fix(MCP): 重构MCPClient为后台协程 + AsyncExitStack管理，解决进程退出时的“Attempted to exit cancel scope in a different task”错误

# 变更
----
- 将所有stdio_client与ClientSession的创建/销毁都放到同一个后台 task 中
- 使用AsyncExitStack托管异步资源，cleanup时在同一task内执行exit_stack.aclose()
- 外部只通过事件通知后台task退出，避免跨协程调用cancel-scope异常

main/xiaozhi-server/core/mcp/MCPClient.py

@@ -1,86 +1,145 @@
+from __future__ import annotations
+
+import asyncio, os, shutil, concurrent.futures
 from datetime import timedelta
-from typing import Optional
 from contextlib import AsyncExitStack
-import os, shutil
+from typing import Optional, List
+
 from mcp import ClientSession, StdioServerParameters
 from mcp.client.stdio import stdio_client
-
 from config.logger import setup_logging
 
 TAG = __name__
 
+
 class MCPClient:
-    def __init__(self, config):
-        # Initialize session and client objects
-        self.session: Optional[ClientSession] = None
-        self.exit_stack = AsyncExitStack()
+    def __init__(self, config: dict):
         self.logger = setup_logging()
         self.config = config
-        self.tolls = []
+
+        # Back‑worker task & 状态同步
+        self._worker_task: Optional[asyncio.Task] = None
+        self._ready_evt = asyncio.Event()
+        self._shutdown_evt = asyncio.Event()
+
+        # 运行时资源
+        self.session: Optional[ClientSession] = None
+        self.tools: List = []
 
     async def initialize(self):
-        args = self.config.get("args", [])
+        """
+        启动后台 task，并等待其就绪（拿到 `tools`）。
+        """
+        if self._worker_task:
+            return  # 已经 init 过
 
-        command = (
-            shutil.which("npx")
-            if self.config["command"] == "npx"
-            else self.config["command"]
-        )
-        
-        env={**os.environ}
-        if self.config.get("env"):
-            env.update(self.config["env"])
-        
-        server_params = StdioServerParameters(
-            command=command,
-            args=args,
-            env=env
-        )
-        
-        stdio_transport = await self.exit_stack.enter_async_context(stdio_client(server_params))
-        self.stdio, self.write = stdio_transport
-        time_out_delta =  timedelta(seconds=15)
-        self.session = await self.exit_stack.enter_async_context(ClientSession(read_stream=self.stdio, write_stream=self.write, read_timeout_seconds=time_out_delta))
-        
-        await self.session.initialize()
-        
-        # List available tools
-        response = await self.session.list_tools()
-        tools = response.tools
-        self.tools = tools
-        self.logger.bind(tag=TAG).info(f"Connected to server with tools:{[tool.name for tool in tools]}")
-    
-    def has_tool(self, tool_name):
-        return any(tool.name == tool_name for tool in self.tools)
-    
-    def get_available_tools(self):
-        available_tools = [{"type": "function", "function":{ 
-            "name": tool.name,
-            "description": tool.description,
-            "parameters": tool.inputSchema
-        } } for tool in self.tools]
+        # 在当前 loop 创建后台 task
+        self._worker_task = asyncio.create_task(self._worker(), name="MCPClientWorker")
+        await self._ready_evt.wait()  # 等待 worker 初始化完成
 
-        return available_tools
-    
-    async def call_tool(self, tool_name: str, tool_args: dict):
-        self.logger.bind(tag=TAG).info(f"MCPClient Calling tool {tool_name} with args: {tool_args}")
-        try:
-            response = await self.session.call_tool(tool_name, tool_args)
-        except Exception as e:
-            self.logger.bind(tag=TAG).error(f"Error calling tool {tool_name}: {e}")
-            from types import SimpleNamespace
-            error_content = SimpleNamespace(
-                type='text',
-                text=f"Error calling tool {tool_name}: {e}"
-            )
-            error_response = SimpleNamespace(
-                content=[error_content],
-                isError=True
-            )
-            return error_response
-        self.logger.bind(tag=TAG).info(f"MCPClient Response from tool {tool_name}: {response}")
-        return response
+        # 此时 tools 已填充
+        self.logger.bind(tag=TAG).info(
+            f"Connected, tools = {[t.name for t in self.tools]}"
+        )
 
     async def cleanup(self):
-        """Clean up resources"""
-        await self.exit_stack.aclose()
+        """
+        对外关闭接口：
+            · 只负责发出 “关机信号”
+            · 等待后台 task 正常退出
+        在任何 loop / task 调用都安全。
+        """
+        if not self._worker_task:
+            return
+
+        self._shutdown_evt.set()  # 发信号
+        try:
+            await asyncio.wait_for(self._worker_task, timeout=15)
+        except (asyncio.TimeoutError, Exception) as e:
+            self.logger.bind(tag=TAG).error(f"worker shutdown err: {e}")
+        finally:
+            self._worker_task = None
+
+    # ----------------------------- 工具接口 -----------------------------
+
+    def has_tool(self, name: str) -> bool:
+        return any(t.name == name for t in self.tools)
+
+    def get_available_tools(self):
+        return [
+            {
+                "type": "function",
+                "function": {
+                    "name": t.name,
+                    "description": t.description,
+                    "parameters": t.inputSchema,
+                },
+            }
+            for t in self.tools
+        ]
+
+    async def call_tool(self, name: str, args: dict):
+        """
+        转发到 session.call_tool。
+        若在 worker 之外的 task 调用，会通过 run_coroutine_threadsafe
+        投递到 worker 所在 loop 中执行，保证线程安全。
+        """
+        if not self.session:  # 尚未就绪
+            raise RuntimeError("MCPClient not initialized")
+
+        loop = self._worker_task.get_loop()
+        coro = self.session.call_tool(name, args)
+
+        # 在同一个 loop ➜ 直接 await
+        if loop is asyncio.get_running_loop():
+            return await coro
+
+        # 跨 loop ➜ run_coroutine_threadsafe
+        fut: concurrent.futures.Future = asyncio.run_coroutine_threadsafe(coro, loop)
+        return await asyncio.wrap_future(fut)
+
+    # ----------------------------- 后台 task -----------------------------
+
+    async def _worker(self):
+        """
+        单线程协程：
+            1. 创建所有异步资源
+            2. set_ready → 供外部使用
+            3. 等待 shutdown_evt
+            4. 自动随 AsyncExitStack 退出而清理资源
+        """
+        async with AsyncExitStack() as stack:
+            try:
+                # ---------- 启动后端进程 ----------
+                cmd = shutil.which("npx") if self.config["command"] == "npx" else self.config["command"]
+                env = {**os.environ, **self.config.get("env", {})}
+                params = StdioServerParameters(
+                    command=cmd,
+                    args=self.config.get("args", []),
+                    env=env,
+                )
+                stdio_r, stdio_w = await stack.enter_async_context(stdio_client(params))
+
+                # ---------- 会话 ----------
+                self.session = await stack.enter_async_context(
+                    ClientSession(
+                        read_stream=stdio_r,
+                        write_stream=stdio_w,
+                        read_timeout_seconds=timedelta(seconds=15),
+                    )
+                )
+                await self.session.initialize()
+
+                # ---------- 工具 ----------
+                self.tools = (await self.session.list_tools()).tools
+
+                # 初始化完成，放行外部
+                self._ready_evt.set()
+
+                # ---------- 挂起等待关闭 ----------
+                await self._shutdown_evt.wait()
+
+            except Exception as e:
+                self.logger.bind(tag=TAG).error(f"worker error: {e}")
+                self._ready_evt.set()  # 确保外部不会卡死
+                raise

main/xiaozhi-server/core/mcp/manager.py

@@ -1,5 +1,5 @@
 """MCP服务管理器"""
-
+import asyncio
 import os, json
 from typing import Dict, Any, List
 from .MCPClient import MCPClient
@@ -94,8 +94,8 @@ class MCPManager:
         """
         for tool in self.tools:
             if (
-                tool.get("function") != None
-                and tool["function"].get("name") == tool_name
+                    tool.get("function") != None
+                    and tool["function"].get("name") == tool_name
             ):
                 return True
         return False
@@ -120,12 +120,13 @@ class MCPManager:
         raise ValueError(f"Tool {tool_name} not found in any MCP server")
 
     async def cleanup_all(self) -> None:
-        for name, client in self.client.items():
+        """依次关闭所有 MCPClient，不让异常阻断整体流程。"""
+        for name, client in list(self.client.items()):
             try:
-                await client.cleanup()
-                self.logger.bind(tag=TAG).info(f"Cleaned up MCP client: {name}")
-            except Exception as e:
+                await asyncio.wait_for(client.cleanup(), timeout=20)
+                self.logger.bind(tag=TAG).info(f"MCP client closed: {name}")
+            except (asyncio.TimeoutError, Exception) as e:
                 self.logger.bind(tag=TAG).error(
-                    f"Error cleaning up MCP client {name}: {e}"
+                    f"Error closing MCP client {name}: {e}"
                 )
         self.client.clear()