Add streamable HTTP server mode

[syucream]

Summary

• update MCP SDK to ^1.1.0
• add ability to run server either on stdio or streamable HTTP
• support --port command line flag to enable HTTP mode
• document --port flag in README
• validate port is not within well-known port range (1024-65535)

Testing

• npm run lint
• npm test

[Copilot]

Pull Request Overview

Adds an HTTP-based SSE server alongside the existing stdio transport, upgrades the MCP SDK, and updates docs.

• Upgrades @modelcontextprotocol/sdk to ^1.1.0
• Introduces --port flag to switch between stdio and HTTP/SSE modes with port validation
• Updates README to document the new --port usage

Reviewed Changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 2 comments.

File	Description
src/index.ts	Added startHttpServer, updated main to parse --port, and renamed runServer to startStdioServer
README.md	Documented --port flag usage and example for HTTP/SSE server mode

Files not reviewed (1)

• package.json: Language not supported

Comments suppressed due to low confidence (1)

src/index.ts:479

• The new HTTP and stdio server flows lack dedicated tests. Add unit or integration tests to cover both code paths and verify SSE handshake and message handling.

async function main() {

[Copilot]

This only tracks a single SSE transport instance, so concurrent clients will overwrite each other. Consider mapping transports by sessionId and parameterizing the POST endpoint to support multiple simultaneous connections.

Suggested change

	let transport: SSEServerTransport | undefined;
	app.get('/sse', async (_req, res) => {
	transport = new SSEServerTransport('/message', res);
	await server.connect(transport);
	console.error(
	`Lightdash MCP Server new SSE connection ${transport.sessionId}`
	);
	});
	app.post('/message', async (req, res) => {
	if (!transport) {
	res.status(404).send('Session not initialized');
	return;
	}
	await transport.handlePostMessage(req, res, req.body);
	const transports: Map<string, SSEServerTransport> = new Map();
	app.get('/sse', async (_req, res) => {
	const transport = new SSEServerTransport('/message', res);
	transports.set(transport.sessionId, transport);
	await server.connect(transport);
	console.error(
	`Lightdash MCP Server new SSE connection ${transport.sessionId}`
	);
	res.on('close', () => {
	transports.delete(transport.sessionId);
	console.error(`SSE connection closed: ${transport.sessionId}`);
	});
	});
	app.post('/message', async (req, res) => {
	const { sessionId, message } = req.body;
	const transport = transports.get(sessionId);
	if (!transport) {
	res.status(404).send('Session not found');
	return;
	}
	await transport.handlePostMessage(req, res, message);

[Copilot]

[nitpick] It may help to document the POST /message endpoint usage after the SSE connection, so consumers know how to send messages back to the server.