fix(dev-server): keep HTTP sockets alive through proxy request deadlines

packages/dev-server/src/gateway.ts

@@ -654,6 +654,8 @@ export async function startGateway(opts: GatewayOptions): Promise<RunningGateway
       port,
       hostname,
       development: mode === "development",
+      // Keep the socket alive long enough to return the configured proxy timeout.
+      idleTimeout: Math.min(255, Math.max(35, Math.ceil((limits.timeoutMs ?? 30_000) / 1000) + 5)),
       maxRequestBodySize: maxBodyBytes,
       async fetch(req, srv) {
         const url = new URL(req.url);

packages/dev-server/src/index.ts

@@ -634,6 +634,8 @@ export async function startServer(opts: ServeOptions): Promise<RunningServer> {
     port,
     hostname,
     development: mode === "development",
+    // Cold page compilation can exceed Bun's default connection idle window.
+    idleTimeout: 35,
     maxRequestBodySize: 10 * 1024 * 1024,
     ...(opts.tls ? { tls: opts.tls } : {}),
     fetch(request, server) {