增加了thread几何基础操作

backend/engine/cdsl_engine/capabilities.py

@@ -29,11 +29,16 @@ _ACTIVE_BODY_REQUIRED = frozenset({
 })
 _BODY_MUTATING_ATOMICS = frozenset({
     "extrude_add_blind", "extrude_add_two_sided", "extrude_cut_blind",
-    "revolve_add", "revolve_cut", "sphere_add", *_HOLE_ATOMICS, "fillet", "chamfer",
+    "revolve_add", "revolve_cut", "sphere_add", "thread_add",
+    *_HOLE_ATOMICS, "fillet", "chamfer",
 })
 # A pattern may replay a previous pattern as well as a direct body mutation.
-# Context-only features have no geometry definition to instance.
-_REPLAYABLE_ATOMICS = _BODY_MUTATING_ATOMICS | frozenset({"pattern_linear", "pattern_mirror"})
+# Context-only features have no geometry definition to instance.  thread_add is
+# excluded: pattern translation does not yet move its parametric axis, so a
+# replayed thread would silently re-fuse at the original location.
+_REPLAYABLE_ATOMICS = (
+    _BODY_MUTATING_ATOMICS - frozenset({"thread_add"})
+) | frozenset({"pattern_linear", "pattern_mirror"})
 _SUPPORTED_EXTENTS = frozenset({
     "blind", "mid_plane", "through_all", "through_all_both", "through_all_and_blind",
     "up_to_surface", "up_to_vertex", "offset_from_surface", "through_next", "up_to_body",
@@ -427,7 +432,7 @@ class CapabilityAnalyzer:
                     body_available = True
         body_producers = {
             "extrude_add_blind", "extrude_add_two_sided", "extrude_cut_blind",
-            "revolve_add", "revolve_cut", "sphere_add",
+            "revolve_add", "revolve_cut", "sphere_add", "thread_add",
         }
         document_blockers: list[RuntimeDiagnostic] = []
         if not any(node.atomic_id in body_producers for node in plan):