feat: 新增 react_reason 循环思考过程的流式显示

- 修改 react_nodes.py，在推理时保存推理过程到状态
- 修改 agent_service.py，检测并发送推理过程事件到前端
- 修改 chat_area.py，接收并显示推理过程
- 修改 useChat.ts，添加对推理过程事件的支持

backend/app/agent/agent_service.py

@@ -258,6 +258,34 @@ class AIAgentService:
                     info(f"🔄 处理updates chunk")
                     updates_data = chunk["data"]
                     serialized_data = self._serialize_value(updates_data)
+                    
+                    # 检查是否有最新的推理内容（来自 react_reason_node）
+                    if isinstance(serialized_data, dict):
+                        # 遍历所有节点的数据
+                        for node_name, node_data in serialized_data.items():
+                            if isinstance(node_data, dict) and "debug_info" in node_data:
+                                debug_info = node_data["debug_info"]
+                                latest_reasoning = debug_info.get("latest_reasoning")
+                                if latest_reasoning and not latest_reasoning.get("sent"):
+                                    # 发送推理过程到前端
+                                    step = latest_reasoning.get("step", 1)
+                                    action = latest_reasoning.get("action", "unknown")
+                                    confidence = latest_reasoning.get("confidence", 0)
+                                    reasoning = latest_reasoning.get("reasoning", "")
+                                    
+                                    info(f"[Agent Service] 发送推理过程 #{step}: {action}")
+                                    
+                                    # 发送推理事件
+                                    yield {
+                                        "type": "react_reasoning",
+                                        "step": step,
+                                        "action": action,
+                                        "confidence": confidence,
+                                        "reasoning": reasoning
+                                    }
+                                    
+                                    # 标记为已发送（避免重复发送）
+                                    latest_reasoning["sent"] = True
 
                     # 检查是否有人工审核请求
                     if "review_pending" in serialized_data and serialized_data["review_pending"]:

backend/app/main_graph/nodes/react_nodes.py

@@ -26,11 +26,12 @@ from app.main_graph.utils.retry_utils import (
     RetryConfig,
     SUBGRAPH_RETRY_CONFIG
 )
+from app.logger import info
 
 
 # ========== 1. React 推理节点 ==========
 
-def react_reason_node(state: MainGraphState) -> MainGraphState:
+def react_reason_node(state: MainGraphState, config: Optional[Dict[str, Any]] = None) -> MainGraphState:
     """
     React 模式推理节点：判断下一步做什么
     
@@ -38,6 +39,22 @@ def react_reason_node(state: MainGraphState) -> MainGraphState:
     """
     state.current_phase = "react_reasoning"
     state.reasoning_step += 1
+    
+    # 发送推理开始事件
+    if config:
+        try:
+            from langchain_core.runnables.config import RunnableConfig
+            # 尝试获取回调管理器并发送自定义事件
+            callbacks = config.get("callbacks")
+            if callbacks:
+                from langchain_core.callbacks.manager import adispatch_custom_event
+                # 注意：这是异步操作，我们需要特殊处理
+                # 这里我们使用自定义流式写入器（如果存在）
+                pass
+        except Exception as e:
+            info(f"[react_reason] 无法发送回调事件: {e}")
+    
+    info(f"[react_reason] 第 {state.reasoning_step} 次推理开始")
 
     # 检查是否超过最大步数
     if state.reasoning_step > state.max_steps:
@@ -61,6 +78,10 @@ def react_reason_node(state: MainGraphState) -> MainGraphState:
     # 使用 intent.py 进行推理
     # 注意：这里使用同步版本，内部会根据情况处理
     result: ReasoningResult = react_reason(state.user_query, context)
+    
+    info(f"[react_reason] 推理结果: action={result.action.name}, confidence={result.confidence}")
+    if result.reasoning:
+        info(f"[react_reason] 推理过程: {result.reasoning}")
 
     # 记录推理历史
     state.reasoning_history.append({
@@ -83,6 +104,16 @@ def react_reason_node(state: MainGraphState) -> MainGraphState:
 
     # 确定下一步动作
     state.last_action = result.action.name
+    
+    # 发送推理完成事件（通过状态更新，agent_service 会处理）
+    # 我们在状态中保存推理内容，以便 agent_service 可以通过 state_update 事件发送
+    state.debug_info["latest_reasoning"] = {
+        "step": state.reasoning_step,
+        "action": result.action.name,
+        "confidence": result.confidence,
+        "reasoning": result.reasoning,
+        "sent": False  # 标记是否已发送到前端
+    }
 
     return state
 

frontend/src/components/chat_area.py

@@ -139,7 +139,26 @@ def _handle_ai_response():
             import logging
             logging.debug(f"[Frontend Stream] 收到事件: {event_type}, 完整内容: {repr(event)}")
             
-            # 1. 处理各种控制事件，显示到思考过程
+            # 1. 处理推理过程事件 - 这是新增的！
+            if event_type == "react_reasoning":
+                step = event.get("step", 1)
+                action = event.get("action", "unknown")
+                confidence = event.get("confidence", 0)
+                reasoning = event.get("reasoning", "")
+                
+                logging.info(f"[Frontend] 收到推理过程 #{step}: {action}")
+                
+                # 添加到思考过程
+                api_thought += f"\n\n🤔 **第 {step} 次推理**"
+                api_thought += f"\n   📋 决策: {action}"
+                api_thought += f"\n   📊 置信度: {confidence:.2f}"
+                if reasoning:
+                    api_thought += f"\n   💭 推理过程: {reasoning}"
+                
+                display_thought = api_thought
+                thought_placeholder.info(f"**🤔 思考过程 (正在思考...)**\n\n{display_thought}▌")
+            
+            # 2. 处理各种控制事件，显示到思考过程
             if event_type == "intent_classified":
                 intent = event.get("intent", "unknown")
                 confidence = event.get("confidence", 0)

frontend/src/components/useChat.ts

@@ -181,8 +181,20 @@ export function useChat() {
     try {
       for await (const event of apiClient.chatStream(text, threadId, model)) {
         switch (event.type) {
+          // 新增：处理推理过程事件
+          case "react_reasoning":
+            console.log(`🤔 收到推理过程 #${event.step}: ${event.action}`);
+            updateCurrentMessage({
+              reasoning: (currentMessageRef.current?.reasoning || "") + 
+                `\n\n🤔 **第 ${event.step} 次推理**` +
+                `\n   📋 决策: ${event.action}` +
+                `\n   📊 置信度: ${event.confidence.toFixed(2)}` +
+                (event.reasoning ? `\n   💭 推理过程: ${event.reasoning}` : "")
+            });
+            break;
+            
           // 新增：处理意图分类事件
-          case 'intent_classified':
+          case "intent_classified":
             console.log(`🧠 意图识别: ${event.intent} (置信度: ${event.confidence})`);
             setLastIntent({
               intent: event.intent,