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/summarize.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, info, error, warning
 
 
-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_summarize_node(mem0_client: Mem0Client):
     """
     工厂函数：创建记忆存储节点
@@ -33,12 +25,12 @@ def create_summarize_node(mem0_client: Mem0Client):
     
     from langchain_core.runnables.config import RunnableConfig
     
-    async def summarize_conversation(state, config: RunnableConfig) -> Dict[str, Any]:
+    async def summarize_conversation(state: MainGraphState, config: RunnableConfig) -> Dict[str, Any]:
         """
         记忆存储节点 - 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:
@@ -46,7 +38,7 @@ def create_summarize_node(mem0_client: Mem0Client):
         """
         log_state_change("summarize", state, "进入")
 
-        messages = _get_attr(state, "messages", [])
+        messages = state.messages
         if len(messages) < 4:
             debug("📝 [记忆添加] 对话过短，跳过")
             return {"turns_since_last_summary": 0}