fix(ssr): preload client reference modules before first SSR render

packages/vinext/src/server/app-dev-server.ts

@@ -2296,6 +2296,7 @@ import { setNavigationContext, ServerInsertedHTMLContext } from "next/navigation
 import { runWithNavigationContext as _runWithNavCtx } from "vinext/navigation-state";
 import { safeJsonStringify } from "vinext/html";
 import { createElement as _ssrCE } from "react";
+import * as _clientRefs from "virtual:vite-rsc/client-references";
 
 /**
  * Collect all chunks from a ReadableStream into an array of text strings.
@@ -2420,6 +2421,21 @@ function createRscEmbedTransform(embedStream) {
  *   and the data needs to be passed to SSR since they're separate module instances.
  */
 export async function handleSsr(rscStream, navContext, fontData) {
+  // Eagerly preload all client reference modules before SSR rendering.
+  // On the first request after server start, client component modules are
+  // loaded lazily via async import(). Without this preload, React's
+  // renderToReadableStream rejects because the shell can't resolve client
+  // components synchronously (there is no Suspense boundary wrapping the
+  // root). The memoized require cache ensures this is only async on the
+  // very first call; subsequent requests resolve from cache immediately.
+  if (_clientRefs?.default && globalThis.__vite_rsc_client_require__) {
+    await Promise.all(
+      Object.keys(_clientRefs.default).map((id) =>
+        globalThis.__vite_rsc_client_require__(id).catch?.(() => {})
+      )
+    );
+  }
+
   // Wrap in a navigation ALS scope for per-request isolation in the SSR
   // environment. The SSR environment has separate module instances from RSC,
   // so it needs its own ALS scope.