重构：移除对 debug_info 的依赖，只使用新的结构化状态字段

backend/app/main_graph/nodes/reasoning.py

@@ -47,22 +47,14 @@ async def react_reason_node(state: MainGraphState, config: Optional[RunnableConf
         "timestamp": datetime.now().isoformat()
     })
 
-    # 步骤4: 更新调试信息（同时更新旧的 debug_info 和新的结构化字段）
-    state.debug_info["last_reasoning"] = {
-        "action": result.action.name,
-        "confidence": result.confidence,
-        "reasoning": result.reasoning
-    }
-    state.debug_info["reasoning_result"] = result
-    state.last_action = result.action.name
-    
-    # 更新新的结构化字段
+    # 步骤3: 更新状态 - 只使用新的结构化字段
     state.react_reasoning.last_reasoning = {
         "action": result.action.name,
         "confidence": result.confidence,
         "reasoning": result.reasoning
     }
     state.react_reasoning.reasoning_result = result
+    state.last_action = result.action.name
 
     # 步骤5: 发送推理事件
     await dispatch_custom_event(