fix(plugin-react): use '/' base in bundledDev preamble to fix non-root base paths

In bundled dev mode (`experimental.bundledDev: true`), Rolldown resolves
module specifiers at build time without any URL-level base stripping.
Using `config.base` in `getPreambleCode` produced an import like
`/@react-refresh` prefixed with the custom base (e.g. `/static/@react-refresh`),
which Rolldown couldn't resolve since the `resolveId` hook only matches
the exact string `/@react-refresh`.

Fix by passing `'/'` instead of `config.base` to `getPreambleCode` in the
`viteReactRefreshBundledDevMode` plugin, consistent with how
`virtualPreamblePlugin` already handles this case.

Fixes #1190

Made-with: Cursor

Author: JustInCache

packages/plugin-react/src/index.ts

@@ -172,7 +172,10 @@ export default function viteReact(opts: Options = {}): Plugin[] {
             {
               tag: 'script',
               attrs: { type: 'module' },
-              children: getPreambleCode(base),
+              // In bundled dev mode, Rolldown resolves module specifiers at build
+              // time without URL-level base stripping, so we must use '/' instead
+              // of config.base to match the resolveId hook for '/@react-refresh'.
+              children: getPreambleCode('/'),
             },
           ]
       },

playground/bundled-dev-base-path/App.jsx

@@ -0,0 +1,15 @@
+import { useState } from 'react'
+
+function App() {
+  const [count, setCount] = useState(0)
+  return (
+    <div>
+      <h1>bundledDev + base path</h1>
+      <button id="state-button" onClick={() => setCount((c) => c + 1)}>
+        count is: {count}
+      </button>
+    </div>
+  )
+}
+
+export default App

playground/bundled-dev-base-path/__tests__/bundled-dev-base-path.spec.ts

@@ -0,0 +1,29 @@
+import { expect, test } from 'vitest'
+import { browserErrors, isServe, page, viteTestUrl } from '~utils'
+
+// Regression test for https://github.com/vitejs/vite-plugin-react/issues/1190
+// bundledDev mode with a non-root base should not fail to resolve /@react-refresh.
+test.runIf(isServe)(
+  'should load without UNRESOLVED_IMPORT error for @react-refresh',
+  async () => {
+    await page.goto(viteTestUrl)
+    // bundledDev shows "Bundling in progress" until the first bundle is ready.
+    await page.waitForSelector('h1')
+    await expect
+      .poll(() => page.textContent('h1'))
+      .toMatch('bundledDev + base path')
+    expect(browserErrors).toHaveLength(0)
+  },
+)
+
+test.runIf(isServe)('should render and update state', async () => {
+  await page.goto(viteTestUrl)
+  await page.waitForSelector('#state-button')
+  await expect
+    .poll(() => page.textContent('#state-button'))
+    .toMatch('count is: 0')
+  await page.click('#state-button')
+  await expect
+    .poll(() => page.textContent('#state-button'))
+    .toMatch('count is: 1')
+})

playground/bundled-dev-base-path/index.html

@@ -0,0 +1,10 @@
+<div id="app"></div>
+<script type="module">
+  import React from 'react'
+  import ReactDOM from 'react-dom/client'
+  import App from './App.jsx'
+
+  ReactDOM.createRoot(document.getElementById('app')).render(
+    React.createElement(App),
+  )
+</script>

playground/bundled-dev-base-path/package.json

@@ -0,0 +1,17 @@
+{
+  "name": "@vitejs/test-bundled-dev-base-path",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "dev": "vite",
+    "build": "vite build",
+    "preview": "vite preview"
+  },
+  "dependencies": {
+    "react": "^19.2.5",
+    "react-dom": "^19.2.5"
+  },
+  "devDependencies": {
+    "@vitejs/plugin-react": "workspace:*"
+  }
+}

playground/bundled-dev-base-path/vite.config.ts

@@ -0,0 +1,13 @@
+import react from '@vitejs/plugin-react'
+import type { UserConfig } from 'vite'
+
+const config: UserConfig = {
+  server: { port: 8930 /* Should be unique */ },
+  mode: 'development',
+  base: '/static/',
+  plugins: [react()],
+  experimental: { bundledDev: true },
+  build: { minify: false },
+}
+
+export default config