From cf0a245143262a676a72abc0dbbcce9b88915373 Mon Sep 17 00:00:00 2001
From: Jan Petykiewicz <jan@mpxd.net>
Date: Thu, 2 Apr 2026 10:09:38 -0700
Subject: [PATCH] [dxf] ignore unreferenced internal dxf blocks

---
 masque/file/dxf.py      | 31 ++++++++++++++++++++++++++++++-
 masque/test/test_dxf.py | 12 ++++++++++++
 2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/masque/file/dxf.py b/masque/file/dxf.py
index 301910d..237b1d8 100644
--- a/masque/file/dxf.py
+++ b/masque/file/dxf.py
@@ -192,8 +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
diff --git a/masque/test/test_dxf.py b/masque/test/test_dxf.py
index 4c8d195..f6dd177 100644
--- a/masque/test/test_dxf.py
+++ b/masque/test/test_dxf.py
@@ -170,3 +170,15 @@ def test_dxf_read_legacy_polyline() -> None:
     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"}