Function startServer

apps/host-selfhost/src/serve.ts:110–167

()

  );

export const startServer = async (): Promise<void> => {
  const config = loadConfig();
  const { AppLayer, betterAuth } = await makeSelfHostApp();

  // Serve the built SPA, split by cacheability so a redeploy is picked up at
  // once instead of stranding browsers on a stale shell:
  //   - `/assets/*` are Vite content-hashed (a new build emits new filenames),
  //     so they're safe to cache forever.
  //   - index.html (and the SPA fallback for client routes) is the mutable
  //     entry point that references those hashes; it must always revalidate, or
  //     a browser keeps an old index.html plus its old hashed bundles (still in
  //     cache) and renders a stale UI until a hard refresh.
  // Without explicit headers `HttpStaticServer` sends no Cache-Control at all,
  // so browsers heuristically cache index.html across deploys. The hashed
  // `/assets` route is the more specific match, so it wins over the SPA
  // catch-all. Other built-in API/docs/auth/mcp routes still take precedence;
  // `spa: true` falls back to index.html for any remaining path (client routing).
  const AssetsLive = HttpStaticServer.layer({
    root: assetsDir,
    prefix: "/assets",
    cacheControl: "public, max-age=31536000, immutable",
  }).pipe(Layer.provide(BunFileSystem.layer), Layer.provide(BunPath.layer));

  const SpaLive = HttpStaticServer.layer({
    root: distDir,
    spa: true,
    cacheControl: "no-cache",
  }).pipe(Layer.provide(BunFileSystem.layer), Layer.provide(BunPath.layer));

  // Server-scope finalizer: flush buffered analytics on graceful shutdown.
  const AnalyticsFlushLive = Layer.effectDiscard(
    Effect.addFinalizer(() => Effect.promise(() => disposeAnalytics())),
  );

  // OTLP export, or `Layer.empty` when no collector is configured (see
  // ./telemetry). The `http.server` envelope span each request's `withSpan`
  // children parent under is NOT wired here: `HttpEffect.toHandled` already
  // wraps every served app in `HttpMiddleware.tracer`, which also continues an
  // inbound `traceparent` so a request arriving through a tunnel keeps one
  // trace id. Adding it here as well produced two identical `http.server`
  // spans per request, one the parent of the other.
  const TelemetryLive = makeTelemetryLive();

  const ServerLive = HttpRouter.serve(Layer.mergeAll(AppLayer, AssetsLive, SpaLive), {
    middleware: selfHostHttpMiddleware(betterAuth),
  }).pipe(
    Layer.provide(
      BunHttpServer.layer({ hostname: config.host, port: config.port, idleTimeout: 0 }),
    ),
  );

  // Provided UNDER the server, not merged beside it: the tracer must already be
  // in scope while the app's layers build, or spans created during construction
  // resolve the default no-op tracer and are silently dropped.
  await BunRuntime.runMain(
    Layer.launch(Layer.merge(ServerLive, AnalyticsFlushLive).pipe(Layer.provide(TelemetryLive))),
  );
};