彻底重构状态系统：整合所有旧状态到 MainGraphState，修复所有节点

backend/app/main_graph/nodes/retrieve_memory.py

@@ -6,20 +6,12 @@
 from typing import Any, Dict
 
 # 本地模块
-from app.main_graph.state import MessagesState
+from app.main_graph.state import MainGraphState
 from app.memory.mem0_client import Mem0Client
 from app.utils.logging import log_state_change
 from app.logger import debug
 
 
-def _get_attr(state, attr_name, default=None):
-    """通用方法：兼容 dict 和 dataclass 两种状态格式"""
-    if isinstance(state, dict):
-        return state.get(attr_name, default)
-    else:
-        return getattr(state, attr_name, default)
-
-
 def create_retrieve_memory_node(mem0_client: Mem0Client):
     """
     工厂函数：创建记忆检索节点
@@ -33,12 +25,12 @@ def create_retrieve_memory_node(mem0_client: Mem0Client):
     
     from langchain_core.runnables.config import RunnableConfig
     
-    async def retrieve_memory(state, config: RunnableConfig) -> Dict[str, Any]:
+    async def retrieve_memory(state: MainGraphState, config: RunnableConfig) -> Dict[str, Any]:
         """
         记忆检索节点 - 使用 Mem0
         
         Args:
-            state: 当前对话状态（兼容 dict 和 dataclass）
+            state: 当前对话状态
             config: 运行时配置
         
         Returns:
@@ -49,16 +41,16 @@ def create_retrieve_memory_node(mem0_client: Mem0Client):
         # 从 metadata 中获取 user_id
         user_id = config.get("metadata", {}).get("user_id", "default_user")
         
-        # 兼容 dict 和对象两种消息格式
-        messages = _get_attr(state, "messages", [])
+        # 获取最后一条消息
+        messages = state.messages
         last_msg = messages[-1] if messages else None
+        query = ""
         if last_msg:
             if isinstance(last_msg, dict):
                 query = str(last_msg.get("content", ""))
             else:
                 query = str(last_msg.content)
-        else:
-            query = ""
+        
         memory_text_parts = []
 
         # 确保 Mem0 已初始化（懒加载）
@@ -83,7 +75,7 @@ def create_retrieve_memory_node(mem0_client: Mem0Client):
 
         memory_context = "\n\n".join(memory_text_parts) if memory_text_parts else "暂无用户信息"
         result = {"memory_context": memory_context}
-        log_state_change("retrieve_memory", {**state, **result} if isinstance(state, dict) else state, "离开")
+        log_state_change("retrieve_memory", state, "离开")
         return result
     
     return retrieve_memory