[Pather] improve cost calculation for S-first

masque/builder/pather.py

@@ -1127,8 +1127,9 @@ class Pather(PortList):
         three-bend routes; other families try zero-to-two-bend routes before
         four-bend routes. The first band with a legal candidate wins. Within a
         band, candidates are ordered by total cost, adapter count, step count,
-        and deterministic discovery order. `strategy` controls straight-first
-        vs turn-first discovery order and therefore only the final tie-break.
+        the requested straight-vs-turn topology preference, and deterministic
+        discovery order. `strategy` therefore affects only otherwise tied
+        candidates.
         Custom planning options may be supplied through `tool_options`; they
         are forwarded only to primitive offer generation.
 

masque/builder/planner/planner.py

@@ -32,6 +32,7 @@ from __future__ import annotations
 from collections.abc import Iterable, Mapping, Sequence
 from dataclasses import dataclass, replace
 from itertools import combinations
+from math import isclose as math_isclose
 from typing import Any, Literal
 
 import numpy
@@ -71,6 +72,8 @@ from .interface import (
     )
 
 RouteTieBreakStrategy = Literal['straight_first', 'turn_first']
+COST_RTOL = 1e-10
+COST_ATOL = 1e-8
 
 
 class NoLegalRouteError(BuildError):
@@ -89,6 +92,11 @@ def is_close(a: float, b: float) -> bool:
     return scalar_close(a, b)
 
 
+def costs_equal(a: float, b: float) -> bool:
+    """Treat sub-resolution solver noise as equal during cost ranking."""
+    return math_isclose(float(a), float(b), rel_tol=COST_RTOL, abs_tol=COST_ATOL)
+
+
 def clean_parameter(value: float) -> float:
     """Snap tiny solver noise in primitive parameters before domain checks."""
     rounded = round(float(value))
@@ -274,7 +282,7 @@ class SolverRequest:
     max_bends: int | None = None
     """Optional override for grammar bend budget."""
     strategy: RouteTieBreakStrategy = 'straight_first'
-    """Discovery-order tie-break strategy for straight-vs-turn placement."""
+    """Final topology tie-break preference for straight-vs-turn placement."""
 
     @property
     def route_name(self) -> str:
@@ -339,6 +347,15 @@ class Solver:
                 count += 2
         return count
 
+    def strategy_rank(self, steps: Sequence[SelectedPrimitive]) -> tuple[int, ...]:
+        """Lexicographically rank every main straight-vs-turn placement."""
+        preferred_kind = 'straight' if self.request.strategy == 'straight_first' else 'turn'
+        return tuple(
+            int(('straight' if step.offer.kind == 'straight' else 'turn') != preferred_kind)
+            for step in steps
+            if step.role != 'adapter'
+            )
+
     def candidate_key(self, candidate: Candidate) -> tuple[Any, ...]:
         """Return a deterministic key for duplicate solved candidates."""
         def endpoint_key(port: Port) -> tuple[float, float, float | None, str | None]:
@@ -425,12 +442,14 @@ class Solver:
                     ) from last_error
             raise NoLegalRouteError(f'No legal primitive offer for {self.request.route_name}')
 
+        minimum_cost = min(candidate.cost for candidate in candidates)
+        cost_tied = [candidate for candidate in candidates if costs_equal(candidate.cost, minimum_cost)]
         return min(
-            candidates,
+            cost_tied,
             key=lambda candidate: (
-                round(float(candidate.cost), 9),
                 sum(step.role == 'adapter' for step in candidate.steps),
                 len(candidate.steps),
+                self.strategy_rank(candidate.steps),
                 candidate.order,
                 ),
             )
@@ -793,10 +812,7 @@ class Solver:
             residual_jog: float,
             ) -> Iterable[tuple[SelectedPrimitive, ...]]:
         """Recursively enumerate normal/adapter/turn blocks within the bend budget."""
-        straight_options = self.straight_options(steps)
-        if self.request.strategy == 'straight_first':
-            straight_options = (*straight_options[1:], straight_options[0])
-        for normal in straight_options:
+        for normal in self.straight_options(steps):
             after_normal = (*steps, *normal)
             suffix_options = (
                 self.adapter_options(after_normal, residual_jog=0)
@@ -955,10 +971,10 @@ class Solver:
 
     def finalize(self, steps: Sequence[SelectedPrimitive]) -> Candidate:
         """
-        Try all small solve sets for one raw sequence and return the first match.
+        Try all small solve sets for one raw sequence and return the cheapest match.
 
-        Solve-set order is deterministic and becomes part of the candidate
-        ordering only after cost and structural tie-breakers.
+        Recoverable failures reject only the current solve set. Solve-set order
+        breaks ties between equally priced parameter allocations.
         """
         constraints: list[tuple[Literal['x', 'y'], float]] = []
         if self.request.length is not None:
@@ -978,24 +994,35 @@ class Solver:
         for solve_size in range(1, max_solve + 1):
             solve_sets.extend(combinations(adjustable, solve_size))
 
-        for solve_indices in solve_sets:
-            solved = self.solve_parameters(steps, solve_indices, route_constraints)
+        feasible: list[tuple[float, int, tuple[SelectedPrimitive, ...], Port]] = []
+        errors: list[Exception] = []
+        for solve_order, solve_indices in enumerate(solve_sets):
+            try:
+                solved = self.solve_parameters(steps, solve_indices, route_constraints)
+            except (BuildError, NotImplementedError, PortError) as err:
+                raise_if_fatal(err)
+                errors.append(err)
+                continue
             if solved is None:
                 continue
             selected_steps, end_port = solved
             if not self.endpoint_matches(end_port, route_constraints):
                 continue
-            order = self.order
-            self.order += 1
-            public_length = float(end_port.x) if self.request.length is None else float(self.request.length)
-            return Candidate(
-                tuple(selected_steps),
-                end_port,
-                sum(step.cost for step in selected_steps),
-                order,
-                public_length,
-                )
-        raise BuildError(f'{self.request.route_name} composed primitive route is unsupported')
+            cost = sum(step.cost for step in selected_steps)
+            feasible.append((float(cost), solve_order, tuple(selected_steps), end_port))
+
+        if not feasible:
+            if errors:
+                raise errors[-1]
+            raise BuildError(f'{self.request.route_name} composed primitive route is unsupported')
+
+        minimum_cost = min(result[0] for result in feasible)
+        cost_tied = [result for result in feasible if costs_equal(result[0], minimum_cost)]
+        cost, _solve_order, selected_steps, end_port = min(cost_tied, key=lambda result: result[1])
+        order = self.order
+        self.order += 1
+        public_length = float(end_port.x) if self.request.length is None else float(self.request.length)
+        return Candidate(selected_steps, end_port, cost, order, public_length)
 
 
 @dataclass(frozen=True, slots=True)

masque/test/test_autotool_planning.py

@@ -950,6 +950,59 @@ def test_autotool_sbend_explicit_cost_can_override_geometric_cost() -> None:
     assert_allclose(out_port.offset, [20, 4])
 
 
+@pytest.mark.parametrize('jog', [41_988.0, -41_988.0])
+def test_autotool_strategy_orders_main_steps_across_adapters(jog: float) -> None:
+    radius = 60_000.0
+    transition_length = 50_000.0
+    route_length = 545_929.0
+    primary = 'primary'
+    secondary = 'secondary'
+    sbend_endpoint = circular_arc_sbend_endpoint(radius, primary)
+
+    def make_primary_sbend(offset: float) -> Pattern:
+        pattern = Pattern()
+        pattern.ports['A'] = Port((0, 0), 0, ptype=primary)
+        pattern.ports['B'] = sbend_endpoint(offset)
+        return pattern
+
+    library = Library()
+    library['bend'] = make_bend(radius, ptype=primary)
+    transition = Pattern()
+    transition.ports['P'] = Port((0, 0), 0, ptype=primary)
+    transition.ports['S'] = Port((transition_length, 0), pi, ptype=secondary)
+    library['transition'] = transition
+    tool = (
+        AutoTool(bbox_library=library)
+        .add_straight(lambda length: make_straight(length, ptype=primary), primary, 'A')
+        .add_straight(
+            lambda length: make_straight(length, ptype=secondary),
+            secondary,
+            'A',
+            cost=0.3,
+            )
+        .add_bend(library.abstract('bend'), 'A', 'B', clockwise=True)
+        .add_sbend(
+            make_primary_sbend,
+            primary,
+            'A',
+            'B',
+            jog_range=(0, 2 * radius),
+            endpoint=sbend_endpoint,
+            )
+        .add_transition(library.abstract('transition'), 'P', 'S')
+        )
+
+    selected_kinds = {}
+    for strategy in ('straight_first', 'turn_first'):
+        pather = Pather(library, tools=tool, render='deferred')
+        pather.ports['A'] = Port((0, 0), 0, ptype=primary)
+        pather.jog('A', jog, length=route_length, out_ptype=primary, strategy=strategy)
+        selected_kinds[strategy] = [step.kind for step in pather._paths['A']]
+
+    assert selected_kinds['straight_first'] == ['straight', 'straight', 'straight', 's']
+    assert selected_kinds['turn_first'] == ['s', 'straight', 'straight', 'straight']
+
+
 def test_autotool_add_methods_propagate_callable_cost_to_all_created_offers() -> None:
     def cost(parameter: float, endpoint: Port) -> float:
         return abs(parameter) + abs(endpoint.x) + abs(endpoint.y)

masque/test/test_pather_primitive_offers.py

@@ -122,6 +122,74 @@ def test_solver_offer_cache_accepts_unhashable_request_tool_options() -> None:
     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