feat: add seat-scoped static and dynamic assistant modes

tests/integration/test_custom_mode_creation_matrix.py

@@ -754,7 +754,11 @@ def test_incomplete_ambiguous_or_unsupported_scene_never_creates_partial_draft(
 
     assert result["status"] != "succeeded"
     assert result.get("mode_profile_draft") is None
-    assert result.get("orchestration_route") != "mode_profile_create_preview"
+    # Seat policy can reject on the creation route before compiling any action.
+    assert not (result.get("intent_ir") or {}).get("spec", {}).get("actions")
+    assert not result.get("actions")
+    assert result.get("command_plan") is None
+    assert not result.get("command_plans")
     assert result.get("validation")
     failure = result.get("mode_creation_failure")
     assert isinstance(failure, dict)