ChatGPT MCP Backend

1import {
2  createServer,
3  type IncomingMessage,
4  type ServerResponse,
5} from 'node:http';
6import { URL } from 'node:url';
7 
8import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
9import { SSEServerTransport } from '@modelcontextprotocol/sdk/server/sse.js';
10 
11import { registerAdd } from '@/registry/default/chatgpt-app/add';
12 
13function createUtilCnServer(): McpServer {
14  const server = new McpServer({
15    name: 'utilcn-mcp',
16    version: '0.1.0',
17  });
18 
19  registerAdd(server);
20  return server;
21}
22 
23type SessionRecord = {
24  server: McpServer;
25  transport: SSEServerTransport;
26};
27 
28const sessions = new Map<string, SessionRecord>();
29 
30const ssePath = '/mcp';
31const postPath = '/mcp/messages';
32 
33async function handleSseRequest(res: ServerResponse) {
34  res.setHeader('Access-Control-Allow-Origin', '*');
35  const server = createUtilCnServer();
36  const transport = new SSEServerTransport(postPath, res);
37  const sessionId = transport.sessionId;
38 
39  sessions.set(sessionId, { server, transport });
40 
41  transport.onclose = () => {
42    sessions.delete(sessionId);
43  };
44 
45  transport.onerror = (error) => {
46    console.error('SSE transport error', error);
47  };
48 
49  try {
50    await server.connect(transport);
51  } catch (error) {
52    sessions.delete(sessionId);
53    console.error('Failed to start SSE session', error);
54    if (!res.headersSent) {
55      res.writeHead(500).end('Failed to establish SSE connection');
56    }
57  }
58}
59 
60async function handlePostMessage(
61  req: IncomingMessage,
62  res: ServerResponse,
63  url: URL,
64) {
65  res.setHeader('Access-Control-Allow-Origin', '*');
66  res.setHeader('Access-Control-Allow-Headers', 'content-type');
67  const sessionId = url.searchParams.get('sessionId');
68 
69  if (!sessionId) {
70    res.writeHead(400).end('Missing sessionId query parameter');
71    return;
72  }
73 
74  const session = sessions.get(sessionId);
75 
76  if (!session) {
77    res.writeHead(404).end('Unknown session');
78    return;
79  }
80 
81  try {
82    await session.transport.handlePostMessage(req, res);
83  } catch (error) {
84    console.error('Failed to process message', error);
85    if (!res.headersSent) {
86      res.writeHead(500).end('Failed to process message');
87    }
88  }
89}
90 
91const portEnv = Number(process.env.PORT ?? 8000);
92const port = Number.isFinite(portEnv) ? portEnv : 8000;
93 
94const httpServer = createServer(
95  async (req: IncomingMessage, res: ServerResponse) => {
96    if (!req.url) {
97      res.writeHead(400).end('Missing URL');
98      return;
99    }
100 
101// … truncated