+    assert len(result) == 1
+    assert_allclose(result[0].get_bounds_single(), [[1, 1], [2, 2]], atol=1e-10)
+
+
+def test_polygon_boolean_shortcut_with_pyclipper() -> None:
+    pytest.importorskip("pyclipper")
+
+    poly = Polygon([[0, 0], [2, 0], [2, 2], [0, 2]])
+    result = poly.boolean(
+        Polygon([[1, 1], [3, 1], [3, 3], [1, 3]]),
+        operation='intersection',
+    )
+
+    assert len(result) == 1
+    assert_allclose(result[0].get_bounds_single(), [[1, 1], [2, 2]], atol=1e-10)
+
+
+def test_boolean_union_difference_and_xor_with_pyclipper() -> None:
+    pytest.importorskip("pyclipper")
+    from masque.utils.boolean import boolean
+
+    rect_a = Polygon([[0, 0], [2, 0], [2, 2], [0, 2]])
+    rect_b = Polygon([[1, 1], [3, 1], [3, 3], [1, 3]])
+
+    union = boolean([rect_a], [rect_b], operation='union')
+    assert len(union) == 1
+    assert_allclose(union[0].get_bounds_single(), [[0, 0], [3, 3]], atol=1e-10)
+    assert_allclose(_poly_area(union[0]), 7, atol=1e-10)
+
+    difference = boolean([rect_a], [rect_b], operation='difference')
+    assert len(difference) == 1
+    assert_allclose(difference[0].get_bounds_single(), [[0, 0], [2, 2]], atol=1e-10)
+    assert_allclose(_poly_area(difference[0]), 3, atol=1e-10)
+
+    xor = boolean([rect_a], [rect_b], operation='xor')
+    assert len(xor) == 2
+    assert_allclose(sorted(_poly_area(poly) for poly in xor), [3, 3], atol=1e-10)
+    xor_bounds = sorted(tuple(map(tuple, poly.get_bounds_single())) for poly in xor)
+    assert xor_bounds == [((0.0, 0.0), (2.0, 2.0)), ((1.0, 1.0), (3.0, 3.0))]
+
+
+def test_boolean_accepts_raw_vertices_and_single_shape_inputs() -> None:
+    pytest.importorskip("pyclipper")
+    from masque.utils.boolean import boolean
+
+    raw_result = boolean(
+        [numpy.array([[0, 0], [2, 0], [2, 2], [0, 2]])],
+        numpy.array([[1, 1], [3, 1], [3, 3], [1, 3]]),
+        operation='intersection',
+    )
+    assert len(raw_result) == 1
+    assert_allclose(raw_result[0].get_bounds_single(), [[1, 1], [2, 2]], atol=1e-10)
+    assert_allclose(_poly_area(raw_result[0]), 1, atol=1e-10)
+
+    single_shape_result = boolean(
+        Polygon([[0, 0], [2, 0], [2, 2], [0, 2]]),
+        Polygon([[1, 1], [3, 1], [3, 3], [1, 3]]),
+        operation='intersection',
+    )
+    assert len(single_shape_result) == 1
+    assert_allclose(single_shape_result[0].get_bounds_single(), [[1, 1], [2, 2]], atol=1e-10)
+
+
+def test_boolean_handles_multi_polygon_inputs() -> None:
+    pytest.importorskip("pyclipper")
+    from masque.utils.boolean import boolean
+
+    result = boolean(
+        [
+            Polygon([[0, 0], [2, 0], [2, 2], [0, 2]]),
+            Polygon([[10, 0], [12, 0], [12, 2], [10, 2]]),
+        ],
+        [
+            Polygon([[1, 1], [3, 1], [3, 3], [1, 3]]),
+            Polygon([[11, 1], [13, 1], [13, 3], [11, 3]]),
+        ],
+        operation='intersection',
+    )
+    assert len(result) == 2
+    assert_allclose(sorted(_poly_area(poly) for poly in result), [1, 1], atol=1e-10)
+    result_bounds = sorted(tuple(map(tuple, poly.get_bounds_single())) for poly in result)
+    assert result_bounds == [((1.0, 1.0), (2.0, 2.0)), ((11.0, 1.0), (12.0, 2.0))]
+
+
+def test_boolean_difference_preserves_hole_area_via_bridged_polygon() -> None:
+    pytest.importorskip("pyclipper")
+    from masque.utils.boolean import boolean
+
+    outer = Polygon([[0, 0], [10, 0], [10, 10], [0, 10]])
+    hole = Polygon([[2, 2], [8, 2], [8, 8], [2, 8]])
+    result = boolean([outer], [hole], operation='difference')
+
+    assert len(result) == 1
+    assert_allclose(result[0].get_bounds_single(), [[0, 0], [10, 10]], atol=1e-10)
+    assert_allclose(_poly_area(result[0]), 64, atol=1e-10)
+
+
+def test_boolean_nested_hole_and_island_case() -> None:
+    pytest.importorskip("pyclipper")
+    from masque.utils.boolean import boolean
+
+    outer = Polygon([[0, 0], [10, 0], [10, 10], [0, 10]])
+    hole = Polygon([[2, 2], [8, 2], [8, 8], [2, 8]])
+    island = Polygon([[4, 4], [6, 4], [6, 6], [4, 6]])
+
+    result = boolean([outer, island], [hole], operation='union')
+
+    assert len(result) == 1
+    assert_allclose(result[0].get_bounds_single(), [[0, 0], [10, 10]], atol=1e-10)
+    assert_allclose(_poly_area(result[0]), 100, atol=1e-10)
+
+
+def test_boolean_empty_inputs_follow_set_semantics() -> None:
+    pytest.importorskip("pyclipper")
+    from masque.utils.boolean import boolean
+
+    rect = Polygon([[1, 1], [3, 1], [3, 3], [1, 3]])
+
+    union = boolean([], [rect], operation='union')
+    assert len(union) == 1
+    assert_allclose(union[0].get_bounds_single(), [[1, 1], [3, 3]], atol=1e-10)
+
+    intersection = boolean([], [rect], operation='intersection')
+    assert intersection == []
+
+    difference = boolean([], [rect], operation='difference')
+    assert difference == []
+
+    xor = boolean([], [rect], operation='xor')
+    assert len(xor) == 1
+    assert_allclose(xor[0].get_bounds_single(), [[1, 1], [3, 3]], atol=1e-10)
+
+    clip_empty_union = boolean([rect], [], operation='union')
+    assert len(clip_empty_union) == 1
+    assert_allclose(clip_empty_union[0].get_bounds_single(), [[1, 1], [3, 3]], atol=1e-10)
+
+    clip_empty_intersection = boolean([rect], [], operation='intersection')
+    assert clip_empty_intersection == []
+
+    clip_empty_difference = boolean([rect], [], operation='difference')
+    assert len(clip_empty_difference) == 1
+    assert_allclose(clip_empty_difference[0].get_bounds_single(), [[1, 1], [3, 3]], atol=1e-10)
+
+    clip_empty_xor = boolean([rect], [], operation='xor')
+    assert len(clip_empty_xor) == 1
+    assert_allclose(clip_empty_xor[0].get_bounds_single(), [[1, 1], [3, 3]], atol=1e-10)
+
+
+def test_boolean_invalid_inputs_raise_pattern_error() -> None:
+    pytest.importorskip("pyclipper")
+    from masque.utils.boolean import boolean
+
+    rect = Polygon([[0, 0], [1, 0], [1, 1], [0, 1]])
+
+    for bad in (123, object(), [123]):
+        with pytest.raises(PatternError, match='Unsupported type'):
+            boolean([rect], bad, operation='intersection')

masque/test/test_builder.py

@@ -0,0 +1,254 @@
+import numpy
+import pytest
+from numpy.testing import assert_equal, assert_allclose
+from numpy import pi
+
+from ..builder import MinimumStatus, Pather, RouteFailureDetails
+from ..builder.utils import ell
+from ..error import BuildError
+from ..library import Library
+from ..pattern import Pattern
+from ..ports import Port
+
+
+def test_builder_public_imports() -> None:
+    from masque import PortPather as TopPortPather
+    from masque import RenderStep as TopRenderStep
+    from masque import RouteError as TopRouteError
+    from masque import RouteFailureDetails as TopRouteFailureDetails
+    from masque import RouteFailurePolicy as TopRouteFailurePolicy
+    from masque import MinimumStatus as TopMinimumStatus
+    from masque.builder import PortPather as BuilderPortPather
+    from masque.builder import RenderStep as BuilderRenderStep
+    from masque.builder import RouteError as BuilderRouteError
+    from masque.builder import RouteFailureDetails as BuilderRouteFailureDetails
+    from masque.builder import RouteFailurePolicy as BuilderRouteFailurePolicy
+    from masque.builder import MinimumStatus as BuilderMinimumStatus
+
+    assert TopPortPather is BuilderPortPather
+    assert TopRenderStep is BuilderRenderStep
+    assert TopRouteError is BuilderRouteError
+    assert TopRouteFailureDetails is BuilderRouteFailureDetails
+    assert TopRouteFailurePolicy is BuilderRouteFailurePolicy
+    assert TopMinimumStatus is BuilderMinimumStatus
+
+
+def test_route_failure_details_enforces_minimum_status_invariants() -> None:
+    common = {
+        'operation': 'trace',
+        'portspec': 'A',
+        'in_ptype': 'wire',
+        'out_ptype': 'wide',
+        'request': {},
+        'resolved_length': 1,
+        'resolved_jog': None,
+        'cause': 'no route',
+        }
+
+    with pytest.raises(BuildError, match='FOUND requires minimum_length'):
+        RouteFailureDetails(
+            **common,
+            minimum_length=None,
+            minimum_status=MinimumStatus.FOUND,
+            )
+
+    with pytest.raises(BuildError, match='requires minimum_length=None'):
+        RouteFailureDetails(
+            **common,
+            minimum_length=2,
+            minimum_status=MinimumStatus.NO_ROUTE,
+            )
+
+
+def test_plain_build_error_does_not_include_stacktrace() -> None:
+    assert str(BuildError('plain builder failure')) == 'plain builder failure'
+
+
+def test_builder_init() -> None:
+    lib = Library()
+    b = Pather(lib, name="mypat")
+    assert b.pattern is lib["mypat"]
+    assert b.library is lib
+
+
+def test_builder_place() -> None:
+    lib = Library()
+    child = Pattern()
+    child.ports["A"] = Port((0, 0), 0)
+    lib["child"] = child
+
+    b = Pather(lib)
+    b.place("child", offset=(10, 20), port_map={"A": "child_A"})
+
+    assert "child_A" in b.ports
+    assert_equal(b.ports["child_A"].offset, [10, 20])
+    assert "child" in b.pattern.refs
+
+
+def test_builder_plug() -> None:
+    lib = Library()
+
+    wire = Pattern()
+    wire.ports["in"] = Port((0, 0), 0)
+    wire.ports["out"] = Port((10, 0), pi)
+    lib["wire"] = wire
+
+    b = Pather(lib)
+    b.ports["start"] = Port((100, 100), 0)
+
+    # Plug wire's "in" port into builder's "start" port
+    # Wire's "out" port should be renamed to "start" because thru=True (default) and wire has 2 ports
+    # builder start: (100, 100) rotation 0
+    # wire in: (0, 0) rotation 0
+    # wire out: (10, 0) rotation pi
+    # Plugging wire in (rot 0) to builder start (rot 0) means wire is rotated by pi (180 deg)
+    # so wire in is at (100, 100), wire out is at (100 - 10, 100) = (90, 100)
+    b.plug("wire", map_in={"start": "in"})
+
+    assert "start" in b.ports
+    assert_equal(b.ports["start"].offset, [90, 100])
+    assert b.ports["start"].rotation is not None
+    assert_allclose(b.ports["start"].rotation, 0, atol=1e-10)
+
+
+def test_builder_interface() -> None:
+    lib = Library()
+    source = Pattern()
+    source.ports["P1"] = Port((0, 0), 0)
+    lib["source"] = source
+
+    b = Pather.interface("source", library=lib, name="iface")
+    assert "in_P1" in b.ports
+    assert "P1" in b.ports
+    assert b.pattern is lib["iface"]
+
+
+def test_builder_set_dead() -> None:
+    lib = Library()
+    lib["sub"] = Pattern()
+    b = Pather(lib)
+    b.set_dead()
+
+    b.place("sub")
+    assert not b.pattern.has_refs()
+
+
+def test_builder_dead_ports() -> None:
+    lib = Library()
+    pat = Pattern()
+    pat.ports['A'] = Port((0, 0), 0)
+    b = Pather(lib, pattern=pat)
+    b.set_dead()
+
+    # Attempt to plug a device where ports don't line up
+    # A has rotation 0, C has rotation 0. plug() expects opposing rotations (pi difference).
+    other = Pattern(ports={'C': Port((10, 10), 0), 'D': Port((20, 20), 0)})
+
+    # This should NOT raise PortError because b is dead
+    b.plug(other, map_in={'A': 'C'}, map_out={'D': 'B'})
+
+    # Port A should be removed, and Port B (renamed from D) should be added
+    assert 'A' not in b.ports
+    assert 'B' in b.ports
+
+    # Verify geometry was not added
+    assert not b.pattern.has_refs()
+    assert not b.pattern.has_shapes()
+
+
+def test_dead_plug_best_effort() -> None:
+    lib = Library()
+    pat = Pattern()
+    pat.ports['A'] = Port((0, 0), 0)
+    b = Pather(lib, pattern=pat)
+    b.set_dead()
+
+    # Device with multiple ports, none of which line up correctly
+    other = Pattern(ports={
+        'P1': Port((10, 10), 0),  # Wrong rotation (0 instead of pi)
+        'P2': Port((20, 20), pi)  # Correct rotation but wrong offset
+    })
+
+    # Try to plug. find_transform will fail.
+    # It should fall back to aligning the first pair ('A' and 'P1').
+    b.plug(other, map_in={'A': 'P1'}, map_out={'P2': 'B'})
+
+    assert 'A' not in b.ports
+    assert 'B' in b.ports
+
+    # Dummy transform aligns A (0,0) with P1 (10,10)
+    # A rotation 0, P1 rotation 0 -> rotation = (0 - 0 - pi) = -pi
+    # P2 (20,20) rotation pi:
+    # 1. Translate P2 so P1 is at origin: (20,20) - (10,10) = (10,10)
+    # 2. Rotate (10,10) by -pi: (-10,-10)
+    # 3. Translate by s_port.offset (0,0): (-10,-10)
+    assert_allclose(b.ports['B'].offset, [-10, -10], atol=1e-10)
+    # P2 rot pi + transform rot -pi = 0
+    assert b.ports['B'].rotation is not None
+    assert_allclose(b.ports['B'].rotation, 0, atol=1e-10)
+
+
+def test_ell_validates_spacing_length() -> None:
+    ports = {
+        'A': Port((0, 0), 0),
+        'B': Port((0, 1), 0),
+        'C': Port((0, 2), 0),
+    }
+
+    with pytest.raises(BuildError, match='spacing must be scalar or have length 2'):
+        ell(ports, True, 'min_extension', 5, spacing=[1, 2, 3])
+
+    with pytest.raises(BuildError, match='spacing must be scalar or have length 2'):
+        ell(ports, True, 'min_extension', 5, spacing=[])
+
+
+def test_ell_handles_array_spacing_when_ccw_none() -> None:
+    ports = {
+        'A': Port((0, 0), 0),
+        'B': Port((0, 1), 0),
+    }
+
+    scalar = ell(ports, None, 'min_extension', 5, spacing=0)
+    array_zero = ell(ports, None, 'min_extension', 5, spacing=numpy.array([0, 0]))
+    assert scalar == array_zero
+
+    with pytest.raises(BuildError, match='Spacing must be 0 or None'):
+        ell(ports, None, 'min_extension', 5, spacing=numpy.array([1, 0]))
+
+
+@pytest.mark.parametrize('bound_type', ['emin', 'emax', 'min_past_furthest'])
+@pytest.mark.parametrize(
+    ('rotation', 'expected'),
+    [
+        (0, 5),
+        (pi / 2, 7),
+        (pi / 6, 5),
+        (pi / 3, 7),
+        (pi / 4, 5),
+    ],
+    )
+def test_ell_extension_vector_selects_dominant_route_axis(
+        bound_type: str,
+        rotation: float,
+        expected: float,
+        ) -> None:
+    result = ell({'A': Port((0, 0), rotation)}, None, bound_type, (5, 7), spacing=0)
+
+    assert_allclose(result['A'], expected)
+
+
+@pytest.mark.parametrize('bound', [(-1, 2), (1, -2), (numpy.nan, 2), (1, numpy.inf), (1, 2, 3)])
+def test_ell_rejects_invalid_extension_vector(bound: tuple[float, ...]) -> None:
+    with pytest.raises(BuildError, match='bound|negative'):
+        ell({'A': Port((0, 0), 0)}, None, 'emin', bound, spacing=0)
+
+
+def test_ell_position_vector_still_projects_onto_route_direction() -> None:
+    result = ell({'A': Port((0, 0), pi)}, None, 'pmax', (5, 7), spacing=0)
+
+    assert_allclose(result['A'], 5)
+
+
+def test_ell_rejects_invalid_bound_type() -> None:
+    with pytest.raises(BuildError, match='Invalid bound type'):
+        ell({'A': Port((0, 0), 0)}, None, 'nearest', 5, spacing=0)

masque/test/test_circle.py

@@ -0,0 +1,17 @@
+from numpy.testing import assert_equal, assert_allclose
+
+from ..shapes import Circle, Polygon
+
+
+def test_circle_init() -> None:
+    c = Circle(radius=10, offset=(5, 5))
+    assert c.radius == 10
+    assert_equal(c.offset, [5, 5])
+
+def test_circle_to_polygons() -> None:
+    c = Circle(radius=10)
+    polys = c.to_polygons(num_vertices=32)
+    assert len(polys) == 1
+    assert isinstance(polys[0], Polygon)
+    bounds = polys[0].get_bounds_single()
+    assert_allclose(bounds, [[-10, -10], [10, 10]], atol=1e-10)

masque/test/test_curve_polygonization.py

@@ -0,0 +1,26 @@
+from numpy import pi
+
+from ..shapes import Arc, Circle, Ellipse
+from .helpers import assert_closed_edges_within
+
+
+def test_shape_arclen() -> None:
+    e = Ellipse(radii=(10, 5))
+    polys = e.to_polygons(max_arclen=5)
+    v = polys[0].vertices
+    assert_closed_edges_within(v, 5)
+    assert len(v) > 10
+
+    a = Arc(radii=(10, 10), angles=(0, pi / 2), width=2)
+    polys = a.to_polygons(max_arclen=2)
+    assert_closed_edges_within(polys[0].vertices, 2)
+
+def test_curve_polygonizers_clamp_large_max_arclen() -> None:
+    for shape in (
+            Circle(radius=10),
+            Ellipse(radii=(10, 20)),
+            Arc(radii=(10, 20), angles=(0, 1), width=2),
+            ):
+        polys = shape.to_polygons(num_vertices=None, max_arclen=1e9)
+        assert len(polys) == 1
+        assert len(polys[0].vertices) >= 3

masque/test/test_dxf.py

@@ -0,0 +1,168 @@
+import io
+import numpy
+import ezdxf
+from numpy.testing import assert_allclose
+from pathlib import Path
+
+from ..pattern import Pattern
+from ..library import Library
+from ..shapes import Path as MPath, Polygon
+from ..repetition import Grid
+from ..file import dxf
+
+
+def _matches_open_path(actual: numpy.ndarray, expected: numpy.ndarray) -> bool:
+    return bool(
+        numpy.allclose(actual, expected)
+        or numpy.allclose(actual, expected[::-1])
+    )
+
+
+def _matches_closed_vertices(actual: numpy.ndarray, expected: numpy.ndarray) -> bool:
+    return {tuple(row) for row in actual.tolist()} == {tuple(row) for row in expected.tolist()}
+
+
+def test_dxf_roundtrip(tmp_path: Path):
+    lib = Library()
+    pat = Pattern()
+
+    poly_verts = numpy.array([[0, 0], [10, 0], [10, 10], [0, 10]])
+    pat.polygon("1", vertices=poly_verts)
+
+    path_verts = numpy.array([[20, 0], [30, 0], [30, 10]])
+    pat.path("2", vertices=path_verts, width=2)
+
+    # Two-point paths remain paths rather than being polygonized.
+    path2_verts = numpy.array([[40, 0], [50, 10]])
+    pat.path("3", vertices=path2_verts, width=0)
+
+    subpat = Pattern()
+    subpat.polygon("sub", vertices=[[0, 0], [1, 0], [1, 1]])
+    lib["sub"] = subpat
+
+    pat.ref("sub", offset=(100, 100), repetition=Grid(a_vector=(10, 0), a_count=2, b_vector=(0, 10), b_count=3))
+
+    lib["top"] = pat
+
+    dxf_file = tmp_path / "test.dxf"
+    dxf.writefile(lib, "top", dxf_file)
+
+    read_lib, _ = dxf.readfile(dxf_file)
+
+    top_pat = read_lib.get("Model") or read_lib.get("top") or list(read_lib.values())[0]
+
+    polys = [s for s in top_pat.shapes["1"] if isinstance(s, Polygon)]
+    assert len(polys) >= 1
+    poly_read = polys[0]
+    assert _matches_closed_vertices(poly_read.vertices, poly_verts)
+
+    paths = [s for s in top_pat.shapes["2"] if isinstance(s, MPath)]
+    assert len(paths) >= 1
+    path_read = paths[0]
+    assert _matches_open_path(path_read.vertices, path_verts)
+    assert path_read.width == 2
+
+    paths2 = [s for s in top_pat.shapes["3"] if isinstance(s, MPath)]
+    assert len(paths2) >= 1
+    path2_read = paths2[0]
+    assert _matches_open_path(path2_read.vertices, path2_verts)
+    assert path2_read.width == 0
+
+    assert "sub" in read_lib
+
+    found_grid = False
+    for target, reflist in top_pat.refs.items():
+        if target.upper() == "SUB":
+            for ref in reflist:
+                if isinstance(ref.repetition, Grid):
+                    assert ref.repetition.a_count == 2
+                    assert ref.repetition.b_count == 3
+                    assert_allclose(ref.repetition.a_vector, (10, 0))
+                    assert_allclose(ref.repetition.b_vector, (0, 10))
+                    found_grid = True
+    assert found_grid, f"Manhattan Grid repetition should have been preserved. Targets: {list(top_pat.refs.keys())}"
+
+def test_dxf_manhattan_precision(tmp_path: Path):
+    lib = Library()
+    sub = Pattern()
+    sub.polygon("1", vertices=[[0, 0], [1, 0], [1, 1]])
+    lib["sub"] = sub
+
+    top = Pattern()
+    angle = numpy.pi / 2 # 90 degrees
+    top.ref("sub", offset=(0, 0), rotation=angle,
+            repetition=Grid(a_vector=(10, 0), a_count=2, b_vector=(0, 10), b_count=2))
+
+    lib["top"] = top
+
+    dxf_file = tmp_path / "precision.dxf"
+    dxf.writefile(lib, "top", dxf_file)
+
+    # Near-integer rotated basis vectors round-trip as a Manhattan Grid.
+    read_lib, _ = dxf.readfile(dxf_file)
+    read_top = read_lib.get("Model") or read_lib.get("top") or list(read_lib.values())[0]
+
+    target_name = next(k for k in read_top.refs if k.upper() == "SUB")
+    ref = read_top.refs[target_name][0]
+    assert isinstance(ref.repetition, Grid), "Grid should be preserved for 90-degree rotation"
+
+
+def test_dxf_rotated_grid_roundtrip_preserves_basis_and_counts(tmp_path: Path):
+    lib = Library()
+    sub = Pattern()
+    sub.polygon("1", vertices=[[0, 0], [1, 0], [1, 1]])
+    lib["sub"] = sub
+
+    top = Pattern()
+    top.ref(
+        "sub",
+        offset=(0, 0),
+        rotation=numpy.pi / 2,
+        repetition=Grid(a_vector=(10, 0), a_count=3, b_vector=(0, 20), b_count=2),
+        )
+    lib["top"] = top
+
+    dxf_file = tmp_path / "rotated_grid.dxf"
+    dxf.writefile(lib, "top", dxf_file)
+
+    read_lib, _ = dxf.readfile(dxf_file)
+    read_top = read_lib.get("Model") or read_lib.get("top") or list(read_lib.values())[0]
+
+    target_name = next(k for k in read_top.refs if k.upper() == "SUB")
+    ref = read_top.refs[target_name][0]
+    assert isinstance(ref.repetition, Grid)
+    actual = ref.repetition.displacements
+    expected = Grid(a_vector=(10, 0), a_count=3, b_vector=(0, 20), b_count=2).displacements
+    assert_allclose(
+        actual[numpy.lexsort((actual[:, 1], actual[:, 0]))],
+        expected[numpy.lexsort((expected[:, 1], expected[:, 0]))],
+        )
+
+
+def test_dxf_read_legacy_polyline() -> None:
+    doc = ezdxf.new()
+    msp = doc.modelspace()
+    msp.add_polyline2d([(0, 0), (10, 0), (10, 10)], dxfattribs={"layer": "legacy"}).close(True)
+
+    stream = io.StringIO()
+    doc.write(stream)
+    stream.seek(0)
+
+    read_lib, _ = dxf.read(stream)
+    top_pat = read_lib.get("Model") or list(read_lib.values())[0]
+
+    polys = [shape for shape in top_pat.shapes["legacy"] if isinstance(shape, Polygon)]
+    assert len(polys) == 1
+    assert _matches_closed_vertices(polys[0].vertices, numpy.array([[0, 0], [10, 0], [10, 10]]))
+
+
+def test_dxf_read_ignores_unreferenced_setup_blocks() -> None:
+    lib = Library({"top": Pattern()})
+    stream = io.StringIO()
+
+    dxf.write(lib, "top", stream)
+    stream.seek(0)
+
+    read_lib, _ = dxf.read(stream)
+
+    assert set(read_lib) == {"Model"}

masque/test/test_ellipse.py

@@ -0,0 +1,29 @@
+from numpy import pi
+from numpy.testing import assert_equal, assert_allclose
+
+from ..shapes import Ellipse
+
+
+def test_ellipse_init() -> None:
+    e = Ellipse(radii=(10, 5), offset=(1, 2), rotation=pi / 4)
+    assert_equal(e.radii, [10, 5])
+    assert_equal(e.offset, [1, 2])
+    assert e.rotation == pi / 4
+
+def test_ellipse_to_polygons() -> None:
+    e = Ellipse(radii=(10, 5))
+    polys = e.to_polygons(num_vertices=64)
+    assert len(polys) == 1
+    bounds = polys[0].get_bounds_single()
+    assert_allclose(bounds, [[-10, -5], [10, 5]], atol=1e-10)
+
+def test_rotated_ellipse_bounds_match_polygonized_geometry() -> None:
+    ellipse = Ellipse(radii=(10, 20), rotation=pi / 4, offset=(100, 200))
+    bounds = ellipse.get_bounds_single()
+    poly_bounds = ellipse.to_polygons(num_vertices=8192)[0].get_bounds_single()
+    assert_allclose(bounds, poly_bounds, atol=1e-3)
+
+def test_ellipse_integer_radii_scale_cleanly() -> None:
+    ellipse = Ellipse(radii=(10, 20))
+    ellipse.scale_by(0.5)
+    assert_allclose(ellipse.radii, [5, 10])

masque/test/test_fdfd.py

@@ -0,0 +1,24 @@
+# ruff: noqa
+# ruff: noqa: ARG001
+
+
+import dataclasses
+import pytest  # type: ignore
+import numpy
+from numpy import pi
+from numpy.typing import NDArray
+# from numpy.testing import assert_allclose, assert_array_equal
+
+from .. import Pattern, Arc, Circle
+
+
+def test_circle_mirror():
+    cc = Circle(radius=4, offset=(10, 20))
+    cc.flip_across(axis=0)  # flip across y=0
+    assert cc.offset[0] == 10
+    assert cc.offset[1] == -20
+    assert cc.radius == 4
+    cc.flip_across(axis=1)  # flip across x=0
+    assert cc.offset[0] == -10
+    assert cc.offset[1] == -20
+    assert cc.radius == 4

masque/test/test_file_format_roundtrip.py

@@ -0,0 +1,138 @@
+from pathlib import Path
+from typing import cast
+import pytest
+from numpy.testing import assert_allclose
+
+from ..pattern import Pattern
+from ..library import Library
+from ..shapes import Path as MPath, Circle, Polygon, RectCollection
+from ..repetition import Grid, Arbitrary
+
+def create_test_library(for_gds: bool = False) -> Library:
+    lib = Library()
+
+    pat_poly = Pattern()
+    pat_poly.polygon((1, 0), vertices=[[0, 0], [10, 0], [5, 10]])
+    lib["polygons"] = pat_poly
+
+    pat_paths = Pattern()
+    pat_paths.path((2, 0), vertices=[[0, 0], [20, 0]], width=2, cap=MPath.Cap.Flush)
+    pat_paths.path((2, 1), vertices=[[0, 10], [20, 10]], width=2, cap=MPath.Cap.Square)
+    if for_gds:
+        pat_paths.path((2, 2), vertices=[[0, 20], [20, 20]], width=2, cap=MPath.Cap.Circle)
+    pat_paths.path((2, 3), vertices=[[0, 30], [20, 30]], width=2, cap=MPath.Cap.SquareCustom, cap_extensions=(1, 5))
+    lib["paths"] = pat_paths
+
+    pat_circles = Pattern()
+    if for_gds:
+        pat_circles.shapes[(3, 0)].append(Circle(radius=5, offset=(10, 10)).to_polygons()[0])
+    else:
+        pat_circles.shapes[(3, 0)].append(Circle(radius=5, offset=(10, 10)))
+    lib["circles"] = pat_circles
+
+    pat_refs = Pattern()
+    pat_refs.ref("polygons", offset=(0, 0))
+    pat_refs.ref("polygons", offset=(100, 0), repetition=Grid(a_vector=(20, 0), a_count=3, b_vector=(0, 20), b_count=2))
+    pat_refs.ref("polygons", offset=(0, 100), repetition=Arbitrary(displacements=[[0, 0], [10, 20], [30, -10]]))
+    lib["refs"] = pat_refs
+
+    pat_rep_shapes = Pattern()
+    poly_rep = Polygon(vertices=[[0, 0], [5, 0], [5, 5], [0, 5]], repetition=Grid(a_vector=(10, 0), a_count=5))
+    pat_rep_shapes.shapes[(4, 0)].append(poly_rep)
+    lib["rep_shapes"] = pat_rep_shapes
+
+    if for_gds:
+        lib.wrap_repeated_shapes()
+
+    return lib
+
+def test_gdsii_full_roundtrip(tmp_path: Path) -> None:
+    from ..file import gdsii
+    lib = create_test_library(for_gds=True)
+    gds_file = tmp_path / "full_test.gds"
+    gdsii.writefile(lib, gds_file, meters_per_unit=1e-9)
+
+    read_lib, _ = gdsii.readfile(gds_file)
+
+    for name in lib:
+        assert name in read_lib
+
+    read_paths = read_lib["paths"]
+    p_flush = cast("MPath", read_paths.shapes[(2, 0)][0])
+    assert p_flush.cap == MPath.Cap.Flush
+
+    p_square = cast("MPath", read_paths.shapes[(2, 1)][0])
+    assert p_square.cap == MPath.Cap.Square
+
+    p_circle = cast("MPath", read_paths.shapes[(2, 2)][0])
+    assert p_circle.cap == MPath.Cap.Circle
+
+    p_custom = cast("MPath", read_paths.shapes[(2, 3)][0])
+    assert p_custom.cap == MPath.Cap.SquareCustom
+    assert p_custom.cap_extensions is not None
+    assert_allclose(p_custom.cap_extensions, (1, 5))
+
+    read_refs = read_lib["refs"]
+    assert len(read_refs.refs["polygons"]) >= 3 # Simple, Grid (becomes 1 AREF), Arbitrary (becomes 3 SREFs)
+
+    arefs = [r for r in read_refs.refs["polygons"] if r.repetition is not None]
+    assert len(arefs) == 1
+    assert isinstance(arefs[0].repetition, Grid)
+    assert arefs[0].repetition.a_count == 3
+    assert arefs[0].repetition.b_count == 2
+
+    # GDS stores repeated shapes through refs created by wrap_repeated_shapes().
+    assert len(read_lib["rep_shapes"].refs) > 0
+
+def test_oasis_full_roundtrip(tmp_path: Path) -> None:
+    pytest.importorskip("fatamorgana")
+    from ..file import oasis
+    lib = create_test_library(for_gds=False)
+    oas_file = tmp_path / "full_test.oas"
+    oasis.writefile(lib, oas_file, units_per_micron=1000)
+
+    read_lib, _ = oasis.readfile(oas_file)
+
+    for name in lib:
+        assert name in read_lib
+
+    read_circles = read_lib["circles"]
+    assert isinstance(read_circles.shapes[(3, 0)][0], Circle)
+    assert read_circles.shapes[(3, 0)][0].radius == 5
+
+    read_paths = read_lib["paths"]
+    assert cast("MPath", read_paths.shapes[(2, 0)][0]).cap == MPath.Cap.Flush
+    assert cast("MPath", read_paths.shapes[(2, 1)][0]).cap == MPath.Cap.Square
+
+    read_rep_shapes = read_lib["rep_shapes"]
+    poly = read_rep_shapes.shapes[(4, 0)][0]
+    assert poly.repetition is not None
+    assert isinstance(poly.repetition, Grid)
+    assert poly.repetition.a_count == 5
+
+
+def test_gdsii_rect_collection_roundtrip(tmp_path: Path) -> None:
+    from ..file import gdsii
+
+    lib = Library()
+    pat = Pattern()
+    pat.shapes[(5, 0)].append(
+        RectCollection(
+            rects=[[0, 0, 10, 5], [20, -5, 30, 10]],
+            annotations={'1': ['rects']},
+            )
+        )
+    lib['rects'] = pat
+
+    gds_file = tmp_path / 'rect_collection.gds'
+    gdsii.writefile(lib, gds_file, meters_per_unit=1e-9)
+
+    read_lib, _ = gdsii.readfile(gds_file)
+    polys = read_lib['rects'].shapes[(5, 0)]
+
+    assert len(polys) == 2
+    assert all(isinstance(poly, Polygon) for poly in polys)
+    assert_allclose(polys[0].vertices, [[0, 0], [0, 5], [10, 5], [10, 0]])
+    assert_allclose(polys[1].vertices, [[20, -5], [20, 10], [30, 10], [30, -5]])
+    assert polys[0].annotations == {'1': ['rects']}
+    assert polys[1].annotations == {'1': ['rects']}

masque/test/test_gdsii.py

@@ -0,0 +1,85 @@
+from pathlib import Path
+from typing import cast
+import numpy
+import pytest
+from numpy.testing import assert_equal, assert_allclose
+
+from ..error import LibraryError
+from ..pattern import Pattern
+from ..library import Library
+from ..file import gdsii
+from ..shapes import Path as MPath, Polygon
+
+
+def test_gdsii_roundtrip(tmp_path: Path) -> None:
+    lib = Library()
+
+    # Simple polygon cell
+    pat1 = Pattern()
+    pat1.polygon((1, 0), vertices=[[0, 0], [10, 0], [10, 10], [0, 10]])
+    lib["poly_cell"] = pat1
+
+    # Path cell
+    pat2 = Pattern()
+    pat2.path((2, 5), vertices=[[0, 0], [100, 0]], width=10)
+    lib["path_cell"] = pat2
+
+    # Cell with Ref
+    pat3 = Pattern()
+    pat3.ref("poly_cell", offset=(50, 50), rotation=numpy.pi / 2)
+    lib["ref_cell"] = pat3
+
+    gds_file = tmp_path / "test.gds"
+    gdsii.writefile(lib, gds_file, meters_per_unit=1e-9)
+
+    read_lib, info = gdsii.readfile(gds_file)
+
+    assert "poly_cell" in read_lib
+    assert "path_cell" in read_lib
+    assert "ref_cell" in read_lib
+
+    # Check polygon
+    read_poly = cast("Polygon", read_lib["poly_cell"].shapes[(1, 0)][0])
+    # GDSII closes polygons, so it might have an extra vertex or different order
+    assert len(read_poly.vertices) >= 4
+    # Check bounds as a proxy for geometry correctness
+    assert_equal(read_lib["poly_cell"].get_bounds(), [[0, 0], [10, 10]])
+
+    # Check path
+    read_path = cast("MPath", read_lib["path_cell"].shapes[(2, 5)][0])
+    assert isinstance(read_path, MPath)
+    assert read_path.width == 10
+    assert_equal(read_path.vertices, [[0, 0], [100, 0]])
+
+    # Check Ref
+    read_ref = read_lib["ref_cell"].refs["poly_cell"][0]
+    assert_equal(read_ref.offset, [50, 50])
+    assert_allclose(read_ref.rotation, numpy.pi / 2, atol=1e-5)
+
+
+def test_gdsii_annotations(tmp_path: Path) -> None:
+    lib = Library()
+    pat = Pattern()
+    # GDS only supports integer keys in range [1, 126] for properties
+    pat.polygon((1, 0), vertices=[[0, 0], [1, 0], [1, 1]], annotations={"1": ["hello"]})
+    lib["cell"] = pat
+
+    gds_file = tmp_path / "test_ann.gds"
+    gdsii.writefile(lib, gds_file, meters_per_unit=1e-9)
+
+    read_lib, _ = gdsii.readfile(gds_file)
+    read_ann = read_lib["cell"].shapes[(1, 0)][0].annotations
+    assert read_ann is not None
+    assert read_ann["1"] == ["hello"]
+
+
+def test_gdsii_check_valid_names_validates_generator_lengths() -> None:
+    names = (name for name in ("a" * 40,))
+
+    with pytest.raises(LibraryError, match="invalid names"):
+        gdsii.check_valid_names(names)
+
+
+def test_gdsii_does_not_export_codec_helpers() -> None:
+    assert not hasattr(gdsii, 'read_elements')
+    assert not hasattr(gdsii, 'rint_cast')

masque/test/test_gdsii_arrow.py

@@ -0,0 +1,604 @@
+from pathlib import Path
+import subprocess
+import sys
+import textwrap
+
+import klamath
+import numpy
+import pytest
+
+pytest.importorskip('pyarrow')
+
+from .. import Ref, Label, PatternError
+from ..library import Library
+from ..pattern import Pattern
+from ..repetition import Grid
+from ..shapes import Path as MPath, Polygon, PolyCollection, RectCollection
+from ..file import gdsii
+from ..file.gdsii import arrow as gdsii_arrow
+from tools.generate_gds_perf import write_fixture
+
+
+if not gdsii_arrow.is_available():
+    pytest.skip('klamath_rs_ext shared library is not available', allow_module_level=True)
+
+
+def _annotations_key(annotations: dict[str, list[object]] | None) -> tuple[tuple[str, tuple[object, ...]], ...] | None:
+    if not annotations:
+        return None
+    return tuple(sorted((key, tuple(values)) for key, values in annotations.items()))
+
+
+def _coord_key(values: object) -> tuple[int, ...] | tuple[tuple[int, int], ...]:
+    arr = numpy.rint(numpy.asarray(values, dtype=float)).astype(int)
+    if arr.ndim == 1:
+        return tuple(arr.tolist())
+    return tuple(tuple(row.tolist()) for row in arr)
+
+
+def _canonical_polygon_key(vertices: object) -> tuple[tuple[int, int], ...]:
+    arr = numpy.rint(numpy.asarray(vertices, dtype=float)).astype(int)
+    rows = [tuple(tuple(row.tolist()) for row in numpy.roll(arr, -shift, axis=0)) for shift in range(arr.shape[0])]
+    rev = arr[::-1]
+    rows.extend(tuple(tuple(row.tolist()) for row in numpy.roll(rev, -shift, axis=0)) for shift in range(rev.shape[0]))
+    return min(rows)
+
+
+def _shape_key(shape: object, layer: tuple[int, int]) -> list[tuple[object, ...]]:
+    if isinstance(shape, MPath):
+        cap_extensions = None if shape.cap_extensions is None else _coord_key(shape.cap_extensions)
+        return [(
+            'path',
+            layer,
+            _coord_key(shape.vertices),
+            _coord_key(shape.offset),
+            int(round(float(shape.width))),
+            shape.cap.name,
+            cap_extensions,
+            _annotations_key(shape.annotations),
+            )]
+
+    keys = []
+    for poly in shape.to_polygons():
+        keys.append((
+            'polygon',
+            layer,
+            _canonical_polygon_key(poly.vertices),
+            _coord_key(poly.offset),
+            _annotations_key(poly.annotations),
+            ))
+    return keys
+
+
+def _ref_keys(target: str, ref: object) -> list[tuple[object, ...]]:
+    keys = []
+    for transform in ref.as_transforms():
+        keys.append((
+            target,
+            _coord_key(transform[:2]),
+            round(float(transform[2]), 8),
+            round(float(transform[4]), 8),
+            bool(int(round(float(transform[3])))),
+            _annotations_key(ref.annotations),
+            ))
+    return keys
+
+
+def _label_key(layer: tuple[int, int], label: object) -> tuple[object, ...]:
+    return (
+        layer,
+        label.string,
+        _coord_key(label.offset),
+        _annotations_key(label.annotations),
+        )
+
+
+def _pattern_summary(pattern: Pattern) -> dict[str, object]:
+    shape_keys: list[tuple[object, ...]] = []
+    for layer, shapes in pattern.shapes.items():
+        for shape in shapes:
+            shape_keys.extend(_shape_key(shape, layer))
+
+    ref_keys: list[tuple[object, ...]] = []
+    for target, refs in pattern.refs.items():
+        for ref in refs:
+            ref_keys.extend(_ref_keys(target, ref))
+
+    label_keys = [
+        _label_key(layer, label)
+        for layer, labels in pattern.labels.items()
+        for label in labels
+        ]
+
+    return {
+        'shapes': sorted(shape_keys),
+        'refs': sorted(ref_keys),
+        'labels': sorted(label_keys),
+        }
+
+
+def _library_summary(lib: Library) -> dict[str, dict[str, object]]:
+    return {name: _pattern_summary(pattern) for name, pattern in lib.items()}
+
+
+def _make_arrow_test_library() -> Library:
+    lib = Library()
+
+    leaf = Pattern()
+    leaf.polygon((1, 0), vertices=[[0, 0], [10, 0], [10, 10], [0, 10]], annotations={'1': ['leaf-poly']})
+    leaf.polygon((2, 0), vertices=[[40, 0], [50, 0], [50, 10], [40, 10]])
+    leaf.polygon((1, 0), vertices=[[20, 0], [30, 0], [30, 10], [20, 10]])
+    leaf.polygon((1, 0), vertices=[[80, 0], [90, 0], [90, 10], [80, 10]])
+    leaf.polygon((2, 0), vertices=[[60, 0], [70, 0], [70, 10], [60, 10]], annotations={'18': ['leaf-poly-2']})
+    leaf.label((10, 0), string='LEAF', offset=(3, 4), annotations={'10': ['leaf-label']})
+    lib['leaf'] = leaf
+
+    child = Pattern()
+    child.path(
+        (2, 0),
+        vertices=[[0, 0], [15, 5], [30, 5]],
+        width=6,
+        cap=MPath.Cap.SquareCustom,
+        cap_extensions=(2, 4),
+        annotations={'2': ['child-path']},
+        )
+    child.label((11, 0), string='CHILD', offset=(7, 8), annotations={'11': ['child-label']})
+    child.ref('leaf', offset=(100, 200), rotation=numpy.pi / 2, mirrored=True, scale=1.25, annotations={'12': ['child-ref']})
+    lib['child'] = child
+
+    sibling = Pattern()
+    sibling.polygon((3, 0), vertices=[[0, 0], [5, 0], [5, 6], [0, 6]])
+    sibling.label((12, 0), string='SIB', offset=(1, 2), annotations={'13': ['sib-label']})
+    sibling.ref(
+        'leaf',
+        offset=(-50, 60),
+        repetition=Grid(a_vector=(20, 0), a_count=3, b_vector=(0, 30), b_count=2),
+        annotations={'14': ['sib-ref']},
+        )
+    lib['sibling'] = sibling
+
+    fanout = Pattern()
+    fanout.ref('leaf', offset=(0, 0))
+    fanout.ref('child', offset=(10, 0), mirrored=True, rotation=numpy.pi / 6, scale=1.1)
+    fanout.ref('leaf', offset=(20, 0))
+    fanout.ref('leaf', offset=(30, 0), repetition=Grid(a_vector=(5, 0), a_count=2, b_vector=(0, 7), b_count=3))
+    fanout.ref('child', offset=(40, 0), mirrored=True, rotation=numpy.pi / 4, scale=1.2,
+               repetition=Grid(a_vector=(9, 0), a_count=2, b_vector=(0, 11), b_count=2))
+    fanout.ref('leaf', offset=(50, 0), repetition=Grid(a_vector=(6, 0), a_count=3, b_vector=(0, 8), b_count=2))
+    fanout.ref('leaf', offset=(60, 0), annotations={'19': ['fanout-sref']})
+    fanout.ref('child', offset=(70, 0), repetition=Grid(a_vector=(4, 0), a_count=2, b_vector=(0, 5), b_count=2),
+               annotations={'20': ['fanout-aref']})
+    lib['fanout'] = fanout
+
+    top = Pattern()
+    top.ref('child', offset=(500, 600), annotations={'15': ['top-child-ref']})
+    top.ref('sibling', offset=(-100, 50), rotation=numpy.pi, annotations={'16': ['top-sibling-ref']})
+    top.ref('fanout', offset=(250, -75))
+    top.label((13, 0), string='TOP', offset=(0, 0), annotations={'17': ['top-label']})
+    lib['top'] = top
+
+    return lib
+
+
+def _write_invalid_path_type_fixture(path: Path) -> None:
+    with path.open('wb') as stream:
+        header = klamath.library.FileHeader(
+            name=b'test',
+            user_units_per_db_unit=1.0,
+            meters_per_db_unit=1e-9,
+        )
+        header.write(stream)
+        elem = klamath.elements.Path(
+            layer=(1, 0),
+            path_type=3,
+            width=10,
+            extension=(0, 0),
+            xy=numpy.array([[0, 0], [10, 0]], dtype=numpy.int32),
+            properties={},
+        )
+        klamath.library.write_struct(stream, name=b'top', elements=[elem])
+        klamath.records.ENDLIB.write(stream, None)
+
+
+def test_gdsii_arrow_matches_gdsii_readfile(tmp_path: Path) -> None:
+    lib = _make_arrow_test_library()
+    gds_file = tmp_path / 'arrow_roundtrip.gds'
+    gdsii.writefile(lib, gds_file, meters_per_unit=1e-9)
+
+    canonical_lib, canonical_info = gdsii.readfile(gds_file)
+    arrow_lib, arrow_info = gdsii_arrow.readfile(gds_file)
+
+    assert canonical_info == arrow_info
+    assert _library_summary(canonical_lib) == _library_summary(arrow_lib)
+
+
+def test_gdsii_arrow_matches_gdsii_readfile_for_gzipped_file(tmp_path: Path) -> None:
+    lib = _make_arrow_test_library()
+    gds_file = tmp_path / 'arrow_roundtrip.gds.gz'
+    gdsii.writefile(lib, gds_file, meters_per_unit=1e-9)
+
+    canonical_lib, canonical_info = gdsii.readfile(gds_file)
+    arrow_lib, arrow_info = gdsii_arrow.readfile(gds_file)
+
+    assert canonical_info == arrow_info
+    assert _library_summary(canonical_lib) == _library_summary(arrow_lib)
+
+
+def test_gdsii_arrow_readfile_arrow_returns_native_payload(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'many_cells_native.gds'
+    manifest = write_fixture(gds_file, preset='many_cells', scale=0.001)
+
+    libarr, info = gdsii_arrow.readfile_arrow(gds_file)
+
+    assert info['name'] == manifest.library_name
+    assert libarr['lib_name'].as_py() == manifest.library_name
+    assert len(libarr['cells']) == manifest.cells
+    assert 0 < len(libarr['layers']) <= manifest.layers
+
+
+def test_gdsii_arrow_readfile_arrow_reads_gzipped_file(tmp_path: Path) -> None:
+    lib = _make_arrow_test_library()
+    gds_file = tmp_path / 'native_payload.gds.gz'
+    gdsii.writefile(lib, gds_file, meters_per_unit=1e-9)
+
+    libarr, info = gdsii_arrow.readfile_arrow(gds_file)
+
+    assert info['name'] == 'masque-klamath'
+    assert libarr['lib_name'].as_py() == 'masque-klamath'
+    assert len(libarr['cells']) == len(lib)
+    assert len(libarr['layers']) > 0
+
+
+def test_gdsii_arrow_removed_raw_mode_arg(tmp_path: Path) -> None:
+    lib = _make_arrow_test_library()
+    gds_file = tmp_path / 'removed_raw_mode.gds'
+    gdsii.writefile(lib, gds_file, meters_per_unit=1e-9)
+
+    libarr, _ = gdsii_arrow.readfile_arrow(gds_file)
+
+    with pytest.raises(TypeError):
+        gdsii_arrow.readfile(gds_file, raw_mode=False)
+
+    with pytest.raises(TypeError):
+        gdsii_arrow.read_arrow(libarr, raw_mode=False)
+
+
+def test_gdsii_arrow_invalid_input_raises_klamath_error(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'invalid.gds'
+    gds_file.write_bytes(b'not-a-gds')
+
+    script = textwrap.dedent(f"""
+        from masque.file.gdsii import arrow as gdsii_arrow
+        try:
+            gdsii_arrow.readfile({str(gds_file)!r})
+        except Exception as exc:
+            print(type(exc).__module__)
+            print(type(exc).__qualname__)
+            print(exc)
+        else:
+            raise SystemExit('expected gdsii_arrow.readfile() to fail')
+        """)
+    result = subprocess.run([sys.executable, '-c', script], capture_output=True, text=True, check=False)
+
+    assert result.returncode == 0, result.stderr
+    assert 'klamath.basic' in result.stdout
+    assert 'KlamathError' in result.stdout
+
+
+def test_gdsii_arrow_reads_small_perf_fixture(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'many_cells_smoke.gds'
+    manifest = write_fixture(gds_file, preset='many_cells', scale=0.001)
+
+    lib, info = gdsii_arrow.readfile(gds_file)
+
+    assert info['name'] == manifest.library_name
+    assert len(lib) == manifest.cells
+    assert 'TOP' in lib
+    assert sum(len(refs) for refs in lib['TOP'].refs.values()) > 0
+
+
+def test_gdsii_arrow_degenerate_aref_decodes_as_single_transform(tmp_path: Path) -> None:
+    lib = Library()
+    leaf = Pattern()
+    leaf.polygon((1, 0), vertices=[[0, 0], [5, 0], [5, 5], [0, 5]])
+    lib['leaf'] = leaf
+
+    top = Pattern()
+    top.ref('leaf', offset=(100, 200), repetition=Grid(a_vector=(7, 0), a_count=1, b_vector=(0, 9), b_count=1))
+    lib['top'] = top
+
+    gds_file = tmp_path / 'degenerate_aref.gds'
+    gdsii.writefile(lib, gds_file, meters_per_unit=1e-9)
+
+    canonical_lib, _ = gdsii.readfile(gds_file)
+    arrow_lib, _ = gdsii_arrow.readfile(gds_file)
+    assert _library_summary(arrow_lib) == _library_summary(canonical_lib)
+
+    decoded_ref = arrow_lib['top'].refs['leaf'][0]
+    assert decoded_ref.repetition is None
+
+
+def test_gdsii_arrow_plain_srefs_decode_without_arbitrary(tmp_path: Path) -> None:
+    lib = _make_arrow_test_library()
+    gds_file = tmp_path / 'plain_srefs.gds'
+    gdsii.writefile(lib, gds_file, meters_per_unit=1e-9)
+
+    arrow_lib, _ = gdsii_arrow.readfile(gds_file)
+    fanout = arrow_lib['fanout']
+
+    plain_leaf_refs = [
+        ref
+        for ref in fanout.refs['leaf']
+        if ref.annotations is None and ref.repetition is None
+        ]
+    assert len(plain_leaf_refs) == 2
+    assert all(type(ref.repetition) is not Grid for ref in plain_leaf_refs)
+
+
+def test_gdsii_arrow_degenerate_aref_schema_normalizes_to_sref(tmp_path: Path) -> None:
+    lib = Library()
+    leaf = Pattern()
+    leaf.polygon((1, 0), vertices=[[0, 0], [5, 0], [5, 5], [0, 5]])
+    lib['leaf'] = leaf
+
+    top = Pattern()
+    top.ref('leaf', offset=(100, 200), repetition=Grid(a_vector=(7, 0), a_count=1, b_vector=(0, 9), b_count=1))
+    lib['top'] = top
+
+    gds_file = tmp_path / 'degenerate_aref_schema.gds'
+    gdsii.writefile(lib, gds_file, meters_per_unit=1e-9)
+
+    libarr = gdsii_arrow._read_to_arrow(gds_file)[0]
+    cells = libarr['cells'].values
+    cell_ids = cells.field('id').to_numpy()
+    cell_names = libarr['cell_names'].as_py()
+    top_index = next(ii for ii, cell_id in enumerate(cell_ids) if cell_names[cell_id] == 'top')
+
+    srefs = cells.field('srefs')[top_index].as_py()
+    arefs = cells.field('arefs')[top_index].as_py()
+
+    assert len(srefs) == 1
+    assert len(arefs) == 0
+    assert cell_names[srefs[0]['target']] == 'leaf'
+
+
+def test_gdsii_arrow_boundary_batch_schema(tmp_path: Path) -> None:
+    lib = _make_arrow_test_library()
+    gds_file = tmp_path / 'arrow_batches.gds'
+    gdsii.writefile(lib, gds_file, meters_per_unit=1e-9)
+
+    libarr = gdsii_arrow._read_to_arrow(gds_file)[0]
+    cells = libarr['cells'].values
+    cell_ids = cells.field('id').to_numpy()
+    cell_names = libarr['cell_names'].as_py()
+    layer_table = [
+        ((int(layer) >> 16) & 0xFFFF, int(layer) & 0xFFFF)
+        for layer in libarr['layers'].values.to_numpy()
+        ]
+
+    leaf_index = next(ii for ii, cell_id in enumerate(cell_ids) if cell_names[cell_id] == 'leaf')
+
+    rect_batches = cells.field('rect_batches')[leaf_index].as_py()
+    boundary_batches = cells.field('boundary_batches')[leaf_index].as_py()
+    boundary_props = cells.field('boundary_props')[leaf_index].as_py()
+
+    assert len(rect_batches) == 2
+    assert len(boundary_batches) == 0
+    assert len(boundary_props) == 2
+
+    rects_by_layer = {tuple(layer_table[entry['layer']]): entry for entry in rect_batches}
+    assert rects_by_layer[(1, 0)]['rects'] == [20, 0, 30, 10, 80, 0, 90, 10]
+    assert rects_by_layer[(2, 0)]['rects'] == [40, 0, 50, 10]
+
+    props_by_layer = {tuple(layer_table[entry['layer']]): entry for entry in boundary_props}
+    assert sorted(props_by_layer) == [(1, 0), (2, 0)]
+    assert props_by_layer[(1, 0)]['properties'][0]['value'] == 'leaf-poly'
+    assert props_by_layer[(2, 0)]['properties'][0]['value'] == 'leaf-poly-2'
+
+
+def test_gdsii_arrow_rect_batch_schema_for_mixed_layer(tmp_path: Path) -> None:
+    lib = Library()
+    top = Pattern()
+    top.shapes[(1, 0)].append(RectCollection(rects=[[0, 0, 10, 10], [20, 0, 30, 10], [40, 0, 50, 10], [60, 0, 70, 10]]))
+    top.polygon((1, 0), vertices=[[80, 0], [85, 10], [90, 0]])
+    top.polygon((1, 0), vertices=[[100, 0], [105, 10], [110, 0]])
+    lib['top'] = top
+
+    gds_file = tmp_path / 'arrow_rect_batches.gds'
+    gdsii.writefile(lib, gds_file, meters_per_unit=1e-9)
+
+    libarr = gdsii_arrow._read_to_arrow(gds_file)[0]
+    cells = libarr['cells'].values
+    cell_ids = cells.field('id').to_numpy()
+    cell_names = libarr['cell_names'].as_py()
+    layer_table = [
+        ((int(layer) >> 16) & 0xFFFF, int(layer) & 0xFFFF)
+        for layer in libarr['layers'].values.to_numpy()
+        ]
+    top_index = next(ii for ii, cell_id in enumerate(cell_ids) if cell_names[cell_id] == 'top')
+
+    rect_batches = cells.field('rect_batches')[top_index].as_py()
+    boundary_batches = cells.field('boundary_batches')[top_index].as_py()
+
+    assert len(rect_batches) == 1
+    assert tuple(layer_table[rect_batches[0]['layer']]) == (1, 0)
+    assert rect_batches[0]['rects'] == [
+        0, 0, 10, 10,
+        20, 0, 30, 10,
+        40, 0, 50, 10,
+        60, 0, 70, 10,
+        ]
+
+    assert len(boundary_batches) == 1
+    assert tuple(layer_table[boundary_batches[0]['layer']]) == (1, 0)
+    assert boundary_batches[0]['vertex_offsets'] == [0, 3]
+
+
+def test_gdsii_arrow_ref_schema(tmp_path: Path) -> None:
+    lib = _make_arrow_test_library()
+    gds_file = tmp_path / 'arrow_ref_batches.gds'
+    gdsii.writefile(lib, gds_file, meters_per_unit=1e-9)
+
+    libarr = gdsii_arrow._read_to_arrow(gds_file)[0]
+    cells = libarr['cells'].values
+    cell_ids = cells.field('id').to_numpy()
+    cell_names = libarr['cell_names'].as_py()
+
+    fanout_index = next(ii for ii, cell_id in enumerate(cell_ids) if cell_names[cell_id] == 'fanout')
+
+    srefs = cells.field('srefs')[fanout_index].as_py()
+    arefs = cells.field('arefs')[fanout_index].as_py()
+    sref_props = cells.field('sref_props')[fanout_index].as_py()
+    aref_props = cells.field('aref_props')[fanout_index].as_py()
+
+    sref_target_ids = [entry['target'] for entry in srefs]
+    sref_targets = [cell_names[target] for target in sref_target_ids]
+    assert sorted(sref_targets) == ['child', 'leaf', 'leaf']
+    assert sref_target_ids == sorted(sref_target_ids)
+    sref_by_target = {}
+    for entry in srefs:
+        sref_by_target.setdefault(cell_names[entry['target']], []).append(entry)
+    assert [entry['invert_y'] for entry in sref_by_target['child']] == [True]
+    assert [entry['scale'] for entry in sref_by_target['child']] == pytest.approx([1.1])
+    assert len(sref_by_target['leaf']) == 2
+
+    aref_target_ids = [entry['target'] for entry in arefs]
+    aref_targets = [cell_names[target] for target in aref_target_ids]
+    assert sorted(aref_targets) == ['child', 'leaf', 'leaf']
+    assert aref_target_ids == sorted(aref_target_ids)
+    aref_by_target = {}
+    for entry in arefs:
+        aref_by_target.setdefault(cell_names[entry['target']], []).append(entry)
+    assert [entry['invert_y'] for entry in aref_by_target['child']] == [True]
+    assert [entry['scale'] for entry in aref_by_target['child']] == pytest.approx([1.2])
+    assert len(aref_by_target['leaf']) == 2
+
+    assert len(sref_props) == 1
+    assert cell_names[sref_props[0]['target']] == 'leaf'
+    assert sref_props[0]['properties'][0]['value'] == 'fanout-sref'
+
+    assert len(aref_props) == 1
+    assert cell_names[aref_props[0]['target']] == 'child'
+    assert aref_props[0]['properties'][0]['value'] == 'fanout-aref'
+
+
+def test_gdsii_arrow_invalid_path_type_matches_gdsii(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'invalid_path_type.gds'
+    _write_invalid_path_type_fixture(gds_file)
+
+    with pytest.raises(PatternError, match='Unrecognized path type: 3'):
+        gdsii.readfile(gds_file)
+
+    with pytest.raises(PatternError, match='Unrecognized path type: 3'):
+        gdsii_arrow.readfile(gds_file)
+
+
+def test_raw_ref_grid_label_constructors_match_public() -> None:
+    raw_grid = Grid._from_raw(
+        a_vector=numpy.array([20, 0]),
+        a_count=3,
+        b_vector=numpy.array([0, 30]),
+        b_count=2,
+        )
+    public_grid = Grid(a_vector=(20, 0), a_count=3, b_vector=(0, 30), b_count=2)
+    assert raw_grid == public_grid
+
+    raw_poly = Polygon._from_raw(
+        vertices=numpy.array([[0.0, 0.0], [5.0, 0.0], [5.0, 5.0], [0.0, 5.0]]),
+        annotations={'1': ['poly']},
+        )
+    public_poly = Polygon(
+        vertices=[[0, 0], [5, 0], [5, 5], [0, 5]],
+        annotations={'1': ['poly']},
+        )
+    assert raw_poly == public_poly
+
+    raw_poly_collection = PolyCollection._from_raw(
+        vertex_lists=numpy.array([
+            [0.0, 0.0], [2.0, 0.0], [2.0, 2.0],
+            [10.0, 10.0], [12.0, 10.0], [12.0, 12.0],
+            ]),
+        vertex_offsets=numpy.array([0, 3], dtype=numpy.uint32),
+        annotations={'2': ['pc']},
+        )
+    public_poly_collection = PolyCollection(
+        vertex_lists=[[0, 0], [2, 0], [2, 2], [10, 10], [12, 10], [12, 12]],
+        vertex_offsets=[0, 3],
+        annotations={'2': ['pc']},
+        )
+    assert raw_poly_collection == public_poly_collection
+    assert [tuple(s.indices(len(raw_poly_collection.vertex_lists))) for s in raw_poly_collection.vertex_slices] == [(0, 3, 1), (3, 6, 1)]
+
+    raw_rect_collection = RectCollection._from_raw(
+        rects=numpy.array([[10.0, 10.0, 12.0, 12.0], [0.0, 0.0, 5.0, 5.0]]),
+        annotations={'3': ['rects']},
+        )
+    public_rect_collection = RectCollection(
+        rects=[[0, 0, 5, 5], [10, 10, 12, 12]],
+        annotations={'3': ['rects']},
+        )
+    assert raw_rect_collection == public_rect_collection
+
+    raw_ref_empty = Ref._from_raw(
+        offset=numpy.array([100, 200]),
+        rotation=numpy.pi / 2,
+        mirrored=False,
+        scale=1.0,
+        repetition=None,
+        annotations=None,
+        )
+    public_ref_empty = Ref(
+        offset=(100, 200),
+        rotation=numpy.pi / 2,
+        mirrored=False,
+        scale=1.0,
+        repetition=None,
+        annotations=None,
+        )
+    assert raw_ref_empty.annotations is None
+    assert raw_ref_empty == public_ref_empty
+
+    raw_ref = Ref._from_raw(
+        offset=numpy.array([100, 200]),
+        rotation=numpy.pi / 2,
+        mirrored=True,
+        scale=1.25,
+        repetition=raw_grid,
+        annotations={'12': ['child-ref']},
+        )
+    public_ref = Ref(
+        offset=(100, 200),
+        rotation=numpy.pi / 2,
+        mirrored=True,
+        scale=1.25,
+        repetition=public_grid,
+        annotations={'12': ['child-ref']},
+        )
+    assert raw_ref == public_ref
+    assert numpy.array_equal(raw_ref.as_transforms(), public_ref.as_transforms())
+
+    raw_label_empty = Label._from_raw(
+        'LEAF',
+        offset=numpy.array([3, 4]),
+        annotations=None,
+        )
+    public_label_empty = Label(
+        'LEAF',
+        offset=(3, 4),
+        annotations=None,
+        )
+    assert raw_label_empty.annotations is None
+    assert raw_label_empty == public_label_empty
+
+    raw_label = Label._from_raw(
+        'LEAF',
+        offset=numpy.array([3, 4]),
+        annotations={'10': ['leaf-label']},
+        )
+    public_label = Label(
+        'LEAF',
+        offset=(3, 4),
+        annotations={'10': ['leaf-label']},
+        )
+    assert raw_label == public_label
+    assert numpy.array_equal(raw_label.get_bounds_single(), public_label.get_bounds_single())

masque/test/test_gdsii_lazy.py

@@ -0,0 +1,580 @@
+from pathlib import Path
+import gzip
+import io
+
+import numpy
+import pytest
+from numpy.testing import assert_allclose
+
+from ..file import gdsii
+from ..file.gdsii import lazy as gdsii_lazy
+from ..file.gdsii import writer as gdsii_writer
+from ..file.utils import preflight_source_aware
+from ..error import LibraryError
+from ..pattern import Pattern
+from ..ports import Port
+from ..library import (
+    IBorrowing, IMaterializable, LayerMappedView, LazyLibrary, Library, LibraryView,
+    OverlayLibrary, PortLoadView,
+    )
+
+
+def _make_lazy_port_library() -> Library:
+    lib = Library()
+
+    leaf = Pattern()
+    leaf.label(layer=(10, 0), string='A:type1 0', offset=(5, 0))
+    lib['leaf'] = leaf
+
+    child = Pattern()
+    child.ref('leaf', offset=(10, 20), rotation=numpy.pi / 2)
+    lib['child'] = child
+
+    top = Pattern()
+    top.ref('child', offset=(100, 200))
+    lib['top'] = top
+
+    return lib
+
+
+def test_gdsii_write_requires_units_without_gds_metadata() -> None:
+    lib = Library({'top': Pattern()})
+    lib.library_info = None     # type: ignore[attr-defined]
+
+    with pytest.raises(LibraryError, match='meters_per_unit is required'):
+        gdsii.write(lib, io.BytesIO())
+
+
+def test_gdsii_write_plain_library_defaults() -> None:
+    lib = _make_lazy_port_library()
+    stream = io.BytesIO()
+    gdsii.write(lib, stream, 1e-9)
+    stream.seek(0)
+    _roundtrip, info = gdsii.read(stream)
+    assert info == {
+        'name': 'masque-klamath',
+        'meters_per_unit': 1e-9,
+        'logical_units_per_unit': 1,
+        }
+
+
+def test_gdsii_lazy_write_materializes_transiently() -> None:
+    lib = LazyLibrary()
+    lib['top'] = Pattern()
+
+    stream = io.BytesIO()
+    gdsii.write(
+        lib,
+        stream,
+        meters_per_unit=1e-9,
+        logical_units_per_unit=1,
+        library_name='transient',
+    )
+
+    assert not lib.cache
+    stream.seek(0)
+    roundtrip, info = gdsii.read(stream)
+    assert set(roundtrip) == {'top'}
+    assert info['name'] == 'transient'
+
+
+def test_gdsii_raw_copy_provenance_cycle_falls_back() -> None:
+    class SelfBorrowingView(LibraryView, IBorrowing):
+        def borrowed_sources(self) -> tuple['SelfBorrowingView', ...]:
+            return (self,)
+
+        def source_cell(self, name: str) -> tuple['SelfBorrowingView', str] | None:
+            return self, name
+
+    view = SelfBorrowingView({'top': Pattern()})
+
+    assert gdsii_writer._resolve_raw_struct(view, 'top') is None
+
+
+def test_gdsii_lazy_source_exposes_order_and_graph_without_materializing(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'lazy_source.gds'
+    src = _make_lazy_port_library()
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='classic-lazy')
+
+    lib, info = gdsii_lazy.readfile(gds_file)
+
+    assert info['name'] == 'classic-lazy'
+    assert lib.source_order() == ('leaf', 'child', 'top')
+    assert lib.child_graph(dangling='ignore') == {
+        'leaf': set(),
+        'child': {'leaf'},
+        'top': {'child'},
+    }
+    assert lib.parent_graph() == {
+        'leaf': {'child'},
+        'child': {'top'},
+        'top': set(),
+    }
+    assert lib.tops() == ['top']
+    global_refs = lib.find_refs_global('leaf')
+    assert_allclose(global_refs[('top', 'child', 'leaf')], [[110, 220, numpy.pi / 2, 0, 1]])
+    assert not lib._cache
+
+    with pytest.raises(ValueError, match='dangling-reference mode'):
+        lib.child_graph(dangling='typo')
+    with pytest.raises(ValueError, match='dangling-reference mode'):
+        lib.find_refs_local('leaf', dangling='typo')
+
+    child = lib['child']
+    assert list(child.refs.keys()) == ['leaf']
+    assert set(lib._cache) == {'child'}
+
+
+def test_gdsii_lazy_graph_hooks_observe_cached_edits(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'lazy_cached_graph.gds'
+    gdsii.writefile(_make_lazy_port_library(), gds_file, meters_per_unit=1e-9)
+
+    lib, _ = gdsii_lazy.readfile(gds_file)
+    del lib['child'].refs['leaf']
+
+    assert lib.child_graph(dangling='ignore')['child'] == set()
+    assert lib.find_refs_local('leaf') == {}
+
+
+def test_gdsii_lazy_subtree_stays_borrowed_and_preserves_write_metadata(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'lazy_subtree_source.gds'
+    src = _make_lazy_port_library()
+    src['unused'] = Pattern()
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='classic-subtree')
+
+    raw, _ = gdsii_lazy.readfile(gds_file)
+    subtree = raw.subtree('top')
+
+    assert isinstance(raw, IMaterializable)
+    assert not isinstance(raw, IBorrowing)
+    assert isinstance(subtree, IMaterializable)
+    assert isinstance(subtree, IBorrowing)
+    assert subtree.source_order() == ('leaf', 'child', 'top')
+    assert not hasattr(subtree, 'library_info')
+    assert not raw._cache
+
+    out_file = tmp_path / 'lazy_subtree_out.gds'
+    gdsii.writefile(subtree, out_file)
+    assert not raw._cache
+
+    roundtrip, info = gdsii.readfile(out_file)
+    assert info['name'] == 'classic-subtree'
+    assert set(roundtrip) == {'leaf', 'child', 'top'}
+
+
+def test_gdsii_lazy_borrowed_sources_require_matching_units(tmp_path: Path) -> None:
+    gds_a = tmp_path / 'units_a.gds'
+    gds_b = tmp_path / 'units_b.gds'
+    source = Library({'top': Pattern()})
+    gdsii.writefile(source, gds_a, meters_per_unit=1e-9, library_name='units-a')
+    gdsii.writefile(source, gds_b, meters_per_unit=2e-9, library_name='units-b')
+
+    lazy_a, _ = gdsii_lazy.readfile(gds_a)
+    lazy_b, _ = gdsii_lazy.readfile(gds_b)
+    overlay = OverlayLibrary()
+    overlay.add_source(lazy_a)
+    overlay.add_source(lazy_b, rename_theirs=lambda lib, name: lib.get_name(name))
+
+    with pytest.raises(LibraryError, match='identical units'):
+        gdsii.write(overlay, io.BytesIO())
+
+
+def test_gdsii_lazy_overlay_subtree_preserves_source_laziness(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'lazy_overlay_subtree_source.gds'
+    src = _make_lazy_port_library()
+    src['unused'] = Pattern()
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='overlay-subtree')
+
+    raw, _ = gdsii_lazy.readfile(gds_file)
+    overlay = OverlayLibrary()
+    overlay.add_source(raw)
+    subtree = overlay.subtree('top')
+
+    assert isinstance(subtree, OverlayLibrary)
+    assert subtree.borrowed_sources() == (raw,)
+
+    out_file = tmp_path / 'lazy_overlay_subtree_out.gds'
+    gdsii.writefile(subtree, out_file)
+
+    assert not raw._cache
+    roundtrip, info = gdsii.readfile(out_file)
+    assert info['name'] == 'overlay-subtree'
+    assert set(roundtrip) == {'leaf', 'child', 'top'}
+
+
+def test_gdsii_lazy_port_load_view_keeps_raw_source_unmodified(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'lazy_ports.gds'
+    src = _make_lazy_port_library()
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='classic-ports')
+
+    raw, _ = gdsii_lazy.readfile(gds_file)
+    processed = PortLoadView(raw, layers=[(10, 0)], max_depth=2)
+    assert not hasattr(processed, 'library_info')
+
+    top = processed['top']
+    assert set(top.ports) == {'A'}
+    assert_allclose(top.ports['A'].offset, [110, 225], atol=1e-10)
+    assert not raw._cache
+
+    raw_top = raw['top']
+    assert not raw_top.ports
+
+
+def test_gdsii_lazy_port_load_view_detaches_previously_cached_source(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'lazy_cached_ports.gds'
+    src = _make_lazy_port_library()
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='classic-cached-ports')
+
+    raw, _ = gdsii_lazy.readfile(gds_file)
+    raw_top = raw['top']
+    processed = PortLoadView(raw, ports={
+        'top': {
+            'P': Port((1, 2), rotation=0, ptype='wire'),
+        },
+    })
+
+    processed_top = processed['top']
+
+    assert processed_top is not raw_top
+    assert not raw_top.ports
+    assert set(processed_top.ports) == {'P'}
+    assert raw['top'] is raw_top
+    assert not hasattr(processed, 'close')
+
+
+def test_gdsii_lazy_port_overrides_without_data_stay_lazy(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'lazy_port_overrides.gds'
+    src = _make_lazy_port_library()
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='classic-overrides')
+
+    raw, _ = gdsii_lazy.readfile(gds_file)
+    processed = PortLoadView(raw, ports={
+        'top': {
+            'P': Port((1, 2), rotation=0, ptype='wire'),
+        },
+    })
+
+    top = processed['top']
+    assert set(top.ports) == {'P'}
+    assert_allclose(top.ports['P'].offset, [1, 2], atol=1e-10)
+    assert top.ports['P'].rotation == 0
+    assert top.ports['P'].ptype == 'wire'
+    assert not raw._cache
+
+    raw_top = raw['top']
+    assert not raw_top.ports
+
+
+def test_gdsii_lazy_port_overrides_apply_after_extraction(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'lazy_ports_override_extracted.gds'
+    src = _make_lazy_port_library()
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='classic-override-extracted')
+
+    raw, _ = gdsii_lazy.readfile(gds_file)
+    processed = PortLoadView(
+        raw,
+        layers=[(10, 0)],
+        max_depth=2,
+        ports={
+            'top': {
+                'A': Port((1, 2), rotation=numpy.pi, ptype='manual'),
+                'B': Port((3, 4), rotation=None, ptype=None),
+            },
+        },
+    )
+
+    top = processed['top']
+    assert set(top.ports) == {'A', 'B'}
+    assert_allclose(top.ports['A'].offset, [1, 2], atol=1e-10)
+    assert top.ports['A'].rotation == numpy.pi
+    assert top.ports['A'].ptype == 'manual'
+    assert_allclose(top.ports['B'].offset, [3, 4], atol=1e-10)
+    assert top.ports['B'].rotation is None
+    assert top.ports['B'].ptype is None
+    assert not raw._cache
+
+
+def test_gdsii_lazy_port_overrides_replace_extracted_ports(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'lazy_ports_replace.gds'
+    src = _make_lazy_port_library()
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='classic-replace-ports')
+
+    raw, _ = gdsii_lazy.readfile(gds_file)
+    processed = PortLoadView(
+        raw,
+        layers=[(10, 0)],
+        max_depth=2,
+        ports={
+            'top': {
+                'B': Port((3, 4), rotation=None, ptype=None),
+            },
+        },
+        replace=True,
+    )
+
+    top = processed['top']
+    assert set(top.ports) == {'B'}
+    assert_allclose(top.ports['B'].offset, [3, 4], atol=1e-10)
+    assert not raw._cache
+
+
+def test_gdsii_lazy_overlay_add_source_stays_lazy_for_processed_view(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'lazy_overlay.gds'
+    src = _make_lazy_port_library()
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='classic-overlay')
+
+    raw, _ = gdsii_lazy.readfile(gds_file)
+    processed = PortLoadView(raw, layers=[(10, 0)], max_depth=2)
+
+    overlay = OverlayLibrary()
+    overlay.add_source(processed)
+
+    assert not raw._cache
+    assert not processed._cache
+
+    abstract = overlay.abstract('top')
+    assert set(abstract.ports) == {'A'}
+
+
+def test_gdsii_lazy_overlay_add_source_sees_port_overrides(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'lazy_overlay_override.gds'
+    src = _make_lazy_port_library()
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='classic-overlay-override')
+
+    raw, _ = gdsii_lazy.readfile(gds_file)
+    processed = PortLoadView(raw, ports={
+        'top': {
+            'P': Port((1, 2), rotation=0, ptype='wire'),
+        },
+    })
+
+    overlay = OverlayLibrary()
+    overlay.add_source(processed)
+
+    assert not raw._cache
+    assert not processed._cache
+
+    abstract = overlay.abstract('top')
+    assert set(abstract.ports) == {'P'}
+    assert_allclose(abstract.ports['P'].offset, [1, 2], atol=1e-10)
+
+
+def test_gdsii_lazy_overlay_add_source_can_rename_every_source_cell() -> None:
+    src = _make_lazy_port_library()
+    overlay = OverlayLibrary()
+
+    rename_map = overlay.add_source(
+        src,
+        rename_theirs=lambda _lib, name: f'mapped_{name}',
+        rename_when='always',
+    )
+
+    assert rename_map == {
+        'leaf': 'mapped_leaf',
+        'child': 'mapped_child',
+        'top': 'mapped_top',
+    }
+    assert tuple(overlay.keys()) == ('mapped_leaf', 'mapped_child', 'mapped_top')
+    assert 'mapped_leaf' in overlay['mapped_child'].refs
+
+
+def test_gdsii_lazy_overlay_add_source_rename_when_validation() -> None:
+    src = _make_lazy_port_library()
+
+    with pytest.raises(TypeError, match='rename_theirs'):
+        OverlayLibrary().add_source(src, rename_theirs=None, rename_when='always')
+
+    with pytest.raises(ValueError, match='rename mode'):
+        OverlayLibrary().add_source(src, rename_when='sometimes')   # type: ignore[arg-type]
+
+
+def test_gdsii_lazy_processed_write_roundtrips_without_explicit_units(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'lazy_roundtrip.gds'
+    src = _make_lazy_port_library()
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='classic-roundtrip')
+
+    raw, _ = gdsii_lazy.readfile(gds_file)
+    processed = PortLoadView(raw, layers=[(10, 0)], max_depth=2)
+
+    out_file = tmp_path / 'lazy_roundtrip_out.gds'
+    gdsii.writefile(processed, out_file)
+
+    assert out_file.read_bytes() == gds_file.read_bytes()
+
+
+def test_gdsii_lazy_source_aware_write_copies_untouched_structures(
+        tmp_path: Path,
+        monkeypatch: pytest.MonkeyPatch,
+        ) -> None:
+    gds_file = tmp_path / 'classic_copy_source.gds'
+    src = _make_lazy_port_library()
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='classic-copy')
+
+    raw, _ = gdsii_lazy.readfile(gds_file)
+    ports = PortLoadView(raw, layers=[(10, 0)], max_depth=2)
+    mapped = LayerMappedView(ports, lambda layer: (20, 0) if layer == (10, 0) else layer, copy_through=True)
+    prepared = preflight_source_aware(mapped)
+    copied: list[str] = []
+    raw_reader = raw.raw_struct_bytes
+
+    def record_raw_read(name: str) -> bytes:
+        copied.append(name)
+        return raw_reader(name)
+
+    def fail_materialize(_name: str, *, persist: bool = True) -> Pattern:     # noqa: ARG001
+        raise AssertionError('untouched cells must not be materialized')
+
+    monkeypatch.setattr(raw, 'raw_struct_bytes', record_raw_read)
+    monkeypatch.setattr(raw, 'materialize', fail_materialize)
+    out_file = tmp_path / 'classic_copy_out.gds'
+    gdsii.writefile(prepared, out_file)
+
+    assert copied == ['leaf', 'child', 'top']
+    assert not raw._cache
+    assert not ports._cache
+    assert not mapped._cache
+    assert out_file.read_bytes() == gds_file.read_bytes()
+
+
+@pytest.mark.parametrize('use_mmap', [False, True])
+def test_gdsii_lazy_raw_copy_stream_backends(tmp_path: Path, use_mmap: bool) -> None:
+    gds_file = tmp_path / 'classic_stream_source.gds'
+    src = _make_lazy_port_library()
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='classic-stream')
+
+    raw, _ = gdsii_lazy.readfile(gds_file, use_mmap=use_mmap)
+    out_file = tmp_path / f'classic_stream_{use_mmap}.gds'
+    gdsii.writefile(raw, out_file)
+
+    assert not raw._cache
+    assert out_file.read_bytes() == gds_file.read_bytes()
+
+
+def test_gdsii_lazy_raw_copy_gzipped_source(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'classic_gzip_source.gds'
+    gz_file = tmp_path / 'classic_gzip_source.gds.gz'
+    src = _make_lazy_port_library()
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='classic-gzip')
+    with gzip.open(gz_file, 'wb') as stream:
+        stream.write(gds_file.read_bytes())
+
+    raw, _ = gdsii_lazy.readfile(gz_file, use_mmap=False)
+    for name in raw.source_order():
+        raw.raw_struct_bytes(name)
+        assert raw._source.stream.tell() == raw._cells[name].struct_end
+    out_file = tmp_path / 'classic_gzip_out.gds'
+    gdsii.writefile(raw, out_file)
+
+    assert not raw._cache
+    assert out_file.read_bytes() == gds_file.read_bytes()
+
+
+def test_gdsii_lazy_cached_source_cell_disables_only_its_raw_copy(
+        tmp_path: Path,
+        monkeypatch: pytest.MonkeyPatch,
+        ) -> None:
+    gds_file = tmp_path / 'classic_cached_source.gds'
+    src = _make_lazy_port_library()
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='classic-cached')
+
+    raw, _ = gdsii_lazy.readfile(gds_file)
+    assert raw.can_copy_raw_struct('leaf')
+    raw['leaf'].label((30, 0), string='cached', offset=(1, 2))
+    assert not raw.can_copy_raw_struct('leaf')
+    copied: list[str] = []
+    raw_reader = raw.raw_struct_bytes
+
+    def record_raw_read(name: str) -> bytes:
+        copied.append(name)
+        return raw_reader(name)
+
+    monkeypatch.setattr(raw, 'raw_struct_bytes', record_raw_read)
+    out_file = tmp_path / 'classic_cached_out.gds'
+    gdsii.writefile(raw, out_file)
+
+    assert copied == ['child', 'top']
+    roundtrip, _ = gdsii.readfile(out_file)
+    assert set(roundtrip['leaf'].labels) == {(10, 0), (30, 0)}
+
+
+def test_gdsii_lazy_detached_processing_copies_only_cached_patterns(
+        tmp_path: Path,
+        monkeypatch: pytest.MonkeyPatch,
+        ) -> None:
+    gds_file = tmp_path / 'classic_detached_source.gds'
+    gdsii.writefile(_make_lazy_port_library(), gds_file, meters_per_unit=1e-9)
+    raw, _ = gdsii_lazy.readfile(gds_file)
+    mapped = LayerMappedView(raw, lambda layer: layer)
+
+    original_deepcopy = Pattern.deepcopy
+    copied: list[Pattern] = []
+
+    def count_deepcopy(pattern: Pattern) -> Pattern:
+        copied.append(pattern)
+        return original_deepcopy(pattern)
+
+    monkeypatch.setattr(Pattern, 'deepcopy', count_deepcopy)
+    fresh = mapped.materialize_detached('top')
+    assert not copied
+    assert not raw._cache
+    assert not mapped._cache
+
+    cached = raw['top']
+    copied.clear()
+    detached = mapped.materialize_detached('top')
+    assert copied == [cached]
+    assert detached is not cached
+    assert detached is not fresh
+
+
+def test_gdsii_lazy_materialized_cell_disables_only_its_raw_copy(
+        tmp_path: Path,
+        monkeypatch: pytest.MonkeyPatch,
+        ) -> None:
+    gds_file = tmp_path / 'classic_partial_copy_source.gds'
+    src = _make_lazy_port_library()
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='classic-partial-copy')
+
+    raw, _ = gdsii_lazy.readfile(gds_file)
+    mapped = LayerMappedView(raw, lambda layer: (20, 0) if layer == (10, 0) else layer, copy_through=True)
+    assert set(mapped['leaf'].labels) == {(20, 0)}
+    prepared = preflight_source_aware(mapped)
+    copied: list[str] = []
+    raw_reader = raw.raw_struct_bytes
+
+    def record_raw_read(name: str) -> bytes:
+        copied.append(name)
+        return raw_reader(name)
+
+    monkeypatch.setattr(raw, 'raw_struct_bytes', record_raw_read)
+    out_file = tmp_path / 'classic_partial_copy_out.gds'
+    gdsii.writefile(prepared, out_file)
+
+    assert copied == ['child', 'top']
+    assert not raw._cache
+    roundtrip, _ = gdsii.readfile(out_file)
+    assert set(roundtrip['leaf'].labels) == {(20, 0)}
+
+
+def test_gdsii_lazy_layer_mapped_write_materializes_without_source_cache(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'lazy_layer_source.gds'
+    src = _make_lazy_port_library()
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='classic-layers')
+
+    raw, _ = gdsii_lazy.readfile(gds_file)
+    mapped = LayerMappedView(raw, lambda layer: (20, 0) if layer == (10, 0) else layer)
+    out_file = tmp_path / 'lazy_layer_mapped.gds'
+    gdsii.writefile(mapped, out_file)
+
+    assert not raw._cache
+    roundtrip, info = gdsii.readfile(out_file)
+    assert info['name'] == 'classic-layers'
+    assert set(roundtrip['leaf'].labels) == {(20, 0)}
+    assert (10, 0) not in roundtrip['leaf'].labels
+
+
+def test_gdsii_removed_closure_based_lazy_loader() -> None:
+    assert not hasattr(gdsii, 'load_library')
+    assert not hasattr(gdsii, 'load_libraryfile')
+    assert not hasattr(gdsii_lazy, 'write')
+    assert not hasattr(gdsii_lazy, 'writefile')

masque/test/test_gdsii_lazy_arrow.py

@@ -0,0 +1,547 @@
+from pathlib import Path
+import subprocess
+import sys
+import textwrap
+
+import klamath
+import numpy
+import pytest
+
+pytest.importorskip('pyarrow')
+
+from .. import PatternError
+from ..library import IBorrowing, IMaterializable, LayerMappedView, Library, OverlayLibrary, PortLoadView
+from ..pattern import Pattern
+from ..repetition import Grid
+from ..file import gdsii
+from ..file.utils import preflight_source_aware
+from ..file.gdsii import lazy_arrow as gdsii_lazy_arrow
+from ..file.gdsii import arrow as gdsii_arrow
+from ..file.gdsii import writer as gdsii_writer
+from tools.generate_gds_perf import write_fixture
+
+
+if not gdsii_arrow.is_available():
+    pytest.skip('klamath_rs_ext shared library is not available', allow_module_level=True)
+
+
+def test_gdsii_lazy_arrow_has_reader_only_surface() -> None:
+    assert not hasattr(gdsii_lazy_arrow, 'is_available')
+    assert not hasattr(gdsii_lazy_arrow, 'write')
+    assert not hasattr(gdsii_lazy_arrow, 'writefile')
+
+
+def _make_small_library() -> Library:
+    lib = Library()
+
+    leaf = Pattern()
+    leaf.polygon((1, 0), vertices=[[0, 0], [10, 0], [10, 5], [0, 5]])
+    lib['leaf'] = leaf
+
+    mid = Pattern()
+    mid.ref('leaf', offset=(10, 20))
+    mid.ref('leaf', offset=(40, 0), repetition=Grid(a_vector=(12, 0), a_count=2, b_vector=(0, 9), b_count=2))
+    lib['mid'] = mid
+
+    top = Pattern()
+    top.ref('mid', offset=(100, 200))
+    lib['top'] = top
+    return lib
+
+
+def _make_complex_ref_library() -> Library:
+    lib = Library()
+
+    leaf = Pattern()
+    leaf.polygon((1, 0), vertices=[[0, 0], [10, 0], [10, 10], [0, 10]])
+    lib['leaf'] = leaf
+
+    child = Pattern()
+    child.ref('leaf', offset=(100, 200), rotation=numpy.pi / 2, mirrored=True, scale=1.25)
+    lib['child'] = child
+
+    sibling = Pattern()
+    sibling.ref(
+        'leaf',
+        offset=(-50, 60),
+        repetition=Grid(a_vector=(20, 0), a_count=3, b_vector=(0, 30), b_count=2),
+        )
+    lib['sibling'] = sibling
+
+    fanout = Pattern()
+    fanout.ref('leaf', offset=(0, 0))
+    fanout.ref('child', offset=(10, 0), mirrored=True, rotation=numpy.pi / 6, scale=1.1)
+    fanout.ref('leaf', offset=(30, 0), repetition=Grid(a_vector=(5, 0), a_count=2, b_vector=(0, 7), b_count=3))
+    fanout.ref(
+        'child',
+        offset=(40, 0),
+        mirrored=True,
+        rotation=numpy.pi / 4,
+        scale=1.2,
+        repetition=Grid(a_vector=(9, 0), a_count=2, b_vector=(0, 11), b_count=2),
+        )
+    lib['fanout'] = fanout
+
+    top = Pattern()
+    top.ref('child', offset=(500, 600))
+    top.ref('sibling', offset=(-100, 50), rotation=numpy.pi)
+    top.ref('fanout', offset=(250, -75))
+    lib['top'] = top
+
+    return lib
+
+
+def _write_invalid_path_type_fixture(path: Path) -> None:
+    with path.open('wb') as stream:
+        header = klamath.library.FileHeader(
+            name=b'test',
+            user_units_per_db_unit=1.0,
+            meters_per_db_unit=1e-9,
+        )
+        header.write(stream)
+        elem = klamath.elements.Path(
+            layer=(1, 0),
+            path_type=3,
+            width=10,
+            extension=(0, 0),
+            xy=numpy.array([[0, 0], [10, 0]], dtype=numpy.int32),
+            properties={},
+        )
+        klamath.library.write_struct(stream, name=b'top', elements=[elem])
+        klamath.records.ENDLIB.write(stream, None)
+
+
+def _transform_rows_key(values: numpy.ndarray) -> tuple[tuple[object, ...], ...]:
+    arr = numpy.asarray(values, dtype=float)
+    arr = numpy.atleast_2d(arr)
+    rows = [
+        (
+            round(float(row[0]), 8),
+            round(float(row[1]), 8),
+            round(float(row[2]), 8),
+            bool(int(round(float(row[3])))),
+            round(float(row[4]), 8),
+            )
+        for row in arr
+        ]
+    return tuple(sorted(rows))
+
+
+def _local_refs_key(refs: dict[str, list[numpy.ndarray]]) -> dict[str, tuple[tuple[object, ...], ...]]:
+    return {
+        parent: _transform_rows_key(numpy.concatenate(transforms))
+        for parent, transforms in refs.items()
+        }
+
+
+def _global_refs_key(refs: dict[tuple[str, ...], numpy.ndarray]) -> dict[tuple[str, ...], tuple[tuple[object, ...], ...]]:
+    return {
+        path: _transform_rows_key(transforms)
+        for path, transforms in refs.items()
+        }
+
+
+def test_gdsii_lazy_arrow_loads_perf_fixture(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'many_cells_lazy.gds'
+    manifest = write_fixture(gds_file, preset='many_cells', scale=0.001)
+
+    lib, info = gdsii_lazy_arrow.readfile(gds_file)
+
+    assert info['name'] == manifest.library_name
+    assert len(lib) == manifest.cells
+    assert lib.top() == 'TOP'
+    assert 'TOP' in lib.child_graph(dangling='ignore')
+
+
+def test_gdsii_lazy_arrow_local_and_global_refs(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'refs.gds'
+    src = _make_small_library()
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='lazy-refs')
+
+    lib, _ = gdsii_lazy_arrow.readfile(gds_file)
+
+    local = lib.find_refs_local('leaf')
+    assert set(local) == {'mid'}
+    assert sum(arr.shape[0] for arr in local['mid']) == 5
+
+    global_refs = lib.find_refs_global('leaf')
+    assert set(global_refs) == {('top', 'mid', 'leaf')}
+    assert global_refs[('top', 'mid', 'leaf')].shape[0] == 5
+
+
+def test_gdsii_lazy_arrow_graph_hooks_observe_cached_edits(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'lazy_arrow_cached_graph.gds'
+    gdsii.writefile(_make_small_library(), gds_file, meters_per_unit=1e-9)
+
+    lib, _ = gdsii_lazy_arrow.readfile(gds_file)
+    del lib['mid'].refs['leaf']
+
+    assert lib.child_graph(dangling='ignore')['mid'] == set()
+    assert lib.find_refs_local('leaf') == {}
+
+
+def test_gdsii_lazy_arrow_ref_queries_match_eager_reader(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'complex_refs.gds'
+    src = _make_complex_ref_library()
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='lazy-complex-refs')
+
+    eager, _ = gdsii.readfile(gds_file)
+    lazy, _ = gdsii_lazy_arrow.readfile(gds_file)
+
+    for name in ('leaf', 'child'):
+        assert _local_refs_key(lazy.find_refs_local(name)) == _local_refs_key(eager.find_refs_local(name))
+        assert _global_refs_key(lazy.find_refs_global(name)) == _global_refs_key(eager.find_refs_global(name))
+
+
+def test_gdsii_lazy_arrow_detached_batch_preserves_native_batching(
+        tmp_path: Path,
+        monkeypatch: pytest.MonkeyPatch,
+        ) -> None:
+    gds_file = tmp_path / 'lazy_arrow_detached_batch.gds'
+    gdsii.writefile(_make_small_library(), gds_file, meters_per_unit=1e-9)
+    raw, _ = gdsii_lazy_arrow.readfile(gds_file)
+    mapped = LayerMappedView(raw, lambda layer: layer)
+
+    original_read = gdsii_arrow._read_selected_cells_to_arrow
+    call_count = 0
+
+    def count_read(*args, **kwargs) -> object:
+        nonlocal call_count
+        call_count += 1
+        return original_read(*args, **kwargs)
+
+    monkeypatch.setattr(gdsii_arrow, '_read_selected_cells_to_arrow', count_read)
+    detached = mapped.materialize_many_detached(('leaf', 'mid', 'leaf'))
+
+    assert tuple(detached) == ('leaf', 'mid')
+    assert call_count == 1
+    assert not raw._cache
+    assert not mapped._cache
+
+
+def test_gdsii_lazy_arrow_invalid_input_raises_klamath_error(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'invalid.gds'
+    gds_file.write_bytes(b'not-a-gds')
+
+    script = textwrap.dedent(f"""
+        from masque.file.gdsii import lazy_arrow as gdsii_lazy_arrow
+        try:
+            gdsii_lazy_arrow.readfile({str(gds_file)!r})
+        except Exception as exc:
+            print(type(exc).__module__)
+            print(type(exc).__qualname__)
+            print(exc)
+        else:
+            raise SystemExit('expected gdsii_lazy_arrow.readfile() to fail')
+        """)
+    result = subprocess.run([sys.executable, '-c', script], capture_output=True, text=True, check=False)
+
+    assert result.returncode == 0, result.stderr
+    assert 'klamath.basic' in result.stdout
+    assert 'KlamathError' in result.stdout
+
+
+def test_gdsii_lazy_arrow_invalid_path_type_raises_pattern_error(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'invalid_path_type.gds'
+    _write_invalid_path_type_fixture(gds_file)
+
+    lib, _ = gdsii_lazy_arrow.readfile(gds_file)
+
+    with pytest.raises(PatternError, match='Unrecognized path type: 3'):
+        lib['top']
+
+
+def test_gdsii_lazy_arrow_untouched_write_is_copy_through(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'copy_source.gds'
+    src = _make_small_library()
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='copy-through')
+
+    lib, info = gdsii_lazy_arrow.readfile(gds_file)
+    out_file = tmp_path / 'copy_out.gds'
+    gdsii.writefile(
+        lib,
+        out_file,
+        meters_per_unit=info['meters_per_unit'],
+        logical_units_per_unit=info['logical_units_per_unit'],
+        library_name=info['name'],
+    )
+
+    assert out_file.read_bytes() == gds_file.read_bytes()
+
+
+def test_gdsii_raw_copy_resolves_generic_borrowing_views(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
+    gds_file = tmp_path / 'provenance_source.gds'
+    gdsii.writefile(_make_small_library(), gds_file, meters_per_unit=1e-9, library_name='provenance')
+
+    raw, _ = gdsii_lazy_arrow.readfile(gds_file)
+    ports = PortLoadView(raw)
+    subtree = ports.subtree('top')
+    overlay = OverlayLibrary()
+    overlay.add_source(subtree)
+
+    copied: list[str] = []
+    raw_reader = raw.raw_struct_bytes
+
+    def record_raw_read(name: str) -> bytes:
+        copied.append(name)
+        return raw_reader(name)
+
+    monkeypatch.setattr(raw, 'raw_struct_bytes', record_raw_read)
+    out_file = tmp_path / 'provenance_out.gds'
+    gdsii.writefile(overlay, out_file)
+
+    assert copied == ['leaf', 'mid', 'top']
+    assert out_file.read_bytes() == gds_file.read_bytes()
+
+    renamed = OverlayLibrary()
+    renamed.add_source(raw)
+    renamed.rename('top', 'renamed_top')
+    assert gdsii_writer._resolve_raw_struct(renamed, 'renamed_top') is None
+
+    remapped = OverlayLibrary()
+    remapped.add_source(raw)
+    remapped.rename('leaf', 'renamed_leaf', move_references=True)
+    assert gdsii_writer._resolve_raw_struct(remapped, 'mid') is None
+
+
+def test_gdsii_layer_mapped_view_controls_raw_copy_through(
+        tmp_path: Path,
+        monkeypatch: pytest.MonkeyPatch,
+        ) -> None:
+    gds_file = tmp_path / 'layer_mapped_source.gds'
+    gdsii.writefile(_make_small_library(), gds_file, meters_per_unit=1e-9, library_name='layer-mapped')
+
+    raw, _ = gdsii_lazy_arrow.readfile(gds_file)
+    copied: list[str] = []
+    raw_reader = raw.raw_struct_bytes
+
+    def record_raw_read(name: str) -> bytes:
+        copied.append(name)
+        return raw_reader(name)
+
+    def map_layer(layer):  # noqa: ANN001,ANN202
+        return (20, 0) if layer == (1, 0) else layer
+
+    monkeypatch.setattr(raw, 'raw_struct_bytes', record_raw_read)
+
+    mapped = LayerMappedView(raw, map_layer)
+    mapped_file = tmp_path / 'layer_mapped_all.gds'
+    gdsii.writefile(mapped, mapped_file)
+
+    assert copied == []
+    assert not raw._cache
+    roundtrip, info = gdsii.readfile(mapped_file)
+    assert info['name'] == 'layer-mapped'
+    assert set(roundtrip['leaf'].shapes) == {(20, 0)}
+
+    passthrough = LayerMappedView(raw, map_layer, copy_through=True)
+    preflighted = preflight_source_aware(passthrough)
+    assert isinstance(preflighted, OverlayLibrary)
+    copied_file = tmp_path / 'layer_mapped_copied.gds'
+    gdsii.writefile(preflighted, copied_file)
+
+    assert copied == ['leaf', 'mid', 'top']
+    assert copied_file.read_bytes() == gds_file.read_bytes()
+    assert not raw._cache
+
+    copied.clear()
+    assert set(passthrough['leaf'].shapes) == {(20, 0)}
+    preflighted = preflight_source_aware(passthrough)
+    materialized_file = tmp_path / 'layer_mapped_materialized.gds'
+    gdsii.writefile(preflighted, materialized_file)
+
+    assert copied == ['mid', 'top']
+    assert not raw._cache
+    roundtrip, _ = gdsii.readfile(materialized_file)
+    assert set(roundtrip['leaf'].shapes) == {(20, 0)}
+
+
+def test_gdsii_lazy_arrow_processed_cell_edit_disables_raw_copy(
+        tmp_path: Path,
+        monkeypatch: pytest.MonkeyPatch,
+        ) -> None:
+    gds_file = tmp_path / 'processed_edit_source.gds'
+    src = _make_small_library()
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='processed-edit')
+
+    raw, _ = gdsii_lazy_arrow.readfile(gds_file)
+    processed = PortLoadView(raw)
+    processed['top'].polygon((7, 0), vertices=[[0, 0], [4, 0], [0, 4]])
+
+    copied: list[str] = []
+    raw_reader = raw.raw_struct_bytes
+
+    def record_raw_read(name: str) -> bytes:
+        copied.append(name)
+        return raw_reader(name)
+
+    monkeypatch.setattr(raw, 'raw_struct_bytes', record_raw_read)
+
+    out_file = tmp_path / 'processed_edit_out.gds'
+    gdsii.writefile(processed, out_file)
+
+    assert 'top' not in copied
+    roundtrip, _ = gdsii.readfile(out_file)
+    assert len(roundtrip['top'].shapes[(7, 0)]) == 1
+
+
+def test_gdsii_lazy_arrow_subtree_preserves_raw_copy_and_ref_queries(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'subtree_copy_source.gds'
+    src = _make_small_library()
+    src['unused'] = Pattern()
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='subtree-copy')
+
+    raw, _ = gdsii_lazy_arrow.readfile(gds_file)
+    subtree = raw.subtree('top')
+
+    assert isinstance(raw, IMaterializable)
+    assert not isinstance(raw, IBorrowing)
+    assert isinstance(subtree, IMaterializable)
+    assert isinstance(subtree, IBorrowing)
+    assert subtree.source_order() == ('leaf', 'mid', 'top')
+    assert _global_refs_key(subtree.find_refs_global('leaf')) == _global_refs_key(raw.find_refs_global('leaf'))
+    assert not raw._cache
+
+    out_file = tmp_path / 'subtree_copy_out.gds'
+    gdsii.writefile(subtree, out_file)
+
+    assert not raw._cache
+    roundtrip, info = gdsii.readfile(out_file)
+    assert info['name'] == 'subtree-copy'
+    assert set(roundtrip) == {'leaf', 'mid', 'top'}
+
+
+def test_gdsii_lazy_arrow_overlay_subtree_preserves_raw_copy(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'overlay_subtree_source.gds'
+    src = _make_small_library()
+    src['unused'] = Pattern()
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='overlay-subtree-copy')
+
+    raw, _ = gdsii_lazy_arrow.readfile(gds_file)
+    overlay = OverlayLibrary()
+    overlay.add_source(raw)
+    subtree = overlay.subtree('top')
+
+    assert isinstance(subtree, OverlayLibrary)
+    assert subtree.borrowed_sources() == (raw,)
+    assert not raw._cache
+
+    out_file = tmp_path / 'overlay_subtree_out.gds'
+    gdsii.writefile(subtree, out_file)
+
+    assert not raw._cache
+    roundtrip, info = gdsii.readfile(out_file)
+    assert info['name'] == 'overlay-subtree-copy'
+    assert set(roundtrip) == {'leaf', 'mid', 'top'}
+
+
+def test_gdsii_lazy_arrow_gzipped_copy_through(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'copy_source.gds.gz'
+    src = _make_small_library()
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='copy-through-gz')
+
+    lib, info = gdsii_lazy_arrow.readfile(gds_file)
+    out_file = tmp_path / 'copy_out.gds.gz'
+    gdsii.writefile(
+        lib,
+        out_file,
+        meters_per_unit=info['meters_per_unit'],
+        logical_units_per_unit=info['logical_units_per_unit'],
+        library_name=info['name'],
+    )
+
+    assert out_file.read_bytes() == gds_file.read_bytes()
+
+
+def test_gdsii_lazy_overlay_merge_and_write(tmp_path: Path) -> None:
+    base_a = Library()
+    leaf_a = Pattern()
+    leaf_a.polygon((1, 0), vertices=[[0, 0], [8, 0], [8, 8], [0, 8]])
+    base_a['leaf'] = leaf_a
+    top_a = Pattern()
+    top_a.ref('leaf', offset=(0, 0))
+    base_a['top_a'] = top_a
+
+    base_b = Library()
+    leaf_b = Pattern()
+    leaf_b.polygon((2, 0), vertices=[[0, 0], [5, 0], [5, 5], [0, 5]])
+    base_b['leaf'] = leaf_b
+    top_b = Pattern()
+    top_b.ref('leaf', offset=(20, 30))
+    base_b['top_b'] = top_b
+
+    gds_a = tmp_path / 'a.gds'
+    gds_b = tmp_path / 'b.gds'
+    gdsii.writefile(base_a, gds_a, meters_per_unit=1e-9, library_name='overlay')
+    gdsii.writefile(base_b, gds_b, meters_per_unit=1e-9, library_name='overlay')
+
+    lib_a, _ = gdsii_lazy_arrow.readfile(gds_a)
+    lib_b, _ = gdsii_lazy_arrow.readfile(gds_b)
+
+    overlay = OverlayLibrary()
+    overlay.add_source(lib_a)
+    rename_map = overlay.add_source(lib_b, rename_theirs=lambda lib, name: lib.get_name(name))
+    renamed_leaf = rename_map['leaf']
+
+    assert rename_map == {'leaf': renamed_leaf}
+    assert renamed_leaf != 'leaf'
+    assert len(lib_a._cache) == 0
+    assert len(lib_b._cache) == 0
+
+    overlay.move_references('leaf', renamed_leaf)
+
+    out_file = tmp_path / 'overlay_out.gds'
+    gdsii.writefile(overlay, out_file)
+
+    roundtrip, _ = gdsii.readfile(out_file)
+    assert set(roundtrip.keys()) == {'leaf', renamed_leaf, 'top_a', 'top_b'}
+    assert 'top_b' in roundtrip
+    assert list(roundtrip['top_b'].refs.keys()) == [renamed_leaf]
+
+
+def test_gdsii_writer_accepts_overlay_library(tmp_path: Path) -> None:
+    gds_file = tmp_path / 'overlay_source.gds'
+    src = _make_small_library()
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='overlay-src')
+
+    lib, info = gdsii_lazy_arrow.readfile(gds_file)
+
+    overlay = OverlayLibrary()
+    overlay.add_source(lib)
+    overlay.rename('leaf', 'leaf_copy', move_references=True)
+
+    out_file = tmp_path / 'overlay_via_eager_writer.gds'
+    gdsii.writefile(
+        overlay,
+        out_file,
+        meters_per_unit=info['meters_per_unit'],
+        logical_units_per_unit=info['logical_units_per_unit'],
+        library_name=info['name'],
+    )
+
+    roundtrip, _ = gdsii.readfile(out_file)
+    assert set(roundtrip.keys()) == {'leaf_copy', 'mid', 'top'}
+    assert list(roundtrip['mid'].refs.keys()) == ['leaf_copy']
+
+
+def test_svg_writer_uses_detached_materialized_copy(tmp_path: Path) -> None:
+    pytest.importorskip('svgwrite')
+    from ..file import svg
+    from ..shapes import Path as MPath
+
+    gds_file = tmp_path / 'svg_source.gds'
+    src = _make_small_library()
+    src['top'].path((3, 0), vertices=[[0, 0], [0, 20]], width=4)
+    gdsii.writefile(src, gds_file, meters_per_unit=1e-9, library_name='svg-src')
+
+    lib, _ = gdsii_lazy_arrow.readfile(gds_file)
+    top_pat = lib['top']
+    assert list(top_pat.refs.keys()) == ['mid']
+    assert any(isinstance(shape, MPath) for shape in top_pat.shapes[(3, 0)])
+
+    svg_path = tmp_path / 'lazy.svg'
+    svg.writefile(lib, 'top', str(svg_path))
+
+    assert svg_path.exists()
+    assert list(top_pat.refs.keys()) == ['mid']
+    assert any(isinstance(shape, MPath) for shape in top_pat.shapes[(3, 0)])

masque/test/test_gdsii_perf.py

@@ -0,0 +1,24 @@
+from dataclasses import asdict
+import json
+from pathlib import Path
+
+from ..file import gdsii
+from tools.generate_gds_perf import fixture_manifest, write_fixture
+
+
+def test_gdsii_perf_fixture_smoke(tmp_path: Path) -> None:
+    output = tmp_path / 'many_cells.gds'
+    manifest = write_fixture(output, preset='many_cells', scale=0.002)
+    expected = fixture_manifest(output, preset='many_cells', scale=0.002)
+
+    assert output.exists()
+    assert manifest == expected
+
+    sidecar = json.loads(output.with_suffix('.gds.json').read_text())
+    assert sidecar == asdict(manifest)
+
+    read_lib, info = gdsii.readfile(output)
+    assert info['name'] == manifest.library_name
+    assert len(read_lib) == manifest.cells
+    assert 'TOP' in read_lib
+    assert len(read_lib['TOP'].refs) > 0

masque/test/test_label.py

@@ -0,0 +1,54 @@
+import copy
+from numpy.testing import assert_equal, assert_allclose
+from numpy import pi
+
+from ..label import Label
+from ..repetition import Grid
+from ..utils import annotations_eq
+
+
+def test_label_init() -> None:
+    lbl = Label("test", offset=(10, 20))
+    assert lbl.string == "test"
+    assert_equal(lbl.offset, [10, 20])
+
+
+def test_label_transform() -> None:
+    lbl = Label("test", offset=(10, 0))
+    # Rotate 90 deg CCW around (0,0)
+    lbl.rotate_around((0, 0), pi / 2)
+    assert_allclose(lbl.offset, [0, 10], atol=1e-10)
+
+    # Translate
+    lbl.translate((5, 5))
+    assert_allclose(lbl.offset, [5, 15], atol=1e-10)
+
+
+def test_label_repetition() -> None:
+    rep = Grid(a_vector=(10, 0), a_count=3)
+    lbl = Label("rep", offset=(0, 0), repetition=rep)
+    assert lbl.repetition is rep
+    assert_equal(lbl.get_bounds_single(), [[0, 0], [0, 0]])
+    # Note: Bounded.get_bounds_nonempty() for labels with repetition doesn't
+    # seem to automatically include repetition bounds in label.py itself,
+    # it's handled during pattern bounding.
+
+
+def test_label_copy() -> None:
+    l1 = Label("test", offset=(1, 2), annotations={"a": [1]})
+    l2 = copy.deepcopy(l1)
+
+    print(f"l1: string={l1.string}, offset={l1.offset}, repetition={l1.repetition}, annotations={l1.annotations}")
+    print(f"l2: string={l2.string}, offset={l2.offset}, repetition={l2.repetition}, annotations={l2.annotations}")
+    print(f"annotations_eq: {annotations_eq(l1.annotations, l2.annotations)}")
+
+    assert l1 == l2
+    assert l1 is not l2
+    l2.offset[0] = 100
+    assert l1.offset[0] == 1
+
+
+def test_label_eq_unrelated_objects_is_false() -> None:
+    lbl = Label("test")
+    assert not (lbl == None)
+    assert not (lbl == object())

masque/test/test_manhattanize.py

@@ -0,0 +1,17 @@
+import pytest
+import numpy
+
+from ..shapes import Polygon
+
+
+def test_manhattanize() -> None:
+    pytest.importorskip("float_raster")
+    pytest.importorskip("skimage.measure")
+    poly = Polygon([[0, 5], [5, 10], [10, 5], [5, 0]])
+    grid = numpy.arange(0, 11, 1)
+
+    manhattan_polys = poly.manhattanize(grid, grid)
+    assert len(manhattan_polys) >= 1
+    for mp in manhattan_polys:
+        dv = numpy.diff(mp.vertices, axis=0)
+        assert numpy.all((dv[:, 0] == 0) | (dv[:, 1] == 0))

masque/test/test_oasis.py

@@ -0,0 +1,60 @@
+import io
+from pathlib import Path
+import pytest
+from numpy.testing import assert_equal
+
+from ..error import PatternError
+from ..pattern import Pattern
+from ..library import Library
+from ..shapes import Path as MPath
+
+
+def test_oasis_roundtrip(tmp_path: Path) -> None:
+    # Skip if fatamorgana is not installed
+    pytest.importorskip("fatamorgana")
+    from ..file import oasis
+
+    lib = Library()
+    pat1 = Pattern()
+    pat1.polygon((1, 0), vertices=[[0, 0], [10, 0], [10, 10], [0, 10]])
+    lib["cell1"] = pat1
+
+    oas_file = tmp_path / "test.oas"
+    # OASIS needs units_per_micron
+    oasis.writefile(lib, oas_file, units_per_micron=1000)
+
+    read_lib, info = oasis.readfile(oas_file)
+    assert "cell1" in read_lib
+
+    # Check bounds
+    assert_equal(read_lib["cell1"].get_bounds(), [[0, 0], [10, 10]])
+
+
+def test_oasis_properties_to_annotations_merges_repeated_keys() -> None:
+    pytest.importorskip("fatamorgana")
+    import fatamorgana.records as fatrec
+    from ..file.oasis import properties_to_annotations
+
+    annotations = properties_to_annotations(
+        [
+            fatrec.Property("k", [1], is_standard=False),
+            fatrec.Property("k", [2, 3], is_standard=False),
+        ],
+        {},
+        {},
+    )
+
+    assert annotations == {"k": [1, 2, 3]}
+
+
+def test_oasis_write_rejects_circle_path_caps() -> None:
+    pytest.importorskip("fatamorgana")
+    from ..file import oasis
+
+    lib = Library()
+    pat = Pattern()
+    pat.path((1, 0), vertices=[[0, 0], [10, 0]], width=2, cap=MPath.Cap.Circle)
+    lib["cell1"] = pat
+
+    with pytest.raises(PatternError, match="does not support path cap"):
+        oasis.write(lib, io.BytesIO(), units_per_micron=1000)

masque/test/test_pack2d.py

@@ -0,0 +1,96 @@
+from ..utils.pack2d import maxrects_bssf, guillotine_bssf_sas, pack_patterns
+from ..library import Library
+from ..pattern import Pattern
+
+
+def test_maxrects_bssf_simple() -> None:
+    # Pack two 10x10 squares into one 20x10 container
+    rects = [[10, 10], [10, 10]]
+    containers = [[0, 0, 20, 10]]
+
+    locs, rejects = maxrects_bssf(rects, containers)
+
+    assert not rejects
+    # They should be at (0,0) and (10,0)
+    assert {tuple(loc) for loc in locs} == {(0.0, 0.0), (10.0, 0.0)}
+
+
+def test_maxrects_bssf_reject() -> None:
+    # Try to pack a too-large rectangle
+    rects = [[10, 10], [30, 30]]
+    containers = [[0, 0, 20, 20]]
+
+    locs, rejects = maxrects_bssf(rects, containers, allow_rejects=True)
+    assert 1 in rejects  # Second rect rejected
+    assert 0 not in rejects
+
+
+def test_maxrects_bssf_exact_fill_rejects_remaining() -> None:
+    rects = [[20, 20], [1, 1]]
+    containers = [[0, 0, 20, 20]]
+
+    locs, rejects = maxrects_bssf(rects, containers, presort=False, allow_rejects=True)
+
+    assert tuple(locs[0]) == (0.0, 0.0)
+    assert rejects == {1}
+
+
+def test_maxrects_bssf_presort_reject_mapping() -> None:
+    rects = [[10, 12], [19, 14], [13, 11]]
+    containers = [[0, 0, 20, 20]]
+
+    _locs, rejects = maxrects_bssf(rects, containers, presort=True, allow_rejects=True)
+
+    assert rejects == {0, 2}
+
+
+def test_guillotine_bssf_sas_presort_reject_mapping() -> None:
+    rects = [[2, 1], [17, 15], [16, 11]]
+    containers = [[0, 0, 20, 20]]
+
+    _locs, rejects = guillotine_bssf_sas(rects, containers, presort=True, allow_rejects=True)
+
+    assert rejects == {2}
+
+
+def test_pack_patterns() -> None:
+    lib = Library()
+    p1 = Pattern()
+    p1.polygon((1, 0), vertices=[[0, 0], [10, 0], [10, 10], [0, 10]])
+    lib["p1"] = p1
+
+    p2 = Pattern()
+    p2.polygon((1, 0), vertices=[[0, 0], [5, 0], [5, 5], [0, 5]])
+    lib["p2"] = p2
+
+    # Containers: one 20x20
+    containers = [[0, 0, 20, 20]]
+    # 2um spacing
+    pat, rejects = pack_patterns(lib, ["p1", "p2"], containers, spacing=(2, 2))
+
+    assert not rejects
+    assert len(pat.refs) == 2
+    assert "p1" in pat.refs
+    assert "p2" in pat.refs
+
+    # Check that they don't overlap (simple check via bounds)
+    # p1 size 10x10, effectively 12x12
+    # p2 size 5x5, effectively 7x7
+    # Both should fit in 20x20
+
+
+def test_pack_patterns_reject_names_match_original_patterns() -> None:
+    lib = Library()
+    for name, (lx, ly) in {
+            "p0": (10, 12),
+            "p1": (19, 14),
+            "p2": (13, 11),
+            }.items():
+        pat = Pattern()
+        pat.rect((1, 0), xmin=0, xmax=lx, ymin=0, ymax=ly)
+        lib[name] = pat
+
+    pat, rejects = pack_patterns(lib, ["p0", "p1", "p2"], [[0, 0, 20, 20]], spacing=(0, 0))
+
+    assert set(rejects) == {"p0", "p2"}
+    assert set(pat.refs) == {"p1"}

masque/test/test_path.py

@@ -0,0 +1,101 @@
+from numpy.testing import assert_equal, assert_allclose
+
+from ..shapes import Path, Path as MPath
+
+
+def test_path_init() -> None:
+    p = Path(vertices=[[0, 0], [10, 0]], width=2, cap=Path.Cap.Flush)
+    assert_equal(p.vertices, [[0, 0], [10, 0]])
+    assert p.width == 2
+    assert p.cap == Path.Cap.Flush
+
+
+def test_path_to_polygons_flush() -> None:
+    p = Path(vertices=[[0, 0], [10, 0]], width=2, cap=Path.Cap.Flush)
+    polys = p.to_polygons()
+    assert len(polys) == 1
+    bounds = polys[0].get_bounds_single()
+    assert_equal(bounds, [[0, -1], [10, 1]])
+
+
+def test_path_to_polygons_square() -> None:
+    p = Path(vertices=[[0, 0], [10, 0]], width=2, cap=Path.Cap.Square)
+    polys = p.to_polygons()
+    assert len(polys) == 1
+    bounds = polys[0].get_bounds_single()
+    assert_equal(bounds, [[-1, -1], [11, 1]])
+
+
+def test_path_to_polygons_circle() -> None:
+    p = Path(vertices=[[0, 0], [10, 0]], width=2, cap=Path.Cap.Circle)
+    polys = p.to_polygons(num_vertices=32)
+    assert len(polys) >= 3
+
+    bounds = p.get_bounds_single()
+    assert_equal(bounds, [[-1, -1], [11, 1]])
+
+
+def test_path_custom_cap() -> None:
+    p = Path(vertices=[[0, 0], [10, 0]], width=2, cap=Path.Cap.SquareCustom, cap_extensions=(5, 10))
+    polys = p.to_polygons()
+    assert len(polys) == 1
+    bounds = polys[0].get_bounds_single()
+    assert_equal(bounds, [[-5, -1], [20, 1]])
+
+
+def test_path_bend() -> None:
+    p = Path(vertices=[[0, 0], [10, 0], [10, 10]], width=2)
+    polys = p.to_polygons()
+    assert len(polys) == 1
+    bounds = polys[0].get_bounds_single()
+    assert_equal(bounds, [[0, -1], [11, 10]])
+
+
+def test_path_mirror() -> None:
+    p = Path(vertices=[[10, 5], [20, 10]], width=2)
+    p.mirror(0)
+    assert_equal(p.vertices, [[10, -5], [20, -10]])
+
+
+def test_path_scale() -> None:
+    p = Path(vertices=[[0, 0], [10, 0]], width=2)
+    p.scale_by(2)
+    assert_equal(p.vertices, [[0, 0], [20, 0]])
+    assert p.width == 4
+
+
+def test_path_scale_custom_cap_extensions() -> None:
+    p = Path(vertices=[[0, 0], [10, 0]], width=2, cap=Path.Cap.SquareCustom, cap_extensions=(1, 2))
+    p.scale_by(3)
+
+    assert_equal(p.vertices, [[0, 0], [30, 0]])
+    assert p.width == 6
+    assert p.cap_extensions is not None
+    assert_allclose(p.cap_extensions, [3, 6])
+    assert_equal(p.to_polygons()[0].get_bounds_single(), [[-3, -3], [36, 3]])
+
+
+def test_path_normalized_form_preserves_width_and_custom_cap_extensions() -> None:
+    p = Path(vertices=[[0, 0], [10, 0]], width=2, cap=Path.Cap.SquareCustom, cap_extensions=(1, 2))
+
+    intrinsic, _extrinsic, ctor = p.normalized_form(5)
+    q = ctor()
+
+    assert intrinsic[-1] == (0.2, 0.4)
+    assert q.width == 2
+    assert q.cap_extensions is not None
+    assert_allclose(q.cap_extensions, [1, 2])
+
+
+def test_path_normalized_form_distinguishes_custom_caps() -> None:
+    p1 = Path(vertices=[[0, 0], [10, 0]], width=2, cap=Path.Cap.SquareCustom, cap_extensions=(1, 2))
+    p2 = Path(vertices=[[0, 0], [10, 0]], width=2, cap=Path.Cap.SquareCustom, cap_extensions=(3, 4))
+
+    assert p1.normalized_form(1)[0] != p2.normalized_form(1)[0]
+
+
+def test_path_edge_cases() -> None:
+    p = MPath(vertices=[[0, 0], [0, 0], [10, 0]], width=2)
+    polys = p.to_polygons()
+    assert len(polys) == 1
+    assert_equal(polys[0].get_bounds_single(), [[0, -1], [10, 1]])

masque/test/test_pather_autotool.py

@@ -0,0 +1,107 @@
+import pytest
+import numpy
+from numpy import pi
+from numpy.testing import assert_allclose
+
+from masque import Pather, Library, Pattern, Port
+from masque.builder.tools import AutoTool
+
+
+def make_straight(length: float, width: float = 2, ptype: str = "wire") -> Pattern:
+    pat = Pattern()
+    pat.rect((1, 0), xmin=0, xmax=length, yctr=0, ly=width)
+    pat.ports["A"] = Port((0, 0), 0, ptype=ptype)
+    pat.ports["B"] = Port((length, 0), pi, ptype=ptype)
+    return pat
+
+def make_bend(radius: float, width: float = 2, ptype: str = "wire", clockwise: bool = True) -> Pattern:
+    pat = Pattern()
+    # Rectangular approximation of a 90 degree bend.
+    if clockwise:
+        pat.rect((1, 0), xmin=0, xmax=radius, yctr=0, ly=width)
+        pat.rect((1, 0), xctr=radius, lx=width, ymin=-radius, ymax=0)
+        pat.ports["A"] = Port((0, 0), 0, ptype=ptype)
+        pat.ports["B"] = Port((radius, -radius), pi/2, ptype=ptype)
+    else:
+        pat.rect((1, 0), xmin=0, xmax=radius, yctr=0, ly=width)
+        pat.rect((1, 0), xctr=radius, lx=width, ymin=0, ymax=radius)
+        pat.ports["A"] = Port((0, 0), 0, ptype=ptype)
+        pat.ports["B"] = Port((radius, radius), -pi/2, ptype=ptype)
+    return pat
+
+@pytest.fixture
+def multi_bend_tool() -> tuple[AutoTool, Library]:
+    lib = Library()
+
+    lib["b1"] = make_bend(2, ptype="wire")
+    b1_abs = lib.abstract("b1")
+    lib["b2"] = make_bend(5, ptype="wire")
+    b2_abs = lib.abstract("b2")
+
+    tool = (
+        AutoTool()
+        .add_straight(make_straight, "wire", "A", length_range=(0, 10))
+        .add_straight(lambda length: make_straight(length, width=4), "wire", "A", length_range=(10, 1e8))
+        .add_bend(b1_abs, "A", "B", clockwise=True, mirror=True)
+        .add_bend(b2_abs, "A", "B", clockwise=True, mirror=True)
+        )
+    return tool, lib
+
+def test_autotool_uturn() -> None:
+    from masque.builder.tools import AutoTool
+    lib = Library()
+
+    def make_straight(length: float) -> Pattern:
+        pat = Pattern()
+        pat.rect(layer='M1', xmin=0, xmax=length, yctr=0, ly=1000)
+        pat.ports['in'] = Port((0, 0), 0)
+        pat.ports['out'] = Port((length, 0), pi)
+        return pat
+
+    bend_pat = Pattern()
+    bend_pat.polygon(layer='M1', vertices=[(0, -500), (0, 500), (1000, -500)])
+    bend_pat.ports['in'] = Port((0, 0), 0)
+    bend_pat.ports['out'] = Port((500, -500), pi/2)
+    lib['bend'] = bend_pat
+
+    tool = (
+        AutoTool()
+        .add_straight(make_straight, 'wire', 'in')
+        .add_bend(lib.abstract('bend'), 'in', 'out', clockwise=True)
+        )
+
+    p = Pather(lib, tools=tool)
+    p.pattern.ports['A'] = Port((0, 0), 0)
+
+    p.at('A').uturn(offset=-2000, length=1000)
+
+    # U-turn plan output is transformed into the port extension frame.
+    assert numpy.allclose(p.pattern.ports['A'].offset, (-1000, 2000))
+    assert p.pattern.ports['A'].rotation is not None
+    assert numpy.isclose(p.pattern.ports['A'].rotation, pi)
+
+def test_deferred_render_autotool_double_L(multi_bend_tool: tuple[AutoTool, Library]) -> None:
+    tool, lib = multi_bend_tool
+    rp = Pather(lib, tools=tool)
+    rp.ports["A"] = Port((0,0), 0, ptype="wire")
+
+    rp.jog("A", 10, length=20)
+
+    assert_allclose(rp.ports["A"].offset, [-20, -10])
+    assert_allclose(rp.ports["A"].rotation, 0)
+
+    rp.render()
+    assert len(rp.pattern.refs) > 0
+
+def test_pather_uturn_fallback_no_heuristic(multi_bend_tool: tuple[AutoTool, Library]) -> None:
+    tool, lib = multi_bend_tool
+
+    p = Pather(lib, tools=tool)
+    p.ports["A"] = Port((0,0), 0, ptype="wire")
+
+    p.uturn("A", 10, length=5)
+
+    # Fallback U-turn uses two CCW bends: (7, 2) then (8, 2) in local tool frames,
+    # yielding a global endpoint at (-5, -10).
+    assert_allclose(p.ports["A"].offset, [-5, -10])
+    assert_allclose(p.ports["A"].rotation, pi)

masque/test/test_pather_core.py

@@ -0,0 +1,614 @@
+from typing import Any
+
+import pytest
+import numpy
+from numpy import pi
+from numpy.testing import assert_allclose, assert_equal
+
+from masque import Pather, Library, Pattern, Port, RouteError
+from masque.builder import PathTool, PrimitiveOffer, StraightOffer
+from masque.builder.planner import RoutingPlanner
+from masque.error import BuildError, PortError
+
+
+@pytest.fixture
+def pather_setup() -> tuple[Pather, PathTool, Library]:
+    lib = Library()
+    tool = PathTool(layer=(1, 0), width=2, ptype="wire")
+    p = Pather(lib, tools=tool)
+    # Port rotation points into the device, so path extension moves in the opposite direction.
+    p.ports["start"] = Port((0, 0), pi / 2, ptype="wire")
+    return p, tool, lib
+
+
+def test_builder_tool_symbol_exports() -> None:
+    import masque
+    import masque.builder
+    import masque.builder.tools as builder_tools
+
+    package_root_exports = (
+        'RenderStep',
+        'PortPather',
+        )
+    builder_tool_names = (
+        'PrimitiveOffer',
+        'StraightOffer',
+        'BendOffer',
+        'SOffer',
+        'UOffer',
+        )
+    internal_names = (
+        'PTypeMatch',
+        'canonicalize_domain_value',
+        'ptype_match',
+        'ptypes_compatible',
+        )
+
+    for name in (*package_root_exports, *builder_tool_names):
+        assert hasattr(masque.builder, name)
+
+    for name in package_root_exports:
+        assert hasattr(masque, name)
+
+    for name in (*builder_tool_names, *internal_names):
+        assert not hasattr(masque, name)
+
+    for name in internal_names:
+        assert not hasattr(masque.builder, name)
+
+    for name in builder_tool_names:
+        assert hasattr(masque.builder, name)
+        assert hasattr(builder_tools, name)
+
+
+def test_pather_pending_render_steps_are_private() -> None:
+    p = Pather(Library(), tools=PathTool(layer=(1, 0), width=1))
+
+    assert not hasattr(p, 'paths')
+    assert hasattr(p, '_paths')
+
+
+def test_pather_accepts_and_reuses_planner_instance() -> None:
+    class CountingPlanner(RoutingPlanner):
+        def __init__(self) -> None:
+            self.trace_to_calls = 0
+
+        def plan_trace_to_route(self, *args: Any, **kwargs: Any) -> Any:
+            self.trace_to_calls += 1
+            return super().plan_trace_to_route(*args, **kwargs)
+
+    planner = CountingPlanner()
+    p = Pather(
+        Library(),
+        tools=PathTool(layer=(1, 0), width=1),
+        render='deferred',
+        planner=planner,
+        )
+    p.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+
+    p.straight('A', 1)
+    p.straight('A', 2)
+
+    assert p.planner is planner
+    assert planner.trace_to_calls == 2
+
+
+def test_pather_copies_and_forwards_plan_options_to_planner() -> None:
+    class RecordingPlanner(RoutingPlanner):
+        def __init__(self) -> None:
+            super().__init__()
+            self.received_plan_options: Any = None
+
+        def plan_trace_to_route(
+                self,
+                *args: Any,
+                plan_options: Any = None,
+                **kwargs: Any,
+                ) -> Any:
+            self.received_plan_options = plan_options
+            return super().plan_trace_to_route(
+                *args,
+                plan_options=plan_options,
+                **kwargs,
+                )
+
+    planner = RecordingPlanner()
+    p = Pather(
+        Library(),
+        tools=PathTool(layer=(1, 0), width=1),
+        render='deferred',
+        planner=planner,
+        )
+    p.ports['A'] = Port((0, 0), rotation=0)
+    supplied = {'strategy': 'turn_first'}
+
+    p.straight('A', 1, plan_options=supplied)
+
+    assert planner.received_plan_options == supplied
+    assert planner.received_plan_options is not supplied
+
+
+def test_port_tool_policy_and_portpather_selection_follow_names() -> None:
+    default_tool = PathTool(layer=(1, 0), width=1, ptype='wire')
+    named_tool = PathTool(layer=(2, 0), width=1, ptype='wire')
+    p = Pather(
+        Library(),
+        ports={'A': Port((0, 0), rotation=0, ptype='wire')},
+        tools={None: default_tool, 'A': named_tool},
+        render='deferred',
+        )
+    selected = p.at('A')
+
+    p.rename_ports({'A': 'B'})
+
+    assert selected.ports == ['A']
+    assert p.tools['A'] is named_tool
+    assert 'B' not in p.tools
+    p.straight('B', 1)
+    assert p._paths['B'][0].tool is default_tool
+
+    p.mkport('A', Port((10, 0), rotation=0, ptype='wire'))
+    p.straight('A', 1)
+    assert p._paths['A'][0].tool is named_tool
+
+
+def test_pather_straight(pather_setup: tuple[Pather, PathTool, Library]) -> None:
+    p, tool, lib = pather_setup
+    p.straight("start", 10)
+
+    assert_allclose(p.ports["start"].offset, [0, -10], atol=1e-10)
+    assert p.ports["start"].rotation is not None
+    assert_allclose(p.ports["start"].rotation, pi / 2, atol=1e-10)
+
+def test_pather_bend(pather_setup: tuple[Pather, PathTool, Library]) -> None:
+    p, tool, lib = pather_setup
+    p.cw("start", 10)
+
+    assert_allclose(p.ports["start"].offset, [-1, -10], atol=1e-10)
+    assert p.ports["start"].rotation is not None
+    assert_allclose(p.ports["start"].rotation, 0, atol=1e-10)
+
+def test_pather_path_to(pather_setup: tuple[Pather, PathTool, Library]) -> None:
+    p, tool, lib = pather_setup
+    p.straight("start", y=-50)
+    assert_equal(p.ports["start"].offset, [0, -50])
+
+def test_pather_mpath(pather_setup: tuple[Pather, PathTool, Library]) -> None:
+    p, tool, lib = pather_setup
+    p.ports["A"] = Port((0, 0), pi / 2, ptype="wire")
+    p.ports["B"] = Port((10, 0), pi / 2, ptype="wire")
+
+    p.straight(["A", "B"], ymin=-20)
+    assert_equal(p.ports["A"].offset, [0, -20])
+    assert_equal(p.ports["B"].offset, [10, -20])
+
+def test_pather_at_chaining(pather_setup: tuple[Pather, PathTool, Library]) -> None:
+    p, tool, lib = pather_setup
+    p.at("start").straight(10).ccw(10)
+    assert_allclose(p.ports["start"].offset, [1, -20], atol=1e-10)
+    assert p.ports["start"].rotation is not None
+    assert_allclose(p.ports["start"].rotation, pi, atol=1e-10)
+
+def test_pather_dead_ports() -> None:
+    lib = Library()
+    tool = PathTool(layer=(1, 0), width=1)
+    p = Pather(lib, ports={"in": Port((0, 0), 0)}, tools=tool)
+    p.set_dead()
+
+    with pytest.raises(RouteError, match='finite and nonnegative'):
+        p.straight("in", -10)
+
+    assert_allclose(p.ports["in"].offset, [0, 0], atol=1e-10)
+
+    p.straight("in", 20)
+    assert_allclose(p.ports["in"].offset, [-20, 0], atol=1e-10)
+
+    assert not p.pattern.has_shapes()
+
+def test_pather_trace_basic() -> None:
+    lib = Library()
+    tool = PathTool(layer='M1', width=1000)
+    p = Pather(lib, tools=tool)
+
+    # Routing extends opposite the port's inward-facing rotation.
+    p.pattern.ports['A'] = Port((0, 0), rotation=0)
+
+    p.at('A').trace(None, 5000)
+    assert numpy.allclose(p.pattern.ports['A'].offset, (-5000, 0))
+
+    p.at('A').trace(True, 5000) # CCW bend
+    assert numpy.allclose(p.pattern.ports['A'].offset, (-10000, -500))
+    assert p.pattern.ports['A'].rotation is not None
+    assert numpy.isclose(p.pattern.ports['A'].rotation, pi/2)
+
+def test_pather_trace_to() -> None:
+    lib = Library()
+    tool = PathTool(layer='M1', width=1000)
+    p = Pather(lib, tools=tool)
+
+    p.pattern.ports['A'] = Port((0, 0), rotation=0)
+
+    p.at('A').trace_to(None, x=-10000)
+    assert numpy.allclose(p.pattern.ports['A'].offset, (-10000, 0))
+
+    p.at('A').trace_to(None, p=-20000)
+    assert numpy.allclose(p.pattern.ports['A'].offset, (-20000, 0))
+
+def test_pather_bundle_trace() -> None:
+    lib = Library()
+    tool = PathTool(layer='M1', width=1000)
+    p = Pather(lib, tools=tool)
+
+    p.pattern.ports['A'] = Port((0, 0), rotation=0)
+    p.pattern.ports['B'] = Port((0, 2000), rotation=0)
+
+    p.at(['A', 'B']).straight(xmin=-10000)
+    assert numpy.isclose(p.pattern.ports['A'].offset[0], -10000)
+    assert numpy.isclose(p.pattern.ports['B'].offset[0], -10000)
+
+    p.at(['A', 'B']).ccw(xmin=-20000, spacing=2000)
+    # The lower port is on the inner bend, so `xmin` applies to that route.
+    assert numpy.isclose(p.pattern.ports['A'].offset[0], -20000)
+    assert numpy.isclose(p.pattern.ports['B'].offset[0], -22000)
+
+def test_portpather_default_spacing_matches_explicit_spacing() -> None:
+    lib_default = Library()
+    tool_default = PathTool(layer='M1', width=1000)
+    p_default = Pather(lib_default, tools=tool_default)
+    p_default.pattern.ports['A'] = Port((0, 0), rotation=0)
+    p_default.pattern.ports['B'] = Port((0, 2000), rotation=0)
+
+    lib_explicit = Library()
+    tool_explicit = PathTool(layer='M1', width=1000)
+    p_explicit = Pather(lib_explicit, tools=tool_explicit)
+    p_explicit.pattern.ports['A'] = Port((0, 0), rotation=0)
+    p_explicit.pattern.ports['B'] = Port((0, 2000), rotation=0)
+
+    p_default.at(['A', 'B'], spacing=2000).ccw(xmin=-20000)
+    p_explicit.at(['A', 'B']).ccw(xmin=-20000, spacing=2000)
+
+    assert_allclose(p_default.pattern.ports['A'].offset, p_explicit.pattern.ports['A'].offset)
+    assert_allclose(p_default.pattern.ports['B'].offset, p_explicit.pattern.ports['B'].offset)
+
+def test_portpather_default_spacing_reused_and_overridden() -> None:
+    p_default = Pather(Library(), tools=PathTool(layer='M1', width=1000))
+    p_default.pattern.ports['A'] = Port((0, 0), rotation=0)
+    p_default.pattern.ports['B'] = Port((0, 2000), rotation=0)
+
+    p_explicit = Pather(Library(), tools=PathTool(layer='M1', width=1000))
+    p_explicit.pattern.ports['A'] = Port((0, 0), rotation=0)
+    p_explicit.pattern.ports['B'] = Port((0, 2000), rotation=0)
+
+    pp_default = p_default.at(['A', 'B'], spacing=2000)
+    pp_default.ccw(xmin=-20000)
+    pp_default.cw(emin=1000)
+    p_explicit.at(['A', 'B']).ccw(xmin=-20000, spacing=2000).cw(emin=1000, spacing=2000)
+
+    assert_allclose(p_default.pattern.ports['A'].offset, p_explicit.pattern.ports['A'].offset)
+    assert_allclose(p_default.pattern.ports['B'].offset, p_explicit.pattern.ports['B'].offset)
+
+    p_override = Pather(Library(), tools=PathTool(layer='M1', width=1000))
+    p_override.pattern.ports['A'] = Port((0, 0), rotation=0)
+    p_override.pattern.ports['B'] = Port((0, 2000), rotation=0)
+
+    p_override_explicit = Pather(Library(), tools=PathTool(layer='M1', width=1000))
+    p_override_explicit.pattern.ports['A'] = Port((0, 0), rotation=0)
+    p_override_explicit.pattern.ports['B'] = Port((0, 2000), rotation=0)
+
+    p_override.at(['A', 'B'], spacing=2000).ccw(xmin=-20000, spacing=3000)
+    p_override_explicit.at(['A', 'B']).ccw(xmin=-20000, spacing=3000)
+
+    assert_allclose(p_override.pattern.ports['A'].offset, p_override_explicit.pattern.ports['A'].offset)
+    assert_allclose(p_override.pattern.ports['B'].offset, p_override_explicit.pattern.ports['B'].offset)
+
+def test_portpather_default_spacing_not_injected_for_straight_bundle() -> None:
+    lib = Library()
+    tool = PathTool(layer='M1', width=1000)
+    p = Pather(lib, tools=tool)
+    p.pattern.ports['A'] = Port((0, 0), rotation=0)
+    p.pattern.ports['B'] = Port((0, 2000), rotation=0)
+
+    p.at(['A', 'B'], spacing=2000).straight(xmin=-10000)
+
+    assert numpy.isclose(p.pattern.ports['A'].offset[0], -10000)
+    assert numpy.isclose(p.pattern.ports['B'].offset[0], -10000)
+
+def test_portpather_default_spacing_vector_revalidated_after_selection_change() -> None:
+    lib = Library()
+    tool = PathTool(layer='M1', width=1000)
+    p = Pather(lib, tools=tool)
+    p.pattern.ports['A'] = Port((0, 0), rotation=0)
+    p.pattern.ports['B'] = Port((0, 2000), rotation=0)
+    p.pattern.ports['C'] = Port((0, 4000), rotation=0)
+
+    pp = p.at(['A', 'B', 'C'], spacing=[2000, 3000])
+    pp.deselect('C')
+
+    with pytest.raises(BuildError, match='spacing must be scalar or have length 1'):
+        pp.ccw(xmin=-20000)
+
+def test_pather_each_bound() -> None:
+    lib = Library()
+    tool = PathTool(layer='M1', width=1000)
+    p = Pather(lib, tools=tool)
+
+    p.pattern.ports['A'] = Port((0, 0), rotation=0)
+    p.pattern.ports['B'] = Port((-1000, 2000), rotation=0)
+
+    p.at(['A', 'B']).trace(None, each=5000)
+    assert numpy.allclose(p.pattern.ports['A'].offset, (-5000, 0))
+    assert numpy.allclose(p.pattern.ports['B'].offset, (-6000, 2000))
+
+def test_selection_management() -> None:
+    lib = Library()
+    p = Pather(lib)
+    p.pattern.ports['A'] = Port((0, 0), rotation=0)
+    p.pattern.ports['B'] = Port((0, 0), rotation=0)
+
+    pp = p.at('A')
+    assert pp.ports == ['A']
+
+    pp.select('B')
+    assert pp.ports == ['A', 'B']
+
+    pp.deselect('A')
+    assert pp.ports == ['B']
+
+    pp.select(['A'])
+    assert pp.ports == ['B', 'A']
+
+    pp.drop()
+    assert 'A' not in p.pattern.ports
+    assert 'B' not in p.pattern.ports
+    assert pp.ports == []
+
+
+@pytest.mark.parametrize('action', ['plug', 'plugged', 'rename', 'mark', 'fork'])
+def test_empty_selection_exact_one_operations_raise_build_error(action: str) -> None:
+    p = Pather(Library())
+    pp = p.at([])
+    operations = {
+        'plug': lambda: pp.plug('unused', 'A'),
+        'plugged': lambda: pp.plugged('A'),
+        'rename': lambda: pp.rename('new'),
+        'mark': lambda: pp.mark('new'),
+        'fork': lambda: pp.fork('new'),
+        }
+
+    with pytest.raises(BuildError, match='expected exactly one'):
+        operations[action]()
+
+def test_mark_fork() -> None:
+    lib = Library()
+    p = Pather(lib)
+    p.pattern.ports['A'] = Port((100, 200), rotation=1)
+
+    pp = p.at('A')
+    pp.mark('B')
+    assert 'B' in p.pattern.ports
+    assert numpy.allclose(p.pattern.ports['B'].offset, (100, 200))
+    assert p.pattern.ports['B'].rotation == 1
+    assert pp.ports == ['A']
+
+    pp.fork('C')
+    assert 'C' in p.pattern.ports
+    assert pp.ports == ['C']
+
+def test_mark_fork_reject_overwrite_and_duplicate_targets() -> None:
+    lib = Library()
+
+    p_mark = Pather(lib, pattern=Pattern(ports={
+        'A': Port((0, 0), rotation=0),
+        'C': Port((2, 0), rotation=0),
+    }))
+    with pytest.raises(PortError, match='overwrite existing ports'):
+        p_mark.at('A').mark('C')
+    assert numpy.allclose(p_mark.pattern.ports['C'].offset, (2, 0))
+
+    p_fork = Pather(lib, pattern=Pattern(ports={
+        'A': Port((0, 0), rotation=0),
+        'B': Port((1, 0), rotation=0),
+    }))
+    pp = p_fork.at(['A', 'B'])
+    with pytest.raises(PortError, match='targets would collide'):
+        pp.fork({'A': 'X', 'B': 'X'})
+    assert set(p_fork.pattern.ports) == {'A', 'B'}
+    assert pp.ports == ['A', 'B']
+
+def test_mark_fork_dead_overwrite_and_duplicate_targets() -> None:
+    lib = Library()
+    p = Pather(lib, pattern=Pattern(ports={
+        'A': Port((0, 0), rotation=0),
+        'B': Port((1, 0), rotation=0),
+        'C': Port((2, 0), rotation=0),
+    }))
+    p.set_dead()
+
+    p.at('A').mark('C')
+    assert numpy.allclose(p.pattern.ports['C'].offset, (0, 0))
+
+    pp = p.at(['A', 'B'])
+    pp.fork({'A': 'X', 'B': 'X'})
+    assert numpy.allclose(p.pattern.ports['X'].offset, (1, 0))
+    assert pp.ports == ['X']
+
+def test_mark_fork_reject_missing_sources() -> None:
+    lib = Library()
+    p = Pather(lib, pattern=Pattern(ports={
+        'A': Port((0, 0), rotation=0),
+        'B': Port((1, 0), rotation=0),
+    }))
+
+    with pytest.raises(PortError, match='selected ports'):
+        p.at(['A', 'B']).mark({'Z': 'C'})
+
+    with pytest.raises(PortError, match='selected ports'):
+        p.at(['A', 'B']).fork({'Z': 'C'})
+
+def test_rename() -> None:
+    lib = Library()
+    p = Pather(lib)
+    p.pattern.ports['A'] = Port((0, 0), rotation=0)
+
+    p.at('A').rename('B')
+    assert 'A' not in p.pattern.ports
+    assert 'B' in p.pattern.ports
+
+    p.pattern.ports['C'] = Port((0, 0), rotation=0)
+    pp = p.at(['B', 'C'])
+    pp.rename({'B': 'D', 'C': 'E'})
+    assert 'B' not in p.pattern.ports
+    assert 'C' not in p.pattern.ports
+    assert 'D' in p.pattern.ports
+    assert 'E' in p.pattern.ports
+    assert set(pp.ports) == {'D', 'E'}
+
+def test_pather_dead_fallback_preserves_out_ptype() -> None:
+    lib = Library()
+    tool = PathTool(layer='M1', width=1000, ptype='wire')
+    p = Pather(lib, tools=tool)
+    p.pattern.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+    p.set_dead()
+
+    p.straight('A', 1000, out_ptype='other')
+
+    assert numpy.allclose(p.pattern.ports['A'].offset, (-1000, 0))
+    assert p.pattern.ports['A'].ptype == 'other'
+    assert len(p._paths['A']) == 0
+
+def test_pather_dead_fallback_does_not_hide_fatal_route_errors() -> None:
+    class MismatchedEndpointTool(PathTool):
+        def primitive_offers(
+                self,
+                kind,           # noqa: ANN001
+                *,
+                in_ptype=None,  # noqa: ANN001
+                out_ptype=None, # noqa: ANN001,ARG002
+                **kwargs,       # noqa: ANN003
+                ) -> tuple[PrimitiveOffer, ...]:
+            _ = kwargs
+            if kind != 'straight':
+                return ()
+
+            def endpoint(length: float) -> Port:
+                return Port((length, 0), rotation=pi, ptype='wire')
+
+            return (StraightOffer(
+                in_ptype=in_ptype,
+                out_ptype='other',
+                endpoint_planner=endpoint,
+                commit_planner=lambda length: {'length': length},
+                ),)
+
+    p = Pather(Library(), tools=MismatchedEndpointTool(layer='M1', width=1000, ptype='wire'))
+    p.pattern.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+    p.set_dead()
+
+    with pytest.raises(BuildError, match='does not match declared offer out_ptype'):
+        p.straight('A', 1000)
+
+    assert numpy.allclose(p.pattern.ports['A'].offset, (0, 0))
+    assert p.pattern.ports['A'].ptype == 'wire'
+    assert len(p._paths['A']) == 0
+
+
+def test_pather_valid_candidate_does_not_hide_fatal_route_errors() -> None:
+    class PartlyMismatchedEndpointTool(PathTool):
+        def primitive_offers(
+                self,
+                kind,           # noqa: ANN001
+                *,
+                in_ptype=None,  # noqa: ANN001
+                out_ptype=None, # noqa: ANN001,ARG002
+                **kwargs,       # noqa: ANN003
+                ) -> tuple[PrimitiveOffer, ...]:
+            _ = kwargs
+            if kind != 'straight':
+                return ()
+
+            def mismatched_endpoint(length: float) -> Port:
+                ptype = 'wire' if numpy.isclose(length, 0) else 'other'
+                return Port((length, 0), rotation=pi, ptype=ptype)
+
+            def valid_endpoint(length: float) -> Port:
+                return Port((length, 0), rotation=pi, ptype='wire')
+
+            return (
+                StraightOffer(
+                    in_ptype=in_ptype,
+                    out_ptype='wire',
+                    endpoint_planner=mismatched_endpoint,
+                    commit_planner=lambda length: {'kind': 'mismatched', 'length': length},
+                    ),
+                StraightOffer(
+                    in_ptype=in_ptype,
+                    out_ptype='wire',
+                    endpoint_planner=valid_endpoint,
+                    commit_planner=lambda length: {'kind': 'valid', 'length': length},
+                    ),
+                )
+
+    p = Pather(Library(), tools=PartlyMismatchedEndpointTool(layer='M1', width=1000, ptype='wire'))
+    p.pattern.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+
+    with pytest.raises(BuildError, match='does not match declared offer out_ptype'):
+        p.straight('A', 1000)
+
+    assert numpy.allclose(p.pattern.ports['A'].offset, (0, 0))
+    assert p.pattern.ports['A'].ptype == 'wire'
+    assert len(p._paths['A']) == 0
+
+
+def test_pather_dead_place_overwrites_colliding_ports_last_wins() -> None:
+    lib = Library()
+    p = Pather(lib, pattern=Pattern(ports={
+        'A': Port((5, 5), rotation=0),
+        'keep': Port((9, 9), rotation=0),
+    }))
+    p.set_dead()
+
+    other = Pattern()
+    other.ports['X'] = Port((1, 0), rotation=0)
+    other.ports['Y'] = Port((2, 0), rotation=pi / 2)
+
+    p.place(other, port_map={'X': 'A', 'Y': 'A'})
+
+    assert set(p.pattern.ports) == {'A', 'keep'}
+    assert numpy.allclose(p.pattern.ports['A'].offset, (2, 0))
+    assert p.pattern.ports['A'].rotation is not None
+    assert numpy.isclose(p.pattern.ports['A'].rotation, pi / 2)
+
+def test_pather_dead_plug_overwrites_colliding_outputs_last_wins() -> None:
+    lib = Library()
+    tool = PathTool(layer='M1', width=1000, ptype='wire')
+    p = Pather(lib, tools=tool, pattern=Pattern(ports={
+        'A': Port((0, 0), rotation=0, ptype='wire'),
+        'B': Port((99, 99), rotation=0, ptype='wire'),
+    }))
+    p.set_dead()
+
+    other = Pattern()
+    other.ports['in'] = Port((0, 0), rotation=pi, ptype='wire')
+    other.ports['X'] = Port((10, 0), rotation=0, ptype='wire')
+    other.ports['Y'] = Port((20, 0), rotation=0, ptype='wire')
+
+    p.plug(other, map_in={'A': 'in'}, map_out={'X': 'B', 'Y': 'B'})
+
+    assert 'A' not in p.pattern.ports
+    assert 'B' in p.pattern.ports
+    assert numpy.allclose(p.pattern.ports['B'].offset, (20, 0))
+    assert p.pattern.ports['B'].rotation is not None
+    assert numpy.isclose(p.pattern.ports['B'].rotation, 0)
+
+def test_pather_dead_rename_overwrites_colliding_ports_last_wins() -> None:
+    p = Pather(Library(), pattern=Pattern(ports={
+        'A': Port((0, 0), rotation=0),
+        'B': Port((1, 0), rotation=0),
+        'C': Port((2, 0), rotation=0),
+    }))
+    p.set_dead()
+
+    p.rename_ports({'A': 'C', 'B': 'C'})
+
+    assert set(p.pattern.ports) == {'C'}
+    assert numpy.allclose(p.pattern.ports['C'].offset, (1, 0))

masque/test/test_pather_place_plug.py

@@ -0,0 +1,120 @@
+import pytest
+import numpy
+from numpy import pi
+
+from masque import Pather, Library, Pattern, Port
+from masque.builder.tools import PathTool
+from masque.error import PortError, PatternError
+
+
+def test_pather_place_treeview_resolves_once() -> None:
+    lib = Library()
+    tool = PathTool(layer='M1', width=1000)
+    p = Pather(lib, tools=tool, render='deferred')
+
+    tree = {'child': Pattern(ports={'B': Port((1, 0), pi)})}
+
+    p.place(tree)
+
+    assert len(lib) == 1
+    assert 'child' in lib
+    assert 'child' in p.pattern.refs
+    assert 'B' in p.pattern.ports
+
+def test_pather_plug_treeview_resolves_once() -> None:
+    lib = Library()
+    tool = PathTool(layer='M1', width=1000)
+    p = Pather(lib, tools=tool, render='deferred')
+    p.pattern.ports['A'] = Port((0, 0), rotation=0)
+
+    tree = {'child': Pattern(ports={'B': Port((0, 0), pi)})}
+
+    p.plug(tree, {'A': 'B'})
+
+    assert len(lib) == 1
+    assert 'child' in lib
+    assert 'child' in p.pattern.refs
+    assert 'A' not in p.pattern.ports
+
+def test_pather_failed_plug_does_not_add_break_marker() -> None:
+    lib = Library()
+    tool = PathTool(layer='M1', width=1000)
+    p = Pather(lib, tools=tool, render='deferred')
+    p.pattern.annotations = {'k': [1]}
+    p.pattern.ports['A'] = Port((0, 0), rotation=0)
+
+    p.at('A').trace(None, 5000)
+    assert [step.opcode for step in p._paths['A']] == ['L']
+
+    other = Pattern(
+        annotations={'k': [2]},
+        ports={'X': Port((0, 0), pi), 'Y': Port((5, 0), 0)},
+        )
+
+    with pytest.raises(PatternError, match='Annotation keys overlap'):
+        p.plug(other, {'A': 'X'}, map_out={'Y': 'Z'}, append=True)
+
+    assert [step.opcode for step in p._paths['A']] == ['L']
+    assert set(p.pattern.ports) == {'A'}
+
+def test_pather_place_reused_deleted_name_keeps_break_marker() -> None:
+    lib = Library()
+    tool = PathTool(layer='M1', width=1000)
+    p = Pather(lib, tools=tool, render='deferred')
+    p.pattern.ports['A'] = Port((0, 0), rotation=0)
+
+    p.at('A').straight(5000)
+    p.rename_ports({'A': None})
+
+    other = Pattern(ports={'X': Port((-5000, 0), rotation=0)})
+    p.place(other, port_map={'X': 'A'}, append=True)
+    p.at('A').straight(2000)
+
+    assert [step.opcode for step in p._paths['A']] == ['L', 'P', 'L']
+
+    p.render()
+    assert p.pattern.has_shapes()
+    assert 'A' in p.pattern.ports
+    assert numpy.allclose(p.pattern.ports['A'].offset, (-7000, 0))
+
+def test_pather_plug_reused_deleted_name_keeps_break_marker() -> None:
+    lib = Library()
+    tool = PathTool(layer='M1', width=1000)
+    p = Pather(lib, tools=tool, render='deferred')
+    p.pattern.ports['A'] = Port((0, 0), rotation=0)
+    p.pattern.ports['B'] = Port((0, 0), rotation=0)
+
+    p.at('A').straight(5000)
+    p.rename_ports({'A': None})
+
+    other = Pattern(
+        ports={
+            'X': Port((0, 0), rotation=pi),
+            'Y': Port((-5000, 0), rotation=0),
+            },
+        )
+    p.plug(other, {'B': 'X'}, map_out={'Y': 'A'}, append=True)
+    p.at('A').straight(2000)
+
+    assert [step.opcode for step in p._paths['A']] == ['L', 'P', 'L']
+
+    p.render()
+    assert p.pattern.has_shapes()
+    assert 'A' in p.pattern.ports
+    assert 'B' not in p.pattern.ports
+    assert numpy.allclose(p.pattern.ports['A'].offset, (-7000, 0))
+
+def test_pather_failed_plugged_does_not_add_break_marker() -> None:
+    lib = Library()
+    tool = PathTool(layer='M1', width=1000)
+    p = Pather(lib, tools=tool, render='deferred')
+    p.pattern.ports['A'] = Port((0, 0), rotation=0)
+
+    p.at('A').straight(5000)
+    assert [step.opcode for step in p._paths['A']] == ['L']
+
+    with pytest.raises(PortError, match='Connection destination ports were not found'):
+        p.plugged({'A': 'missing'})
+
+    assert [step.opcode for step in p._paths['A']] == ['L']
+    assert set(p._paths) == {'A'}

masque/test/test_pather_primitive_offers.py

@@ -0,0 +1,910 @@
+from collections.abc import Callable
+from dataclasses import dataclass
+from typing import Any, Literal
+
+import numpy
+import pytest
+from numpy import pi
+
+from masque import Library, Path, Port, Pather, ToolContractError
+from masque.builder.planner import RoutingPlanner
+from masque.builder.planner.planner import Solver, SolverRequest
+from masque.builder.tools import (
+    BendOffer,
+    PathTool,
+    PrimitiveOffer,
+    SOffer,
+    StraightOffer,
+    Tool,
+    UOffer,
+)
+from masque.error import BuildError
+from masque.utils import PTypeMatch, ptype_match
+
+
+def offer_callbacks(planner: Callable[[float], tuple[Port, Any]]) -> dict[str, Callable[[float], Any]]:
+    return {
+        'endpoint_planner': lambda parameter: planner(parameter)[0],
+        'commit_planner': lambda parameter: planner(parameter)[1],
+        }
+
+
+class PlanningOnlyTool(Tool):
+    def primitive_offers(
+            self,
+            kind: Literal['straight', 'bend', 's', 'u'],
+            *,
+            in_ptype: str | None = None,
+            out_ptype: str | None = None,
+            **kwargs: Any,
+            ) -> tuple[PrimitiveOffer, ...]:
+        _ = kind, in_ptype, out_ptype, kwargs
+        return ()
+
+    def render(self, batch, *, port_names=('A', 'B'), **kwargs) -> Library:      # noqa: ANN001,ANN202,ARG002
+        tree, pat = Library.mktree('planning_only_tool')
+        pat.add_port_pair(names=port_names, ptype=batch[0].start_port.ptype if batch else 'unk')
+        return tree
+
+
+def test_tool_contract_error_is_fatal_even_when_an_alternate_offer_exists() -> None:
+    class BrokenTool(PlanningOnlyTool):
+        def primitive_offers(self, kind, *, in_ptype=None, out_ptype=None, **kwargs):  # noqa: ANN001,ANN202,ARG002
+            if kind != 'straight':
+                return ()
+            return (
+                StraightOffer(
+                    in_ptype='wire',
+                    out_ptype='wire',
+                    endpoint_planner=lambda length: Port((length, 0), pi, ptype='wrong'),
+                    commit_planner=lambda length: length,
+                    ),
+                StraightOffer.generated('wire', lambda length: length),
+                )
+
+    pather = Pather(
+        Library(),
+        ports={'A': Port((0, 0), rotation=0, ptype='wire')},
+        tools=BrokenTool(),
+        render='deferred',
+        )
+    with pytest.raises(ToolContractError, match='declared offer out_ptype'):
+        pather.straight('A', 5)
+
+
+def test_callback_build_error_remains_recoverable_candidate_rejection() -> None:
+    class RecoverableTool(PlanningOnlyTool):
+        def primitive_offers(self, kind, *, in_ptype=None, out_ptype=None, **kwargs):  # noqa: ANN001,ANN202,ARG002
+            if kind != 'straight':
+                return ()
+
+            def rejected(length: float) -> Port:
+                raise BuildError(f'unsupported length {length}')
+
+            return (
+                StraightOffer(
+                    in_ptype='wire',
+                    out_ptype='wire',
+                    endpoint_planner=rejected,
+                    commit_planner=lambda length: length,
+                    ),
+                StraightOffer.generated('wire', lambda length: length),
+                )
+
+    pather = Pather(
+        Library(),
+        ports={'A': Port((0, 0), rotation=0, ptype='wire')},
+        tools=RecoverableTool(),
+        render='deferred',
+        )
+    pather.straight('A', 5)
+    assert numpy.allclose(pather.ports['A'].offset, (-5, 0))
+
+
+def test_solver_offer_cache_accepts_unhashable_request_tool_options() -> None:
+    class CountingTool(PlanningOnlyTool):
+        calls = 0
+
+        def primitive_offers(self, kind, *, in_ptype=None, out_ptype=None, **kwargs):  # noqa: ANN001,ANN202,ARG002
+            self.calls += 1
+            assert kwargs == {'nested': []}
+            return ()
+
+    tool = CountingTool()
+    solver = Solver(SolverRequest(
+        family='straight',
+        tool=tool,
+        in_ptype='wire',
+        tool_options={'nested': []},
+        ))
+    solver.primitive_offers('straight', 'wire')
+    solver.primitive_offers('straight', 'wire')
+    assert tool.calls == 1
+
+
+def test_solver_finalize_chooses_cheapest_parameter_allocation() -> None:
+    tool = PlanningOnlyTool()
+    solver = Solver(SolverRequest(
+        family='straight',
+        tool=tool,
+        in_ptype='wire',
+        tool_options={},
+        length=10,
+        ))
+    expensive_offer = StraightOffer.generated('wire', lambda length: length, cost=1)
+    cheap_offer = StraightOffer.generated('wire', lambda length: length, cost=0.3)
+    expensive = solver.evaluate(expensive_offer, 0, 'wire', out_ptype=None, role='main')
+    cheap = solver.evaluate(cheap_offer, 0, 'wire', out_ptype=None, role='main')
+
+    for steps in ((expensive, cheap), (cheap, expensive)):
+        candidate = solver.finalize(steps)
+        parameters = {step.offer: step.parameter for step in candidate.steps}
+
+        assert parameters[cheap_offer] == pytest.approx(10)
+        assert parameters[expensive_offer] == pytest.approx(0)
+        assert candidate.cost == pytest.approx(3)
+
+
+def test_solver_strategy_rank_covers_all_main_steps_and_ignores_adapters() -> None:
+    tool = PlanningOnlyTool()
+    straight_first = Solver(SolverRequest(
+        family='s',
+        tool=tool,
+        in_ptype='wire',
+        tool_options={},
+        strategy='straight_first',
+        ))
+    turn_first = Solver(SolverRequest(
+        family='s',
+        tool=tool,
+        in_ptype='wire',
+        tool_options={},
+        strategy='turn_first',
+        ))
+    straight_offer = StraightOffer.generated('wire', lambda length: length)
+    bend_offer = BendOffer.prebuilt(
+        'wire',
+        'wire',
+        Port((1, 1), 3 * pi / 2, ptype='wire'),
+        None,
+        ccw=True,
+        )
+    adapter_offer = StraightOffer.prebuilt(
+        'wire',
+        'adapted',
+        Port((1, 0), pi, ptype='adapted'),
+        None,
+        )
+    straight = straight_first.evaluate(straight_offer, 0, 'wire', out_ptype=None, role='main')
+    turn = straight_first.evaluate(bend_offer, 1, 'wire', out_ptype=None, role='main')
+    adapter = straight_first.evaluate(adapter_offer, 1, 'wire', out_ptype=None, role='adapter')
+    alternating = (straight, turn, adapter, straight, turn)
+    delayed_straight = (straight, turn, adapter, turn, straight)
+
+    assert straight_first.strategy_rank(alternating) < straight_first.strategy_rank(delayed_straight)
+    assert turn_first.strategy_rank(delayed_straight) < turn_first.strategy_rank(alternating)
+    assert straight_first.strategy_rank(alternating) == straight_first.strategy_rank(
+        (straight, turn, straight, turn),
+        )
+    assert straight_first.strategy_rank((straight,)) < straight_first.strategy_rank((turn,))
+    assert turn_first.strategy_rank((turn,)) < turn_first.strategy_rank((straight,))
+
+
+def test_tool_requires_primitive_offers_override() -> None:
+    class RenderOnlyTool(Tool):
+        def render(self, batch, *, port_names=('A', 'B'), **kwargs) -> Library:      # noqa: ANN001,ANN202,ARG002
+            return Library()
+
+    with pytest.raises(TypeError):
+        RenderOnlyTool()
+
+
+def test_tool_base_primitive_offers_is_not_no_offer_fallback() -> None:
+    class BaseCallingTool(Tool):
+        def primitive_offers(
+                self,
+                kind: Literal['straight', 'bend', 's', 'u'],
+                *,
+                in_ptype: str | None = None,
+                out_ptype: str | None = None,
+                **kwargs: Any,
+                ) -> tuple[PrimitiveOffer, ...]:
+            return Tool.primitive_offers(self, kind, in_ptype=in_ptype, out_ptype=out_ptype, **kwargs)
+
+        def render(self, batch, *, port_names=('A', 'B'), **kwargs) -> Library:      # noqa: ANN001,ANN202,ARG002
+            return Library()
+
+    with pytest.raises(NotImplementedError):
+        BaseCallingTool().primitive_offers('straight')
+
+
+def canonicalize_offer_parameter(value: float, domain: tuple[float, float]) -> float:
+    offer = StraightOffer(in_ptype='wire', out_ptype='wire', length_domain=domain)
+    return offer.canonicalize_parameter(value)
+
+
+def test_offer_canonicalize_parameter_half_open_and_singleton() -> None:
+    assert canonicalize_offer_parameter(-1e-13, (0, 10)) == 0
+    assert canonicalize_offer_parameter(3, (0, 10)) == 3
+
+    with pytest.raises(BuildError, match='outside half-open domain'):
+        canonicalize_offer_parameter(10, (0, 10))
+
+    assert canonicalize_offer_parameter(5 + 1e-13, (5, 5)) == 5
+
+    with pytest.raises(BuildError, match='outside singleton domain'):
+        canonicalize_offer_parameter(5.1, (5, 5))
+
+
+@pytest.mark.parametrize('value', [numpy.nan, numpy.inf, -numpy.inf])
+def test_offer_canonicalize_parameter_rejects_non_finite_parameter(value: float) -> None:
+    with pytest.raises(BuildError, match='must be finite'):
+        canonicalize_offer_parameter(value, (0, 10))
+
+
+def test_offer_canonicalize_parameter_rejects_reversed_domain() -> None:
+    with pytest.raises(BuildError, match='lower bound must not exceed upper bound'):
+        StraightOffer(in_ptype='wire', out_ptype='wire', length_domain=(10, 0))
+
+
+@pytest.mark.parametrize('domain', [(numpy.nan, 1), (1, numpy.nan), (numpy.inf, numpy.inf)])
+def test_offer_rejects_invalid_domain_at_construction(domain: tuple[float, float]) -> None:
+    with pytest.raises(BuildError, match='domain'):
+        StraightOffer(in_ptype='wire', out_ptype='wire', length_domain=domain)
+
+
+@pytest.mark.parametrize('domain', [(-1, 2), (-numpy.inf, 2)])
+def test_length_offer_requires_finite_nonnegative_minimum(domain: tuple[float, float]) -> None:
+    with pytest.raises(BuildError, match='finite, nonnegative minimum'):
+        StraightOffer(in_ptype='wire', out_ptype='wire', length_domain=domain)
+
+
+def test_ptype_match_distinguishes_exact_wildcard_and_mismatch() -> None:
+    assert ptype_match('wire', 'wire') is PTypeMatch.EXACT
+    assert ptype_match(None, 'wire') is PTypeMatch.WILDCARD
+    assert ptype_match('unk', 'wire') is PTypeMatch.WILDCARD
+    assert ptype_match('wire', 'metal') is PTypeMatch.MISMATCH
+
+
+def test_offer_split_endpoint_and_commit_callbacks_are_independent() -> None:
+    endpoint_calls: list[float] = []
+    commit_calls: list[float] = []
+
+    def endpoint(length: float) -> Port:
+        endpoint_calls.append(length)
+        return Port((length, 2), rotation=pi, ptype='wire')
+
+    def commit(length: float) -> dict[str, float]:
+        commit_calls.append(length)
+        return {'length': length}
+
+    offer = StraightOffer(
+        in_ptype='wire',
+        out_ptype='wire',
+        length_domain=(5, 5),
+        endpoint_planner=endpoint,
+        commit_planner=commit,
+        )
+
+    assert numpy.allclose(offer.endpoint_at(5 + 1e-13).offset, (5, 2))
+    assert offer.cost_at(5 + 1e-13) == 5 + pi
+    assert commit_calls == []
+
+    assert offer.commit(5 + 1e-13) == {'length': 5}
+    assert endpoint_calls == [5, 5]
+    assert commit_calls == [5]
+
+
+def test_straight_offer_generated_factory_uses_default_endpoint_and_data_bbox() -> None:
+    def data_at(length: float) -> dict[str, float]:
+        return {'length': length}
+
+    offer = StraightOffer.generated(
+        'wire',
+        data_at,
+        length_domain=(2, 8),
+        cost=3,
+        bbox_for_data=lambda data: numpy.array([[0, 0], [data['length'], 1]]),
+        )
+
+    endpoint = offer.endpoint_at(4)
+
+    assert offer.length_domain == (2, 8)
+    assert offer.cost == 3
+    assert offer.cost_at(4) == 12
+    assert numpy.allclose(endpoint.offset, [4, 0])
+    assert endpoint.rotation == pi
+    assert endpoint.ptype == 'wire'
+    assert offer.commit(4) == {'length': 4}
+    assert numpy.allclose(offer.bbox_at(4), [[0, 0], [4, 1]])
+
+
+def test_s_offer_generated_factory_keeps_endpoint_and_commit_data_independent() -> None:
+    def endpoint_at(jog: float) -> Port:
+        return Port((10, jog), rotation=pi, ptype='wire')
+
+    def data_at(jog: float) -> dict[str, Any]:
+        return {'jog': abs(jog), 'mirrored': jog < 0}
+
+    offer = SOffer.generated(
+        'wire',
+        endpoint_at,
+        data_at,
+        jog_domain=(-5, 5),
+        bbox_for_data=lambda data: numpy.array([[0, -data['jog']], [10, data['jog']]]),
+        )
+
+    endpoint = offer.endpoint_at(-3)
+
+    assert numpy.allclose(endpoint.offset, [10, -3])
+    assert offer.commit(-3) == {'jog': 3, 'mirrored': True}
+    assert numpy.allclose(offer.bbox_at(-3), [[0, -3], [10, 3]])
+
+
+def test_bend_offer_generated_factory_uses_explicit_endpoint_and_data_bbox() -> None:
+    def endpoint_at(length: float) -> Port:
+        return Port((length, length), rotation=-pi / 2, ptype='wire')
+
+    def data_at(length: float) -> dict[str, float]:
+        return {'length': length}
+
+    offer = BendOffer.generated(
+        'wire',
+        endpoint_at,
+        data_at,
+        ccw=True,
+        length_domain=(4, 4),
+        bbox_for_data=lambda data: numpy.array([[0, 0], [data['length'], data['length']]]),
+        )
+
+    endpoint = offer.endpoint_at(4)
+
+    assert offer.ccw
+    assert offer.length_domain == (4, 4)
+    assert numpy.allclose(endpoint.offset, [4, 4])
+    assert endpoint.rotation == 3 * pi / 2
+    assert offer.commit(4) == {'length': 4}
+    assert numpy.allclose(offer.bbox_at(4), [[0, 0], [4, 4]])
+
+
+def test_u_offer_generated_factory_uses_explicit_endpoint_and_data_bbox() -> None:
+    def endpoint_at(jog: float) -> Port:
+        return Port((12, jog), rotation=0, ptype='wire')
+
+    def data_at(jog: float) -> dict[str, float]:
+        return {'jog': jog}
+
+    offer = UOffer.generated(
+        'wire',
+        endpoint_at,
+        data_at,
+        jog_domain=(-6, 6),
+        bbox_for_data=lambda data: numpy.array([[0, min(0, data['jog'])], [12, max(0, data['jog'])]]),
+        )
+
+    endpoint = offer.endpoint_at(-4)
+
+    assert offer.jog_domain == (-6, 6)
+    assert numpy.allclose(endpoint.offset, [12, -4])
+    assert endpoint.rotation == 0
+    assert offer.commit(-4) == {'jog': -4}
+    assert numpy.allclose(offer.bbox_at(-4), [[0, -4], [12, 0]])
+
+
+def test_prebuilt_offer_factories_return_fresh_endpoint_copies() -> None:
+    data = {'kind': 'prebuilt'}
+    bbox_for_data = lambda _data: numpy.array([[-1, -2], [6, 3]])      # noqa: E731
+    endpoint = Port((5, 2), rotation=pi / 2, ptype='out')
+    cases = [
+        (StraightOffer.prebuilt('in', 'out', endpoint, data, bbox_for_data=bbox_for_data), 5),
+        (BendOffer.prebuilt('in', 'out', endpoint, data, ccw=True, bbox_for_data=bbox_for_data), 5),
+        (SOffer.prebuilt('in', 'out', endpoint, data, bbox_for_data=bbox_for_data), 2),
+        (UOffer.prebuilt('in', 'out', endpoint, data, bbox_for_data=bbox_for_data), 2),
+        ]
+
+    for offer, parameter in cases:
+        first = offer.endpoint_at(parameter)
+        first.offset[:] = 99
+        second = offer.endpoint_at(parameter)
+
+        assert numpy.allclose(second.offset, [5, 2])
+        assert second.rotation == pi / 2
+        assert second.ptype == 'out'
+        assert offer.commit(parameter) is data
+        assert numpy.allclose(offer.bbox_at(parameter), [[-1, -2], [6, 3]])
+
+
+@pytest.mark.parametrize('cost', [-1, numpy.inf, numpy.nan, 'expensive'])
+def test_offer_rejects_invalid_cost_factor(cost: Any) -> None:
+    with pytest.raises(BuildError, match='cost factor'):
+        StraightOffer(in_ptype='wire', out_ptype='wire', cost=cost)
+
+
+@pytest.mark.parametrize('result', [-1, numpy.inf, numpy.nan, 'expensive'])
+def test_offer_rejects_invalid_callable_cost_result(result: Any) -> None:
+    offer = StraightOffer(
+        in_ptype='wire',
+        out_ptype='wire',
+        cost=lambda _parameter, _endpoint: result,
+        **offer_callbacks(lambda length: (Port((length, 0), rotation=pi, ptype='wire'), None)),
+        )
+
+    with pytest.raises(BuildError, match='Primitive cost'):
+        offer.cost_at(5)
+
+
+def test_offer_callable_cost_replaces_default_cost() -> None:
+    seen: list[tuple[float, Port]] = []
+
+    def cost(parameter: float, endpoint: Port) -> float:
+        seen.append((parameter, endpoint))
+        return parameter + endpoint.y
+
+    offer = SOffer(
+        in_ptype='wire',
+        out_ptype='wire',
+        cost=cost,
+        jog_domain=(2, 2),
+        **offer_callbacks(lambda jog: (Port((10, jog), rotation=pi, ptype='wire'), None)),
+        )
+
+    assert offer.cost_at(2 + 1e-13) == 4
+    assert seen[0][0] == 2
+    assert numpy.allclose(seen[0][1].offset, (10, 2))
+
+
+def test_offer_rejects_one_sided_split_callbacks() -> None:
+    def endpoint(length: float) -> Port:
+        return Port((length, 0), rotation=pi, ptype='wire')
+
+    with pytest.raises(BuildError, match='require both'):
+        StraightOffer(in_ptype='wire', out_ptype='wire', endpoint_planner=endpoint)
+
+
+def test_offer_bbox_at_validates_bounds() -> None:
+    offer = StraightOffer(
+        in_ptype='wire',
+        out_ptype='wire',
+        bbox_planner=lambda _length: numpy.array([[0, 0], [1, 2]]),
+        **offer_callbacks(lambda length: (Port((length, 0), rotation=pi, ptype='wire'), {'length': length})),
+        )
+
+    assert numpy.allclose(offer.bbox_at(3), [[0, 0], [1, 2]])
+
+    bad = StraightOffer(
+        in_ptype='wire',
+        out_ptype='wire',
+        bbox_planner=lambda _length: numpy.array([0, 1]),
+        **offer_callbacks(lambda length: (Port((length, 0), rotation=pi, ptype='wire'), {'length': length})),
+        )
+    with pytest.raises(BuildError, match='shape'):
+        bad.bbox_at(3)
+
+
+def test_pathtool_straight_offer_bbox_matches_path_bounds() -> None:
+    tool = PathTool(layer=(1, 0), width=2, ptype='wire')
+    offer = tool.primitive_offers('straight', in_ptype='wire')[0]
+
+    bounds = offer.bbox_at(10)
+    expected = Path(vertices=[(0, 0), (10, 0)], width=2).get_bounds_single()
+
+    assert numpy.allclose(bounds, expected)
+
+
+def test_pathtool_bend_offer_bbox_matches_path_bounds() -> None:
+    tool = PathTool(layer=(1, 0), width=2, ptype='wire')
+    offer = tool.primitive_offers('bend', in_ptype='wire', ccw=True)[0]
+
+    bounds = offer.bbox_at(1)
+    expected = Path(vertices=[(0, 0), (1, 0), (1, 1)], width=2).get_bounds_single()
+
+    assert isinstance(offer, BendOffer)
+    assert offer.length_domain == (1, 1)
+    assert numpy.allclose(bounds, expected)
+
+
+def test_pathtool_s_offer_bbox_uses_intrinsic_minimum_length() -> None:
+    tool = PathTool(layer=(1, 0), width=2, ptype='wire')
+    offer = tool.primitive_offers('s', in_ptype='wire')[0]
+
+    bounds = offer.bbox_at(3)
+    expected = Path(vertices=[(0, 0), (1, 0), (1, 3), (2, 3)], width=2).get_bounds_single()
+
+    assert isinstance(offer, SOffer)
+    assert numpy.allclose(bounds, expected)
+
+
+def test_pathtool_u_offers_remain_unsupported() -> None:
+    tool = PathTool(layer=(1, 0), width=2, ptype='wire')
+
+    assert tool.primitive_offers('u', in_ptype='wire') == ()
+
+
+@pytest.mark.parametrize(
+    ('kind', 'kwargs'),
+    [
+        ('straight', {}),
+        ('bend', {'ccw': True}),
+        ('s', {}),
+    ],
+)
+def test_pathtool_out_ptype_unk_is_wildcard(
+        kind: Literal['straight', 'bend', 's'],
+        kwargs: dict[str, Any],
+        ) -> None:
+    tool = PathTool(layer=(1, 0), width=2, ptype='wire')
+
+    offers = tool.primitive_offers(kind, in_ptype='wire', out_ptype='unk', **kwargs)
+
+    assert offers
+    assert offers[0].out_ptype == 'wire'
+
+
+def test_pathtool_rejects_unsupported_planning_options() -> None:
+    tool = PathTool(layer='M1', width=1)
+    with pytest.raises(BuildError, match='does not support tool options: marker'):
+        tool.primitive_offers('straight', marker='sentinel')
+
+
+def test_pather_treats_notimplemented_offer_query_as_no_offers() -> None:
+    class NoOfferTool(PlanningOnlyTool):
+        def primitive_offers(
+                self,
+                kind: Literal['straight', 'bend', 's', 'u'],
+                *,
+                in_ptype: str | None = None,
+                out_ptype: str | None = None,
+                **kwargs: Any,
+                ) -> tuple[PrimitiveOffer, ...]:
+            _ = kind, in_ptype, out_ptype, kwargs
+            raise NotImplementedError
+
+    p = Pather(Library(), tools=NoOfferTool())
+    p.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+
+    with pytest.raises(BuildError, match='No legal primitive offer for trace'):
+        p.straight('A', 5)
+
+
+@pytest.mark.parametrize('err_type', [BuildError, KeyError, TypeError])
+def test_pather_propagates_offer_query_errors(err_type: type[Exception]) -> None:
+    class BrokenTool(PlanningOnlyTool):
+        def primitive_offers(
+                self,
+                kind: Literal['straight', 'bend', 's', 'u'],
+                *,
+                in_ptype: str | None = None,
+                out_ptype: str | None = None,
+                **kwargs: Any,
+                ) -> tuple[PrimitiveOffer, ...]:
+            _ = kind, in_ptype, out_ptype, kwargs
+            raise err_type('offer query failed')
+
+    p = Pather(Library(), tools=BrokenTool())
+    p.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+
+    with pytest.raises(err_type):
+        p.straight('A', 5)
+
+
+def test_pather_selects_lowest_cost_offer() -> None:
+    class MultiOfferTool(PlanningOnlyTool):
+        def primitive_offers(
+                self,
+                kind: Literal['straight', 'bend', 's', 'u'],
+                *,
+                in_ptype: str | None = None,
+                out_ptype: str | None = None,
+                **kwargs: Any,
+                ) -> tuple[PrimitiveOffer, ...]:
+            _ = kwargs
+            if kind != 'straight':
+                return ()
+
+            def high(length: float) -> tuple[Port, dict[str, str | float]]:
+                return Port((length, 0), rotation=pi, ptype=out_ptype or in_ptype), {'kind': 'high'}
+
+            def low(length: float) -> tuple[Port, dict[str, str | float]]:
+                return Port((length, 0), rotation=pi, ptype=out_ptype or in_ptype), {'kind': 'low'}
+
+            return (
+                StraightOffer(in_ptype=in_ptype, out_ptype=out_ptype, cost=10, **offer_callbacks(high)),
+                StraightOffer(in_ptype=in_ptype, out_ptype=out_ptype, cost=1, **offer_callbacks(low)),
+                )
+
+    p = Pather(Library(), tools=MultiOfferTool(), render='deferred')
+    p.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+
+    p.straight('A', 7)
+
+    assert p._paths['A'][0].data == {'kind': 'low'}
+    assert numpy.allclose(p.ports['A'].offset, (-7, 0))
+
+
+def test_planner_deduplication_distinguishes_offer_costs() -> None:
+    @dataclass(frozen=True, slots=True)
+    class MarkedStraightOffer(StraightOffer):
+        marker: str = ''
+
+        def commit(self, parameter: float) -> dict[str, str | float]:
+            return {'kind': self.marker, 'length': self.canonicalize_parameter(parameter)}
+
+    def endpoint(length: float) -> Port:
+        return Port((length, 0), rotation=pi, ptype='wire')
+
+    def shared_commit(length: float) -> dict[str, float]:
+        return {'length': length}
+
+    class DuplicateGeometryTool(PlanningOnlyTool):
+        def primitive_offers(
+                self,
+                kind: Literal['straight', 'bend', 's', 'u'],
+                *,
+                in_ptype: str | None = None,
+                out_ptype: str | None = None,
+                **kwargs: Any,
+                ) -> tuple[PrimitiveOffer, ...]:
+            _ = kwargs
+            if kind != 'straight':
+                return ()
+            common = {
+                'in_ptype': in_ptype,
+                'out_ptype': out_ptype,
+                'endpoint_planner': endpoint,
+                'commit_planner': shared_commit,
+                }
+            return (
+                MarkedStraightOffer(cost=100, marker='expensive', **common),
+                MarkedStraightOffer(cost=1, marker='cheap', **common),
+                )
+
+    pather = Pather(Library(), tools=DuplicateGeometryTool(), render='deferred')
+    pather.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+
+    pather.straight('A', 7)
+
+    assert pather._paths['A'][0].data == {'kind': 'cheap', 'length': 7}
+
+
+class StrategyTieTool(PlanningOnlyTool):
+    def __init__(self) -> None:
+        self.seen_kwargs: list[dict[str, Any]] = []
+
+    def primitive_offers(
+            self,
+            kind: Literal['straight', 'bend', 's', 'u'],
+            *,
+            in_ptype: str | None = None,
+            out_ptype: str | None = None,
+            **kwargs: Any,
+            ) -> tuple[PrimitiveOffer, ...]:
+        self.seen_kwargs.append(dict(kwargs))
+        endpoint_ptype = out_ptype or in_ptype
+        marker = kwargs.get('marker')
+        if kind == 'straight':
+            return (StraightOffer(
+                in_ptype=in_ptype,
+                out_ptype=endpoint_ptype,
+                **offer_callbacks(lambda length: (
+                    Port((length, 0), rotation=pi, ptype=endpoint_ptype),
+                    {'kind': 'straight', 'length': length, 'marker': marker},
+                    )),
+                ),)
+        if kind == 's':
+            return (SOffer(
+                in_ptype=in_ptype,
+                out_ptype=endpoint_ptype,
+                **offer_callbacks(lambda jog: (
+                    Port((3, jog), rotation=pi, ptype=endpoint_ptype),
+                    {'kind': 's', 'jog': jog, 'marker': marker},
+                    )),
+                ),)
+        return ()
+
+
+def pather_with_strategy_tool(
+        planner: RoutingPlanner | None = None,
+        ) -> tuple[Pather, StrategyTieTool]:
+    tool = StrategyTieTool()
+    pather = Pather(Library(), tools=tool, planner=planner, render='deferred')
+    pather.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+    return pather, tool
+
+
+def test_pather_route_strategy_defaults_to_straight_first() -> None:
+    pather, _tool = pather_with_strategy_tool()
+
+    pather.jog('A', 4, length=10)
+
+    assert [step.data['kind'] for step in pather._paths['A']] == ['straight', 's']
+    assert pather._paths['A'][0].data['length'] == 7
+
+
+def test_pather_route_strategy_uses_planner_default() -> None:
+    pather, _tool = pather_with_strategy_tool(RoutingPlanner(strategy='turn_first'))
+
+    pather.jog('A', 4, length=10)
+
+    assert [step.data['kind'] for step in pather._paths['A']] == ['s', 'straight']
+    assert pather._paths['A'][1].data['length'] == 7
+
+
+def test_pather_route_strategy_per_route_overrides_planner_default() -> None:
+    pather, _tool = pather_with_strategy_tool(RoutingPlanner(strategy='turn_first'))
+
+    pather.jog('A', 4, length=10, plan_options={'strategy': 'straight_first'})
+
+    assert [step.data['kind'] for step in pather._paths['A']] == ['straight', 's']
+
+
+def test_pather_route_strategy_per_route_can_request_turn_first() -> None:
+    pather, _tool = pather_with_strategy_tool()
+
+    pather.jog('A', 4, length=10, plan_options={'strategy': 'turn_first'})
+
+    assert [step.data['kind'] for step in pather._paths['A']] == ['s', 'straight']
+
+
+def test_pather_plan_options_are_not_forwarded_to_tool() -> None:
+    pather, tool = pather_with_strategy_tool()
+
+    pather.jog(
+        'A',
+        4,
+        length=10,
+        plan_options={'strategy': 'turn_first'},
+        tool_options={'marker': 'sentinel'},
+        )
+
+    assert tool.seen_kwargs
+    assert all('strategy' not in kwargs for kwargs in tool.seen_kwargs)
+    assert any(kwargs.get('marker') == 'sentinel' for kwargs in tool.seen_kwargs)
+    assert all(step.data['marker'] == 'sentinel' for step in pather._paths['A'])
+
+
+def test_pather_route_strategy_rejects_invalid_values() -> None:
+    with pytest.raises(BuildError, match='Invalid route strategy'):
+        RoutingPlanner(strategy='sideways')
+
+    pather, _tool = pather_with_strategy_tool()
+    with pytest.raises(BuildError, match='Invalid route strategy'):
+        pather.jog('A', 4, length=10, plan_options={'strategy': 'sideways'})
+
+
+def test_solver_rejects_rotation_impossible_candidates_before_parameter_solving() -> None:
+    invalid_parameters: list[float] = []
+
+    class RotationOfferTool(PlanningOnlyTool):
+        def primitive_offers(
+                self,
+                kind: Literal['straight', 'bend', 's', 'u'],
+                *,
+                in_ptype: str | None = None,
+                out_ptype: str | None = None,
+                **kwargs: Any,
+                ) -> tuple[PrimitiveOffer, ...]:
+            _ = kwargs
+            if kind != 'straight':
+                return ()
+
+            def invalid_endpoint(length: float) -> Port:
+                invalid_parameters.append(length)
+                return Port((length, 0), rotation=0, ptype=out_ptype or in_ptype)
+
+            def valid_endpoint(length: float) -> Port:
+                return Port((length, 0), rotation=pi, ptype=out_ptype or in_ptype)
+
+            return (
+                StraightOffer(
+                    in_ptype=in_ptype,
+                    out_ptype=out_ptype,
+                    endpoint_planner=invalid_endpoint,
+                    commit_planner=lambda length: {'kind': 'invalid', 'length': length},
+                    ),
+                StraightOffer(
+                    in_ptype=in_ptype,
+                    out_ptype=out_ptype,
+                    endpoint_planner=valid_endpoint,
+                    commit_planner=lambda length: {'kind': 'valid', 'length': length},
+                    ),
+                )
+
+    p = Pather(Library(), tools=RotationOfferTool(), render='deferred')
+    p.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+
+    p.straight('A', 7)
+
+    assert p._paths['A'][0].data == {'kind': 'valid', 'length': 7}
+    assert invalid_parameters == [0.0]
+
+
+def test_pather_commits_only_selected_offer() -> None:
+    committed: list[str] = []
+
+    class RecordingTool(PlanningOnlyTool):
+        def primitive_offers(
+                self,
+                kind: Literal['straight', 'bend', 's', 'u'],
+                *,
+                in_ptype: str | None = None,
+                out_ptype: str | None = None,
+                **kwargs: Any,
+                ) -> tuple[PrimitiveOffer, ...]:
+            _ = kwargs
+            if kind != 'straight':
+                return ()
+
+            def make(label: str, cost: float) -> StraightOffer:
+                def endpoint(length: float) -> Port:
+                    return Port((length, 0), rotation=pi, ptype=out_ptype or in_ptype)
+
+                def commit(length: float) -> dict[str, float | str]:
+                    committed.append(label)
+                    return {'kind': label, 'length': length}
+
+                return StraightOffer(
+                    in_ptype=in_ptype,
+                    out_ptype=out_ptype,
+                    cost=cost,
+                    endpoint_planner=endpoint,
+                    commit_planner=commit,
+                    )
+
+            return (make('expensive', 100), make('cheap', 1))
+
+    p = Pather(Library(), tools=RecordingTool(), render='deferred')
+    p.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+
+    p.straight('A', 5)
+
+    assert committed == ['cheap']
+    assert p._paths['A'][0].data == {'kind': 'cheap', 'length': 5}
+
+
+def test_pather_routes_with_offer_only_s_and_u_tool() -> None:
+    class OfferOnlyTool(PlanningOnlyTool):
+        def primitive_offers(
+                self,
+                kind: Literal['straight', 'bend', 's', 'u'],
+                *,
+                in_ptype: str | None = None,
+                out_ptype: str | None = None,
+                **kwargs: Any,
+                ) -> tuple[PrimitiveOffer, ...]:
+            _ = kwargs
+            endpoint_ptype = out_ptype or in_ptype
+            if kind == 'straight':
+                return (StraightOffer(
+                    in_ptype=in_ptype,
+                    out_ptype=endpoint_ptype,
+                    **offer_callbacks(lambda length: (
+                        Port((length, 0), rotation=pi, ptype=endpoint_ptype),
+                        {'kind': 'straight', 'length': length},
+                        )),
+                    ),)
+            if kind == 's':
+                return (SOffer(
+                    in_ptype=in_ptype,
+                    out_ptype=endpoint_ptype,
+                    **offer_callbacks(lambda jog: (
+                        Port((5, jog), rotation=pi, ptype=endpoint_ptype),
+                        {'kind': 's', 'jog': jog},
+                        )),
+                    ),)
+            if kind == 'u':
+                return (UOffer(
+                    in_ptype=in_ptype,
+                    out_ptype=endpoint_ptype,
+                    **offer_callbacks(lambda jog: (
+                        Port((2, jog), rotation=0, ptype=endpoint_ptype),
+                        {'kind': 'u', 'jog': jog},
+                        )),
+                    ),)
+            return ()
+
+    p = Pather(Library(), tools=OfferOnlyTool(), render='deferred')
+    p.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+    p.jog('A', 3)
+    p.uturn('A', 4)
+
+    assert [step.data['kind'] for step in p._paths['A']] == ['s', 'u']

masque/test/test_pather_rendering.py

@@ -0,0 +1,627 @@
+from typing import TYPE_CHECKING, cast
+import logging
+
+import pytest
+import numpy
+from numpy import pi
+from numpy.testing import assert_allclose
+
+from ..builder import Pather, RouteError, ToolContractError
+from ..builder.tools import PathTool, RenderStep, StraightOffer, Tool
+from ..error import BuildError
+from ..library import Library
+from ..pattern import Pattern
+from ..ports import Port
+
+if TYPE_CHECKING:
+    from ..shapes import Path
+
+
+@pytest.fixture
+def deferred_render_setup() -> tuple[Pather, PathTool, Library]:
+    lib = Library()
+    tool = PathTool(layer=(1, 0), width=2, ptype="wire")
+    rp = Pather(lib, tools=tool, render='deferred')
+    rp.ports["start"] = Port((0, 0), pi / 2, ptype="wire")
+    return rp, tool, lib
+
+
+def add_pending_straight(pather: Pather) -> None:
+    pather.ports["start"] = Port((0, 0), pi / 2, ptype="wire")
+    pather.straight("start", 10)
+
+
+def route_in_context(pather: Pather) -> None:
+    with pather:
+        add_pending_straight(pather)
+
+
+def fail_in_context(pather: Pather) -> None:
+    with pather:
+        add_pending_straight(pather)
+        raise RuntimeError('body failed')
+
+
+def test_deferred_render_stores_pending_paths_until_render(deferred_render_setup: tuple[Pather, PathTool, Library]) -> None:
+    rp, tool, lib = deferred_render_setup
+    rp.at("start").straight(10).straight(10)
+
+    assert not rp.pattern.has_shapes()
+    assert len(rp._paths["start"]) == 2
+
+    rp.render()
+    assert rp.pattern.has_shapes()
+    assert len(rp.pattern.shapes[(1, 0)]) == 1
+
+    # PathTool renders length steps in the port extension direction.
+    path_shape = cast("Path", rp.pattern.shapes[(1, 0)][0])
+    assert len(path_shape.vertices) == 3
+    assert_allclose(path_shape.vertices, [[0, 0], [0, -10], [0, -20]], atol=1e-10)
+
+def test_deferred_render_bend(deferred_render_setup: tuple[Pather, PathTool, Library]) -> None:
+    rp, tool, lib = deferred_render_setup
+    rp.at("start").straight(10).cw(10)
+
+    rp.render()
+    path_shape = cast("Path", rp.pattern.shapes[(1, 0)][0])
+    # The bend route is explicit straight run plus a fixed-size bend.
+    assert len(path_shape.vertices) == 5
+    assert_allclose(path_shape.vertices, [[0, 0], [0, -10], [0, -19], [0, -20], [-1, -20]], atol=1e-10)
+
+def test_deferred_render_jog_uses_lowest_cost_two_bend_route(deferred_render_setup: tuple[Pather, PathTool, Library]) -> None:
+    rp, tool, lib = deferred_render_setup
+    rp.at("start").jog(4, length=10)
+
+    assert [step.opcode for step in rp._paths["start"]] == ["L", "L", "L", "L"]
+
+    rp.render()
+    path_shape = cast("Path", rp.pattern.shapes[(1, 0)][0])
+    assert_allclose(path_shape.vertices, [[0, 0], [0, -8], [0, -9], [1, -9], [3, -9], [4, -9], [4, -10]], atol=1e-10)
+    assert_allclose(rp.ports["start"].offset, [4, -10], atol=1e-10)
+
+def test_deferred_render_mirror_preserves_planned_bend_geometry(deferred_render_setup: tuple[Pather, PathTool, Library]) -> None:
+    rp, tool, lib = deferred_render_setup
+    rp.at("start").straight(10).cw(10)
+
+    rp.mirror(0)
+    rp.render()
+
+    path_shape = cast("Path", rp.pattern.shapes[(1, 0)][0])
+    assert_allclose(path_shape.vertices, [[0, 0], [0, 10], [0, 19], [0, 20], [-1, 20]], atol=1e-10)
+
+def test_deferred_render_retool(deferred_render_setup: tuple[Pather, PathTool, Library]) -> None:
+    rp, tool1, lib = deferred_render_setup
+    tool2 = PathTool(layer=(2, 0), width=4, ptype="wire")
+
+    rp.at("start").straight(10)
+    rp.retool(tool2, keys=["start"])
+    rp.at("start").straight(10)
+
+    rp.render()
+    assert len(rp.pattern.shapes[(1, 0)]) == 1
+    assert len(rp.pattern.shapes[(2, 0)]) == 1
+
+
+def test_deferred_render_batches_tools_by_identity() -> None:
+    class CountingTool(PathTool):
+        def __init__(self, *args, **kwargs) -> None:  # noqa: ANN002,ANN003
+            super().__init__(*args, **kwargs)
+            self.render_calls = 0
+
+        def render(self, *args, **kwargs):  # noqa: ANN002,ANN003,ANN202
+            self.render_calls += 1
+            return super().render(*args, **kwargs)
+
+    lib = Library()
+    tool1 = CountingTool(layer=(1, 0), width=2, ptype='wire')
+    tool2 = CountingTool(layer=(1, 0), width=2, ptype='wire')
+    assert tool1 == tool2
+    assert tool1 is not tool2
+    p = Pather(
+        lib,
+        ports={'A': Port((0, 0), rotation=0, ptype='wire')},
+        tools=tool1,
+        render='deferred',
+        )
+
+    p.straight('A', 5)
+    p.retool(tool2, 'A')
+    p.straight('A', 5)
+    p.render()
+
+    assert tool1.render_calls == 1
+    assert tool2.render_calls == 1
+    assert len(p.pattern.shapes[(1, 0)]) == 2
+
+
+def test_deleted_name_reuse_does_not_retarget_pending_render_steps() -> None:
+    lib = Library()
+    tool = PathTool(layer=(1, 0), width=2, ptype='wire')
+    p = Pather(
+        lib,
+        ports={'A': Port((0, 0), rotation=0, ptype='wire')},
+        tools=tool,
+        render='deferred',
+        )
+
+    p.straight('A', 5)
+    original_step = p._paths['A'][0]
+    p.rename_ports({'A': None})
+    p.mkport('A', Port((100, 0), rotation=0, ptype='wire'))
+    p.straight('A', 5)
+
+    assert len(p._paths['A']) == 2
+    assert_allclose(original_step.start_port.offset, (0, 0))
+    assert_allclose(original_step.end_port.offset, (-5, 0))
+    assert_allclose(p._paths['A'][1].start_port.offset, (100, 0))
+
+def test_portpather_translate_only_affects_future_steps(deferred_render_setup: tuple[Pather, PathTool, Library]) -> None:
+    rp, tool, lib = deferred_render_setup
+    pp = rp.at("start")
+    pp.straight(10)
+    pp.translate((5, 0))
+    pp.straight(10)
+
+    rp.render()
+
+    shapes = rp.pattern.shapes[(1, 0)]
+    assert len(shapes) == 2
+    assert_allclose(cast("Path", shapes[0]).vertices, [[0, 0], [0, -10]], atol=1e-10)
+    assert_allclose(cast("Path", shapes[1]).vertices, [[5, -10], [5, -20]], atol=1e-10)
+    assert_allclose(rp.ports["start"].offset, [5, -20], atol=1e-10)
+
+def test_deferred_render_dead_ports() -> None:
+    lib = Library()
+    tool = PathTool(layer=(1, 0), width=1)
+    rp = Pather(lib, ports={"in": Port((0, 0), 0)}, tools=tool, render='deferred')
+    rp.set_dead()
+
+    with pytest.raises(RouteError, match='finite and nonnegative'):
+        rp.straight("in", -10)
+
+    assert_allclose(rp.ports["in"].offset, [0, 0], atol=1e-10)
+
+    assert len(rp._paths["in"]) == 0
+
+    rp.render()
+    assert not rp.pattern.has_shapes()
+
+
+def test_pather_default_auto_policy_renders_immediately_outside_context() -> None:
+    lib = Library()
+    tool = PathTool(layer=(1, 0), width=2, ptype="wire")
+    p = Pather(lib, tools=tool)
+    p.ports["start"] = Port((0, 0), pi / 2, ptype="wire")
+
+    p.straight("start", 10)
+
+    assert p.pattern.has_shapes()
+    assert not any(p._paths.values())
+
+
+def test_pather_default_auto_policy_defers_until_clean_context_exit() -> None:
+    lib = Library()
+    tool = PathTool(layer=(1, 0), width=2, ptype="wire")
+
+    with Pather(lib, tools=tool) as p:
+        add_pending_straight(p)
+        assert not p.pattern.has_shapes()
+        assert len(p._paths["start"]) == 1
+
+    assert p.pattern.has_shapes()
+    assert not any(p._paths.values())
+
+
+def test_pather_context_warn_policy_logs_pending_paths(caplog: pytest.LogCaptureFixture) -> None:
+    lib = Library()
+    tool = PathTool(layer=(1, 0), width=2, ptype="wire")
+
+    with caplog.at_level(logging.WARNING, logger="masque.builder.pather"), Pather(lib, tools=tool, render='warn') as p:
+        add_pending_straight(p)
+
+    records = [
+        record
+        for record in caplog.records
+        if 'Pather context exited with 1 pending render step on 1 port' in record.getMessage()
+        ]
+    assert len(records) == 1
+    assert records[0].stack_info is None
+    assert len(p._paths["start"]) == 1
+    assert not p.pattern.has_shapes()
+
+
+def test_pather_context_error_policy_rejects_pending_paths() -> None:
+    lib = Library()
+    tool = PathTool(layer=(1, 0), width=2, ptype="wire")
+    p = Pather(lib, tools=tool, render='error')
+
+    with pytest.raises(BuildError, match='1 pending render step on 1 port'):
+        route_in_context(p)
+
+    assert len(p._paths["start"]) == 1
+    assert not p.pattern.has_shapes()
+
+
+def test_pather_context_ignore_policy_leaves_pending_paths_silent(caplog: pytest.LogCaptureFixture) -> None:
+    lib = Library()
+    tool = PathTool(layer=(1, 0), width=2, ptype="wire")
+
+    with caplog.at_level(logging.WARNING, logger="masque.builder.pather"), Pather(lib, tools=tool, render='ignore') as p:
+        add_pending_straight(p)
+
+    assert not caplog.records
+    assert len(p._paths["start"]) == 1
+    assert not p.pattern.has_shapes()
+
+
+def test_pather_context_policy_does_not_mask_body_exception() -> None:
+    lib = Library()
+    tool = PathTool(layer=(1, 0), width=2, ptype="wire")
+    p = Pather(lib, tools=tool, render='error')
+
+    with pytest.raises(RuntimeError, match='body failed'):
+        fail_in_context(p)
+
+    assert len(p._paths["start"]) == 1
+    assert not p.pattern.has_shapes()
+
+
+def test_pather_rejects_invalid_render_policy() -> None:
+    with pytest.raises(BuildError, match='Invalid render policy'):
+        Pather(Library(), tools=PathTool(layer=(1, 0), width=2), render='later')  # type: ignore[arg-type]
+
+
+def test_deferred_render_rename_port(deferred_render_setup: tuple[Pather, PathTool, Library]) -> None:
+    rp, tool, lib = deferred_render_setup
+    rp.at("start").straight(10)
+    rp.rename_ports({"start": "new_start"})
+    rp.at("new_start").straight(10)
+
+    assert "start" not in rp._paths
+    assert len(rp._paths["new_start"]) == 2
+
+    rp.render()
+    assert rp.pattern.has_shapes()
+    assert len(rp.pattern.shapes[(1, 0)]) == 1
+    path_shape = cast("Path", rp.pattern.shapes[(1, 0)][0])
+    assert_allclose(path_shape.vertices, [[0, 0], [0, -10], [0, -20]], atol=1e-10)
+    assert "new_start" in rp.ports
+    assert_allclose(rp.ports["new_start"].offset, [0, -20], atol=1e-10)
+
+def test_deferred_render_drop_keeps_pending_geometry_without_port(deferred_render_setup: tuple[Pather, PathTool, Library]) -> None:
+    rp, tool, lib = deferred_render_setup
+    rp.at("start").straight(10).drop()
+
+    assert "start" not in rp.ports
+    assert len(rp._paths["start"]) == 1
+
+    rp.render()
+    assert rp.pattern.has_shapes()
+    assert "start" not in rp.ports
+    path_shape = cast("Path", rp.pattern.shapes[(1, 0)][0])
+    assert_allclose(path_shape.vertices, [[0, 0], [0, -10]], atol=1e-10)
+
+def test_pathtool_bend_offer_render_geometry_matches_ports() -> None:
+    tool = PathTool(layer=(1, 0), width=2, ptype="wire")
+
+    offer = tool.primitive_offers("bend", in_ptype="wire", ccw=True)[0]
+    start = Port((0, 0), rotation=pi, ptype="wire")
+    end = offer.endpoint_at(1)
+    tree = tool.render((RenderStep(offer.kind, tool, start, end, offer.commit(1)),))
+    pat = tree.top_pattern()
+    path_shape = cast("Path", pat.shapes[(1, 0)][0])
+
+    assert offer.length_domain == (1, 1)
+    assert_allclose(path_shape.vertices, [[0, 0], [1, 0], [1, 1]], atol=1e-10)
+    assert_allclose(pat.ports["B"].offset, [1, 1], atol=1e-10)
+
+def test_pathtool_s_offer_render_geometry_matches_ports() -> None:
+    tool = PathTool(layer=(1, 0), width=2, ptype="wire")
+
+    offer = tool.primitive_offers("s", in_ptype="wire")[0]
+    start = Port((0, 0), rotation=pi, ptype="wire")
+    end = offer.endpoint_at(4)
+    tree = tool.render((RenderStep(offer.kind, tool, start, end, offer.commit(4)),))
+    pat = tree.top_pattern()
+    path_shape = cast("Path", pat.shapes[(1, 0)][0])
+
+    assert_allclose(path_shape.vertices, [[0, 0], [1, 0], [1, 4], [2, 4]], atol=1e-10)
+    assert_allclose(pat.ports["B"].offset, [2, 4], atol=1e-10)
+    assert_allclose(pat.ports["B"].rotation, pi, atol=1e-10)
+
+def test_deferred_render_uturn_fallback() -> None:
+    lib = Library()
+    tool = PathTool(layer='M1', width=1000)
+    rp = Pather(lib, tools=tool, render='deferred')
+    rp.pattern.ports['A'] = Port((0, 0), rotation=0)
+
+    rp.at('A').uturn(offset=10000, length=5000)
+
+    assert len(rp._paths['A']) == 4
+    assert [step.opcode for step in rp._paths['A']] == ['L', 'L', 'L', 'L']
+
+    rp.render()
+    assert rp.pattern.ports['A'].rotation is not None
+    assert numpy.isclose(rp.pattern.ports['A'].rotation, pi)
+
+def test_pather_render_auto_renames_single_use_tool_children() -> None:
+    class FullTreeTool(Tool):
+        def primitive_offers(self, kind, *, in_ptype=None, out_ptype=None, **kwargs):    # noqa: ANN001,ANN202,ARG002
+            if kind != 'straight':
+                return ()
+            ptype = out_ptype or in_ptype or 'wire'
+            return (StraightOffer(
+                in_ptype=in_ptype,
+                out_ptype=ptype,
+                endpoint_planner=lambda length: Port((length, 0), rotation=pi, ptype=ptype),
+                commit_planner=lambda length: {'length': length},
+                ),)
+
+        def render(self, batch, *, port_names=('A', 'B'), **kwargs) -> Library:      # noqa: ANN001,ANN202,ARG002
+            length = batch[0].data['length']
+            tree = Library()
+            top = Pattern(ports={
+                port_names[0]: Port((0, 0), 0, ptype='wire'),
+                port_names[1]: Port((length, 0), pi, ptype='wire'),
+                })
+            child = Pattern(annotations={'batch': [len(batch)]})
+            top.ref('_seg')
+            tree['_top'] = top
+            tree['_seg'] = child
+            return tree
+
+    lib = Library()
+    p = Pather(lib, tools=FullTreeTool())
+    p.pattern.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+
+    p.straight('A', 10)
+    p.render()
+    p.straight('A', 10)
+    p.render()
+
+    assert len(lib) == 2
+    assert set(lib.keys()) == set(p.pattern.refs.keys())
+    assert len(set(p.pattern.refs.keys())) == 2
+    assert all(name.startswith('_seg') for name in lib)
+    assert p.pattern.referenced_patterns() <= set(lib.keys())
+
+def test_custom_tool_render_preserves_segment_subtrees() -> None:
+    class TraceTreeTool(Tool):
+        def primitive_offers(self, kind, *, in_ptype=None, out_ptype=None, **kwargs):    # noqa: ANN001,ANN202,ARG002
+            if kind != 'straight':
+                return ()
+            ptype = out_ptype or in_ptype or 'wire'
+            return (StraightOffer(
+                in_ptype=in_ptype,
+                out_ptype=ptype,
+                endpoint_planner=lambda length: Port((length, 0), rotation=pi, ptype=ptype),
+                commit_planner=lambda length: self._trace(length),
+                ),)
+
+        def _trace(self, length, *, port_names=('A', 'B')) -> Library:   # noqa: ANN001
+            tree = Library()
+            top = Pattern(ports={
+                port_names[0]: Port((0, 0), 0, ptype='wire'),
+                    port_names[1]: Port((length, 0), pi, ptype='wire'),
+                })
+            child = Pattern(annotations={'length': [length]})
+            top.ref('_seg')
+            tree['_top'] = top
+            tree['_seg'] = child
+            return tree
+
+        def render(self, batch, *, port_names=('A', 'B'), **kwargs) -> Library:      # noqa: ANN001,ANN202,ARG002
+            assert len(batch) == 1
+            assert isinstance(batch[0].data, Library)
+            return batch[0].data
+
+    lib = Library()
+    p = Pather(lib, tools=TraceTreeTool())
+    p.pattern.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+
+    p.straight('A', 10)
+    p.render()
+
+    assert '_seg' in lib
+    assert '_seg' in p.pattern.refs
+    assert p.pattern.referenced_patterns() <= set(lib.keys())
+
+def test_pather_render_rejects_missing_single_use_tool_refs() -> None:
+    class MissingSingleUseTool(Tool):
+        def primitive_offers(self, kind, *, in_ptype=None, out_ptype=None, **kwargs):    # noqa: ANN001,ANN202,ARG002
+            if kind != 'straight':
+                return ()
+            ptype = out_ptype or in_ptype or 'wire'
+            return (StraightOffer(
+                in_ptype=in_ptype,
+                out_ptype=ptype,
+                endpoint_planner=lambda length: Port((length, 0), rotation=pi, ptype=ptype),
+                commit_planner=lambda length: {'length': length},
+                ),)
+
+        def render(self, batch, *, port_names=('A', 'B'), **kwargs) -> Library:      # noqa: ANN001,ANN202,ARG002
+            tree = Library()
+            top = Pattern(ports={
+                port_names[0]: Port((0, 0), 0, ptype='wire'),
+                port_names[1]: Port((1, 0), pi, ptype='wire'),
+                })
+            top.ref('_seg')
+            tree['_top'] = top
+            return tree
+
+    lib = Library()
+    lib['_seg'] = Pattern(annotations={'stale': [1]})
+    p = Pather(lib, tools=MissingSingleUseTool(), render='deferred')
+    p.pattern.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+    p.straight('A', 10)
+
+    with pytest.raises(BuildError, match='missing single-use refs'):
+        p.render()
+
+    assert list(lib.keys()) == ['_seg']
+    assert not p.pattern.refs
+
+def test_pather_render_allows_missing_non_single_use_tool_refs() -> None:
+    class SharedRefTool(Tool):
+        def primitive_offers(self, kind, *, in_ptype=None, out_ptype=None, **kwargs):    # noqa: ANN001,ANN202,ARG002
+            if kind != 'straight':
+                return ()
+            ptype = out_ptype or in_ptype or 'wire'
+            return (StraightOffer(
+                in_ptype=in_ptype,
+                out_ptype=ptype,
+                endpoint_planner=lambda length: Port((length, 0), rotation=pi, ptype=ptype),
+                commit_planner=lambda length: {'length': length},
+                ),)
+
+        def render(self, batch, *, port_names=('A', 'B'), **kwargs) -> Library:      # noqa: ANN001,ANN202,ARG002
+            length = batch[0].data['length']
+            tree = Library()
+            top = Pattern(ports={
+                port_names[0]: Port((0, 0), 0, ptype='wire'),
+                    port_names[1]: Port((length, 0), pi, ptype='wire'),
+                })
+            top.ref('shared')
+            tree['_top'] = top
+            return tree
+
+    lib = Library()
+    lib['shared'] = Pattern(annotations={'shared': [1]})
+    p = Pather(lib, tools=SharedRefTool())
+    p.pattern.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+
+    p.straight('A', 10)
+    p.render()
+
+    assert 'shared' in p.pattern.refs
+    assert p.pattern.referenced_patterns() <= set(lib.keys())
+
+@pytest.mark.parametrize('append', [True, False])
+def test_pather_render_rejects_output_port_that_misses_planned_endpoint(append: bool) -> None:
+    class WrongEndpointTool(Tool):
+        def primitive_offers(self, kind, *, in_ptype=None, out_ptype=None, **kwargs):    # noqa: ANN001,ANN202,ARG002
+            if kind != 'straight':
+                return ()
+            ptype = out_ptype or in_ptype or 'wire'
+            return (StraightOffer(
+                in_ptype=in_ptype,
+                out_ptype=ptype,
+                endpoint_planner=lambda length: Port((length, 0), rotation=pi, ptype=ptype),
+                commit_planner=lambda length: {'length': length},
+                ),)
+
+        def render(self, batch, *, port_names=('A', 'B'), **kwargs) -> Library:      # noqa: ANN001,ANN202,ARG002
+            length = batch[0].data['length']
+            tree = Library()
+            tree['_top'] = Pattern(ports={
+                port_names[0]: Port((0, 0), 0, ptype='wire'),
+                port_names[1]: Port((length + 1, 0), pi, ptype='wire'),
+                })
+            return tree
+
+    lib = Library()
+    p = Pather(lib, tools=WrongEndpointTool(), render='deferred')
+    p.pattern.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+    p.straight('A', 10)
+
+    with pytest.raises(BuildError, match='does not match planned endpoint'):
+        p.render(append=append)
+
+    assert not p.pattern.refs
+    assert not lib
+
+
+def test_pather_render_rejects_opposite_output_rotation() -> None:
+    class WrongRotationTool(Tool):
+        def primitive_offers(self, kind, *, in_ptype=None, out_ptype=None, **kwargs):  # noqa: ANN001,ANN202,ARG002
+            if kind != 'straight':
+                return ()
+            return (StraightOffer.generated('wire', lambda length: length),)
+
+        def render(self, batch, *, port_names=('A', 'B'), **kwargs) -> Library:  # noqa: ANN001,ANN202,ARG002
+            length = batch[0].data
+            tree = Library()
+            tree['_top'] = Pattern(ports={
+                port_names[0]: Port((0, 0), 0, ptype='wire'),
+                port_names[1]: Port((length, 0), 0, ptype='wire'),
+                })
+            return tree
+
+    p = Pather(Library(), tools=WrongRotationTool(), render='deferred')
+    p.pattern.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+    p.straight('A', 10)
+
+    with pytest.raises(ToolContractError, match='does not match planned endpoint'):
+        p.render()
+
+
+def test_pather_render_allows_unspecified_output_rotation() -> None:
+    class UnspecifiedRotationTool(Tool):
+        def primitive_offers(self, kind, *, in_ptype=None, out_ptype=None, **kwargs):  # noqa: ANN001,ANN202,ARG002
+            if kind != 'straight':
+                return ()
+            return (StraightOffer.generated('wire', lambda length: length),)
+
+        def render(self, batch, *, port_names=('A', 'B'), **kwargs) -> Library:  # noqa: ANN001,ANN202,ARG002
+            length = batch[0].data
+            tree = Library()
+            tree['_top'] = Pattern(ports={
+                port_names[0]: Port((0, 0), 0, ptype='wire'),
+                port_names[1]: Port((length, 0), None, ptype='wire'),
+                })
+            return tree
+
+    p = Pather(Library(), tools=UnspecifiedRotationTool(), render='deferred')
+    p.pattern.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+    p.straight('A', 10)
+    p.render()
+
+@pytest.mark.parametrize('append', [True, False])
+def test_pather_render_rejects_output_port_with_wrong_ptype(append: bool) -> None:
+    class WrongPtypeTool(Tool):
+        def primitive_offers(self, kind, *, in_ptype=None, out_ptype=None, **kwargs):    # noqa: ANN001,ANN202,ARG002
+            if kind != 'straight':
+                return ()
+            ptype = out_ptype or in_ptype or 'wire'
+            return (StraightOffer(
+                in_ptype=in_ptype,
+                out_ptype=ptype,
+                endpoint_planner=lambda length: Port((length, 0), rotation=pi, ptype=ptype),
+                commit_planner=lambda length: {'length': length},
+                ),)
+
+        def render(self, batch, *, port_names=('A', 'B'), **kwargs) -> Library:      # noqa: ANN001,ANN202,ARG002
+            length = batch[0].data['length']
+            tree = Library()
+            tree['_top'] = Pattern(ports={
+                port_names[0]: Port((0, 0), 0, ptype='wire'),
+                port_names[1]: Port((length, 0), 0, ptype='metal'),
+                })
+            return tree
+
+    lib = Library()
+    p = Pather(lib, tools=WrongPtypeTool(), render='deferred')
+    p.pattern.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+    p.straight('A', 10)
+
+    with pytest.raises(BuildError, match='does not match planned endpoint'):
+        p.render(append=append)
+
+    assert not p.pattern.refs
+    assert not lib
+
+def test_deferred_render_rename_to_none_keeps_pending_geometry_without_port() -> None:
+    lib = Library()
+    tool = PathTool(layer='M1', width=1000)
+    rp = Pather(lib, tools=tool, render='deferred')
+    rp.pattern.ports['A'] = Port((0, 0), rotation=0)
+
+    rp.at('A').straight(5000)
+    rp.rename_ports({'A': None})
+
+    assert 'A' not in rp.pattern.ports
+    assert len(rp._paths['A']) == 1
+
+    rp.render()
+    assert rp.pattern.has_shapes()
+    assert 'A' not in rp.pattern.ports

masque/test/test_pather_route_completion.py

@@ -0,0 +1,166 @@
+from collections.abc import Mapping, Sequence
+from typing import Any, Literal
+
+import numpy
+import pytest
+
+from masque import Library, Pather, Port
+from masque.builder import PathTool, RenderStep, RouteCompletionCallback, Tool
+from masque.error import BuildError
+
+
+def test_route_completion_can_label_before_automatic_render() -> None:
+    calls = 0
+
+    def label_endpoints(pather: Pather, endpoints: Mapping[str, Port]) -> None:
+        nonlocal calls
+        calls += 1
+        assert not pather.pattern.has_shapes()
+        assert numpy.allclose(pather.ports['A'].offset, endpoints['A'].offset)
+        for name, port in endpoints.items():
+            pather.label('LABELS', string=name, offset=port.offset)
+
+    callback: RouteCompletionCallback = label_endpoints
+    p = Pather(
+        Library(),
+        tools=PathTool(layer='M1', width=1, ptype='wire'),
+        on_route_complete=callback,
+        )
+    p.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+
+    p.at('A').straight(5)
+
+    assert calls == 1
+    assert p.pattern.has_shapes()
+    assert len(p.pattern.labels['LABELS']) == 1
+    assert p.pattern.labels['LABELS'][0].string == 'A'
+    assert numpy.allclose(p.pattern.labels['LABELS'][0].offset, p.ports['A'].offset)
+
+
+def test_bundle_route_completion_is_ordered_read_only_and_isolated() -> None:
+    calls: list[Mapping[str, Port]] = []
+
+    def record(pather: Pather, endpoints: Mapping[str, Port]) -> None:
+        _ = pather
+        calls.append(endpoints)
+        with pytest.raises(TypeError):
+            endpoints['extra'] = Port((0, 0))  # type: ignore[index]
+        endpoints['B'].translate((100, 100))
+
+    p = Pather(
+        Library(),
+        tools=PathTool(layer='M1', width=1, ptype='wire'),
+        render='deferred',
+        on_route_complete=record,
+        )
+    p.ports['B'] = Port((0, 2), rotation=0, ptype='wire')
+    p.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+
+    p.trace(['A', 'B'], None, each=5)
+
+    assert len(calls) == 1
+    assert list(calls[0]) == ['A', 'B']
+    assert numpy.allclose(p.ports['A'].offset, (-5, 0))
+    assert numpy.allclose(p.ports['B'].offset, (-5, 2))
+
+
+def test_trace_into_completion_retains_consumed_source_endpoint() -> None:
+    calls: list[Mapping[str, Port]] = []
+
+    def record(pather: Pather, endpoints: Mapping[str, Port]) -> None:
+        assert set(pather.ports) == {'src'}
+        assert numpy.allclose(pather.ports['src'].offset, (20, 0))
+        calls.append(endpoints)
+
+    p = Pather(
+        Library(),
+        tools=PathTool(layer='M1', width=1, ptype='wire'),
+        render='deferred',
+        on_route_complete=record,
+        )
+    p.ports['src'] = Port((0, 0), rotation=0, ptype='wire')
+    p.ports['dst'] = Port((-10, 0), rotation=numpy.pi, ptype='wire')
+    p.ports['thru'] = Port((20, 0), rotation=0, ptype='wire')
+
+    p.trace_into('src', 'dst', thru='thru')
+
+    assert len(calls) == 1
+    assert list(calls[0]) == ['src']
+    assert numpy.allclose(calls[0]['src'].offset, (-10, 0))
+
+
+def test_route_completion_exception_propagates_before_render() -> None:
+    def fail(pather: Pather, endpoints: Mapping[str, Port]) -> None:
+        _ = pather, endpoints
+        raise RuntimeError('completion failed')
+
+    p = Pather(
+        Library(),
+        tools=PathTool(layer='M1', width=1, ptype='wire'),
+        on_route_complete=fail,
+        )
+    p.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+
+    with pytest.raises(RuntimeError, match='completion failed'):
+        p.straight('A', 5)
+
+    assert numpy.allclose(p.ports['A'].offset, (-5, 0))
+    assert p._paths['A']
+    assert not p.pattern.has_shapes()
+
+
+class NoRouteTool(Tool):
+    def primitive_offers(
+            self,
+            kind: Literal['straight', 'bend', 's', 'u'],
+            **kwargs: Any,
+            ) -> tuple[()]:
+        _ = kind, kwargs
+        return ()
+
+    def render(
+            self,
+            batch: Sequence[RenderStep],
+            *,
+            port_names: tuple[str, str] = ('A', 'B'),
+            **kwargs: Any,
+            ) -> Library:
+        _ = batch, port_names, kwargs
+        return Library()
+
+
+def test_dead_bundle_fallback_invokes_route_completion_once() -> None:
+    calls: list[Mapping[str, Port]] = []
+    p = Pather(
+        Library(),
+        tools=NoRouteTool(),
+        on_route_complete=lambda _pather, endpoints: calls.append(endpoints),
+        )
+    p.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+    p.ports['B'] = Port((0, 2), rotation=0, ptype='wire')
+    p.set_dead()
+
+    p.trace(['B', 'A'], None, each=5)
+
+    assert len(calls) == 1
+    assert list(calls[0]) == ['B', 'A']
+    assert numpy.allclose(calls[0]['B'].offset, (-5, 2))
+    assert numpy.allclose(calls[0]['A'].offset, (-5, 0))
+    assert not p.pattern.has_shapes()
+
+
+def test_failed_route_does_not_invoke_route_completion() -> None:
+    calls = 0
+
+    def record(pather: Pather, endpoints: Mapping[str, Port]) -> None:
+        nonlocal calls
+        _ = pather, endpoints
+        calls += 1
+
+    p = Pather(Library(), tools=NoRouteTool(), on_route_complete=record)
+    p.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+
+    with pytest.raises(BuildError):
+        p.straight('A', 5)
+
+    assert calls == 0

masque/test/test_pather_trace_into.py

@@ -0,0 +1,573 @@
+from typing import Any
+
+import numpy
+import pytest
+from numpy import pi
+from numpy.testing import assert_equal
+
+from masque import Library, PathTool, Port, Pather, RouteFailurePolicy
+from masque.builder.planner import PreparedRouteResult, RoutePlanningError, RoutePortContext, RoutingPlanner
+from masque.builder.planner.planner import Candidate, SolverRequest
+from masque.builder.tools import BendOffer, PrimitiveOffer, StraightOffer, Tool
+from masque.error import BuildError, PortError
+
+
+@pytest.fixture
+def trace_into_setup() -> tuple[Pather, PathTool, Library]:
+    lib = Library()
+    tool = PathTool(layer=(1, 0), width=2, ptype="wire")
+    p = Pather(lib, tools=tool, render='immediate', render_append=False)
+    return p, tool, lib
+
+
+def test_path_into_straight(trace_into_setup: tuple[Pather, PathTool, Library]) -> None:
+    p, _tool, _lib = trace_into_setup
+    p.ports["src"] = Port((0, 0), 0, ptype="wire")
+    p.ports["dst"] = Port((-20, 0), pi, ptype="wire")
+
+    p.trace_into("src", "dst")
+
+    assert "src" not in p.ports
+    assert "dst" not in p.ports
+    assert len(p.pattern.refs) == 1
+
+
+def test_path_into_bend(trace_into_setup: tuple[Pather, PathTool, Library]) -> None:
+    p, _tool, _lib = trace_into_setup
+    p.ports["src"] = Port((0, 0), 0, ptype="wire")
+    p.ports["dst"] = Port((-20, -20), 3 * pi / 2, ptype="wire")
+
+    p.trace_into("src", "dst")
+
+    assert "src" not in p.ports
+    assert "dst" not in p.ports
+    assert len(p.pattern.refs) == 1
+
+
+def test_path_into_sbend(trace_into_setup: tuple[Pather, PathTool, Library]) -> None:
+    p, _tool, _lib = trace_into_setup
+    p.ports["src"] = Port((0, 0), 0, ptype="wire")
+    p.ports["dst"] = Port((-20, -10), pi, ptype="wire")
+
+    p.trace_into("src", "dst")
+
+    assert "src" not in p.ports
+    assert "dst" not in p.ports
+
+
+def test_path_into_thru(trace_into_setup: tuple[Pather, PathTool, Library]) -> None:
+    p, _tool, _lib = trace_into_setup
+    p.ports["src"] = Port((0, 0), 0, ptype="wire")
+    p.ports["dst"] = Port((-20, 0), pi, ptype="wire")
+    p.ports["other"] = Port((10, 10), 0)
+
+    p.trace_into("src", "dst", thru="other")
+
+    assert "src" in p.ports
+    assert_equal(p.ports["src"].offset, [10, 10])
+    assert "other" not in p.ports
+
+
+def test_pather_trace_into_shapes() -> None:
+    lib = Library()
+    tool = PathTool(layer='M1', width=1000)
+    p = Pather(lib, tools=tool)
+
+    p.pattern.ports['A'] = Port((0, 0), rotation=0)
+    p.pattern.ports['B'] = Port((-10000, 0), rotation=pi)
+    p.at('A').trace_into('B', plug_destination=False)
+    assert 'B' in p.pattern.ports
+    assert 'A' in p.pattern.ports
+    assert numpy.allclose(p.pattern.ports['A'].offset, (-10000, 0))
+
+    p.pattern.ports['C'] = Port((0, 0), rotation=0)
+    p.pattern.ports['D'] = Port((-5000, 5000), rotation=pi / 2)
+    p.at('C').trace_into('D', plug_destination=False)
+    assert 'D' in p.pattern.ports
+    assert 'C' in p.pattern.ports
+    assert numpy.allclose(p.pattern.ports['C'].offset, (-5000, 5000))
+
+    p.pattern.ports['E'] = Port((0, 0), rotation=0)
+    p.pattern.ports['F'] = Port((-10000, 2000), rotation=pi)
+    p.at('E').trace_into('F', plug_destination=False)
+    assert 'F' in p.pattern.ports
+    assert 'E' in p.pattern.ports
+    assert numpy.allclose(p.pattern.ports['E'].offset, (-10000, 2000))
+
+    p.pattern.ports['G'] = Port((0, 0), rotation=0)
+    p.pattern.ports['H'] = Port((-10000, 2000), rotation=0)
+    p.at('G').trace_into('H', plug_destination=False)
+    assert 'H' in p.pattern.ports
+    assert 'G' in p.pattern.ports
+    assert numpy.allclose(p.pattern.ports['G'].offset, (-10000, 2000))
+    assert p.pattern.ports['G'].rotation is not None
+    assert numpy.isclose(p.pattern.ports['G'].rotation, pi)
+
+    p.pattern.ports['I'] = Port((0, 0), rotation=pi / 2)
+    p.pattern.ports['J'] = Port((0, -10000), rotation=3 * pi / 2)
+    p.at('I').trace_into('J', plug_destination=False)
+    assert 'J' in p.pattern.ports
+    assert 'I' in p.pattern.ports
+    assert numpy.allclose(p.pattern.ports['I'].offset, (0, -10000))
+    assert p.pattern.ports['I'].rotation is not None
+    assert numpy.isclose(p.pattern.ports['I'].rotation, pi / 2)
+
+
+@pytest.mark.parametrize(
+    'dst',
+    [
+        Port((-10_000, 0), rotation=pi),
+        Port((-10_000, 2_000), rotation=pi),
+        Port((-5_000, 5_000), rotation=pi / 2),
+        Port((-10_000, 2_000), rotation=0),
+    ],
+)
+def test_pather_trace_into_minimal_policy_accepts_required_topologies(dst: Port) -> None:
+    pather = Pather(
+        Library(),
+        tools=PathTool(layer='M1', width=1_000),
+        render='deferred',
+        )
+    pather.ports['src'] = Port((0, 0), rotation=0)
+    pather.ports['dst'] = dst
+
+    pather.trace_into(
+        'src',
+        'dst',
+        plug_destination=False,
+        plan_options={'bend_policy': 'minimal'},
+        )
+
+    assert numpy.allclose(pather.ports['src'].offset, dst.offset)
+    assert pather.ports['src'].rotation is not None
+    assert numpy.isclose((pather.ports['src'].rotation - dst.rotation) % (2 * pi), pi)
+
+
+def test_pather_trace_into_bend_policy_changes_real_solver_fallback() -> None:
+    def make_pather() -> Pather:
+        pather = Pather(
+            Library(),
+            tools=PathTool(layer='M1', width=2, ptype='wire'),
+            render='deferred',
+            )
+        pather.ports['src'] = Port((0, 0), rotation=0, ptype='wire')
+        pather.ports['dst'] = Port((2, 0), rotation=pi, ptype='wire')
+        return pather
+
+    flexible = make_pather()
+    flexible.at('src').trace_into(
+        'dst',
+        plug_destination=False,
+        plan_options={'bend_policy': 'flexible'},
+        )
+
+    assert_equal(flexible.ports['src'].offset, (2, 0))
+    assert flexible.ports['src'].rotation is not None
+    assert numpy.isclose(flexible.ports['src'].rotation, 0)
+    bend_roles = sum(
+        1 if step.kind == 'bend' else 2 if step.kind in ('s', 'u') else 0
+        for step in flexible._paths['src']
+        )
+    assert bend_roles == 4
+
+    minimal = make_pather()
+    with pytest.raises(BuildError):
+        minimal.at('src').trace_into(
+            'dst',
+            plug_destination=False,
+            )
+
+    assert set(minimal.ports) == {'src', 'dst'}
+    assert_equal(minimal.ports['src'].offset, (0, 0))
+    assert numpy.isclose(minimal.ports['src'].rotation, 0)
+    assert_equal(minimal.ports['dst'].offset, (2, 0))
+    assert numpy.isclose(minimal.ports['dst'].rotation, pi)
+    assert not minimal._paths
+
+
+def test_pather_trace_into_large_composed_manhattan_route_plugs() -> None:
+    p = Pather(
+        Library(),
+        tools=PathTool(layer='M1', width=1000, ptype='wire'),
+        render='deferred',
+        )
+    p.ports['src'] = Port((123.25, 456.75), rotation=0, ptype='wire')
+    p.ports['dst'] = Port((-99_999_876.75, 20_000_456.75), rotation=0, ptype='wire')
+
+    p.trace_into('src', 'dst')
+
+    assert 'src' not in p.ports
+    assert 'dst' not in p.ports
+    assert [step.kind for step in p._paths['src']] == ['straight', 'bend', 'straight', 'bend', 'plug']
+
+
+def test_pather_trace_into_refines_output_adapter_route_before_plug() -> None:
+    class TransitionTool(Tool):
+        def primitive_offers(
+                self,
+                kind,           # noqa: ANN001
+                *,
+                in_ptype=None,  # noqa: ANN001
+                out_ptype=None, # noqa: ANN001
+                **kwargs,       # noqa: ANN003
+                ) -> tuple[PrimitiveOffer, ...]:
+            _ = in_ptype
+            if kind == 'straight':
+                def native_endpoint(length: float) -> Port:
+                    return Port((length, 0), rotation=pi, ptype='m1wire')
+
+                native = StraightOffer(
+                    in_ptype='m1wire',
+                    out_ptype='m1wire',
+                    endpoint_planner=native_endpoint,
+                    commit_planner=lambda length: {'kind': 'straight', 'length': length},
+                    )
+                if out_ptype in ('unk', 'm1wire'):
+                    return (native,)
+
+                def transition_endpoint(length: float) -> Port:
+                    return Port((length, 0), rotation=pi, ptype='m2wire')
+
+                transition = StraightOffer(
+                    in_ptype='m1wire',
+                    out_ptype='m2wire',
+                    length_domain=(2500, numpy.inf),
+                    endpoint_planner=transition_endpoint,
+                    commit_planner=lambda length: {'kind': 'transition', 'length': length},
+                    )
+                return native, transition
+
+            if kind == 'bend':
+                ccw = bool(kwargs['ccw'])
+
+                def endpoint(length: float) -> Port:
+                    return Port(
+                        (length, 500 if ccw else -500),
+                        rotation=-pi / 2 if ccw else pi / 2,
+                        ptype='m1wire',
+                        )
+
+                return (BendOffer(
+                    in_ptype='m1wire',
+                    out_ptype='m1wire',
+                    ccw=ccw,
+                    length_domain=(500, numpy.inf),
+                    endpoint_planner=endpoint,
+                    commit_planner=lambda length: {'kind': 'bend', 'length': length},
+                    ),)
+
+            return ()
+
+        def render(self, batch, *, port_names=('A', 'B'), **kwargs) -> Library:  # noqa: ANN001,ANN202,ARG002
+            tree, pat = Library.mktree('transition_tool')
+            pat.add_port_pair(names=port_names, ptype=batch[-1].end_port.ptype if batch else 'm1wire')
+            return tree
+
+    p = Pather(Library(), tools=TransitionTool(), render='deferred')
+    p.pattern.ports['src'] = Port((-65000, -11500), rotation=pi / 2, ptype='m1wire')
+    p.pattern.ports['dst'] = Port((-100000, -100000), rotation=pi, ptype='m2wire')
+
+    p.trace_into('src', 'dst')
+
+    assert 'src' not in p.pattern.ports
+    assert 'dst' not in p.pattern.ports
+
+
+def test_pather_trace_into_dead_updates_ports_without_geometry() -> None:
+    lib = Library()
+    tool = PathTool(layer='M1', width=1000, ptype='wire')
+    p = Pather(lib, tools=tool)
+    p.pattern.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+    p.pattern.ports['B'] = Port((-10000, 0), rotation=pi, ptype='wire')
+    p.set_dead()
+
+    p.trace_into('A', 'B', plug_destination=False)
+
+    assert set(p.pattern.ports) == {'A', 'B'}
+    assert numpy.allclose(p.pattern.ports['A'].offset, (-10000, 0))
+    assert p.pattern.ports['A'].rotation is not None
+    assert numpy.isclose(p.pattern.ports['A'].rotation, 0)
+    assert len(p._paths['A']) == 0
+    assert not p.pattern.has_shapes()
+    assert not p.pattern.has_refs()
+
+
+def test_pather_trace_into_planning_failure_leaves_state_unchanged() -> None:
+    lib = Library()
+    tool = PathTool(layer='M1', width=1, ptype='wire')
+    p = Pather(lib, tools=tool)
+    p.pattern.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+    p.pattern.ports['B'] = Port((-5, 5), rotation=pi / 2, ptype='wire')
+
+    with pytest.raises(BuildError):
+        p.trace_into('A', 'B', plug_destination=False, out_ptype='other')
+
+    assert numpy.allclose(p.pattern.ports['A'].offset, (0, 0))
+    assert numpy.isclose(p.pattern.ports['A'].rotation, 0)
+    assert numpy.allclose(p.pattern.ports['B'].offset, (-5, 5))
+    assert numpy.isclose(p.pattern.ports['B'].rotation, pi / 2)
+    assert len(p._paths['A']) == 0
+
+
+def test_pather_trace_into_rename_failure_propagates() -> None:
+    lib = Library()
+    tool = PathTool(layer='M1', width=1, ptype='wire')
+    p = Pather(lib, tools=tool)
+    p.pattern.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+    p.pattern.ports['B'] = Port((-10, 0), rotation=pi, ptype='wire')
+    p.pattern.ports['other'] = Port((3, 4), rotation=0, ptype='wire')
+
+    with pytest.raises(PortError, match='overwritten'):
+        p.trace_into('A', 'B', plug_destination=False, thru='other')
+
+
+@pytest.mark.parametrize(
+    ('dst', 'kwargs', 'match'),
+    [
+        (Port((-5, 5), rotation=pi / 2, ptype='wire'), {'x': -99}, r'route arguments: x'),
+        (Port((-10, 2), rotation=pi, ptype='wire'), {'length': 1}, r'route arguments: length'),
+        (Port((-10, 2), rotation=0, ptype='wire'), {'length': 1}, r'route arguments: length'),
+    ],
+)
+def test_pather_trace_into_rejects_reserved_route_kwargs(
+        dst: Port,
+        kwargs: dict[str, Any],
+        match: str,
+        ) -> None:
+    lib = Library()
+    tool = PathTool(layer='M1', width=1, ptype='wire')
+    p = Pather(lib, tools=tool)
+    p.pattern.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+    p.pattern.ports['B'] = dst
+
+    _ = match
+    with pytest.raises(TypeError, match='unexpected keyword argument'):
+        p.trace_into('A', 'B', plug_destination=False, **kwargs)
+
+    assert numpy.allclose(p.pattern.ports['A'].offset, (0, 0))
+    assert numpy.isclose(p.pattern.ports['A'].rotation, 0)
+    assert numpy.allclose(p.pattern.ports['B'].offset, dst.offset)
+    assert dst.rotation is not None
+    assert p.pattern.ports['B'].rotation is not None
+    assert numpy.isclose(p.pattern.ports['B'].rotation, dst.rotation)
+    assert len(p._paths['A']) == 0
+
+
+class TraceIntoBudgetSolver:
+    def __init__(self, successes: set[tuple[int, int]], fatal_at: set[tuple[int, int]] | None = None) -> None:
+        self.successes = successes
+        self.fatal_at = set() if fatal_at is None else fatal_at
+        self.attempts: list[tuple[int, int]] = []
+
+    def solve(
+            self,
+            *,
+            min_bends: int = 0,
+            max_bends: int | None = None,
+            ) -> Candidate:
+        assert max_bends is not None
+        band = (min_bends, max_bends)
+        self.attempts.append(band)
+        if band in self.fatal_at:
+            raise RoutePlanningError('fatal', policy=RouteFailurePolicy.FATAL)
+        if band not in self.successes:
+            raise BuildError('try next budget')
+        return Candidate((), Port((0, 0), rotation=0, ptype='wire'), 0.0, 0, 0.0)
+
+
+class TraceIntoBudgetPlanner(RoutingPlanner):
+    def __init__(self, successes: set[tuple[int, int]], fatal_at: set[tuple[int, int]] | None = None) -> None:
+        super().__init__()
+        self.solver = TraceIntoBudgetSolver(successes, fatal_at=fatal_at)
+        self.solver_requests = 0
+
+    def solver_for_request(self, request: SolverRequest) -> Any:
+        _ = request
+        self.solver_requests += 1
+        return self.solver
+
+    def prepared_result_from_legs(
+            self,
+            legs: Any,
+            *,
+            renames: tuple[tuple[str, str], ...] = (),
+            ) -> PreparedRouteResult:
+        _ = legs, renames
+        return PreparedRouteResult(())
+
+
+@pytest.mark.parametrize(
+    ('dst', 'successes', 'attempts'),
+    [
+        (Port((-10, 0), rotation=pi, ptype='wire'), {(0, 2)}, [(0, 2)]),
+        (Port((-10, 0), rotation=pi, ptype='wire'), {(4, 4)}, [(0, 2), (4, 4)]),
+        (Port((-10, -10), rotation=3 * pi / 2, ptype='wire'), {(1, 1)}, [(1, 1)]),
+        (Port((-10, -10), rotation=3 * pi / 2, ptype='wire'), {(3, 3)}, [(1, 1), (3, 3)]),
+    ],
+)
+def test_trace_into_reuses_solver_across_staged_bend_bands(
+        dst: Port,
+        successes: set[tuple[int, int]],
+        attempts: list[tuple[int, int]],
+        ) -> None:
+    planner = TraceIntoBudgetPlanner(successes)
+    context = RoutePortContext('src', Port((0, 0), rotation=0, ptype='wire'), PathTool(layer='M1', width=1, ptype='wire'))
+
+    planner.plan_trace_into(
+        context,
+        'dst',
+        dst,
+        out_ptype=None,
+        plug_destination=True,
+        thru=None,
+        plan_options={'bend_policy': 'flexible'},
+        )
+
+    assert planner.solver.attempts == attempts
+    assert planner.solver_requests == 1
+
+
+def test_trace_into_staged_bend_budget_stops_on_fatal_error() -> None:
+    planner = TraceIntoBudgetPlanner({(4, 4)}, fatal_at={(0, 2)})
+    context = RoutePortContext('src', Port((0, 0), rotation=0, ptype='wire'), PathTool(layer='M1', width=1, ptype='wire'))
+
+    with pytest.raises(RoutePlanningError, match='fatal'):
+        planner.plan_trace_into(
+            context,
+            'dst',
+            Port((-10, 0), rotation=pi, ptype='wire'),
+            out_ptype=None,
+            plug_destination=True,
+            thru=None,
+            plan_options={'bend_policy': 'flexible'},
+            )
+
+    assert planner.solver.attempts == [(0, 2)]
+    assert planner.solver_requests == 1
+
+
+def test_trace_into_bend_bands_respect_max_bends() -> None:
+    class OneBendPlanner(RoutingPlanner):
+        TRACE_INTO_MAX_BENDS = 1
+
+    planner = OneBendPlanner(bend_policy='flexible')
+
+    assert planner.trace_into_bend_bands('straight') == ((0, 0),)
+    assert planner.trace_into_bend_bands('s') == ((0, 0),)
+    assert planner.trace_into_bend_bands('bend') == ((1, 1),)
+
+
+@pytest.mark.parametrize(
+    ('family', 'expected'),
+    [
+        ('straight', ((0, 0),)),
+        ('bend', ((1, 1),)),
+        ('s', ((2, 2),)),
+        ('u', ((2, 2),)),
+    ],
+)
+def test_trace_into_default_minimal_bend_bands(family: str, expected: tuple[tuple[int, int], ...]) -> None:
+    planner = RoutingPlanner()
+
+    assert planner.trace_into_bend_bands(family) == expected
+    assert planner.trace_into_bend_bands(family, bend_policy='flexible') == (
+        ((1, 1), (3, 3)) if family == 'bend' else ((0, 2), (4, 4))
+        )
+
+
+@pytest.mark.parametrize(
+    ('dst', 'required_band'),
+    [
+        (Port((-10, 0), rotation=pi, ptype='wire'), (0, 0)),
+        (Port((-10, -5), rotation=pi, ptype='wire'), (2, 2)),
+        (Port((-10, -10), rotation=3 * pi / 2, ptype='wire'), (1, 1)),
+        (Port((-10, -5), rotation=0, ptype='wire'), (2, 2)),
+    ],
+)
+def test_trace_into_minimal_policy_uses_orientation_required_band(
+        dst: Port,
+        required_band: tuple[int, int],
+        ) -> None:
+    planner = TraceIntoBudgetPlanner({required_band})
+    context = RoutePortContext(
+        'src',
+        Port((0, 0), rotation=0, ptype='wire'),
+        PathTool(layer='M1', width=1, ptype='wire'),
+        )
+
+    planner.plan_trace_into(
+        context,
+        'dst',
+        dst,
+        out_ptype=None,
+        plug_destination=True,
+        thru=None,
+        plan_options={'bend_policy': 'minimal'},
+        )
+
+    assert planner.solver.attempts == [required_band]
+
+
+def test_trace_into_minimal_policy_rejects_fallback_without_mutation() -> None:
+    planner = TraceIntoBudgetPlanner({(4, 4)})
+    pather = Pather(
+        Library(),
+        tools=PathTool(layer='M1', width=1, ptype='wire'),
+        planner=planner,
+        render='deferred',
+        )
+    pather.ports['src'] = Port((0, 0), rotation=0, ptype='wire')
+    pather.ports['dst'] = Port((-10, 0), rotation=pi, ptype='wire')
+
+    with pytest.raises(BuildError, match='try next budget'):
+        pather.trace_into('src', 'dst', plan_options={'bend_policy': 'minimal'})
+
+    assert planner.solver.attempts == [(0, 0)]
+    assert set(pather.ports) == {'src', 'dst'}
+    assert_equal(pather.ports['src'].offset, (0, 0))
+    assert_equal(pather.ports['dst'].offset, (-10, 0))
+    assert not pather._paths
+
+
+def test_trace_into_bend_policy_planner_default_and_route_override() -> None:
+    context = RoutePortContext(
+        'src',
+        Port((0, 0), rotation=0, ptype='wire'),
+        PathTool(layer='M1', width=1, ptype='wire'),
+        )
+    dst = Port((-10, 0), rotation=pi, ptype='wire')
+    minimal_planner = TraceIntoBudgetPlanner({(4, 4)})
+
+    with pytest.raises(BuildError, match='try next budget'):
+        minimal_planner.plan_trace_into(
+            context, 'dst', dst, out_ptype=None, plug_destination=True, thru=None,
+            )
+    assert minimal_planner.solver.attempts == [(0, 0)]
+
+    flexible_planner = TraceIntoBudgetPlanner({(4, 4)})
+    flexible_planner.plan_trace_into(
+        context,
+        'dst',
+        dst,
+        out_ptype=None,
+        plug_destination=True,
+        thru=None,
+        plan_options={'bend_policy': 'flexible'},
+        )
+    assert flexible_planner.solver.attempts == [(0, 2), (4, 4)]
+
+
+def test_trace_into_rejects_invalid_bend_policy() -> None:
+    with pytest.raises(BuildError, match='Invalid trace_into bend policy'):
+        RoutingPlanner(bend_policy='sideways')  # type: ignore[arg-type]
+
+    pather = Pather(
+        Library(),
+        tools=PathTool(layer='M1', width=1, ptype='wire'),
+        render='deferred',
+        )
+    pather.ports['src'] = Port((0, 0), rotation=0, ptype='wire')
+    pather.ports['dst'] = Port((-10, 0), rotation=pi, ptype='wire')
+
+    with pytest.raises(BuildError, match='Invalid trace_into bend policy'):
+        pather.trace_into('src', 'dst', plan_options={'bend_policy': 'sideways'})

masque/test/test_pattern.py

@@ -0,0 +1,310 @@
+import pytest
+import copy
+from typing import cast
+from numpy.testing import assert_equal, assert_allclose
+from numpy import pi
+
+from ..error import PatternError
+from ..abstract import Abstract
+from ..pattern import Pattern
+from ..shapes import Polygon
+from ..ref import Ref
+from ..ports import Port, PortError
+from ..label import Label
+from ..repetition import Grid
+
+
+def test_pattern_init() -> None:
+    pat = Pattern()
+    assert pat.is_empty()
+    assert not pat.has_shapes()
+    assert not pat.has_refs()
+    assert not pat.has_labels()
+    assert not pat.has_ports()
+
+
+def test_pattern_with_elements() -> None:
+    poly = Polygon.square(10)
+    label = Label("test", offset=(5, 5))
+    ref = Ref(offset=(100, 100))
+    port = Port((0, 0), 0)
+
+    pat = Pattern(shapes={(1, 0): [poly]}, labels={(1, 2): [label]}, refs={"sub": [ref]}, ports={"P1": port})
+
+    assert pat.has_shapes()
+    assert pat.has_labels()
+    assert pat.has_refs()
+    assert pat.has_ports()
+    assert not pat.is_empty()
+    assert pat.shapes[(1, 0)] == [poly]
+    assert pat.labels[(1, 2)] == [label]
+    assert pat.refs["sub"] == [ref]
+    assert pat.ports["P1"] == port
+
+
+def test_pattern_append() -> None:
+    pat1 = Pattern()
+    pat1.polygon((1, 0), vertices=[[0, 0], [1, 0], [1, 1]])
+
+    pat2 = Pattern()
+    pat2.polygon((2, 0), vertices=[[10, 10], [11, 10], [11, 11]])
+
+    pat1.append(pat2)
+    assert len(pat1.shapes[(1, 0)]) == 1
+    assert len(pat1.shapes[(2, 0)]) == 1
+
+
+def test_pattern_translate() -> None:
+    pat = Pattern()
+    pat.polygon((1, 0), vertices=[[0, 0], [1, 0], [1, 1]])
+    pat.ports["P1"] = Port((5, 5), 0)
+
+    pat.translate_elements((10, 20))
+
+    # Polygon.translate adds to vertices, and offset is always (0,0)
+    assert_equal(cast("Polygon", pat.shapes[(1, 0)][0]).vertices[0], [10, 20])
+    assert_equal(pat.ports["P1"].offset, [15, 25])
+
+
+def test_pattern_scale() -> None:
+    pat = Pattern()
+    # Polygon.rect sets an offset in its constructor which is immediately translated into vertices
+    pat.rect((1, 0), xmin=0, xmax=1, ymin=0, ymax=1)
+    pat.scale_by(2)
+
+    # Vertices should be scaled
+    assert_equal(cast("Polygon", pat.shapes[(1, 0)][0]).vertices, [[0, 0], [0, 2], [2, 2], [2, 0]])
+
+
+def test_pattern_rotate() -> None:
+    pat = Pattern()
+    pat.polygon((1, 0), vertices=[[10, 0], [11, 0], [10, 1]])
+    # Rotate 90 degrees CCW around (0,0)
+    pat.rotate_around((0, 0), pi / 2)
+
+    # [10, 0] rotated 90 deg around (0,0) is [0, 10]
+    assert_allclose(cast("Polygon", pat.shapes[(1, 0)][0]).vertices[0], [0, 10], atol=1e-10)
+
+
+def test_pattern_mirror() -> None:
+    pat = Pattern()
+    pat.polygon((1, 0), vertices=[[10, 5], [11, 5], [10, 6]])
+    # Mirror across X axis (y -> -y)
+    pat.mirror(0)
+
+    assert_equal(cast("Polygon", pat.shapes[(1, 0)][0]).vertices[0], [10, -5])
+
+
+def test_pattern_get_bounds() -> None:
+    pat = Pattern()
+    pat.polygon((1, 0), vertices=[[0, 0], [10, 0], [10, 10]])
+    pat.polygon((1, 0), vertices=[[-5, -5], [5, -5], [5, 5]])
+
+    bounds = pat.get_bounds()
+    assert_equal(bounds, [[-5, -5], [10, 10]])
+
+
+def test_pattern_flatten_preserves_ports_only_child() -> None:
+    child = Pattern(ports={"P1": Port((1, 2), 0)})
+
+    parent = Pattern()
+    parent.ref("child", offset=(10, 10))
+
+    parent.flatten({"child": child}, flatten_ports=True)
+
+    assert set(parent.ports) == {"P1"}
+    assert parent.ports["P1"].rotation == 0
+    assert tuple(parent.ports["P1"].offset) == (11.0, 12.0)
+
+
+def test_pattern_flatten_repeated_ref_with_ports_raises() -> None:
+    child = Pattern(ports={"P1": Port((1, 2), 0)})
+    child.polygon((1, 0), vertices=[[0, 0], [1, 0], [0, 1]])
+
+    parent = Pattern()
+    parent.ref("child", repetition=Grid(a_vector=(10, 0), a_count=2))
+
+    with pytest.raises(PatternError, match='Cannot flatten ports from repeated ref'):
+        parent.flatten({"child": child}, flatten_ports=True)
+
+
+def test_pattern_place_requires_abstract_for_reference() -> None:
+    parent = Pattern()
+    child = Pattern()
+
+    with pytest.raises(PatternError, match='Must provide an `Abstract`'):
+        parent.place(child)
+
+    assert not parent.ports
+
+
+def test_pattern_place_append_requires_pattern_atomically() -> None:
+    parent = Pattern()
+    child = Abstract("child", {"A": Port((1, 2), 0)})
+
+    with pytest.raises(PatternError, match='Must provide a full `Pattern`'):
+        parent.place(child, append=True)
+
+    assert not parent.ports
+
+
+def test_pattern_place_append_annotation_conflict_is_atomic() -> None:
+    parent = Pattern(annotations={"k": [1]})
+    child = Pattern(annotations={"k": [2]}, ports={"A": Port((1, 2), 0)})
+
+    with pytest.raises(PatternError, match="Annotation keys overlap"):
+        parent.place(child, append=True)
+
+    assert not parent.ports
+    assert parent.annotations == {"k": [1]}
+
+
+def test_pattern_place_skip_geometry_overwrites_colliding_ports_last_wins() -> None:
+    parent = Pattern(ports={
+        "A": Port((5, 5), 0),
+        "keep": Port((9, 9), 0),
+    })
+    child = Pattern(ports={
+        "X": Port((1, 0), 0),
+        "Y": Port((2, 0), pi / 2),
+    })
+
+    parent.place(child, port_map={"X": "A", "Y": "A"}, skip_geometry=True, append=True)
+
+    assert set(parent.ports) == {"A", "keep"}
+    assert_allclose(parent.ports["A"].offset, (2, 0))
+    assert parent.ports["A"].rotation is not None
+    assert_allclose(parent.ports["A"].rotation, pi / 2)
+
+
+def test_pattern_interface() -> None:
+    source = Pattern()
+    source.ports["A"] = Port((10, 20), 0, ptype="test")
+
+    iface = Pattern.interface(source, in_prefix="in_", out_prefix="out_")
+
+    assert "in_A" in iface.ports
+    assert "out_A" in iface.ports
+    assert iface.ports["in_A"].rotation is not None
+    assert_allclose(iface.ports["in_A"].rotation, pi, atol=1e-10)
+    assert iface.ports["out_A"].rotation is not None
+    assert_allclose(iface.ports["out_A"].rotation, 0, atol=1e-10)
+    assert iface.ports["in_A"].ptype == "test"
+    assert iface.ports["out_A"].ptype == "test"
+
+
+def test_pattern_interface_duplicate_port_map_targets_raise() -> None:
+    source = Pattern()
+    source.ports["A"] = Port((10, 20), 0)
+    source.ports["B"] = Port((30, 40), pi)
+
+    with pytest.raises(PortError, match='Duplicate targets in `port_map`'):
+        Pattern.interface(source, port_map={"A": "X", "B": "X"})
+
+
+def test_pattern_interface_empty_port_map_copies_no_ports() -> None:
+    source = Pattern()
+    source.ports["A"] = Port((10, 20), 0)
+    source.ports["B"] = Port((30, 40), pi)
+
+    assert not Pattern.interface(source, port_map={}).ports
+    assert not Pattern.interface(source, port_map=[]).ports
+
+
+def test_pattern_plug_requires_abstract_for_reference_atomically() -> None:
+    parent = Pattern(ports={"X": Port((0, 0), 0)})
+    child = Pattern(ports={"A": Port((0, 0), pi)})
+
+    with pytest.raises(PatternError, match='Must provide an `Abstract`'):
+        parent.plug(child, {"X": "A"})
+
+    assert set(parent.ports) == {"X"}
+
+
+def test_pattern_plug_append_annotation_conflict_is_atomic() -> None:
+    parent = Pattern(
+        annotations={"k": [1]},
+        ports={"X": Port((0, 0), 0), "Q": Port((9, 9), 0)},
+        )
+    child = Pattern(
+        annotations={"k": [2]},
+        ports={"A": Port((0, 0), pi), "B": Port((5, 0), 0)},
+        )
+
+    with pytest.raises(PatternError, match="Annotation keys overlap"):
+        parent.plug(child, {"X": "A"}, map_out={"B": "Y"}, append=True)
+
+    assert set(parent.ports) == {"X", "Q"}
+    assert_allclose(parent.ports["X"].offset, (0, 0))
+    assert_allclose(parent.ports["Q"].offset, (9, 9))
+    assert parent.annotations == {"k": [1]}
+
+
+def test_pattern_plug_skip_geometry_overwrites_colliding_ports_last_wins() -> None:
+    parent = Pattern(ports={
+        "A": Port((0, 0), 0, ptype="wire"),
+        "B": Port((99, 99), 0, ptype="wire"),
+    })
+    child = Pattern(ports={
+        "in": Port((0, 0), pi, ptype="wire"),
+        "X": Port((10, 0), 0, ptype="wire"),
+        "Y": Port((20, 0), 0, ptype="wire"),
+    })
+
+    parent.plug(child, {"A": "in"}, map_out={"X": "B", "Y": "B"}, skip_geometry=True, append=True)
+
+    assert "A" not in parent.ports
+    assert "B" in parent.ports
+    assert_allclose(parent.ports["B"].offset, (20, 0))
+    assert parent.ports["B"].rotation is not None
+    assert_allclose(parent.ports["B"].rotation, 0)
+
+
+def test_pattern_append_port_conflict_is_atomic() -> None:
+    pat1 = Pattern()
+    pat1.ports["A"] = Port((0, 0), 0)
+
+    pat2 = Pattern()
+    pat2.polygon((1, 0), vertices=[[0, 0], [1, 0], [0, 1]])
+    pat2.ports["A"] = Port((1, 0), 0)
+
+    with pytest.raises(PatternError, match="Port names overlap"):
+        pat1.append(pat2)
+
+    assert not pat1.shapes
+    assert set(pat1.ports) == {"A"}
+
+
+def test_pattern_append_annotation_conflict_is_atomic() -> None:
+    pat1 = Pattern(annotations={"k": [1]})
+    pat2 = Pattern(annotations={"k": [2]})
+    pat2.polygon((1, 0), vertices=[[0, 0], [1, 0], [0, 1]])
+
+    with pytest.raises(PatternError, match="Annotation keys overlap"):
+        pat1.append(pat2)
+
+    assert not pat1.shapes
+    assert pat1.annotations == {"k": [1]}
+
+
+def test_pattern_deepcopy_does_not_share_shape_repetitions() -> None:
+    pat = Pattern()
+    pat.polygon((1, 0), vertices=[[0, 0], [1, 0], [0, 1]], repetition=Grid(a_vector=(10, 0), a_count=2))
+
+    pat2 = copy.deepcopy(pat)
+    pat2.scale_by(2)
+
+    assert_allclose(cast("Polygon", pat.shapes[(1, 0)][0]).repetition.a_vector, [10, 0])
+    assert_allclose(cast("Polygon", pat2.shapes[(1, 0)][0]).repetition.a_vector, [20, 0])
+
+
+def test_pattern_flatten_does_not_mutate_child_repetitions() -> None:
+    child = Pattern()
+    child.polygon((1, 0), vertices=[[0, 0], [1, 0], [0, 1]], repetition=Grid(a_vector=(10, 0), a_count=2))
+
+    parent = Pattern()
+    parent.ref("child", scale=2)
+
+    parent.flatten({"child": child})
+
+    assert_allclose(cast("Polygon", child.shapes[(1, 0)][0]).repetition.a_vector, [10, 0])

masque/test/test_poly_collection.py

@@ -0,0 +1,89 @@
+import pytest
+from numpy.testing import assert_equal
+
+from ..error import PatternError
+from ..shapes import Circle, Ellipse, Polygon, PolyCollection
+
+
+def test_poly_collection_init() -> None:
+    verts = [[0, 0], [1, 0], [1, 1], [0, 1], [10, 10], [11, 10], [11, 11], [10, 11]]
+    offsets = [0, 4]
+    pc = PolyCollection(vertex_lists=verts, vertex_offsets=offsets)
+    assert len(list(pc.polygon_vertices)) == 2
+    assert_equal(pc.get_bounds_single(), [[0, 0], [11, 11]])
+
+def test_poly_collection_to_polygons() -> None:
+    verts = [[0, 0], [1, 0], [1, 1], [0, 1], [10, 10], [11, 10], [11, 11], [10, 11]]
+    offsets = [0, 4]
+    pc = PolyCollection(vertex_lists=verts, vertex_offsets=offsets)
+    polys = pc.to_polygons()
+    assert len(polys) == 2
+    assert_equal(polys[0].vertices, [[0, 0], [1, 0], [1, 1], [0, 1]])
+    assert_equal(polys[1].vertices, [[10, 10], [11, 10], [11, 11], [10, 11]])
+
+def test_poly_collection_holes() -> None:
+    # PolyCollection represents separate polygon boundaries, including nested boundaries.
+    verts = [
+        [0, 0],
+        [10, 0],
+        [10, 10],
+        [0, 10],  # Poly 1
+        [2, 2],
+        [2, 8],
+        [8, 8],
+        [8, 2],  # Poly 2
+    ]
+    offsets = [0, 4]
+    pc = PolyCollection(verts, offsets)
+    polys = pc.to_polygons()
+    assert len(polys) == 2
+    assert_equal(polys[0].vertices, [[0, 0], [10, 0], [10, 10], [0, 10]])
+    assert_equal(polys[1].vertices, [[2, 2], [2, 8], [8, 8], [8, 2]])
+
+def test_poly_collection_constituent_empty() -> None:
+    # Duplicate offsets create an empty constituent slice between valid polygons.
+    verts = [
+        [0, 0],
+        [1, 0],
+        [0, 1],  # Tri
+        [10, 10],
+        [11, 10],
+        [11, 11],
+        [10, 11],  # Square
+    ]
+    offsets = [0, 3, 3]
+    pc = PolyCollection(verts, offsets)
+    with pytest.raises(PatternError):
+        pc.to_polygons()
+
+def test_poly_collection_valid() -> None:
+    verts = [[0, 0], [1, 0], [0, 1], [10, 10], [11, 10], [11, 11], [10, 11]]
+    offsets = [0, 3]
+    pc = PolyCollection(verts, offsets)
+    assert len(pc.to_polygons()) == 2
+    shapes = [Circle(radius=20), Circle(radius=10), Polygon([[0, 0], [10, 0], [10, 10]]), Ellipse(radii=(5, 5))]
+    sorted_shapes = sorted(shapes)
+    assert len(sorted_shapes) == 4
+    assert sorted(sorted_shapes) == sorted_shapes
+
+def test_poly_collection_normalized_form_reconstruction_is_independent() -> None:
+    pc = PolyCollection([[0, 0], [1, 0], [0, 1]], [0])
+    _intrinsic, _extrinsic, rebuild = pc.normalized_form(1)
+
+    clone = rebuild()
+    clone.vertex_offsets[:] = [5]
+
+    assert_equal(pc.vertex_offsets, [0])
+    assert_equal(clone.vertex_offsets, [5])
+
+def test_poly_collection_normalized_form_rebuilds_independent_clones() -> None:
+    pc = PolyCollection([[0, 0], [1, 0], [0, 1]], [0])
+    _intrinsic, _extrinsic, rebuild = pc.normalized_form(1)
+
+    first = rebuild()
+    second = rebuild()
+    first.vertex_offsets[:] = [7]
+
+    assert_equal(first.vertex_offsets, [7])
+    assert_equal(second.vertex_offsets, [0])
+    assert_equal(pc.vertex_offsets, [0])