import cors from 'cors';
import express, { type Request, type Response } from 'express';
import { randomUUID } from 'node:crypto';
import { StreamableHTTPServerTransport } from '@modelcontextprotocol/sdk/server/streamableHttp.js';
import { isInitializeRequest } from '@modelcontextprotocol/sdk/types.js';
import { createAlgorandServer } from './serverCore.js';
type Session = {
transport: StreamableHTTPServerTransport;
};
const app = express();
const PORT = Number(process.env.PORT) || 8081;
app.use(express.json({ limit: '2mb' }));
app.use(
cors({
origin: '*',
credentials: true,
methods: ['GET', 'POST', 'DELETE', 'OPTIONS'],
allowedHeaders: ['Content-Type', 'mcp-session-id', 'mcp-protocol-version'],
exposedHeaders: ['mcp-session-id', 'mcp-protocol-version'],
})
);
const sessions = new Map<string, Session>();
async function createSession(): Promise<Session> {
const transport = new StreamableHTTPServerTransport({
sessionIdGenerator: () => randomUUID(),
onsessioninitialized: (sessionId) => {
if (sessionId) {
sessions.set(sessionId, { transport });
}
},
});
transport.onclose = () => {
if (transport.sessionId) {
sessions.delete(transport.sessionId);
}
};
const server = createAlgorandServer();
await server.connect(transport);
return { transport };
}
function getSessionFromRequest(req: Request) {
const sessionId = req.headers['mcp-session-id'] as string | undefined;
return sessionId ? sessions.get(sessionId) : undefined;
}
app.get('/healthz', (_req: Request, res: Response) => {
res.json({ status: 'ok' });
});
app.post('/mcp', async (req: Request, res: Response) => {
try {
let session = getSessionFromRequest(req);
if (!session) {
if (!isInitializeRequest(req.body)) {
res.status(400).json({
jsonrpc: '2.0',
error: {
code: -32000,
message: 'Bad Request: No valid session ID provided',
},
id: null,
});
return;
}
session = await createSession();
}
await session.transport.handleRequest(req, res, req.body);
} catch (error: any) {
console.error('Error handling MCP POST request', error);
if (!res.headersSent) {
res.status(500).json({
jsonrpc: '2.0',
error: {
code: -32603,
message: 'Internal server error',
},
id: null,
});
}
}
});
const handleSessionRequest = async (req: Request, res: Response) => {
const session = getSessionFromRequest(req);
if (!session) {
res.status(400).send('Invalid or missing session ID');
return;
}
await session.transport.handleRequest(req, res);
};
app.get('/mcp', handleSessionRequest);
app.delete('/mcp', handleSessionRequest);
app.listen(PORT, () => {
console.log(`Algorand MCP Streamable HTTP server listening on port ${PORT}`);
});
