fix: improve maintenance and synchronize live conversations

backend/tests/services/test_workflow_execution.py

@@ -19,7 +19,6 @@ from unittest.mock import Mock, patch, AsyncMock, MagicMock
 from uuid import uuid4
 from app.services.workflow_execution import WorkflowExecutionService
 from app.models.workflow_node import WorkflowNode, NodeType, ExitCondition
-from app.agents.chat_agent import ChatResponse
 from app.models.workflow import Workflow, WorkflowStatus