fix(create): broaden demo file matching to catch all demo-prefixed files

The directory-specific filter missed demo support files in /store/, /public/,
at src root (demo.index.css), and example assets (example-guitar-*.jpg).
Replace directory-specific checks with a filename-prefix match so any file
named demo.*, demo-*, example.*, or example-* gets stripped when users
opt out of demo pages, regardless of which directory it lives in.

Add a regression test that exercises demo files across lib, hooks, data,
components, store, public, and routes.

Author: tannerlinsley

.changeset/fix-demo-file-leaks.md

@@ -0,0 +1,12 @@
+---
+'@tanstack/create': patch
+---
+
+Fix demo/example files leaking into projects when users opt out of demo pages.
+
+- Strip add-on demo support files in `src/lib/`, `src/hooks/`, `src/data/`, `src/components/`, `src/store/`, and any `demo.*` / `demo-*` / `example.*` / `example-*` files.
+- Strip example image assets under `public/`.
+- Generate a minimal base starter (no Header, Footer, ThemeToggle, about page, or styled index page) when declining demo/example pages.
+- Render Better Auth header-user component as `null` when its demo route is excluded, instead of linking to a non-existent route.
+
+Closes #422, #409.

packages/create/src/create-app.ts

@@ -20,19 +20,20 @@ import type { Environment, FileBundleHandler, Options } from './types.js'
 function isDemoFilePath(path?: string) {
   if (!path) return false
   const normalized = path.replace(/\\/g, '/')
-  return (
+
+  if (
     normalized.includes('/routes/demo/') ||
-    normalized.includes('/routes/demo.') ||
-    normalized.includes('/routes/example/') ||
-    normalized.includes('/routes/example.') ||
-    normalized.includes('/lib/demo-') ||
-    normalized.includes('/lib/demo.') ||
-    normalized.includes('/hooks/demo-') ||
-    normalized.includes('/hooks/demo.') ||
-    normalized.includes('/data/demo-') ||
-    normalized.includes('/data/demo.') ||
-    normalized.includes('/components/demo-') ||
-    normalized.includes('/components/demo.')
+    normalized.includes('/routes/example/')
+  ) {
+    return true
+  }
+
+  const filename = normalized.split('/').pop() || ''
+  return (
+    filename.startsWith('demo.') ||
+    filename.startsWith('demo-') ||
+    filename.startsWith('example.') ||
+    filename.startsWith('example-')
   )
 }
 

packages/create/tests/create-app.test.ts

@@ -117,4 +117,81 @@ describe('createApp', () => {
     expect(output.files['/src/test2.txt']).toEqual('base64::aGVsbG8=')
     expect(output.commands.some(({ command }) => command === 'echo')).toBe(true)
   })
+
+  it('should strip demo files from add-ons when includeExamples is false', async () => {
+    const { environment, output } = createMemoryEnvironment()
+
+    const demoFiles = [
+      'src/routes/demo/form.simple.tsx',
+      'src/routes/demo.form.tsx',
+      'src/routes/example.chat.tsx',
+      'src/components/demo-AIAssistant.tsx',
+      'src/components/demo.FormComponents.tsx',
+      'src/hooks/demo-useAudioRecorder.ts',
+      'src/hooks/demo.form.ts',
+      'src/lib/demo-store.ts',
+      'src/lib/demo.ai-hook.ts',
+      'src/data/demo-guitars.ts',
+      'src/store/demo.hooks.ts',
+      'src/store/demo.store.ts',
+      'src/demo.index.css',
+      'public/demo-neon.svg',
+      'public/example-guitar-flowers.jpg',
+    ]
+    const keepFiles = [
+      'src/routes/index.tsx',
+      'src/components/Header.tsx',
+      'src/lib/utils.ts',
+    ]
+    const allFiles = [...demoFiles, ...keepFiles]
+
+    await createApp(environment, {
+      ...simpleOptions,
+      includeExamples: false,
+      chosenAddOns: [
+        {
+          id: 'test-addon',
+          type: 'add-on',
+          phase: 'add-on',
+          packageAdditions: { dependencies: {}, devDependencies: {} },
+          routes: [],
+          integrations: [],
+          getFiles: () => allFiles,
+          getFileContents: () => 'content',
+          getDeletedFiles: () => [],
+        } as unknown as AddOn,
+      ],
+    } as Options)
+
+    for (const file of demoFiles) {
+      expect(output.files[`/${file}`]).toBeUndefined()
+    }
+    for (const file of keepFiles) {
+      expect(output.files[`/${file}`]).toBeDefined()
+    }
+  })
+
+  it('should keep demo files from add-ons when includeExamples is true', async () => {
+    const { environment, output } = createMemoryEnvironment()
+
+    await createApp(environment, {
+      ...simpleOptions,
+      includeExamples: true,
+      chosenAddOns: [
+        {
+          id: 'test-addon',
+          type: 'add-on',
+          phase: 'add-on',
+          packageAdditions: { dependencies: {}, devDependencies: {} },
+          routes: [],
+          integrations: [],
+          getFiles: () => ['src/components/demo-AIAssistant.tsx'],
+          getFileContents: () => 'content',
+          getDeletedFiles: () => [],
+        } as unknown as AddOn,
+      ],
+    } as Options)
+
+    expect(output.files['/src/components/demo-AIAssistant.tsx']).toBeDefined()
+  })
 })