diff --git a/backend/app/utils/logging.py b/backend/app/utils/logging.py
index c3137fc..7802895 100644
--- a/backend/app/utils/logging.py
+++ b/backend/app/utils/logging.py
@@ -5,37 +5,27 @@ LangGraph 节点日志工具模块
 
 from app.config import ENABLE_GRAPH_TRACE
 from app.logger import debug, info
+from app.main_graph.state import MainGraphState
 
 
-def log_state_change(node_name: str, state, prefix: str = "进入"):
+def log_state_change(node_name: str, state: MainGraphState, prefix: str = "进入"):
     """
     记录状态变化日志
-    
+
     Args:
         node_name: 节点名称
-        state: 当前状态（兼容 dict 和 dataclass）
+        state: 当前状态
         prefix: 日志前缀（"进入" 或 "离开"）
     """
     from app.logger import info
-    
-    # 获取 messages
-    messages = []
-    if isinstance(state, dict):
-        messages = state.get("messages", [])
-    else:
-        messages = getattr(state, "messages", [])
-    
+
+    messages = state.messages
     msg_count = len(messages)
     last_msg = messages[-1] if messages else None
     last_info = ""
     if last_msg:
-        # 兼容 dict 和对象两种格式
-        if isinstance(last_msg, dict):
-            content_preview = str(last_msg.get("content", ""))[:10].replace("\n", " ")
-            msg_type = last_msg.get("type", "unknown")
-        else:
-            content_preview = str(last_msg.content)[:10].replace("\n", " ")
-            msg_type = getattr(last_msg, 'type', 'unknown')
+        content_preview = str(last_msg.content)[:10].replace("\n", " ")
+        msg_type = getattr(last_msg, 'type', 'unknown')
         last_info = f"{msg_type.upper()}: {content_preview}"
     info(f"🔄 [{node_name}] {prefix} | 消息数:{msg_count} | 最后一条:{last_info}")