refactor: 统一使用新版 React 模式图，移除旧版 GraphBuilder 调用

backend/app/agent/service.py

@@ -7,7 +7,7 @@ import json
 import asyncio
 
 # 本地模块
-from app.main_graph.graph_builder import GraphBuilder, GraphContext
+from app.main_graph.utils.subgraph_builder import build_react_main_graph
 from app.main_graph.tools.graph_tools import AVAILABLE_TOOLS, TOOLS_BY_NAME
 from app.main_graph.config import set_stream_writer
 from ..model_services.chat_services import get_all_chat_services, LocalVLLMChatProvider
@@ -36,13 +36,12 @@ class AIAgentService:
             self.tools.append(rag_tool)
             self.tools_by_name[rag_tool.name] = rag_tool
 
-        # 2. 构建各模型的 Graph
+        # 2. 构建各模型的 Graph（使用新版 React 模式）
         chat_services = get_all_chat_services()
         for name, llm in chat_services.items():
             try:
                 info(f"🔄 初始化模型 '{name}'...")
-                builder = GraphBuilder(llm, self.tools, self.tools_by_name).build()
-                graph = builder.compile(checkpointer=self.checkpointer)
+                graph = build_react_main_graph().compile(checkpointer=self.checkpointer)
                 self.graphs[name] = graph
                 info(f"✅ 模型 '{name}' 初始化成功")
             except Exception as e:
@@ -67,14 +66,22 @@ class AIAgentService:
             "configurable": {"thread_id": thread_id},
             "metadata": {"user_id": user_id}
         }
-        input_state = {"messages": [{"role": "user", "content": message}]}
-        context = GraphContext(user_id=user_id)
+        # 新版状态输入：传入完整的 MainGraphState，关键是 user_query
+        from app.main_graph.state import MainGraphState, CurrentAction
+        input_state = {
+            "user_query": message,
+            "messages": [{"role": "user", "content": message}],
+            "user_id": user_id,
+            "current_action": CurrentAction.NONE
+        }
 
-        result = await graph.ainvoke(input_state, config=config, context=context)
+        result = await graph.ainvoke(input_state, config=config)
 
-        reply = result["messages"][-1].content
-        token_usage = result.get("last_token_usage", {})
-        elapsed_time = result.get("last_elapsed_time", 0.0)
+        reply = result.get("final_result", "")
+        if not reply and result.get("messages"):
+            reply = result["messages"][-1].content
+        token_usage = result.get("debug_info", {}).get("token_usage", {})
+        elapsed_time = result.get("debug_info", {}).get("elapsed_time", 0.0)
 
         return {
             "reply": reply,