Polybrain MCP Server

import type { Server } from "node:http"; import type { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js"; import { StreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/streamableHttp.js"; import express from "express"; import type { Express, Request, Response } from "express"; import { logger } from "./logger.js"; export class HTTPServer { private app: Express; private httpServer: Server | null = null; private mcpServer: McpServer; private port: number; constructor(mcpServer: McpServer, port: number) { this.mcpServer = mcpServer; this.port = port; this.app = express(); this.setupRoutes(); } private setupRoutes(): void { // Health check endpoint this.app.get("/health", (_req: Request, res: Response) => { logger.debug("Health check request"); res.json({ status: "ok" }); }); // Stateless MCP endpoint - create a new transport for each request // This prevents session management complexity and allows stateless operation this.app.post("/mcp", express.json(), async (req: Request, res: Response) => { logger.debug("MCP POST request", { method: req.body?.method }); // Create a new stateless transport for this request const transport = new StreamableHTTPServerTransport({ sessionIdGenerator: undefined, // Stateless mode - no session IDs enableJsonResponse: true, // Return JSON response instead of SSE stream }); // Clean up transport when response is sent or connection closes res.on("close", () => { transport.close(); }); try { // Connect the MCP server to the transport await this.mcpServer.connect(transport); // Handle the request - response will be sent as JSON await transport.handleRequest(req, res, req.body); } catch (error) { logger.error("Error handling MCP request", error as Error); if (!res.headersSent) { res.status(500).json({ error: "Internal server error" }); } } }); // 404 handler this.app.use((_req: Request, res: Response) => { logger.debug("404 - not found", { url: _req.url }); res.status(404).json({ error: "Not found" }); }); } async start(): Promise<void> { return new Promise((resolve, reject) => { try { this.httpServer = this.app.listen(this.port, () => { logger.info("HTTP server started", { port: this.port }); resolve(); }); this.httpServer.on("error", (error: Error) => { logger.error("HTTP server error", error); reject(error); }); } catch (error) { reject(error); } }); } async stop(): Promise<void> { return new Promise((resolve, reject) => { if (!this.httpServer) { resolve(); return; } this.httpServer.close((error) => { if (error) { logger.error("Error closing HTTP server", error); reject(error); } else { logger.info("HTTP server stopped"); resolve(); } }); }); } isRunning(): boolean { return this.httpServer?.listening || false; } getPort(): number { return this.port; } }