mirror of
https://github.com/langbot-app/LangBot.git
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1fc5e75f93
* feat(mcp): add streamable HTTP alongside with frontend UI change, w/ support for stdio * fix(mcp): address copilot reviews * Update src/langbot/pkg/provider/tools/loaders/mcp.py Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> * fix: resolve copilot reviews * fix: Message -> MessageChunk * feat: upgrade mcp module * feat: add i18n * feat(mcp): enhance MCPCardComponent with mode badge and reorder select items in MCPFormDialog --------- Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> Co-authored-by: WangCham <651122857@qq.com> Co-authored-by: Junyan Qin (Chin) <rockchinq@gmail.com>
457 lines
16 KiB
Python
457 lines
16 KiB
Python
from __future__ import annotations
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import enum
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import typing
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from contextlib import AsyncExitStack
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import traceback
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from langbot_plugin.api.entities.events import pipeline_query
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import sqlalchemy
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import asyncio
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import httpx
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import uuid as uuid_module
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from mcp import ClientSession, StdioServerParameters
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from mcp.client.stdio import stdio_client
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from mcp.client.sse import sse_client
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from mcp.client.streamable_http import streamable_http_client
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from .. import loader
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from ....core import app
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import langbot_plugin.api.entities.builtin.resource.tool as resource_tool
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import langbot_plugin.api.entities.builtin.provider.message as provider_message
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from ....entity.persistence import mcp as persistence_mcp
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class MCPSessionStatus(enum.Enum):
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CONNECTING = 'connecting'
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CONNECTED = 'connected'
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ERROR = 'error'
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class RuntimeMCPSession:
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"""运行时 MCP 会话"""
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ap: app.Application
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server_name: str
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server_uuid: str
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server_config: dict
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session: ClientSession | None
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exit_stack: AsyncExitStack
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functions: list[resource_tool.LLMTool] = []
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enable: bool
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# connected: bool
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status: MCPSessionStatus
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_lifecycle_task: asyncio.Task | None
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_shutdown_event: asyncio.Event
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_ready_event: asyncio.Event
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error_message: str | None = None
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def __init__(self, server_name: str, server_config: dict, enable: bool, ap: app.Application):
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self.server_name = server_name
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self.server_uuid = server_config.get('uuid', '')
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self.server_config = server_config
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self.ap = ap
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self.enable = enable
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self.session = None
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self.exit_stack = AsyncExitStack()
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self.functions = []
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self.status = MCPSessionStatus.CONNECTING
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self._lifecycle_task = None
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self._shutdown_event = asyncio.Event()
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self._ready_event = asyncio.Event()
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async def _init_stdio_python_server(self):
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server_params = StdioServerParameters(
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command=self.server_config['command'],
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args=self.server_config['args'],
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env=self.server_config['env'],
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)
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stdio_transport = await self.exit_stack.enter_async_context(stdio_client(server_params))
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stdio, write = stdio_transport
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self.session = await self.exit_stack.enter_async_context(ClientSession(stdio, write))
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await self.session.initialize()
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async def _init_sse_server(self):
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sse_transport = await self.exit_stack.enter_async_context(
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sse_client(
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self.server_config['url'],
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headers=self.server_config.get('headers', {}),
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timeout=self.server_config.get('timeout', 10),
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sse_read_timeout=self.server_config.get('ssereadtimeout', 30),
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)
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)
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sseio, write = sse_transport
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self.session = await self.exit_stack.enter_async_context(ClientSession(sseio, write))
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await self.session.initialize()
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async def _init_streamable_http_server(self):
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transport = await self.exit_stack.enter_async_context(
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streamable_http_client(
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self.server_config['url'],
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http_client=httpx.AsyncClient(
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headers=self.server_config.get('headers', {}),
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timeout=self.server_config.get('timeout', 10),
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follow_redirects=True,
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),
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)
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)
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read, write, _ = transport
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self.session = await self.exit_stack.enter_async_context(ClientSession(read, write))
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await self.session.initialize()
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async def _lifecycle_loop(self):
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"""在后台任务中管理整个MCP会话的生命周期"""
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try:
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if self.server_config['mode'] == 'stdio':
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await self._init_stdio_python_server()
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elif self.server_config['mode'] == 'sse':
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await self._init_sse_server()
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elif self.server_config['mode'] == 'http':
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await self._init_streamable_http_server()
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else:
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raise ValueError(f'无法识别 MCP 服务器类型: {self.server_name}: {self.server_config}')
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await self.refresh()
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self.status = MCPSessionStatus.CONNECTED
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# 通知start()方法连接已建立
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self._ready_event.set()
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# 等待shutdown信号
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await self._shutdown_event.wait()
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except Exception as e:
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self.status = MCPSessionStatus.ERROR
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self.error_message = str(e)
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self.ap.logger.error(f'Error in MCP session lifecycle {self.server_name}: {e}\n{traceback.format_exc()}')
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# 即使出错也要设置ready事件，让start()方法知道初始化已完成
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self._ready_event.set()
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finally:
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# 在同一个任务中清理所有资源
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try:
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if self.exit_stack:
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await self.exit_stack.aclose()
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self.functions.clear()
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self.session = None
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except Exception as e:
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self.ap.logger.error(f'Error cleaning up MCP session {self.server_name}: {e}\n{traceback.format_exc()}')
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async def start(self):
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if not self.enable:
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return
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# 创建后台任务来管理生命周期
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self._lifecycle_task = asyncio.create_task(self._lifecycle_loop())
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# 等待连接建立或失败（带超时）
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try:
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await asyncio.wait_for(self._ready_event.wait(), timeout=30.0)
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except asyncio.TimeoutError:
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self.status = MCPSessionStatus.ERROR
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raise Exception('Connection timeout after 30 seconds')
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# 检查是否有错误
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if self.status == MCPSessionStatus.ERROR:
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raise Exception('Connection failed, please check URL')
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async def refresh(self):
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if not self.session:
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return
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self.functions.clear()
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tools = await self.session.list_tools()
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self.ap.logger.debug(f'Refresh MCP tools: {tools}')
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for tool in tools.tools:
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async def func(*, _tool=tool, **kwargs):
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if not self.session:
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raise Exception("MCP session is not connected")
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result = await self.session.call_tool(_tool.name, kwargs)
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if result.isError:
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error_texts = []
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for content in result.content:
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if content.type == 'text':
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error_texts.append(content.text)
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raise Exception("\n".join(error_texts) if error_texts else "Unknown error from MCP tool")
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result_contents: list[provider_message.ContentElement] = []
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for content in result.content:
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if content.type == 'text':
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result_contents.append(provider_message.ContentElement.from_text(content.text))
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elif content.type == 'image':
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result_contents.append(provider_message.ContentElement.from_image_base64(content.image_base64))
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elif content.type == 'resource':
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# TODO: Handle resource content
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pass
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return result_contents
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func.__name__ = tool.name
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self.functions.append(
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resource_tool.LLMTool(
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name=tool.name,
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human_desc=tool.description or "",
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description=tool.description or "",
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parameters=tool.inputSchema,
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func=func,
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)
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)
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def get_tools(self) -> list[resource_tool.LLMTool]:
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return self.functions
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def get_runtime_info_dict(self) -> dict:
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return {
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'status': self.status.value,
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'error_message': self.error_message,
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'tool_count': len(self.get_tools()),
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'tools': [
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{
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'name': tool.name,
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'description': tool.description,
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}
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for tool in self.get_tools()
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],
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}
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async def shutdown(self):
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"""关闭会话并清理资源"""
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try:
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# 设置shutdown事件，通知lifecycle任务退出
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self._shutdown_event.set()
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# 等待lifecycle任务完成（带超时）
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if self._lifecycle_task and not self._lifecycle_task.done():
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try:
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await asyncio.wait_for(self._lifecycle_task, timeout=5.0)
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except asyncio.TimeoutError:
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self.ap.logger.warning(f'MCP session {self.server_name} shutdown timeout, cancelling task')
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self._lifecycle_task.cancel()
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try:
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await self._lifecycle_task
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except asyncio.CancelledError:
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pass
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self.ap.logger.info(f'MCP session {self.server_name} shutdown complete')
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except Exception as e:
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self.ap.logger.error(f'Error shutting down MCP session {self.server_name}: {e}\n{traceback.format_exc()}')
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# @loader.loader_class('mcp')
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class MCPLoader(loader.ToolLoader):
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"""MCP 工具加载器。
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在此加载器中管理所有与 MCP Server 的连接。
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"""
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sessions: dict[str, RuntimeMCPSession]
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_last_listed_functions: list[resource_tool.LLMTool]
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_hosted_mcp_tasks: list[asyncio.Task]
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def __init__(self, ap: app.Application):
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super().__init__(ap)
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self.sessions = {}
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self._last_listed_functions = []
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self._hosted_mcp_tasks = []
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async def initialize(self):
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await self.load_mcp_servers_from_db()
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async def load_mcp_servers_from_db(self):
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self.ap.logger.info('Loading MCP servers from db...')
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self.sessions = {}
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result = await self.ap.persistence_mgr.execute_async(sqlalchemy.select(persistence_mcp.MCPServer))
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servers = result.all()
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for server in servers:
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config = self.ap.persistence_mgr.serialize_model(persistence_mcp.MCPServer, server)
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task = asyncio.create_task(self.host_mcp_server(config))
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self._hosted_mcp_tasks.append(task)
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async def host_mcp_server(self, server_config: dict):
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self.ap.logger.debug(f'Loading MCP server {server_config}')
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try:
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session = await self.load_mcp_server(server_config)
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self.sessions[server_config['name']] = session
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except Exception as e:
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self.ap.logger.error(
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f'Failed to load MCP server from db: {server_config["name"]}({server_config["uuid"]}): {e}\n{traceback.format_exc()}'
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)
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return
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self.ap.logger.debug(f'Starting MCP server {server_config["name"]}({server_config["uuid"]})')
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try:
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await session.start()
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except Exception as e:
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self.ap.logger.error(
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f'Failed to start MCP server {server_config["name"]}({server_config["uuid"]}): {e}\n{traceback.format_exc()}'
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)
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return
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self.ap.logger.debug(f'Started MCP server {server_config["name"]}({server_config["uuid"]})')
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async def load_mcp_server(self, server_config: dict) -> RuntimeMCPSession:
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"""加载 MCP 服务器到运行时
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Args:
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server_config: 服务器配置字典，必须包含:
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- name: 服务器名称
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- mode: 连接模式 (stdio/sse)
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- enable: 是否启用
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- extra_args: 额外的配置参数 (可选)
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"""
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uuid_ = server_config.get('uuid')
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if not uuid_:
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self.ap.logger.warning(
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'Server UUID is None for MCP server, maybe testing in the config page.'
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)
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uuid_ = str(uuid_module.uuid4())
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server_config['uuid'] = uuid_
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name = server_config['name']
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uuid = server_config['uuid']
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mode = server_config['mode']
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enable = server_config['enable']
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extra_args = server_config.get('extra_args', {})
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mixed_config = {
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'name': name,
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'uuid': uuid,
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'mode': mode,
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'enable': enable,
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**extra_args,
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}
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session = RuntimeMCPSession(name, mixed_config, enable, self.ap)
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return session
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async def get_tools(self, bound_mcp_servers: list[str] | None = None) -> list[resource_tool.LLMTool]:
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all_functions = []
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for session in self.sessions.values():
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# If bound_mcp_servers is specified, only include tools from those servers
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if bound_mcp_servers is not None:
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if session.server_uuid in bound_mcp_servers:
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all_functions.extend(session.get_tools())
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else:
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# If no bound servers specified, include all tools
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all_functions.extend(session.get_tools())
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self._last_listed_functions = all_functions
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return all_functions
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async def has_tool(self, name: str) -> bool:
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"""检查工具是否存在"""
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for session in self.sessions.values():
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for function in session.get_tools():
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if function.name == name:
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return True
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return False
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async def invoke_tool(self, name: str, parameters: dict, query: pipeline_query.Query) -> typing.Any:
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"""执行工具调用"""
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for session in self.sessions.values():
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for function in session.get_tools():
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if function.name == name:
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self.ap.logger.debug(f'Invoking MCP tool: {name} with parameters: {parameters}')
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try:
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result = await function.func(**parameters)
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self.ap.logger.debug(f'MCP tool {name} executed successfully')
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return result
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except Exception as e:
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self.ap.logger.error(f'Error invoking MCP tool {name}: {e}\n{traceback.format_exc()}')
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raise
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raise ValueError(f'Tool not found: {name}')
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async def remove_mcp_server(self, server_name: str):
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"""移除 MCP 服务器"""
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if server_name not in self.sessions:
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self.ap.logger.warning(f'MCP server {server_name} not found in sessions, skipping removal')
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return
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session = self.sessions.pop(server_name)
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await session.shutdown()
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self.ap.logger.info(f'Removed MCP server: {server_name}')
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def get_session(self, server_name: str) -> RuntimeMCPSession | None:
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"""获取指定名称的 MCP 会话"""
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return self.sessions.get(server_name)
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def has_session(self, server_name: str) -> bool:
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"""检查是否存在指定名称的 MCP 会话"""
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return server_name in self.sessions
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def get_all_server_names(self) -> list[str]:
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"""获取所有已加载的 MCP 服务器名称"""
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return list(self.sessions.keys())
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def get_server_tool_count(self, server_name: str) -> int:
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"""获取指定服务器的工具数量"""
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session = self.get_session(server_name)
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return len(session.get_tools()) if session else 0
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def get_all_servers_info(self) -> dict[str, dict]:
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"""获取所有服务器的信息"""
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info = {}
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for server_name, session in self.sessions.items():
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info[server_name] = {
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'name': server_name,
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'mode': session.server_config.get('mode'),
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'enable': session.enable,
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'tools_count': len(session.get_tools()),
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'tool_names': [f.name for f in session.get_tools()],
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}
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return info
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async def shutdown(self):
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"""关闭所有工具"""
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self.ap.logger.info('Shutting down all MCP sessions...')
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for server_name, session in list(self.sessions.items()):
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try:
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await session.shutdown()
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self.ap.logger.debug(f'Shutdown MCP session: {server_name}')
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except Exception as e:
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self.ap.logger.error(f'Error shutting down MCP session {server_name}: {e}\n{traceback.format_exc()}')
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self.sessions.clear()
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self.ap.logger.info('All MCP sessions shutdown complete')
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