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/nodes/react_nodes.py

@@ -121,12 +121,31 @@ async def react_reason_node(state: MainGraphState, config: Optional[Dict[str, An
 
 # ========== 2. 联网搜索节点 ==========
 
-def web_search_node(state: MainGraphState) -> MainGraphState:
+async def web_search_node(state: MainGraphState, config: Optional[Dict[str, Any]] = None) -> MainGraphState:
     """
     联网搜索节点：执行搜索并将结果保存到状态
     """
     state.current_phase = "web_searching"
     
+    # 发送开始事件
+    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": "web_search_start",
+                        "confidence": 1.0,
+                        "reasoning": "开始执行联网搜索..."
+                    },
+                    callbacks=callbacks
+                )
+        except Exception as e:
+            info(f"[web_search_node] 无法发送开始事件: {e}")
+    
     # 获取搜索查询
     reasoning_result = state.debug_info.get("reasoning_result")
     search_query = reasoning_result.metadata.get("search_query", state.user_query) if reasoning_result else state.user_query
@@ -151,6 +170,25 @@ def web_search_node(state: MainGraphState) -> MainGraphState:
         state.success = True
         print(f"[WebSearch] 搜索完成")
         
+        # 发送完成事件
+        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": "web_search_complete",
+                            "confidence": 1.0,
+                            "reasoning": f"联网搜索完成，找到 {len(search_result) if isinstance(search_result, list) else 1} 条结果"
+                        },
+                        callbacks=callbacks
+                    )
+            except Exception as e:
+                info(f"[web_search_node] 无法发送完成事件: {e}")
+        
     except Exception as e:
         from app.main_graph.state import ErrorRecord, ErrorSeverity
         from datetime import datetime
@@ -169,6 +207,25 @@ def web_search_node(state: MainGraphState) -> MainGraphState:
         state.current_error = error_record
         state.current_phase = "error_handling"
         state.success = False
+        
+        # 发送错误事件
+        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": "web_search_error",
+                            "confidence": 1.0,
+                            "reasoning": f"联网搜索失败: {str(e)}"
+                        },
+                        callbacks=callbacks
+                    )
+            except Exception as e:
+                info(f"[web_search_node] 无法发送错误事件: {e}")
     
     return state