mcp-sse-timeout-sse-connection-from-a-client-e-g-cursor-drops-with-d60163d8

THEN Implement a keep-alive mechanism by periodically writing an SSE comment (e.g., `res.write(': keepalive\n\n')`) to the HTTP response stream. Set an interval (e.g., every 25-30 seconds) to send this comment, preventing the connection from being closed due to inactivity. This keeps the SSE stream alive until a real event (tool result, notification) is sent.

// inside the SSE endpoint handler
const KEEP_ALIVE_INTERVAL_MS = 25000;
const keepAliveId = setInterval(() => {
  res.write(': keepalive\n\n');
}, KEEP_ALIVE_INTERVAL_MS);
res.on('close', () => clearInterval(keepAliveId));