SIGINT and SIGTERM handled for graceful shutdown

MCP servers running as child processes receive SIGINT when the user presses Ctrl+C and SIGTERM when the parent process shuts down. Without signal handlers, the Node.js process exits immediately (SIGINT default), potentially mid-write on an in-progress JSON-RPC response. The client receives a truncated or empty message and marks the server as crashed. CWE-404 (improper resource shutdown) covers this: open database connections, file handles, and HTTP keep-alives are abandoned rather than closed, which can leave the remote systems in inconsistent state.

Register SIGINT and SIGTERM handlers that call server.close() before exiting. The SDK's close() drains in-flight messages and closes the transport cleanly.

// src/index.ts
async function shutdown() {
  console.error('Shutting down...')
  await server.close()  // closes transport, drains in-flight messages
  process.exit(0)
}

process.on('SIGINT', shutdown)
process.on('SIGTERM', shutdown)

const transport = new StdioServerTransport()
await server.connect(transport)

If your server holds database connections or open file handles, close them inside shutdown() before calling process.exit(0).