diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 7162bdcb4993..dcf1029cdac8 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -19,7 +19,6 @@ concurrency:
 
 env:
   PLAYWRIGHT_BROWSERS_PATH: ${{ github.workspace }}/.cache/ms-playwright
-  VITEST_GENERATE_UI_TOKEN: 'true'
 
 jobs:
   lint:
diff --git a/.github/workflows/cr.yml b/.github/workflows/cr.yml
index 07075c88b9f1..e953b2e8a0fe 100644
--- a/.github/workflows/cr.yml
+++ b/.github/workflows/cr.yml
@@ -41,7 +41,6 @@ jobs:
       - name: Build
         run: pnpm build
         env:
-          VITEST_GENERATE_UI_TOKEN: 'true'
           VITE_TEST_WATCHER_DEBUG: 'false'
 
       - name: Publish to StackBlitz
diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
index bee9a3d2523a..1aa5ea80c3ad 100644
--- a/.github/workflows/publish.yml
+++ b/.github/workflows/publish.yml
@@ -10,7 +10,6 @@ permissions:
   id-token: write
 
 env:
-  VITEST_GENERATE_UI_TOKEN: 'true'
   VITE_TEST_WATCHER_DEBUG: 'false'
 
 jobs:
diff --git a/packages/ui/CONTRIBUTING.md b/packages/ui/CONTRIBUTING.md
index 847f71a03306..c22b3e26f064 100644
--- a/packages/ui/CONTRIBUTING.md
+++ b/packages/ui/CONTRIBUTING.md
@@ -1,25 +1,56 @@
-At project root, create terminals with each of the following commands:
+# @vitest/ui Development
+
+## UI
+
+Use this setup for developing UI features with Vite HMR. It serves the UI from a separate dev server, so it can differ from the exact `vitest --ui` runtime path.
+
+Start the UI dev server:
+
+```bash
+# Align with the API port configured in test/unit/vite.config.ts.
+VITE_PORT=3023 pnpm -C packages/ui dev:client
+```
+
+Start a Vitest UI/API server for any test project you want to use as the backend. For example, from the repository root this runs the `test/unit` suite with UI enabled:
+
+```bash
+pnpm test --ui --open=false
+```
+
+The UI dev server only needs a real Vitest UI/API server to connect to; the backend can be `test/unit`, `packages/ui`, or another suite.
+
+Open the URL printed by the UI dev server, usually `http://localhost:5173/`.
+
+The UI dev server connects to the Vitest UI/API server on port `51204` by default. The root `test/unit` suite uses port `3023`, so the command above sets `VITE_PORT=3023`. If you use another backend port, pass the same port to the UI dev server:
 
 ```bash
-nr ui:dev
+VITE_PORT=12345 pnpm -C packages/ui dev:client
 ```
 
 ```bash
-nr test --api
+pnpm test --ui --open=false --api=12345
 ```
 
-As the last command, you can use any of the available tests suites instead. Make sure that they run at 51204 port or specify a custom port with `VITE_PORT` environmental variable when running the first command. For example,
+## Browser Mode UI
+
+Use this setup for developing Browser Mode UI features with Vite HMR. It serves the Browser Mode UI from the UI dev server and injects state from a real browser-mode Vitest server.
+
+Start a browser-mode Vitest server:
 
 ```bash
-VITE_PORT=3200 nr ui:dev
+pnpm -C packages/ui test:ui --browser.headless --ui --open=false
 ```
 
+Start the UI dev server in browser preview mode:
+
 ```bash
-nr test --api=3200
+BROWSER_DEV=true pnpm -C packages/ui dev:client
 ```
 
-Open the browser at the URL printed by the first command. For example, `http://localhost:5173/`. If you see a connection error, it means the port is specified incorrectly.
+Open the URL printed by the UI dev server, usually `http://localhost:5173/`.
 
-To preview the browser tab, uncomment the "browser-dev-preview" plugin in `vite.config.ts`.
+The UI dev server fetches browser runner state from the browser runner server on port `63315` by default. If Vitest prints a different browser runner port, pass it to the UI dev server:
 
-To configure the browser state, update the `__vitest_browser_runner__` object in `browser.dev.js`.
+```bash
+BROWSER_DEV_PORT=63316 BROWSER_DEV=true pnpm -C packages/ui dev:client
+```
diff --git a/packages/ui/browser.dev.js b/packages/ui/browser.dev.js
deleted file mode 100644
index 2381161e627e..000000000000
--- a/packages/ui/browser.dev.js
+++ /dev/null
@@ -1,11 +0,0 @@
-window.__vitest_browser_runner__ = {
-  files: [],
-  config: {
-    browser: {
-      name: 'chrome',
-    },
-  },
-  type: 'orchestrator',
-  provider: 'playwright',
-  wrapModule: () => {},
-}
diff --git a/packages/ui/client/constants.ts b/packages/ui/client/constants.ts
index bd4db857be19..3e14532c189c 100644
--- a/packages/ui/client/constants.ts
+++ b/packages/ui/client/constants.ts
@@ -2,6 +2,6 @@ export const PORT = import.meta.hot ? (import.meta.env.VITE_PORT || '51204') : l
 export const HOST = [location.hostname, PORT].filter(Boolean).join(':')
 export const ENTRY_URL = `${
   location.protocol === 'https:' ? 'wss:' : 'ws:'
-}//${HOST}/__vitest_api__?token=${(window as any).VITEST_API_TOKEN || '0'}`
+}//${HOST}/__vitest_api__?token=${(window as any).VITEST_API_TOKEN}`
 export const isReport = !!window.METADATA_PATH
 export const BASE_PATH = isReport ? import.meta.env.BASE_URL : __BASE_PATH__
diff --git a/packages/ui/vite.config.ts b/packages/ui/vite.config.ts
index 586e772c6ac2..7f5bfee461d6 100644
--- a/packages/ui/vite.config.ts
+++ b/packages/ui/vite.config.ts
@@ -1,3 +1,4 @@
+import type { Plugin } from 'vite'
 import Vue from '@vitejs/plugin-vue'
 import { resolve } from 'pathe'
 import { presetAttributify, presetIcons, presetUno, transformerDirectives } from 'unocss'
@@ -54,6 +55,7 @@ export default defineConfig({
     Pages({
       dirs: ['client/pages'],
     }),
+    devUiScriptPlugin(),
     // uncomment to see the HTML reporter preview
     // {
     //   name: 'debug-html-report',
@@ -62,17 +64,6 @@ export default defineConfig({
     //     return html.replace('<!-- !LOAD_METADATA! -->', `<script>window.METADATA_PATH="${debugLink}/html.meta.json.gz"</script>`)
     //   },
     // },
-
-    // uncomment to see the browser tab
-    // {
-    //   name: 'browser-dev-preview',
-    //   apply: 'serve',
-    //   transformIndexHtml() {
-    //     return [
-    //       { tag: 'script', attrs: { src: './browser.dev.js' } },
-    //     ]
-    //   },
-    // },
     {
       // workaround `crossorigin` issues on some browsers
       // https://github.com/vitejs/vite/issues/6648
@@ -89,3 +80,56 @@ export default defineConfig({
     outDir: './dist/client',
   },
 })
+
+function devUiScriptPlugin(): Plugin {
+  const UI_SCRIPT_RE = /<script>(window\.VITEST_API_TOKEN\s*=\s*"[^"]+")<\/script>/
+  const BROWSER_SCRIPT_RE = /<script type="module">([\s\S]*?window\.__vitest_browser_runner__\s*=\s*\{[\s\S]*?window\.VITEST_API_TOKEN\s*=[\s\S]*?)<\/script>/
+
+  const uiUrl = `http://localhost:${process.env.VITE_PORT || '51204'}/__vitest__/`
+  const browserUrl = `http://localhost:${process.env.BROWSER_DEV_PORT || '63315'}/__vitest_test__/`
+
+  return {
+    name: 'dev-ui-script',
+    apply(_config, env) {
+      return env.command === 'serve' && env.mode !== 'test'
+    },
+    async transformIndexHtml() {
+      if (process.env.BROWSER_DEV) {
+        const response = await fetch(browserUrl)
+        if (!response.ok) {
+          throw new Error(`Failed to fetch browser runner HTML from ${browserUrl}`)
+        }
+        const browserHtml = await response.text()
+        const browserScript = browserHtml.match(BROWSER_SCRIPT_RE)?.[1]
+        if (!browserScript) {
+          throw new Error('Failed to extract browser runner state from the response')
+        }
+        return [
+          {
+            tag: 'script',
+            attrs: { type: 'module' },
+            children: browserScript,
+            injectTo: 'head-prepend',
+          },
+        ]
+      }
+
+      const response = await fetch(uiUrl)
+      if (!response.ok) {
+        throw new Error(`Failed to fetch VITEST_API_TOKEN from ${uiUrl}`)
+      }
+      const testHtml = await response.text()
+      const tokenScript = testHtml.match(UI_SCRIPT_RE)?.[1]
+      if (!tokenScript) {
+        throw new Error('Failed to extract VITEST_API_TOKEN from the response')
+      }
+      return [
+        {
+          tag: 'script',
+          children: tokenScript,
+          injectTo: 'head-prepend',
+        },
+      ]
+    },
+  }
+}
diff --git a/packages/vitest/rollup.config.js b/packages/vitest/rollup.config.js
index d3e45cdc43f6..09200e35c63d 100644
--- a/packages/vitest/rollup.config.js
+++ b/packages/vitest/rollup.config.js
@@ -95,10 +95,6 @@ const plugins = [
     transform: {
       target: 'node20',
       define: {
-        // __VITEST_GENERATE_UI_TOKEN__ is set as a global to catch accidental leaking,
-        // in the release version the "if" with this condition should not be present
-        // To test strict token locally, build by e.g. `VITEST_GENERATE_UI_TOKEN=true pnpm build`
-        __VITEST_GENERATE_UI_TOKEN__: process.env.VITEST_GENERATE_UI_TOKEN === 'true' ? 'true' : 'false',
         ...(process.env.VITE_TEST_WATCHER_DEBUG === 'false'
           ? {
               'process.env.VITE_TEST_WATCHER_DEBUG': 'false',
diff --git a/packages/vitest/src/node/config/resolveConfig.ts b/packages/vitest/src/node/config/resolveConfig.ts
index 60b507c11193..a56296b3c8be 100644
--- a/packages/vitest/src/node/config/resolveConfig.ts
+++ b/packages/vitest/src/node/config/resolveConfig.ts
@@ -675,7 +675,7 @@ export function resolveConfig(
 
   // the server has been created, we don't need to override vite.server options
   const api = resolveApiServerConfig(options, defaultPort)
-  resolved.api = { ...api, token: __VITEST_GENERATE_UI_TOKEN__ ? crypto.randomUUID() : '0' }
+  resolved.api = { ...api, token: crypto.randomUUID() }
 
   if (options.related) {
     resolved.related = toArray(options.related).map(file =>
diff --git a/packages/vitest/src/shims.dev.d.ts b/packages/vitest/src/shims.dev.d.ts
deleted file mode 100644
index 291b2a3112f3..000000000000
--- a/packages/vitest/src/shims.dev.d.ts
+++ /dev/null
@@ -1,5 +0,0 @@
-declare global {
-  const __VITEST_GENERATE_UI_TOKEN__: boolean
-}
-
-export {}
diff --git a/scripts/publish-ci.ts b/scripts/publish-ci.ts
index e77fbc0f9eba..7f53a7897195 100644
--- a/scripts/publish-ci.ts
+++ b/scripts/publish-ci.ts
@@ -4,8 +4,8 @@ import { readFileSync } from 'node:fs'
 import { fileURLToPath } from 'node:url'
 import { $ } from 'zx'
 
-if (process.env.VITEST_GENERATE_UI_TOKEN !== 'true' || process.env.VITE_TEST_WATCHER_DEBUG !== 'false') {
-  throw new Error(`Cannot release Vitest without VITEST_GENERATE_UI_TOKEN=${process.env.VITEST_GENERATE_UI_TOKEN} and VITE_TEST_WATCHER_DEBUG=${process.env.VITE_TEST_WATCHER_DEBUG} environment variable. `)
+if (process.env.VITE_TEST_WATCHER_DEBUG !== 'false') {
+  throw new Error(`Cannot release Vitest without VITE_TEST_WATCHER_DEBUG=${process.env.VITE_TEST_WATCHER_DEBUG} environment variable. `)
 }
 
 let version = process.argv[2]
diff --git a/test/test-utils/index.ts b/test/test-utils/index.ts
index c2d4196843df..efc0f5eae6dc 100644
--- a/test/test-utils/index.ts
+++ b/test/test-utils/index.ts
@@ -26,8 +26,6 @@ import { Cli } from './cli'
 
 // override default colors to disable them in tests
 Object.assign(tinyrainbow.default, tinyrainbow.getDefaultColors())
-// @ts-expect-error not typed global
-globalThis.__VITEST_GENERATE_UI_TOKEN__ = true
 
 export interface VitestRunnerCLIOptions {
   std?: 'inherit'
diff --git a/test/unit/test/cli-test.test.ts b/test/unit/test/cli-test.test.ts
index 86f8a2881463..c53863f701ac 100644
--- a/test/unit/test/cli-test.test.ts
+++ b/test/unit/test/cli-test.test.ts
@@ -4,9 +4,6 @@ import { ReportersMap, rolldownVersion } from 'vitest/node'
 import { createCLI, parseCLI } from '../../../packages/vitest/src/node/cli/cac.js'
 import { resolveConfig } from '../../../packages/vitest/src/node/config/resolveConfig.js'
 
-// @ts-expect-error not typed global
-globalThis.__VITEST_GENERATE_UI_TOKEN__ = true
-
 const vitestCli = createCLI()
 
 function parseArguments(commands: string, full = false) {