修改rag，实现混合检索

backend/app/main_graph/nodes/react_nodes.py

@@ -364,20 +364,27 @@ def route_by_reasoning(state: MainGraphState) -> str:
     if "subgraph_completed" in previous_actions or state.final_result:
         return "llm_call"
     
-    # 检查是否刚刚执行完 rag 或 web search，应该继续推理一次然后去 llm_call
-    # 但为了避免死循环，我们设置一个简单的规则
-    if len(previous_actions) > 3:
+    # 关键修复：如果已经执行过 rag_retrieve 并且又执行过推理，直接去 LLM_CALL
+    # 这样的流程：推理1 → RAG → 推理2（判断 RAG 结果） → LLM_CALL
+    rag_count = previous_actions.count("rag_retrieve")
+    if rag_count >= 1 and len(previous_actions) >= rag_count + 1:
+        info(f"[route_by_reasoning] 已完成 RAG 检索和结果判断，直接去 llm_call")
         return "llm_call"
-
+    
+    # 关键修复：限制最多 3 次推理，避免无限循环
+    if len(previous_actions) >= 3:
+        info(f"[route_by_reasoning] 已达到最大推理次数 ({len(previous_actions)})，直接去 llm_call")
+        return "llm_call"
+    
     # 获取推理结果
     reasoning_result: Optional[ReasoningResult] = state.debug_info.get("reasoning_result")
-
+    
     if not reasoning_result:
         return "llm_call"
-
+    
     # 使用 intent.py 提供的路由函数
     route = get_route_by_reasoning(reasoning_result)
-
+    
     # 映射到我们的节点名称
     # 注意：这些名称必须与 main_graph_builder.py 中定义的节点名称一致
     route_mapping = {
@@ -391,7 +398,8 @@ def route_by_reasoning(state: MainGraphState) -> str:
         "dictionary": "dictionary_subgraph",
         "news_analysis": "news_analysis_subgraph",
     }
-
+    
+    info(f"[route_by_reasoning] 推理结果={reasoning_result.action.name}, 路由={route_mapping.get(route, 'llm_call')}, 历史动作={previous_actions}")
     return route_mapping.get(route, "llm_call")