fix: improve maintenance and synchronize live conversations

backend/app/utils/guardrail_runtime.py

@@ -28,7 +28,7 @@ Every entry point here FAILS OPEN: a guardrail bug must degrade to
 "no guardrail", never to "no chat".
 """
 
-from dataclasses import dataclass, field
+from dataclasses import dataclass
 from typing import List, Optional, Tuple
 
 from app.agents.guardrail_policy import CANARY_STRINGS, looks_like_scope_refusal