给关键节点添加思考过程输出

- react_reason_node: 直接发送自定义推理事件
- web_search_node: 添加开始/完成/错误事件
- rag_retrieve_node: 添加开始/完成/重试/错误事件
- 子图包装器: 添加子图开始/完成/错误事件

backend/app/main_graph/utils/main_graph_builder.py

@@ -55,7 +55,26 @@ def wrap_subgraph_for_error_handling(subgraph, name: str):
     
     Returns: 包装后的节点函数
     """
-    def wrapped_node(state: MainGraphState) -> MainGraphState:
+    async def wrapped_node(state: MainGraphState, config: Optional[Dict[str, Any]] = None) -> MainGraphState:
+        # 发送子图开始事件
+        if config:
+            try:
+                from langchain_core.callbacks.manager import adispatch_custom_event
+                callbacks = config.get("callbacks")
+                if callbacks:
+                    await adispatch_custom_event(
+                        "react_reasoning",
+                        {
+                            "step": state.reasoning_step,
+                            "action": f"{name}_subgraph_start",
+                            "confidence": 1.0,
+                            "reasoning": f"开始执行 {name} 子图..."
+                        },
+                        callbacks=callbacks
+                    )
+            except Exception as e:
+                info(f"[{name}_subgraph] 无法发送开始事件: {e}")
+        
         try:
             # 调用子图
             result = subgraph.invoke(state)
@@ -72,7 +91,7 @@ def wrap_subgraph_for_error_handling(subgraph, name: str):
                 state.news_result = result
                 subgraph_result = result.get("final_result", "")
             
-            # 关键：设置最终结果，这样就不需要再回到 react_reason 了
+            # 关键：设置最终结果
             if subgraph_result:
                 state.final_result = subgraph_result
             else:
@@ -89,6 +108,26 @@ def wrap_subgraph_for_error_handling(subgraph, name: str):
                 "reasoning": f"{name}子图执行完成",
                 "timestamp": datetime.now().isoformat()
             })
+            
+            # 发送子图完成事件
+            if config:
+                try:
+                    from langchain_core.callbacks.manager import adispatch_custom_event
+                    callbacks = config.get("callbacks")
+                    if callbacks:
+                        await adispatch_custom_event(
+                            "react_reasoning",
+                            {
+                                "step": state.reasoning_step,
+                                "action": f"{name}_subgraph_complete",
+                                "confidence": 1.0,
+                                "reasoning": f"{name} 子图执行完成"
+                            },
+                            callbacks=callbacks
+                        )
+                except Exception as e:
+                    info(f"[{name}_subgraph] 无法发送完成事件: {e}")
+            
             return state
             
         except Exception as e:
@@ -111,6 +150,25 @@ def wrap_subgraph_for_error_handling(subgraph, name: str):
             state.current_phase = "error_handling"
             state.success = False
             
+            # 发送子图错误事件
+            if config:
+                try:
+                    from langchain_core.callbacks.manager import adispatch_custom_event
+                    callbacks = config.get("callbacks")
+                    if callbacks:
+                        await adispatch_custom_event(
+                            "react_reasoning",
+                            {
+                                "step": state.reasoning_step,
+                                "action": f"{name}_subgraph_error",
+                                "confidence": 1.0,
+                                "reasoning": f"{name} 子图执行失败: {str(e)}"
+                            },
+                            callbacks=callbacks
+                        )
+                except Exception as e:
+                    info(f"[{name}_subgraph] 无法发送错误事件: {e}")
+            
             return state
     
     return wrapped_node