MCP-SuperAssistant/dist/gateways/stdioToSse.js

import express from 'express';
import bodyParser from 'body-parser';
import cors from 'cors';
import { spawn } from 'child_process';
import { Server } from '@modelcontextprotocol/sdk/server/index.js';
import { SSEServerTransport } from '@modelcontextprotocol/sdk/server/sse.js';
import { getVersion } from '../lib/getVersion.js';
import { onSignals } from '../lib/onSignals.js';
import { serializeCorsOrigin } from '../lib/serializeCorsOrigin.js';
const setResponseHeaders = ({ res, headers, }) => Object.entries(headers).forEach(([key, value]) => {
    res.setHeader(key, value);
});
export async function stdioToSse(args) {
    const { stdioCmd, port, host, baseUrl, ssePath, messagePath, logger, corsOrigin, healthEndpoints, headers, } = args;
    logger.info(`  - Headers: ${Object(headers).length ? JSON.stringify(headers) : '(none)'}`);
    logger.info(`  - port: ${port}`);
    logger.info(`  - stdio: ${stdioCmd}`);
    if (baseUrl) {
        logger.info(`  - baseUrl: ${baseUrl}`);
    }
    logger.info(`  - ssePath: ${ssePath}`);
    logger.info(`  - messagePath: ${messagePath}`);
    logger.info(`  - CORS: ${corsOrigin ? `enabled (${serializeCorsOrigin({ corsOrigin })})` : 'disabled'}`);
    logger.info(`  - Health endpoints: ${healthEndpoints.length ? healthEndpoints.join(', ') : '(none)'}`);
    onSignals({ logger });
    const child = spawn(stdioCmd, { shell: true });
    child.on('exit', (code, signal) => {
        logger.error(`Child exited: code=${code}, signal=${signal}`);
        process.exit(code ?? 1);
    });
    const server = new Server({ name: 'mcp-superassistant-proxy', version: getVersion() }, { capabilities: {} });
    const sessions = {};
    const app = express();
    if (corsOrigin) {
        app.use(cors({ origin: corsOrigin }));
    }
    app.use((req, res, next) => {
        if (req.path === messagePath)
            return next();
        return bodyParser.json()(req, res, next);
    });
    for (const ep of healthEndpoints) {
        app.get(ep, (_req, res) => {
            setResponseHeaders({
                res,
                headers,
            });
            res.send('ok');
        });
    }
    app.get(ssePath, async (req, res) => {
        logger.info(`New SSE connection from ${req.ip}`);
        setResponseHeaders({
            res,
            headers,
        });
        const sseTransport = new SSEServerTransport(`${baseUrl}${messagePath}`, res);
        await server.connect(sseTransport);
        const sessionId = sseTransport.sessionId;
        if (sessionId) {
            sessions[sessionId] = { transport: sseTransport, response: res };
        }
        sseTransport.onmessage = (msg) => {
            logger.info(`SSE → Child (session ${sessionId}): ${JSON.stringify(msg)}`);
            child.stdin.write(JSON.stringify(msg) + '\n');
        };
        sseTransport.onclose = () => {
            logger.info(`SSE connection closed (session ${sessionId})`);
            delete sessions[sessionId];
        };
        sseTransport.onerror = (err) => {
            logger.error(`SSE error (session ${sessionId}):`, err);
            delete sessions[sessionId];
        };
        req.on('close', () => {
            logger.info(`Client disconnected (session ${sessionId})`);
            delete sessions[sessionId];
        });
    });
    // @ts-ignore
    app.post(messagePath, async (req, res) => {
        const sessionId = req.query.sessionId;
        setResponseHeaders({
            res,
            headers,
        });
        if (!sessionId) {
            return res.status(400).send('Missing sessionId parameter');
        }
        const session = sessions[sessionId];
        if (session?.transport?.handlePostMessage) {
            logger.info(`POST to SSE transport (session ${sessionId})`);
            await session.transport.handlePostMessage(req, res);
        }
        else {
            res.status(503).send(`No active SSE connection for session ${sessionId}`);
        }
    });
    app.listen(port, host, () => {
        logger.info(`Listening on ${host}:${port}`);
        logger.info(`SSE endpoint: http://${host}:${port}${ssePath}`);
        logger.info(`POST messages: http://${host}:${port}${messagePath}`);
    });
    let buffer = '';
    child.stdout.on('data', (chunk) => {
        buffer += chunk.toString('utf8');
        const lines = buffer.split(/\r?\n/);
        buffer = lines.pop() ?? '';
        lines.forEach((line) => {
            if (!line.trim())
                return;
            try {
                const jsonMsg = JSON.parse(line);
                logger.info('Child → SSE:', jsonMsg);
                for (const [sid, session] of Object.entries(sessions)) {
                    try {
                        session.transport.send(jsonMsg);
                    }
                    catch (err) {
                        logger.error(`Failed to send to session ${sid}:`, err);
                        delete sessions[sid];
                    }
                }
            }
            catch {
                logger.error(`Child non-JSON: ${line}`);
            }
        });
    });
    child.stderr.on('data', (chunk) => {
        logger.error(`Child stderr: ${chunk.toString('utf8')}`);
    });
}
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