Ignore action metadata in extra field validation

server/environment.py

@@ -115,7 +115,7 @@ class HelpdeskTicketRoutingEnvironment(
             f
             for f, v in action.model_dump(exclude_none=True).items()
             if v is not None
-            and f not in {"action_type", "tool_name", "tool_target_ticket_id"}
+            and f not in {"action_type", "tool_name", "tool_target_ticket_id", "metadata"}
         }
         allowed = set(task["allowed_fields"])
         extra_fields = submitted_fields - allowed

tests/test_extra_fields_penalty.py

@@ -132,6 +132,24 @@ class TestExtraFieldsPenalty(unittest.TestCase):
         self.assertEqual(len(result_obs.history), 1)
         self.assertNotIn("penalty_reason", result_obs.history[0])
 
+    def test_action_metadata_is_not_treated_as_extra_field(self) -> None:
+        """OpenEnv Action metadata should not trigger the extra-fields penalty."""
+        env = _make_env()
+        obs = env.reset(seed=42, task_id=1)
+        ticket_id = obs.current_ticket["ticket_id"]
+        current_ticket = env._tickets_by_id[ticket_id]  # noqa: SLF001 - test-only inspection
+
+        result_obs = env.step(
+            HelpdeskTicketAction(
+                issue_type=current_ticket.issue_type,
+                metadata={},
+            )
+        )
+
+        self.assertEqual(len(result_obs.history), 1)
+        self.assertNotIn("penalty_reason", result_obs.history[0])
+        self.assertGreater(result_obs.history[0]["score"], 0.0)
+
     def test_extra_fields_no_exception_raised(self) -> None:
         """Requirement 7.4: extra fields must not raise an unhandled exception."""
         env = _make_env()