change

backend/engine/cdsl_engine/llm_engine.py

@@ -37,6 +37,21 @@ from build123d import (  # noqa: E402
 )
 
 
+# Keep this in sync with the execution branches in run_engine_plan. The
+# agent-facing schema and its parity test prevent unsupported names reaching
+# this low-level dispatcher.
+SUPPORTED_ATOMIC_IDS = frozenset({
+    "extrude_add_blind",
+    "extrude_add_two_sided",
+    "extrude_cut_blind",
+    "revolve_add",
+    "revolve_cut",
+    "hole_blind",
+    "hole_countersink",
+    "hole_counterbore",
+})
+
+
 def _load(path: Path) -> dict[str, Any]:
     return json.loads(path.read_text(encoding="utf-8"))