From c31ff29af3afa89fd8f7262a3f8f821ecceb043f Mon Sep 17 00:00:00 2001
From: Melissa Liu <mellyeliu@meta.com>
Date: Mon, 20 Jul 2026 13:19:35 -0400
Subject: [PATCH 1/2] fix(plugin-rsc): don't run build-only generateBundle in
 bundledDev

In bundledDev mode the client environment runs a Rollup build while
mode === 'dev', so the assets-manifest generateBundle hook fires even
though no RSC build output exists. It then reads manager.bundles['rsc']
(populated only by a production build) and crashes with
'TypeError: Cannot convert undefined or null to object'.

The dev manifest is already served by the load hook, so the build-only
asset copying and buildAssetsManifest construction are unnecessary in dev.
Return early when mode === 'dev'.
---
 packages/plugin-rsc/src/plugin.ts | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/packages/plugin-rsc/src/plugin.ts b/packages/plugin-rsc/src/plugin.ts
index 86cbba631..6ae2b5bd0 100644
--- a/packages/plugin-rsc/src/plugin.ts
+++ b/packages/plugin-rsc/src/plugin.ts
@@ -1121,6 +1121,14 @@ export function createRpcClient(params) {
       },
       // client build
       generateBundle(_options, bundle) {
+        // In bundledDev the client environment runs a Rollup build while
+        // `mode === 'dev'`, so this hook fires even though there is no RSC
+        // build output. The build-only asset copying and `buildAssetsManifest`
+        // construction below assume a production build (`manager.bundles['rsc']`
+        // is populated); in dev the manifest is served by the `load` hook above
+        // instead. Skip the build-only work in dev to avoid crashing on the
+        // absent RSC bundle.
+        if (this.environment.mode === 'dev') return
         // copy assets from rsc build to client build
         if (this.environment.name === 'client') {
           const rscBundle = manager.bundles['rsc']!

From a8e7da93193e0d95baed75f89698c36f509c28d6 Mon Sep 17 00:00:00 2001
From: Melissa Liu <mellyeliu@meta.com>
Date: Mon, 20 Jul 2026 13:26:42 -0400
Subject: [PATCH 2/2] test(plugin-rsc): e2e coverage for bundledDev dev server

Reuses examples/basic with 'pnpm dev --experimental-bundle' and asserts the
dev server starts, renders, and hydrates without the generateBundle crash.
---
 packages/plugin-rsc/e2e/bundled-dev.test.ts | 14 ++++++++++++++
 1 file changed, 14 insertions(+)
 create mode 100644 packages/plugin-rsc/e2e/bundled-dev.test.ts

diff --git a/packages/plugin-rsc/e2e/bundled-dev.test.ts b/packages/plugin-rsc/e2e/bundled-dev.test.ts
new file mode 100644
index 000000000..e47fa9b7d
--- /dev/null
+++ b/packages/plugin-rsc/e2e/bundled-dev.test.ts
@@ -0,0 +1,14 @@
+import { test } from '@playwright/test'
+import { useFixture } from './fixture'
+import { defineStarterTest } from './starter'
+
+// `experimental.bundledDev` runs a client Rollup build in dev, which used to
+// crash the assets-manifest `generateBundle` hook (no RSC bundle in dev).
+test.describe('bundled-dev', () => {
+  const f = useFixture({
+    root: 'examples/starter',
+    mode: 'dev',
+    command: 'pnpm dev --experimental-bundle',
+  })
+  defineStarterTest(f)
+})