[dxf] ignore unreferenced internal dxf blocks

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