修复重构后的导入错误和缺失模块

backend/app/main_graph/nodes/rag_nodes.py

@@ -11,7 +11,7 @@ import asyncio
 from typing import Dict, Any, Optional
 from datetime import datetime
 
-from .state import MainGraphState, ErrorRecord, ErrorSeverity
+from app.main_graph.state import MainGraphState, ErrorRecord, ErrorSeverity
 from .retry_utils import (
     RetryConfig,
     RAG_RETRY_CONFIG,
@@ -19,8 +19,8 @@ from .retry_utils import (
 )
 
 # 真正导入和利用已有 RAG 代码
-from ..rag.tools import create_rag_tool_sync
-from ..rag.pipeline import RAGPipeline
+from app.rag.tools import create_rag_tool_sync
+from app.rag.pipeline import RAGPipeline
 
 
 # ========== 全局 RAG 工具实例（延迟初始化）==========