mcp-sse-transport-setup-when-using-mcp-inspector-to-test-an-sse-mcp-server-178f6304

THEN Implement both a GET /sse route that creates and stores an SSEServerTransport instance (using the response object), and a POST /messages route that calls transport.handlePostMessage(req, res) to handle incoming client messages. For single-connection testing, store the transport in a global variable; for multiple connections, index by session ID.

// GET /sse
app.get("/sse", async (req, res) => {
  const transport = new SSEServerTransport("/messages", res);
  await server.connect(transport);
  // Store transport for POST handler
  activeTransport = transport;
});

// POST /messages
app.post("/messages", async (req, res) => {
  await activeTransport.handlePostMessage(req, res);
});