perf upgrade

server.ts

@@ -343,7 +343,10 @@ async function initializeStaticRoutes(
             gz,
             etag,
             type: metadata.type,
-            immutable: true,
+            // Only Vite's content-hashed output under /assets/ is safe to
+            // cache immutably; unhashed files (favicon, manifest, images)
+            // can change between deploys and must revalidate.
+            immutable: route.startsWith('/assets/'),
             size: bytes.byteLength,
           }
           routes[route] = createResponseHandler(asset)
@@ -529,14 +532,9 @@ async function initializeServer() {
       // Fallback to TanStack Start handler for all other routes
       '/*': async (req: Request) => {
         try {
-          const h3Response = await handler.fetch(req)
-            
-          const body = await h3Response.arrayBuffer()
-          return new Response(body, {
-            status: h3Response.status,
-            statusText: h3Response.statusText,
-            headers: h3Response.headers,
-          })
+          // Return the handler's Response as-is so streaming bodies
+          // (SSR streaming, SSE event streams) pass through unbuffered.
+          return await handler.fetch(req)
         } catch (error) {
           log.error(`Server handler error: ${String(error)}`)
           return new Response('Internal Server Error', { status: 500 })