fix: dev style with non runnable dev environments and basepath support

e2e/e2e-utils/src/fixture.ts

@@ -1,16 +1,36 @@
 import { test as base, expect } from '@playwright/test'
 
 export interface TestFixtureOptions {
+  /**
+   * List of error message patterns to ignore in console output.
+   * Supports both strings (substring match) and RegExp patterns.
+   *
+   * @example
+   * test.use({
+   *   whitelistErrors: [
+   *     'Failed to load resource: net::ERR_NAME_NOT_RESOLVED',
+   *     /Failed to load resource/,
+   *   ],
+   * })
+   */
   whitelistErrors: Array<RegExp | string>
 }
 export const test = base.extend<TestFixtureOptions>({
-  whitelistErrors: [[], { option: true }],
+  whitelistErrors: [
+    // eslint-disable-next-line no-empty-pattern
+    async ({}, use) => {
+      await use([])
+    },
+    { option: true },
+  ],
   page: async ({ page, whitelistErrors }, use) => {
     const errorMessages: Array<string> = []
+    // Ensure whitelistErrors is always an array (defensive fallback)
+    const errors = Array.isArray(whitelistErrors) ? whitelistErrors : []
     page.on('console', (m) => {
       if (m.type() === 'error') {
         const text = m.text()
-        for (const whitelistError of whitelistErrors) {
+        for (const whitelistError of errors) {
           if (
             (typeof whitelistError === 'string' &&
               text.includes(whitelistError)) ||

e2e/react-start/basic/tests/navigation.spec.ts

@@ -4,7 +4,7 @@ import { test } from '@tanstack/router-e2e-utils'
 
 test.use({
   whitelistErrors: [
-    /Failed to load resource: the server responded with a status of 404/,
+    'Failed to load resource: the server responded with a status of 404',
   ],
 })
 test('Navigating to post', async ({ page }) => {

e2e/react-start/basic/tests/not-found.spec.ts

@@ -8,7 +8,7 @@ const combinate = (combinateImport as any).default as typeof combinateImport
 
 test.use({
   whitelistErrors: [
-    /Failed to load resource: the server responded with a status of 404/,
+    'Failed to load resource: the server responded with a status of 404',
     'NotFound error during hydration for routeId',
   ],
 })

e2e/react-start/basic/tests/open-redirect-prevention.spec.ts

@@ -3,7 +3,7 @@ import { test } from '@tanstack/router-e2e-utils'
 
 test.use({
   whitelistErrors: [
-    /Failed to load resource: the server responded with a status of 404/,
+    'Failed to load resource: the server responded with a status of 404',
   ],
 })
 

e2e/react-start/basic/tests/params.spec.ts

@@ -8,7 +8,7 @@ test.beforeEach(async ({ page }) => {
 
 test.use({
   whitelistErrors: [
-    /Failed to load resource: the server responded with a status of 404/,
+    'Failed to load resource: the server responded with a status of 404',
   ],
 })
 test.describe('Unicode route rendering', () => {

e2e/react-start/css-modules/package.json

@@ -6,29 +6,44 @@
   "scripts": {
     "dev": "vite dev --port 3000",
     "dev:e2e": "vite dev --port $PORT",
+    "dev:nitro": "VITE_USE_NITRO=true vite dev --port 3000",
+    "dev:e2e:nitro": "VITE_USE_NITRO=true vite dev --port $PORT",
+    "dev:basepath": "VITE_BASE_PATH=/my-app vite dev --port 3000",
+    "dev:e2e:basepath": "VITE_BASE_PATH=/my-app vite dev --port $PORT",
+    "dev:cloudflare": "echo 'Cloudflare dev mode has React duplication issues - use build+preview instead' && exit 1",
+    "dev:e2e:cloudflare": "echo 'Cloudflare dev mode has React duplication issues - use build+preview instead' && exit 1",
     "build": "vite build && tsc --noEmit",
     "preview": "vite preview",
     "start": "pnpx srvx --prod -s ../client dist/server/server.js",
     "test:e2e:dev": "MODE=dev playwright test --project=chromium",
+    "test:e2e:dev:nitro": "MODE=dev VITE_CONFIG=nitro playwright test --project=chromium",
+    "test:e2e:dev:basepath": "MODE=dev VITE_CONFIG=basepath playwright test --project=chromium",
+    "_test:e2e:dev:cloudflare": "MODE=dev VITE_CONFIG=cloudflare playwright test --project=chromium",
     "test:e2e:prod": "playwright test --project=chromium",
-    "test:e2e": "rm -rf port*.txt; pnpm run test:e2e:dev"
+    "test:e2e": "rm -rf port*.txt; pnpm run test:e2e:dev",
+    "test:e2e:nitro": "rm -rf port*.txt; pnpm run test:e2e:dev:nitro",
+    "test:e2e:basepath": "rm -rf port*.txt; pnpm run test:e2e:dev:basepath",
+    "_test:e2e:cloudflare": "echo 'Cloudflare dev mode disabled - React duplication issues' && exit 0"
   },
   "dependencies": {
-    "@tanstack/react-router": "workspace:^",
-    "@tanstack/react-start": "workspace:^",
+    "@tanstack/react-router": "workspace:*",
+    "@tanstack/react-start": "workspace:*",
     "react": "^19.0.0",
     "react-dom": "^19.0.0"
   },
   "devDependencies": {
+    "@cloudflare/vite-plugin": "^1.15.1",
     "@playwright/test": "^1.50.1",
-    "@tanstack/router-e2e-utils": "workspace:^",
+    "@tanstack/router-e2e-utils": "workspace:*",
     "@types/node": "^22.10.2",
     "@types/react": "^19.0.8",
     "@types/react-dom": "^19.0.3",
     "@vitejs/plugin-react": "^4.3.4",
+    "nitro": "npm:nitro-nightly@latest",
     "srvx": "^0.10.0",
     "typescript": "^5.7.2",
     "vite": "^7.1.7",
-    "vite-tsconfig-paths": "^5.1.4"
+    "vite-tsconfig-paths": "^5.1.4",
+    "wrangler": "^4.22.0"
   }
 }

e2e/react-start/css-modules/playwright.config.ts

@@ -2,9 +2,19 @@ import { defineConfig, devices } from '@playwright/test'
 import { getTestServerPort } from '@tanstack/router-e2e-utils'
 import packageJson from './package.json' with { type: 'json' }
 
-const isDev = process.env.MODE === 'dev'
-const PORT = await getTestServerPort(packageJson.name)
-const baseURL = `http://localhost:${PORT}`
+const mode = process.env.MODE ?? 'prod'
+const isDev = mode === 'dev'
+const viteConfig = process.env.VITE_CONFIG // 'nitro' | 'basepath' | 'cloudflare' | undefined
+const PORT = await getTestServerPort(
+  viteConfig ? `${packageJson.name}-${viteConfig}` : packageJson.name,
+)
+
+// When using basepath config, the app is served at /my-app
+const basePath = viteConfig === 'basepath' ? '/my-app' : ''
+const baseURL = `http://localhost:${PORT}${basePath}`
+
+// Select the appropriate dev command based on VITE_CONFIG
+const devCommand = viteConfig ? `pnpm dev:e2e:${viteConfig}` : 'pnpm dev:e2e'
 
 export default defineConfig({
   testDir: './tests',
@@ -19,7 +29,7 @@ export default defineConfig({
   },
 
   webServer: {
-    command: isDev ? `pnpm dev:e2e` : `pnpm build && PORT=${PORT} pnpm start`,
+    command: isDev ? devCommand : `pnpm build && PORT=${PORT} pnpm start`,
     url: baseURL,
     reuseExistingServer: !process.env.CI,
     stdout: 'pipe',

e2e/react-start/css-modules/tests/css.spec.ts

@@ -1,7 +1,17 @@
 import { expect, request } from '@playwright/test'
 import { test } from '@tanstack/router-e2e-utils'
 
+// Whitelist errors that can occur in CI:
+// - net::ERR_NAME_NOT_RESOLVED: transient network issues
+// - 504 (Outdated Optimize Dep): Vite dependency optimization reload
+const whitelistErrors = [
+  'Failed to load resource: net::ERR_NAME_NOT_RESOLVED',
+  'Failed to load resource: the server responded with a status of 504',
+]
+
 test.describe('CSS styles in SSR (dev mode)', () => {
+  test.use({ whitelistErrors })
+
   // Warmup: trigger Vite's dependency optimization before running tests
   // This prevents "504 (Outdated Optimize Dep)" errors during actual tests
   test.beforeAll(async ({ baseURL }) => {
@@ -21,11 +31,21 @@ test.describe('CSS styles in SSR (dev mode)', () => {
     }
   })
 
+  // Helper to build full URL from baseURL and path
+  // Playwright's goto with absolute paths (like '/modules') ignores baseURL's path portion
+  // So we need to manually construct the full URL
+  const buildUrl = (baseURL: string, path: string) => {
+    return baseURL.replace(/\/$/, '') + path
+  }
+
   test.describe('with JavaScript disabled', () => {
-    test.use({ javaScriptEnabled: false })
+    test.use({ javaScriptEnabled: false, whitelistErrors })
 
-    test('global CSS is applied on initial page load', async ({ page }) => {
-      await page.goto('/')
+    test('global CSS is applied on initial page load', async ({
+      page,
+      baseURL,
+    }) => {
+      await page.goto(buildUrl(baseURL!, '/'))
 
       const element = page.getByTestId('global-styled')
       await expect(element).toBeVisible()
@@ -48,8 +68,11 @@ test.describe('CSS styles in SSR (dev mode)', () => {
       expect(borderRadius).toBe('12px')
     })
 
-    test('CSS modules are applied on initial page load', async ({ page }) => {
-      await page.goto('/modules')
+    test('CSS modules are applied on initial page load', async ({
+      page,
+      baseURL,
+    }) => {
+      await page.goto(buildUrl(baseURL!, '/modules'))
 
       const card = page.getByTestId('module-card')
       await expect(card).toBeVisible()
@@ -77,8 +100,8 @@ test.describe('CSS styles in SSR (dev mode)', () => {
       expect(borderRadius).toBe('8px')
     })
 
-    test('global CSS class names are NOT scoped', async ({ page }) => {
-      await page.goto('/')
+    test('global CSS class names are NOT scoped', async ({ page, baseURL }) => {
+      await page.goto(buildUrl(baseURL!, '/'))
 
       const element = page.getByTestId('global-styled')
       await expect(element).toBeVisible()
@@ -89,8 +112,8 @@ test.describe('CSS styles in SSR (dev mode)', () => {
     })
   })
 
-  test('styles persist after hydration', async ({ page }) => {
-    await page.goto('/')
+  test('styles persist after hydration', async ({ page, baseURL }) => {
+    await page.goto(buildUrl(baseURL!, '/'))
 
     // Wait for hydration
     await page.waitForTimeout(1000)
@@ -102,8 +125,11 @@ test.describe('CSS styles in SSR (dev mode)', () => {
     expect(backgroundColor).toBe('rgb(59, 130, 246)')
   })
 
-  test('CSS modules styles persist after hydration', async ({ page }) => {
-    await page.goto('/modules')
+  test('CSS modules styles persist after hydration', async ({
+    page,
+    baseURL,
+  }) => {
+    await page.goto(buildUrl(baseURL!, '/modules'))
 
     // Wait for hydration
     await page.waitForTimeout(1000)
@@ -117,9 +143,10 @@ test.describe('CSS styles in SSR (dev mode)', () => {
 
   test('styles work correctly after client-side navigation', async ({
     page,
+    baseURL,
   }) => {
     // Start from home
-    await page.goto('/')
+    await page.goto(buildUrl(baseURL!, '/'))
     await page.waitForTimeout(1000)
 
     // Verify initial styles
@@ -132,7 +159,8 @@ test.describe('CSS styles in SSR (dev mode)', () => {
 
     // Navigate to modules page
     await page.getByTestId('nav-modules').click()
-    await page.waitForURL('/modules')
+    // Use glob pattern to match with or without basepath
+    await page.waitForURL('**/modules')
 
     // Verify CSS modules styles
     const card = page.getByTestId('module-card')
@@ -144,7 +172,9 @@ test.describe('CSS styles in SSR (dev mode)', () => {
 
     // Navigate back to home
     await page.getByTestId('nav-home').click()
-    await page.waitForURL('/')
+    // Match home URL with or without trailing slash and optional query string
+    // Matches: /, /?, /my-app, /my-app/, /my-app?foo=bar
+    await page.waitForURL(/\/([^/]*)(\/)?($|\?)/)
 
     // Verify global styles still work
     await expect(globalElement).toBeVisible()

e2e/react-start/css-modules/vite.config.cloudflare.ts

@@ -0,0 +1,16 @@
+import { defineConfig } from 'vite'
+import tsConfigPaths from 'vite-tsconfig-paths'
+import { cloudflare } from '@cloudflare/vite-plugin'
+import { tanstackStart } from '@tanstack/react-start/plugin/vite'
+import viteReact from '@vitejs/plugin-react'
+
+export default defineConfig({
+  plugins: [
+    tsConfigPaths({
+      projects: ['./tsconfig.json'],
+    }),
+    cloudflare({ viteEnvironment: { name: 'ssr' }, inspectorPort: false }),
+    tanstackStart(),
+    viteReact(),
+  ],
+})

e2e/react-start/css-modules/vite.config.ts

@@ -3,15 +3,28 @@ import tsConfigPaths from 'vite-tsconfig-paths'
 import { tanstackStart } from '@tanstack/react-start/plugin/vite'
 import viteReact from '@vitejs/plugin-react'
 
-export default defineConfig({
-  server: {
-    port: 3000,
-  },
-  plugins: [
-    tsConfigPaths({
-      projects: ['./tsconfig.json'],
-    }),
-    tanstackStart(),
-    viteReact(),
-  ],
+// Environment variables for different test configurations:
+// - VITE_BASE_PATH: Set to '/my-app' for basepath testing
+// - VITE_USE_NITRO: Set to 'true' to enable Nitro server
+const basePath = process.env.VITE_BASE_PATH
+const useNitro = process.env.VITE_USE_NITRO === 'true'
+
+export default defineConfig(async () => {
+  // Dynamically import nitro only when needed to avoid loading it when not used
+  const nitroPlugin = useNitro ? [(await import('nitro/vite')).nitro()] : []
+
+  return {
+    base: basePath,
+    server: {
+      port: 3000,
+    },
+    plugins: [
+      tsConfigPaths({
+        projects: ['./tsconfig.json'],
+      }),
+      tanstackStart(),
+      viteReact(),
+      ...nitroPlugin,
+    ],
+  }
 })

e2e/react-start/css-modules/wrangler.jsonc

@@ -0,0 +1,7 @@
+{
+  "$schema": "node_modules/wrangler/config-schema.json",
+  "name": "tanstack-start-css-modules",
+  "compatibility_date": "2025-09-24",
+  "compatibility_flags": ["nodejs_compat"],
+  "main": "@tanstack/react-start/server-entry",
+}

e2e/react-start/serialization-adapters/tests/app.spec.ts

@@ -41,7 +41,7 @@ async function checkNestedData(page: Page) {
 }
 test.use({
   whitelistErrors: [
-    /Failed to load resource: the server responded with a status of 499/,
+    'Failed to load resource: the server responded with a status of 499',
   ],
 })
 test.describe('SSR serialization adapters', () => {

e2e/react-start/server-functions/tests/server-functions.spec.ts

@@ -370,7 +370,7 @@ test.describe('server function sets cookies', () => {
 test.describe('server functions with async validation', () => {
   test.use({
     whitelistErrors: [
-      /Failed to load resource: the server responded with a status of 500/,
+      'Failed to load resource: the server responded with a status of 500',
     ],
   })
 
@@ -739,7 +739,7 @@ test('redirect via server function with middleware does not cause serialization
 
 test.describe('unhandled exception in middleware (issue #5266)', () => {
   // Whitelist the expected 500 error since this test verifies error handling
-  test.use({ whitelistErrors: [/500/] })
+  test.use({ whitelistErrors: ['500'] })
 
   test('does not crash server and shows error component', async ({ page }) => {
     // This test verifies that when a middleware throws an unhandled exception,

e2e/solid-start/basic/tests/navigation.spec.ts

@@ -3,7 +3,7 @@ import { test } from '@tanstack/router-e2e-utils'
 
 test.use({
   whitelistErrors: [
-    /Failed to load resource: the server responded with a status of 404/,
+    'Failed to load resource: the server responded with a status of 404',
   ],
 })
 test('Navigating to post', async ({ page }) => {

e2e/solid-start/basic/tests/not-found.spec.ts

@@ -8,7 +8,7 @@ const combinate = (combinateImport as any).default as typeof combinateImport
 
 test.use({
   whitelistErrors: [
-    /Failed to load resource: the server responded with a status of 404/,
+    'Failed to load resource: the server responded with a status of 404',
     'NotFound error during hydration for routeId',
   ],
 })