fix: improve maintenance and synchronize live conversations

backend/app/repositories/agent.py

@@ -16,7 +16,7 @@ limitations under the License.
 
 from sqlalchemy.orm import Session
 from typing import List, Optional
-from app.models.agent import Agent, AgentType
+from app.models.agent import Agent
 import json
 from sqlalchemy.orm import joinedload
 from uuid import UUID