fix(html): avoid adding filesystem root to watcher

packages/vite/src/node/server/middlewares/__tests__/fixtures/outside.html

@@ -0,0 +1,6 @@
+<!doctype html>
+<html>
+  <body>
+    <div>Outside root</div>
+  </body>
+</html>

packages/vite/src/node/server/middlewares/__tests__/indexHtml.spec.ts

@@ -1,12 +1,14 @@
 import fs from 'node:fs'
 import path from 'node:path'
-import { describe, expect, onTestFinished, test } from 'vitest'
+import { describe, expect, onTestFinished, test, vi } from 'vitest'
 import { FS_PREFIX } from '../../../constants'
 import { createServer } from '../../../server'
 
 const FIXTURE_DIR = path.resolve(import.meta.dirname, 'fixtures')
 const HTML_PATH = path.resolve(FIXTURE_DIR, 'root/index.html')
 const HTML_CONTENT = fs.readFileSync(HTML_PATH, 'utf-8')
+const OUTSIDE_HTML_PATH = path.resolve(FIXTURE_DIR, 'outside.html')
+const OUTSIDE_HTML_CONTENT = fs.readFileSync(OUTSIDE_HTML_PATH, 'utf-8')
 const VITE_PACKAGE_DIR = path.resolve(import.meta.dirname, '../../../../..')
 
 async function createTestServer(rootDir?: string) {
@@ -107,6 +109,32 @@ describe('indexHtml middleware — inline script proxy cache', () => {
   }
 })
 
+describe('indexHtml middleware — file watching', () => {
+  test('watches an /@fs/ HTML file outside root', async () => {
+    const server = await createTestServer()
+    const addSpy = vi
+      .spyOn(server.watcher, 'add')
+      .mockImplementation(() => server.watcher)
+    const fsUrl = path.posix.join(FS_PREFIX, OUTSIDE_HTML_PATH)
+
+    await server.transformIndexHtml(fsUrl, OUTSIDE_HTML_CONTENT)
+
+    expect(addSpy).toHaveBeenCalledWith(OUTSIDE_HTML_PATH)
+  })
+
+  test('does not watch a directory for a root URL with a query', async () => {
+    const server = await createTestServer()
+    const addSpy = vi
+      .spyOn(server.watcher, 'add')
+      .mockImplementation(() => server.watcher)
+    const html = '<style>body { color: red; }</style>'
+
+    await server.transformIndexHtml('/?foo=bar', html)
+
+    expect(addSpy).not.toHaveBeenCalledWith('/')
+  })
+})
+
 describe('indexHtml middleware — HMR timestamp injection with non-root base', () => {
   test('entry script URL gets the lastHMRTimestamp query when base is not root', async () => {
     const root = path.resolve(import.meta.dirname, 'fixtures/base-root')

packages/vite/src/node/server/middlewares/indexHtml.ts

@@ -43,6 +43,7 @@ import {
   normalizePath,
   processSrcSetSync,
   stripBase,
+  tryStatSync,
 } from '../../utils'
 import {
   BasicMinimalPluginContext,
@@ -223,7 +224,8 @@ const devHtmlHook: IndexHtmlTransformHook = async (
   let proxyModuleUrl: string
 
   const trailingSlash = htmlPath.endsWith('/')
-  if (!trailingSlash && fs.existsSync(filename)) {
+  if (!trailingSlash && tryStatSync(filename)?.isFile()) {
+    ensureWatchedFile(watcher, filename, config.root)
     // If htmlPath is a /@fs/ URL (e.g. vitest-browser always uses this form
     // for testerHtmlPath), normalise to an absolute FS path so proxyCacheUrl
     // is always root-relative.
@@ -404,7 +406,6 @@ const devHtmlHook: IndexHtmlTransformHook = async (
           url,
           false,
         )
-      ensureWatchedFile(watcher, mod.file, config.root)
 
       const result =
         await server!.environments.client.pluginContainer.transform(
@@ -431,7 +432,6 @@ const devHtmlHook: IndexHtmlTransformHook = async (
           url,
           false,
         )
-      ensureWatchedFile(watcher, mod.file, config.root)
 
       await server?.environments.client.pluginContainer.transform(code, mod.id!)