feat: unify debug runtime timelines

backend/services/conversation_history.py

@@ -120,6 +120,8 @@ class ConversationRecorder:
     async def _append_workflow_event(self, message: dict) -> None:
         """Persist bounded control-plane history without creating chat rows."""
 
+        if message.get("internalStage") is True:
+            return
         event_id = str(message.get("eventId") or "")
         event_name = str(message.get("event") or "")
         event_key = f"workflow:{event_id}"