Add support/docs for listenTerminalRoute (SSE)

[kristianmandrup]

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I'm trying to use @ts-rest/fastify with Server Side Events (SSE). It was unclear if or how I could do it. I found the following snippet as part of the @ts-rest/fastify implementation and it seems to allow reply as an option argument for the routeImpl which was not clear. This should let me do reply.sse(...)

const registerRoute = (routeImpl, appRoute, fastify, options) => {
    if (options.logInitialization) {
        console.log(`[ts-rest] Initialized ${appRoute.method} ${appRoute.path}`);
    }
    fastify.route({
        method: appRoute.method,
        url: appRoute.path,
        handler: async (request, reply) => {
            const validationResults = validateRequest(request, reply, appRoute, options);
            let result;
            try {
                result = await routeImpl({
                    params: validationResults.paramsResult.data,
                    query: validationResults.queryResult.data,
                    headers: validationResults.headersResult.data,
                    request,
                    body: validationResults.bodyResult.data,
                    reply,
                    appRoute,
                });
            }

ChatGPT helped me out, suggestion the following routeImpl code for my use case

// Route handler function for listening for terminal output updates via SSE
export async function listenTerminalRoute(
  { params }: FastifyRequest<{ Params: RouterListenTerminalParams }>,
  reply: FastifyReply
): Promise<RouterListenTerminalResult> {
  const { sessionId, channel } = params;

  // Check if the sessionId is valid
  if (!userSessions.has(sessionId)) {
    return { status: 400, body: { message: "Invalid sessionId" } };
  }

Describe the solution you'd like A clear and concise description of what you want to happen.

Please make this feature capability more clear in the docs, perhaps with an example in the docs or the code. Thanks I'll try it out myself now.

Describe alternatives you've considered A clear and concise description of any alternative solutions or features you've considered.

You could also perhaps also add a thin wrapper for SSE in the SDK/API?

Additional context Add any other context or screenshots about the feature request here.

[Gabrola]

SSE is beyond the scope of ts-rest as event schemas are inherently not defined by paths, headers, or anything similar.