内螺纹 thread_cut 算子的增加

backend/engine/cdsl_engine/capabilities.py

@@ -26,18 +26,22 @@ _PRIMARY_ATOMICS = frozenset({
 _HOLE_ATOMICS = frozenset({"hole_blind", "hole_countersink", "hole_counterbore", "hole_wizard"})
 _ACTIVE_BODY_REQUIRED = frozenset({
     "extrude_cut_blind", "revolve_cut", *_HOLE_ATOMICS, "fillet", "chamfer",
+    # thread_cut 是 cut 型特征：必须在已有主体（宿主）上做布尔差，不能凭空
+    # 造实体；无宿主时按 active_body 前置阻止而非让 executor 在 None 上崩溃。
+    "thread_cut",
 })
 _BODY_MUTATING_ATOMICS = frozenset({
     "extrude_add_blind", "extrude_add_two_sided", "extrude_cut_blind",
-    "revolve_add", "revolve_cut", "sphere_add", "thread_add",
+    "revolve_add", "revolve_cut", "sphere_add", "thread_add", "thread_cut",
     *_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.  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.
+# Context-only features have no geometry definition to instance.  thread_add
+# and thread_cut are excluded: pattern translation does not yet move their
+# parametric axis, so a replayed thread would silently re-run at the original
+# location.
 _REPLAYABLE_ATOMICS = (
-    _BODY_MUTATING_ATOMICS - frozenset({"thread_add"})
+    _BODY_MUTATING_ATOMICS - frozenset({"thread_add", "thread_cut"})
 ) | frozenset({"pattern_linear", "pattern_mirror"})
 _SUPPORTED_EXTENTS = frozenset({
     "blind", "mid_plane", "through_all", "through_all_both", "through_all_and_blind",
@@ -433,6 +437,9 @@ class CapabilityAnalyzer:
         body_producers = {
             "extrude_add_blind", "extrude_add_two_sided", "extrude_cut_blind",
             "revolve_add", "revolve_cut", "sphere_add", "thread_add",
+            # thread_cut 与 extrude_cut_blind/revolve_cut 一致：无宿主时由
+            # active_body 前置阻止，文档含该类特征即视为携带可执行几何。
+            "thread_cut",
         }
         document_blockers: list[RuntimeDiagnostic] = []
         if not any(node.atomic_id in body_producers for node in plan):