diff --git a/CHANGELOG.prerelease.md b/CHANGELOG.prerelease.md
index 9f2bf2961789..448764798116 100644
--- a/CHANGELOG.prerelease.md
+++ b/CHANGELOG.prerelease.md
@@ -1,3 +1,11 @@
+## 10.3.0-beta.2
+
+- UI: Hide addon panel Drag on pages without a panel - [#34162](https://github.com/storybookjs/storybook/pull/34162), thanks @Sidnioulz!
+- UI: Hide manifest tag for now - [#34165](https://github.com/storybookjs/storybook/pull/34165), thanks @Sidnioulz!
+- UI: Make disabled Buttons keyboard-focusable - [#34166](https://github.com/storybookjs/storybook/pull/34166), thanks @Sidnioulz!
+- UI: Use correct selector for addon panel focus check - [#34164](https://github.com/storybookjs/storybook/pull/34164), thanks @Sidnioulz!
+- Vue: Make globals reactive in decorators - [#34116](https://github.com/storybookjs/storybook/pull/34116), thanks @Sidnioulz!
+
 ## 10.3.0-beta.1
 
 - Addon-Docs: Add React as optimizeDeps entry - [#34176](https://github.com/storybookjs/storybook/pull/34176), thanks @valentinpalkovic!
diff --git a/code/addons/a11y/package.json b/code/addons/a11y/package.json
index 2902a1040c72..3cea3b5a714b 100644
--- a/code/addons/a11y/package.json
+++ b/code/addons/a11y/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/addon-a11y",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook Addon A11y: Test UI component compliance with WCAG web accessibility standards",
   "keywords": [
     "a11y",
diff --git a/code/addons/docs/package.json b/code/addons/docs/package.json
index b681f538b9e3..56198211a649 100644
--- a/code/addons/docs/package.json
+++ b/code/addons/docs/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/addon-docs",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook Docs: Document UI components automatically with stories and MDX",
   "keywords": [
     "docs",
diff --git a/code/addons/links/package.json b/code/addons/links/package.json
index 26dc0f479d73..0738d131c489 100644
--- a/code/addons/links/package.json
+++ b/code/addons/links/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/addon-links",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook Links: Link stories together to build demos and prototypes with your UI components",
   "keywords": [
     "storybook",
diff --git a/code/addons/onboarding/package.json b/code/addons/onboarding/package.json
index a13c19b15e33..94c970b3aa32 100644
--- a/code/addons/onboarding/package.json
+++ b/code/addons/onboarding/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/addon-onboarding",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook Onboarding: Help new users learn how to write stories",
   "keywords": [
     "storybook",
diff --git a/code/addons/pseudo-states/package.json b/code/addons/pseudo-states/package.json
index f8686701f659..e88d8ca9c77e 100644
--- a/code/addons/pseudo-states/package.json
+++ b/code/addons/pseudo-states/package.json
@@ -1,6 +1,6 @@
 {
   "name": "storybook-addon-pseudo-states",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook Pseudo-states addon: Manipulate CSS pseudo states",
   "keywords": [
     "storybook",
diff --git a/code/addons/themes/package.json b/code/addons/themes/package.json
index 55aa7bead9bf..b70b09365b04 100644
--- a/code/addons/themes/package.json
+++ b/code/addons/themes/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/addon-themes",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook Themes addon: Switch between themes from the toolbar",
   "keywords": [
     "css",
diff --git a/code/addons/vitest/package.json b/code/addons/vitest/package.json
index 8da5d09d5ac7..4f7c20148b00 100644
--- a/code/addons/vitest/package.json
+++ b/code/addons/vitest/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/addon-vitest",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook Vitest addon: Blazing fast component testing using stories",
   "keywords": [
     "storybook",
diff --git a/code/addons/vitest/src/postinstall.ts b/code/addons/vitest/src/postinstall.ts
index d627fa416497..f11c43eeff99 100644
--- a/code/addons/vitest/src/postinstall.ts
+++ b/code/addons/vitest/src/postinstall.ts
@@ -199,10 +199,16 @@ export default async function postInstall(options: PostinstallOptions) {
     );
   }
 
-  const getTemplateName = () => {
+  const getTemplateName = (configContent?: string) => {
     if (isVitest4OrNewer) {
       return 'vitest.config.4.template';
     } else if (isVitest3_2To4) {
+      // In Vitest 3.2, `workspace` was deprecated in favor of `projects` but still works.
+      // If the user's existing config already uses `workspace`, use the old template that
+      // also uses `workspace` so that the merge doesn't introduce both keys.
+      if (configContent && configUsesWorkspace(configContent)) {
+        return 'vitest.config.template';
+      }
       return 'vitest.config.3.2.template';
     }
     return 'vitest.config.template';
@@ -264,7 +270,7 @@ export default async function postInstall(options: PostinstallOptions) {
       /\/\/\/\s*<reference\s+types=["']vitest\/config["']\s*\/>/
     );
 
-    const templateName = getTemplateName();
+    const templateName = getTemplateName(configFile);
 
     const alreadyConfigured = isConfigAlreadySetup(rootConfig, configFile);
 
@@ -446,3 +452,42 @@ export function isConfigAlreadySetup(_configPath: string, configContent: string)
 
   return pluginReferenced;
 }
+
+/**
+ * Checks whether an existing config file uses `test.workspace` (Vitest 3.0-3.1 style) rather than
+ * `test.projects` (Vitest 3.2+ style).
+ */
+function configUsesWorkspace(configContent: string): boolean {
+  let ast: ReturnType<typeof babelParse>;
+  try {
+    ast = babelParse(configContent);
+  } catch {
+    return false;
+  }
+
+  let found = false;
+
+  traverse(ast, {
+    ObjectProperty(path) {
+      if (found) {
+        path.stop();
+        return;
+      }
+      const key = path.node.key;
+      if (key.type === 'Identifier' && key.name === 'workspace') {
+        // Check that this is inside a `test` property to avoid false positives
+        const parent = path.parentPath?.parentPath;
+        if (
+          parent?.isObjectProperty() &&
+          parent.node.key.type === 'Identifier' &&
+          parent.node.key.name === 'test'
+        ) {
+          found = true;
+          path.stop();
+        }
+      }
+    },
+  });
+
+  return found;
+}
diff --git a/code/addons/vitest/src/updateVitestFile.config.3.2.test.ts b/code/addons/vitest/src/updateVitestFile.config.3.2.test.ts
new file mode 100644
index 000000000000..477c8c0ddcba
--- /dev/null
+++ b/code/addons/vitest/src/updateVitestFile.config.3.2.test.ts
@@ -0,0 +1,1897 @@
+import { join } from 'node:path';
+
+import { describe, expect, it, vi } from 'vitest';
+
+import * as babel from 'storybook/internal/babel';
+
+import { getDiff } from '../../../core/src/core-server/utils/save-story/getDiff';
+import { loadTemplate, updateConfigFile } from './updateVitestFile';
+
+vi.mock('storybook/internal/node-logger', () => ({
+  logger: {
+    info: vi.fn(),
+    warn: vi.fn(),
+    error: vi.fn(),
+  },
+}));
+
+vi.mock('../../../core/src/shared/utils/module', () => ({
+  resolvePackageDir: vi.fn().mockImplementation(() => join(__dirname, '..')),
+}));
+
+describe('updateConfigFile', () => {
+  it('updates vite config file with existing workspace (falls back to workspace template)', async () => {
+    // When Vitest 3.2 user still has deprecated `workspace` key, postinstall should
+    // detect this and use the old workspace-based template to append to the existing array
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      /// <reference types="vitest/config" />
+      import { defineConfig } from 'vite'
+      import react from '@vitejs/plugin-react'
+
+      // https://vite.dev/config/
+      export default defineConfig({
+        plugins: [react()],
+        test: {
+          globals: true,
+          workspace: ['packages/*']
+        },
+      })
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly — appends to existing workspace array
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  ...
+        import react from '@vitejs/plugin-react';
+        
+        // https://vite.dev/config/
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default defineConfig({
+          plugins: [react()],
+          test: {
+            globals: true,
+        
+      -     workspace: ['packages/*']
+      - 
+      +     workspace: ['packages/*', {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        });"
+    `);
+  });
+
+  it('supports object notation without defineConfig with existing workspace (falls back to workspace template)', async () => {
+    // Same as above: existing `workspace` in target means postinstall uses old template
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      /// <reference types="vitest/config" />
+      import react from '@vitejs/plugin-react'
+
+      // https://vite.dev/config/
+      export default {
+        plugins: [react()],
+        test: {
+          globals: true,
+          workspace: ['packages/*']
+        },
+      }
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly — appends to existing workspace array
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  ...
+        import react from '@vitejs/plugin-react';
+        
+        // https://vite.dev/config/
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { defineConfig } from 'vitest/config';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default {
+          plugins: [react()],
+          test: {
+            globals: true,
+        
+      -     workspace: ['packages/*']
+      - 
+      +     workspace: ['packages/*', {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        };"
+    `);
+  });
+
+  it('does not support function notation', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      /// <reference types="vitest/config" />
+      import react from '@vitejs/plugin-react'
+
+      // https://vite.dev/config/
+      export default defineConfig(() => ({
+        plugins: [react()],
+        test: {
+          globals: true,
+          projects: ['packages/*']
+        },
+      }))
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(false);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was NOT updated
+    expect(after).toBe(before);
+  });
+
+  it('adds projects property to test config', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      /// <reference types="vitest/config" />
+      import { defineConfig } from 'vite'
+      import react from '@vitejs/plugin-react'
+
+      // https://vite.dev/config/
+      export default defineConfig({
+        plugins: [react()],
+        test: {
+          globals: true,
+        },
+      })
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  ...
+        import react from '@vitejs/plugin-react';
+        
+        // https://vite.dev/config/
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default defineConfig({
+          plugins: [react()],
+          test: {
+        
+      -     globals: true
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         globals: true
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        });"
+    `);
+  });
+
+  it('updates config which is not exported immediately', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { defineConfig } from 'vite'
+      import viteReact from '@vitejs/plugin-react'
+      import { fileURLToPath, URL } from 'url'
+
+      const config = defineConfig({
+        resolve: {
+          preserveSymlinks: true,
+          alias: {
+            '@': fileURLToPath(new URL('./src', import.meta.url)),
+          },
+        },
+        plugins: [
+          viteReact(),
+        ],
+      })
+
+      export default config
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+  "  import { defineConfig } from 'vite';
+    import viteReact from '@vitejs/plugin-react';
+    import { fileURLToPath, URL } from 'url';
+    
+  + import path from 'node:path';
+  + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+  + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+  + 
+  + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+  + 
+    const config = defineConfig({
+      resolve: {
+        preserveSymlinks: true,
+        alias: {
+          '@': fileURLToPath(new URL('./src', import.meta.url))
+        }
+      },
+    
+  -   plugins: [viteReact()]
+  - 
+  +   plugins: [viteReact()],
+  +   test: {
+  +     projects: [{
+  +       extends: true,
+  +       plugins: [
+  +       // The plugin will run tests for the stories defined in your Storybook config
+  +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+  +       storybookTest({
+  +         configDir: path.join(dirname, '.storybook')
+  +       })],
+  +       test: {
+  +         name: 'storybook',
+  +         browser: {
+  +           enabled: true,
+  +           headless: true,
+  +           provider: 'playwright',
+  +           instances: [{
+  +             browser: 'chromium'
+  +           }]
+  +         }
+  +       }
+  +     }]
+  +   }
+  + 
+    });
+    export default config;"
+`);
+  });
+
+  it('edits projects property of test config', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      /// <reference types="vitest/config" />
+      import { defineConfig } from 'vite'
+      import react from '@vitejs/plugin-react'
+
+      // https://vite.dev/config/
+      export default defineConfig({
+        plugins: [react()],
+        test: {
+          globals: true,
+          projects: ['packages/*', {some: 'config'}]
+        }
+      })
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  ...
+        import react from '@vitejs/plugin-react';
+        
+        // https://vite.dev/config/
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default defineConfig({
+          plugins: [react()],
+          test: {
+            globals: true,
+            projects: ['packages/*', {
+              some: 'config'
+        
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      + 
+            }]
+          }
+        });"
+    `);
+  });
+
+  it('adds workspace property to test config', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      /// <reference types="vitest/config" />
+      import { defineConfig } from 'vite'
+      import react from '@vitejs/plugin-react'
+
+      // https://vite.dev/config/
+      export default defineConfig({
+        plugins: [react()],
+        test: {
+          globals: true,
+        },
+      })
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  ...
+        import react from '@vitejs/plugin-react';
+        
+        // https://vite.dev/config/
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default defineConfig({
+          plugins: [react()],
+          test: {
+        
+      -     globals: true
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         globals: true
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        });"
+    `);
+  });
+
+  it('adds test property to vite config', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      /// <reference types="vitest/config" />
+      import { defineConfig } from 'vite'
+      import react from '@vitejs/plugin-react'
+
+      // https://vite.dev/config/
+      export default defineConfig({
+        plugins: [react()],
+      })
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  ...
+        import react from '@vitejs/plugin-react';
+        
+        // https://vite.dev/config/
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default defineConfig({
+        
+      -   plugins: [react()]
+      - 
+      +   plugins: [react()],
+      +   test: {
+      +     projects: [{
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      +   }
+      + 
+        });"
+    `);
+  });
+
+  it('supports mergeConfig with multiple defineConfig calls, finding the one with test', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig } from 'vite'
+      import { defineConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      export default mergeConfig(
+        viteConfig,
+        defineConfig({
+          plugins: [react()],
+        }),
+        defineConfig({
+          test: {
+            environment: 'jsdom',
+          }
+        })
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig } from 'vite';
+        import { defineConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, defineConfig({
+          plugins: [react()]
+        }), defineConfig({
+          test: {
+        
+      -     environment: 'jsdom'
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         environment: 'jsdom'
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }));"
+    `);
+  });
+  it('supports mergeConfig without defineConfig calls', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig } from 'vite'
+      import viteConfig from './vite.config'
+
+      export default mergeConfig(
+        viteConfig,
+        {
+          plugins: [react()],
+          test: {
+            environment: 'jsdom',
+          }
+        }
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig } from 'vite';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { defineConfig } from 'vitest/config';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, {
+          plugins: [react()],
+          test: {
+        
+      -     environment: 'jsdom'
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         environment: 'jsdom'
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        });"
+    `);
+  });
+
+  it('supports mergeConfig without config containing test property', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig } from 'vite'
+      import { defineConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      export default mergeConfig(
+        viteConfig,
+        defineConfig({
+          plugins: [react()],
+        })
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig } from 'vite';
+        import { defineConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, defineConfig({
+        
+      -   plugins: [react()]
+      - 
+      +   plugins: [react()],
+      +   test: {
+      +     projects: [{
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      +   }
+      + 
+        }));"
+    `);
+  });
+
+  it('supports mergeConfig with defineConfig pattern using projects (Vitest 3.2+)', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      /// <reference types="vitest/config" />
+      import { mergeConfig, defineConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      // https://vite.dev/config/
+      export default mergeConfig(
+        viteConfig,
+        defineConfig({
+          test: {
+            globals: true,
+          },
+        })
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  ...
+        import viteConfig from './vite.config';
+        
+        // https://vite.dev/config/
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, defineConfig({
+          test: {
+        
+      -     globals: true
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         globals: true
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }));"
+    `);
+  });
+
+  it('appends storybook project to existing test.projects array (no double nesting)', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig, defineConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      export default mergeConfig(
+        viteConfig,
+        defineConfig({
+          test: {
+            expect: { requireAssertions: true },
+            projects: [
+              {
+                extends: "./vite.config.ts",
+                test: { name: "client" },
+              },
+              {
+                extends: "./vite.config.ts",
+                test: { name: "server" },
+              },
+            ],
+          },
+        })
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly (storybook project appended to existing projects, no double nesting)
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig, defineConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, defineConfig({
+          test: {
+            expect: {
+              requireAssertions: true
+      ...
+              test: {
+                name: "server"
+              }
+        
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      + 
+            }]
+          }
+        }));"
+    `);
+  });
+
+  it('extracts coverage config and keeps it at top level when using workspace', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig, defineConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      export default mergeConfig(
+        viteConfig,
+        defineConfig({
+          test: {
+            name: 'node',
+            environment: 'happy-dom',
+            include: ['**/*.test.ts'],
+            coverage: {
+              exclude: [
+                'storybook.setup.ts',
+                '**/*.stories.*',
+              ],
+            },
+          },
+        })
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    // Coverage should stay at the top level, not moved into the workspace
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig, defineConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, defineConfig({
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts'],
+      - 
+            coverage: {
+              exclude: ['storybook.setup.ts', '**/*.stories.*']
+        
+      -     }
+      - 
+      +     },
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }));"
+    `);
+  });
+
+  it('extracts coverage config and keeps it at top level when using projects', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig, defineConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      export default mergeConfig(
+        viteConfig,
+        defineConfig({
+          test: {
+            name: 'node',
+            environment: 'happy-dom',
+            include: ['**/*.test.ts'],
+            coverage: {
+              exclude: [
+                'storybook.setup.ts',
+                '**/*.stories.*',
+              ],
+            },
+          },
+        })
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    // Coverage should stay at the top level, not moved into the projects
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig, defineConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, defineConfig({
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts'],
+      - 
+            coverage: {
+              exclude: ['storybook.setup.ts', '**/*.stories.*']
+        
+      -     }
+      - 
+      +     },
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }));"
+    `);
+  });
+
+  it('supports defineConfig wrapping mergeConfig', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { defineConfig, mergeConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      export default defineConfig(mergeConfig(viteConfig, {
+        test: {
+          name: 'node',
+          environment: 'happy-dom',
+          include: ['**/*.test.ts'],
+        },
+      }))
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { defineConfig, mergeConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default defineConfig(mergeConfig(viteConfig, {
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts']
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }));"
+    `);
+  });
+
+  it('supports defineConfig wrapping mergeConfig with satisfies operator', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { defineConfig, mergeConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+      import type { ViteUserConfig } from 'vitest/config'
+
+      export default defineConfig(
+        mergeConfig(viteConfig, {
+          test: {
+            name: 'node',
+            environment: 'happy-dom',
+            include: ['**/*.test.ts'],
+          },
+        }) satisfies ViteUserConfig
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { defineConfig, mergeConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        import type { ViteUserConfig } from 'vitest/config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default defineConfig(mergeConfig(viteConfig, {
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts']
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }) satisfies ViteUserConfig);"
+    `);
+  });
+
+  it('supports mergeConfig with as operator (TSAsExpression)', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+      import type { ViteUserConfig } from 'vitest/config'
+
+      export default mergeConfig(viteConfig, {
+        test: {
+          name: 'node',
+          environment: 'happy-dom',
+          include: ['**/*.test.ts'],
+        },
+      }) as ViteUserConfig
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        import type { ViteUserConfig } from 'vitest/config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { defineConfig } from 'vitest/config';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, {
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts']
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }) as ViteUserConfig;"
+    `);
+  });
+
+  it('supports mergeConfig with test defined as a constant (shorthand property)', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      const test = {
+        name: 'node',
+        environment: 'happy-dom',
+        include: ['**/*.test.ts'],
+      }
+
+      export default mergeConfig(viteConfig, { test })
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { defineConfig } from 'vitest/config';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        const test = {
+          name: 'node',
+          environment: 'happy-dom',
+          include: ['**/*.test.ts']
+        };
+        export default mergeConfig(viteConfig, {
+        
+      -   test
+      - 
+      +   test: {
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      +   }
+      + 
+        });"
+    `);
+  });
+
+  it('supports const defined config re-exported (export default config)', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { defineConfig, mergeConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      const config = mergeConfig(
+        viteConfig,
+        defineConfig({
+          test: {
+            name: 'node',
+            environment: 'happy-dom',
+            include: ['**/*.test.ts'],
+          },
+        })
+      )
+
+      export default config
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { defineConfig, mergeConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        const config = mergeConfig(viteConfig, defineConfig({
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts']
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }));
+        export default config;"
+    `);
+  });
+
+  it('supports defineProject instead of defineConfig', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { defineProject } from 'vitest/config'
+
+      export default defineProject({
+        test: {
+          name: 'node',
+          environment: 'happy-dom',
+          include: ['**/*.test.ts'],
+        },
+      })
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { defineProject } from 'vitest/config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { defineConfig } from 'vitest/config';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default defineProject({
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts']
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        });"
+    `);
+  });
+
+  it('supports mergeConfig with config object as a constant variable', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      const vitestConfig = {
+        test: {
+          name: 'node',
+          environment: 'happy-dom',
+          include: ['**/*.test.ts'],
+        }
+      }
+
+      export default mergeConfig(viteConfig, vitestConfig)
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { defineConfig } from 'vitest/config';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        const vitestConfig = {
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts']
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        };
+        export default mergeConfig(viteConfig, vitestConfig);"
+    `);
+  });
+
+  it('keeps coverage at top level instead of moving into projects', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig, defineConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      export default mergeConfig(
+        viteConfig,
+        defineConfig({
+          test: {
+            name: 'unit',
+            environment: 'happy-dom',
+            include: ['**/*.test.ts'],
+            env: { CI: 'true' },
+            pool: 'forks',
+            maxWorkers: 4,
+            coverage: {
+              provider: 'v8',
+              exclude: ['**/*.stories.*'],
+            },
+          },
+        })
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig, defineConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, defineConfig({
+          test: {
+        
+      -     name: 'unit',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts'],
+      -     env: {
+      -       CI: 'true'
+      -     },
+      -     pool: 'forks',
+      -     maxWorkers: 4,
+      - 
+            coverage: {
+              provider: 'v8',
+              exclude: ['**/*.stories.*']
+        
+      -     }
+      - 
+      +     },
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'unit',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts'],
+      +         env: {
+      +           CI: 'true'
+      +         },
+      +         pool: 'forks',
+      +         maxWorkers: 4
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }));"
+    `);
+  });
+});
diff --git a/code/addons/vitest/src/updateVitestFile.config.4.test.ts b/code/addons/vitest/src/updateVitestFile.config.4.test.ts
new file mode 100644
index 000000000000..4cf0e1f576f4
--- /dev/null
+++ b/code/addons/vitest/src/updateVitestFile.config.4.test.ts
@@ -0,0 +1,2216 @@
+import { join } from 'node:path';
+
+import { describe, expect, it, vi } from 'vitest';
+
+import * as babel from 'storybook/internal/babel';
+
+import { getDiff } from '../../../core/src/core-server/utils/save-story/getDiff';
+import { loadTemplate, updateConfigFile } from './updateVitestFile';
+
+vi.mock('storybook/internal/node-logger', () => ({
+  logger: {
+    info: vi.fn(),
+    warn: vi.fn(),
+    error: vi.fn(),
+  },
+}));
+
+vi.mock('../../../core/src/shared/utils/module', () => ({
+  resolvePackageDir: vi.fn().mockImplementation(() => join(__dirname, '..')),
+}));
+
+describe('updateConfigFile', () => {
+  it('updates vite config file with existing projects', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    // In Vitest 4, `workspace` doesn't exist — users have `projects`
+    const target = babel.babelParse(`
+      /// <reference types="vitest/config" />
+      import { defineConfig } from 'vite'
+      import react from '@vitejs/plugin-react'
+
+      // https://vite.dev/config/
+      export default defineConfig({
+        plugins: [react()],
+        test: {
+          globals: true,
+          projects: ['packages/*']
+        },
+      })
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly — appends to existing projects array
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  ...
+        import react from '@vitejs/plugin-react';
+        
+        // https://vite.dev/config/
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + import { playwright } from '@vitest/browser-playwright';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default defineConfig({
+          plugins: [react()],
+          test: {
+            globals: true,
+        
+      -     projects: ['packages/*']
+      - 
+      +     projects: ['packages/*', {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: playwright({}),
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        });"
+    `);
+  });
+
+  it('supports object notation without defineConfig with existing projects', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    // In Vitest 4, `workspace` doesn't exist — users have `projects`
+    const target = babel.babelParse(`
+      /// <reference types="vitest/config" />
+      import react from '@vitejs/plugin-react'
+
+      // https://vite.dev/config/
+      export default {
+        plugins: [react()],
+        test: {
+          globals: true,
+          projects: ['packages/*']
+        },
+      }
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly — appends to existing projects array
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  ...
+        import react from '@vitejs/plugin-react';
+        
+        // https://vite.dev/config/
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { defineConfig } from 'vitest/config';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + import { playwright } from '@vitest/browser-playwright';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default {
+          plugins: [react()],
+          test: {
+            globals: true,
+        
+      -     projects: ['packages/*']
+      - 
+      +     projects: ['packages/*', {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: playwright({}),
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        };"
+    `);
+  });
+
+  it('does not support function notation', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      /// <reference types="vitest/config" />
+      import react from '@vitejs/plugin-react'
+
+      // https://vite.dev/config/
+      export default defineConfig(() => ({
+        plugins: [react()],
+        test: {
+          globals: true,
+          projects: ['packages/*']
+        },
+      }))
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(false);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was NOT updated
+    expect(after).toBe(before);
+  });
+
+  it('adds projects property to test config', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      /// <reference types="vitest/config" />
+      import { defineConfig } from 'vite'
+      import react from '@vitejs/plugin-react'
+
+      // https://vite.dev/config/
+      export default defineConfig({
+        plugins: [react()],
+        test: {
+          globals: true,
+        },
+      })
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  ...
+        import react from '@vitejs/plugin-react';
+        
+        // https://vite.dev/config/
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + import { playwright } from '@vitest/browser-playwright';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default defineConfig({
+          plugins: [react()],
+          test: {
+        
+      -     globals: true
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         globals: true
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: playwright({}),
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        });"
+    `);
+  });
+
+  it('updates config which is not exported immediately', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { defineConfig } from 'vite'
+      import viteReact from '@vitejs/plugin-react'
+      import { fileURLToPath, URL } from 'url'
+
+      const config = defineConfig({
+        resolve: {
+          preserveSymlinks: true,
+          alias: {
+            '@': fileURLToPath(new URL('./src', import.meta.url)),
+          },
+        },
+        plugins: [
+          viteReact(),
+        ],
+      })
+
+      export default config
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { defineConfig } from 'vite';
+        import viteReact from '@vitejs/plugin-react';
+        import { fileURLToPath, URL } from 'url';
+        
+      + import path from 'node:path';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + import { playwright } from '@vitest/browser-playwright';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        const config = defineConfig({
+          resolve: {
+            preserveSymlinks: true,
+            alias: {
+              '@': fileURLToPath(new URL('./src', import.meta.url))
+            }
+          },
+        
+      -   plugins: [viteReact()]
+      - 
+      +   plugins: [viteReact()],
+      +   test: {
+      +     projects: [{
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: playwright({}),
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      +   }
+      + 
+        });
+        export default config;"
+    `);
+  });
+
+  it('edits projects property of test config', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      /// <reference types="vitest/config" />
+      import { defineConfig } from 'vite'
+      import react from '@vitejs/plugin-react'
+
+      // https://vite.dev/config/
+      export default defineConfig({
+        plugins: [react()],
+        test: {
+          globals: true,
+          projects: ['packages/*', {some: 'config'}]
+        }
+      })
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  ...
+        import react from '@vitejs/plugin-react';
+        
+        // https://vite.dev/config/
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + import { playwright } from '@vitest/browser-playwright';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default defineConfig({
+          plugins: [react()],
+          test: {
+            globals: true,
+            projects: ['packages/*', {
+              some: 'config'
+        
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: playwright({}),
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      + 
+            }]
+          }
+        });"
+    `);
+  });
+
+  it('adds projects property to test config', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      /// <reference types="vitest/config" />
+      import { defineConfig } from 'vite'
+      import react from '@vitejs/plugin-react'
+
+      // https://vite.dev/config/
+      export default defineConfig({
+        plugins: [react()],
+        test: {
+          globals: true,
+        },
+      })
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  ...
+        import react from '@vitejs/plugin-react';
+        
+        // https://vite.dev/config/
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + import { playwright } from '@vitest/browser-playwright';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default defineConfig({
+          plugins: [react()],
+          test: {
+        
+      -     globals: true
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         globals: true
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: playwright({}),
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        });"
+    `);
+  });
+
+  it('adds test property to vite config', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      /// <reference types="vitest/config" />
+      import { defineConfig } from 'vite'
+      import react from '@vitejs/plugin-react'
+
+      // https://vite.dev/config/
+      export default defineConfig({
+        plugins: [react()],
+      })
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  ...
+        import react from '@vitejs/plugin-react';
+        
+        // https://vite.dev/config/
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + import { playwright } from '@vitest/browser-playwright';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default defineConfig({
+        
+      -   plugins: [react()]
+      - 
+      +   plugins: [react()],
+      +   test: {
+      +     projects: [{
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: playwright({}),
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      +   }
+      + 
+        });"
+    `);
+  });
+
+  it('supports mergeConfig with multiple defineConfig calls, finding the one with test', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig } from 'vite'
+      import { defineConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      export default mergeConfig(
+        viteConfig,
+        defineConfig({
+          plugins: [react()],
+        }),
+        defineConfig({
+          test: {
+            environment: 'jsdom',
+          }
+        })
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig } from 'vite';
+        import { defineConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + import { playwright } from '@vitest/browser-playwright';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, defineConfig({
+          plugins: [react()]
+        }), defineConfig({
+          test: {
+        
+      -     environment: 'jsdom'
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         environment: 'jsdom'
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: playwright({}),
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }));"
+    `);
+  });
+  it('supports mergeConfig without defineConfig calls', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig } from 'vite'
+      import viteConfig from './vite.config'
+
+      export default mergeConfig(
+        viteConfig,
+        {
+          plugins: [react()],
+          test: {
+            environment: 'jsdom',
+          }
+        }
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig } from 'vite';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { defineConfig } from 'vitest/config';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + import { playwright } from '@vitest/browser-playwright';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, {
+          plugins: [react()],
+          test: {
+        
+      -     environment: 'jsdom'
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         environment: 'jsdom'
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: playwright({}),
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        });"
+    `);
+  });
+
+  it('supports mergeConfig without config containing test property', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig } from 'vite'
+      import { defineConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      export default mergeConfig(
+        viteConfig,
+        defineConfig({
+          plugins: [react()],
+        })
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig } from 'vite';
+        import { defineConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + import { playwright } from '@vitest/browser-playwright';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, defineConfig({
+        
+      -   plugins: [react()]
+      - 
+      +   plugins: [react()],
+      +   test: {
+      +     projects: [{
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: playwright({}),
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      +   }
+      + 
+        }));"
+    `);
+  });
+
+  it('supports mergeConfig with defineConfig pattern using projects (Vitest 3.2+)', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      /// <reference types="vitest/config" />
+      import { mergeConfig, defineConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      // https://vite.dev/config/
+      export default mergeConfig(
+        viteConfig,
+        defineConfig({
+          test: {
+            globals: true,
+          },
+        })
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  ...
+        import viteConfig from './vite.config';
+        
+        // https://vite.dev/config/
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + import { playwright } from '@vitest/browser-playwright';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, defineConfig({
+          test: {
+        
+      -     globals: true
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         globals: true
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: playwright({}),
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }));"
+    `);
+  });
+
+  it('appends storybook project to existing test.projects array (no double nesting)', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig, defineConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      export default mergeConfig(
+        viteConfig,
+        defineConfig({
+          test: {
+            expect: { requireAssertions: true },
+            projects: [
+              {
+                extends: "./vite.config.ts",
+                test: { name: "client" },
+              },
+              {
+                extends: "./vite.config.ts",
+                test: { name: "server" },
+              },
+            ],
+          },
+        })
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly (storybook project appended to existing projects, no double nesting)
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig, defineConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + import { playwright } from '@vitest/browser-playwright';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, defineConfig({
+          test: {
+            expect: {
+              requireAssertions: true
+      ...
+              test: {
+                name: "server"
+              }
+        
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: playwright({}),
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      + 
+            }]
+          }
+        }));"
+    `);
+  });
+
+  it('extracts coverage config and keeps it at top level when using workspace', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig, defineConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      export default mergeConfig(
+        viteConfig,
+        defineConfig({
+          test: {
+            name: 'node',
+            environment: 'happy-dom',
+            include: ['**/*.test.ts'],
+            coverage: {
+              exclude: [
+                'storybook.setup.ts',
+                '**/*.stories.*',
+              ],
+            },
+          },
+        })
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    // Coverage should stay at the top level, not moved into the workspace
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig, defineConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + import { playwright } from '@vitest/browser-playwright';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, defineConfig({
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts'],
+      - 
+            coverage: {
+              exclude: ['storybook.setup.ts', '**/*.stories.*']
+        
+      -     }
+      - 
+      +     },
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: playwright({}),
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }));"
+    `);
+  });
+
+  it('extracts coverage config and keeps it at top level when using projects', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig, defineConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      export default mergeConfig(
+        viteConfig,
+        defineConfig({
+          test: {
+            name: 'node',
+            environment: 'happy-dom',
+            include: ['**/*.test.ts'],
+            coverage: {
+              exclude: [
+                'storybook.setup.ts',
+                '**/*.stories.*',
+              ],
+            },
+          },
+        })
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    // Coverage should stay at the top level, not moved into the projects
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig, defineConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + import { playwright } from '@vitest/browser-playwright';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, defineConfig({
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts'],
+      - 
+            coverage: {
+              exclude: ['storybook.setup.ts', '**/*.stories.*']
+        
+      -     }
+      - 
+      +     },
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: playwright({}),
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }));"
+    `);
+  });
+
+  it('supports defineConfig wrapping mergeConfig', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { defineConfig, mergeConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      export default defineConfig(mergeConfig(viteConfig, {
+        test: {
+          name: 'node',
+          environment: 'happy-dom',
+          include: ['**/*.test.ts'],
+        },
+      }))
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { defineConfig, mergeConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + import { playwright } from '@vitest/browser-playwright';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default defineConfig(mergeConfig(viteConfig, {
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts']
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: playwright({}),
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }));"
+    `);
+  });
+
+  it('supports defineConfig wrapping mergeConfig with satisfies operator', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { defineConfig, mergeConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+      import type { ViteUserConfig } from 'vitest/config'
+
+      export default defineConfig(
+        mergeConfig(viteConfig, {
+          test: {
+            name: 'node',
+            environment: 'happy-dom',
+            include: ['**/*.test.ts'],
+          },
+        }) satisfies ViteUserConfig
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { defineConfig, mergeConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        import type { ViteUserConfig } from 'vitest/config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + import { playwright } from '@vitest/browser-playwright';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default defineConfig(mergeConfig(viteConfig, {
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts']
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: playwright({}),
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }) satisfies ViteUserConfig);"
+    `);
+  });
+
+  it('supports mergeConfig with as operator (TSAsExpression)', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+      import type { ViteUserConfig } from 'vitest/config'
+
+      export default mergeConfig(viteConfig, {
+        test: {
+          name: 'node',
+          environment: 'happy-dom',
+          include: ['**/*.test.ts'],
+        },
+      }) as ViteUserConfig
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        import type { ViteUserConfig } from 'vitest/config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { defineConfig } from 'vitest/config';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + import { playwright } from '@vitest/browser-playwright';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, {
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts']
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: playwright({}),
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }) as ViteUserConfig;"
+    `);
+  });
+
+  it('supports mergeConfig with test defined as a constant (shorthand property)', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      const test = {
+        name: 'node',
+        environment: 'happy-dom',
+        include: ['**/*.test.ts'],
+      }
+
+      export default mergeConfig(viteConfig, { test })
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { defineConfig } from 'vitest/config';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + import { playwright } from '@vitest/browser-playwright';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        const test = {
+          name: 'node',
+          environment: 'happy-dom',
+          include: ['**/*.test.ts']
+        };
+        export default mergeConfig(viteConfig, {
+        
+      -   test
+      - 
+      +   test: {
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: playwright({}),
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      +   }
+      + 
+        });"
+    `);
+  });
+
+  it('supports const defined config re-exported (export default config)', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { defineConfig, mergeConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      const config = mergeConfig(
+        viteConfig,
+        defineConfig({
+          test: {
+            name: 'node',
+            environment: 'happy-dom',
+            include: ['**/*.test.ts'],
+          },
+        })
+      )
+
+      export default config
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { defineConfig, mergeConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + import { playwright } from '@vitest/browser-playwright';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        const config = mergeConfig(viteConfig, defineConfig({
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts']
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: playwright({}),
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }));
+        export default config;"
+    `);
+  });
+
+  it('supports defineProject instead of defineConfig', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { defineProject } from 'vitest/config'
+
+      export default defineProject({
+        test: {
+          name: 'node',
+          environment: 'happy-dom',
+          include: ['**/*.test.ts'],
+        },
+      })
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { defineProject } from 'vitest/config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { defineConfig } from 'vitest/config';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + import { playwright } from '@vitest/browser-playwright';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default defineProject({
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts']
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: playwright({}),
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        });"
+    `);
+  });
+
+  it('supports export const config re-exported as default (ExportNamedDeclaration)', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+        import { defineConfig, mergeConfig } from 'vitest/config'
+        import viteConfig from './vite.config'
+  
+        export const config = mergeConfig(
+          viteConfig,
+          defineConfig({
+            test: {
+              name: 'node',
+              environment: 'happy-dom',
+              include: ['**/*.test.ts'],
+            },
+          })
+        )
+  
+        export default config
+      `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { defineConfig, mergeConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + import { playwright } from '@vitest/browser-playwright';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export const config = mergeConfig(viteConfig, defineConfig({
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts']
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: playwright({}),
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }));
+        export default config;"
+    `);
+  });
+
+  it('supports mergeConfig with config object as an exported constant (ExportNamedDeclaration)', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+        import { mergeConfig } from 'vitest/config'
+        import viteConfig from './vite.config'
+  
+        export const vitestConfig = {
+          test: {
+            name: 'node',
+            environment: 'happy-dom',
+            include: ['**/*.test.ts'],
+          }
+        }
+  
+        export default mergeConfig(viteConfig, vitestConfig)
+      `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { defineConfig } from 'vitest/config';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + import { playwright } from '@vitest/browser-playwright';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export const vitestConfig = {
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts']
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: playwright({}),
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        };
+        export default mergeConfig(viteConfig, vitestConfig);"
+    `);
+  });
+
+  it('supports mergeConfig with config object as a constant variable', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      const vitestConfig = {
+        test: {
+          name: 'node',
+          environment: 'happy-dom',
+          include: ['**/*.test.ts'],
+        }
+      }
+
+      export default mergeConfig(viteConfig, vitestConfig)
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { defineConfig } from 'vitest/config';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + import { playwright } from '@vitest/browser-playwright';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        const vitestConfig = {
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts']
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: playwright({}),
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        };
+        export default mergeConfig(viteConfig, vitestConfig);"
+    `);
+  });
+
+  it('supports mergeConfig with aliased defineConfig and updates the config that contains test', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import react from "@vitejs/plugin-react";
+      import { playwright } from "@vitest/browser-playwright";
+      import { defineConfig, mergeConfig } from "vite";
+      import tsconfigPaths from "vite-tsconfig-paths";
+      import { defineConfig as defineVitestConfig } from "vitest/config";
+
+      // https://vitejs.dev/config/
+      const viteConfig = defineConfig({
+        plugins: [tsconfigPaths(), react()],
+        optimizeDeps: {
+          exclude: ["@xmtp/wasm-bindings"],
+        },
+        server: {
+          allowedHosts: true,
+        },
+        build: {
+          sourcemap: true,
+        },
+      });
+
+      const vitestConfig = defineVitestConfig({
+        test: {
+          browser: {
+            provider: playwright(),
+            enabled: true,
+            headless: true,
+            screenshotFailures: false,
+            instances: [
+              {
+                browser: "chromium",
+              },
+            ],
+          },
+          testTimeout: 120000,
+        },
+      });
+
+      export default mergeConfig(viteConfig, vitestConfig);
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  ...
+        import { defineConfig as defineVitestConfig } from "vitest/config";
+        
+        // https://vitejs.dev/config/
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        const viteConfig = defineConfig({
+          plugins: [tsconfigPaths(), react()],
+          optimizeDeps: {
+            exclude: ["@xmtp/wasm-bindings"]
+      ...
+        });
+        const vitestConfig = defineVitestConfig({
+          test: {
+        
+      -     browser: {
+      -       provider: playwright(),
+      -       enabled: true,
+      -       headless: true,
+      -       screenshotFailures: false,
+      -       instances: [{
+      -         browser: "chromium"
+      -       }]
+      -     },
+      -     testTimeout: 120000
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         browser: {
+      +           provider: playwright(),
+      +           enabled: true,
+      +           headless: true,
+      +           screenshotFailures: false,
+      +           instances: [{
+      +             browser: "chromium"
+      +           }]
+      +         },
+      +         testTimeout: 120000
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: playwright({}),
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        });
+        export default mergeConfig(viteConfig, vitestConfig);"
+    `);
+  });
+
+  it('keeps coverage at top level instead of moving into projects', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.4.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig, defineConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      export default mergeConfig(
+        viteConfig,
+        defineConfig({
+          test: {
+            name: 'unit',
+            environment: 'happy-dom',
+            include: ['**/*.test.ts'],
+            env: { CI: 'true' },
+            pool: 'forks',
+            maxWorkers: 4,
+            coverage: {
+              provider: 'v8',
+              exclude: ['**/*.stories.*'],
+            },
+          },
+        })
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig, defineConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + import { playwright } from '@vitest/browser-playwright';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, defineConfig({
+          test: {
+        
+      -     name: 'unit',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts'],
+      -     env: {
+      -       CI: 'true'
+      -     },
+      -     pool: 'forks',
+      -     maxWorkers: 4,
+      - 
+            coverage: {
+              provider: 'v8',
+              exclude: ['**/*.stories.*']
+        
+      -     }
+      - 
+      +     },
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'unit',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts'],
+      +         env: {
+      +           CI: 'true'
+      +         },
+      +         pool: 'forks',
+      +         maxWorkers: 4
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: playwright({}),
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }));"
+    `);
+  });
+});
diff --git a/code/addons/vitest/src/updateVitestFile.config.test.ts b/code/addons/vitest/src/updateVitestFile.config.test.ts
new file mode 100644
index 000000000000..adfb71f7e876
--- /dev/null
+++ b/code/addons/vitest/src/updateVitestFile.config.test.ts
@@ -0,0 +1,2060 @@
+import { join } from 'node:path';
+
+import { describe, expect, it, vi } from 'vitest';
+
+import * as babel from 'storybook/internal/babel';
+
+import { getDiff } from '../../../core/src/core-server/utils/save-story/getDiff';
+import { loadTemplate, updateConfigFile } from './updateVitestFile';
+
+vi.mock('storybook/internal/node-logger', () => ({
+  logger: {
+    info: vi.fn(),
+    warn: vi.fn(),
+    error: vi.fn(),
+  },
+}));
+
+vi.mock('../../../core/src/shared/utils/module', () => ({
+  resolvePackageDir: vi.fn().mockImplementation(() => join(__dirname, '..')),
+}));
+
+describe('updateConfigFile', () => {
+  it('updates vite config file', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      /// <reference types="vitest/config" />
+      import { defineConfig } from 'vite'
+      import react from '@vitejs/plugin-react'
+
+      // https://vite.dev/config/
+      export default defineConfig({
+        plugins: [react()],
+        test: {
+          globals: true,
+          workspace: ['packages/*']
+        },
+      })
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  ...
+        import react from '@vitejs/plugin-react';
+        
+        // https://vite.dev/config/
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default defineConfig({
+          plugins: [react()],
+          test: {
+            globals: true,
+        
+      -     workspace: ['packages/*']
+      - 
+      +     workspace: ['packages/*', {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        });"
+    `);
+  });
+
+  it('supports object notation without defineConfig', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      /// <reference types="vitest/config" />
+      import react from '@vitejs/plugin-react'
+
+      // https://vite.dev/config/
+      export default {
+        plugins: [react()],
+        test: {
+          globals: true,
+          workspace: ['packages/*']
+        },
+      }
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  ...
+        import react from '@vitejs/plugin-react';
+        
+        // https://vite.dev/config/
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { defineConfig } from 'vitest/config';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default {
+          plugins: [react()],
+          test: {
+            globals: true,
+        
+      -     workspace: ['packages/*']
+      - 
+      +     workspace: ['packages/*', {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        };"
+    `);
+  });
+
+  it('does not support function notation', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      /// <reference types="vitest/config" />
+      import react from '@vitejs/plugin-react'
+
+      // https://vite.dev/config/
+      export default defineConfig(() => ({
+        plugins: [react()],
+        test: {
+          globals: true,
+          workspace: ['packages/*']
+        },
+      }))
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(false);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was NOT updated
+    expect(after).toBe(before);
+  });
+
+  it('adds projects property to test config', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      /// <reference types="vitest/config" />
+      import { defineConfig } from 'vite'
+      import react from '@vitejs/plugin-react'
+
+      // https://vite.dev/config/
+      export default defineConfig({
+        plugins: [react()],
+        test: {
+          globals: true,
+        },
+      })
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  ...
+        import react from '@vitejs/plugin-react';
+        
+        // https://vite.dev/config/
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default defineConfig({
+          plugins: [react()],
+          test: {
+        
+      -     globals: true
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         globals: true
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        });"
+    `);
+  });
+
+  it('updates config which is not exported immediately', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { defineConfig } from 'vite'
+      import viteReact from '@vitejs/plugin-react'
+      import { fileURLToPath, URL } from 'url'
+
+      const config = defineConfig({
+        resolve: {
+          preserveSymlinks: true,
+          alias: {
+            '@': fileURLToPath(new URL('./src', import.meta.url)),
+          },
+        },
+        plugins: [
+          viteReact(),
+        ],
+      })
+
+      export default config
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+  "  import { defineConfig } from 'vite';
+    import viteReact from '@vitejs/plugin-react';
+    import { fileURLToPath, URL } from 'url';
+    
+  + import path from 'node:path';
+  + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+  + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+  + 
+  + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+  + 
+    const config = defineConfig({
+      resolve: {
+        preserveSymlinks: true,
+        alias: {
+          '@': fileURLToPath(new URL('./src', import.meta.url))
+        }
+      },
+    
+  -   plugins: [viteReact()]
+  - 
+  +   plugins: [viteReact()],
+  +   test: {
+  +     projects: [{
+  +       extends: true,
+  +       plugins: [
+  +       // The plugin will run tests for the stories defined in your Storybook config
+  +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+  +       storybookTest({
+  +         configDir: path.join(dirname, '.storybook')
+  +       })],
+  +       test: {
+  +         name: 'storybook',
+  +         browser: {
+  +           enabled: true,
+  +           headless: true,
+  +           provider: 'playwright',
+  +           instances: [{
+  +             browser: 'chromium'
+  +           }]
+  +         }
+  +       }
+  +     }]
+  +   }
+  + 
+    });
+    export default config;"
+`);
+  });
+
+  it('edits projects property of test config', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      /// <reference types="vitest/config" />
+      import { defineConfig } from 'vite'
+      import react from '@vitejs/plugin-react'
+
+      // https://vite.dev/config/
+      export default defineConfig({
+        plugins: [react()],
+        test: {
+          globals: true,
+          projects: ['packages/*', {some: 'config'}]
+        }
+      })
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  ...
+        import react from '@vitejs/plugin-react';
+        
+        // https://vite.dev/config/
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default defineConfig({
+          plugins: [react()],
+          test: {
+            globals: true,
+            projects: ['packages/*', {
+              some: 'config'
+        
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      + 
+            }]
+          }
+        });"
+    `);
+  });
+
+  it('adds workspace property to test config', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      /// <reference types="vitest/config" />
+      import { defineConfig } from 'vite'
+      import react from '@vitejs/plugin-react'
+
+      // https://vite.dev/config/
+      export default defineConfig({
+        plugins: [react()],
+        test: {
+          globals: true,
+        },
+      })
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  ...
+        import react from '@vitejs/plugin-react';
+        
+        // https://vite.dev/config/
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default defineConfig({
+          plugins: [react()],
+          test: {
+        
+      -     globals: true
+      - 
+      +     workspace: [{
+      +       extends: true,
+      +       test: {
+      +         globals: true
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        });"
+    `);
+  });
+
+  it('adds test property to vite config', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      /// <reference types="vitest/config" />
+      import { defineConfig } from 'vite'
+      import react from '@vitejs/plugin-react'
+
+      // https://vite.dev/config/
+      export default defineConfig({
+        plugins: [react()],
+      })
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  ...
+        import react from '@vitejs/plugin-react';
+        
+        // https://vite.dev/config/
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default defineConfig({
+        
+      -   plugins: [react()]
+      - 
+      +   plugins: [react()],
+      +   test: {
+      +     workspace: [{
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      +   }
+      + 
+        });"
+    `);
+  });
+
+  it('supports mergeConfig with multiple defineConfig calls, finding the one with test', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig } from 'vite'
+      import { defineConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      export default mergeConfig(
+        viteConfig,
+        defineConfig({
+          plugins: [react()],
+        }),
+        defineConfig({
+          test: {
+            environment: 'jsdom',
+          }
+        })
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig } from 'vite';
+        import { defineConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, defineConfig({
+          plugins: [react()]
+        }), defineConfig({
+          test: {
+        
+      -     environment: 'jsdom'
+      - 
+      +     workspace: [{
+      +       extends: true,
+      +       test: {
+      +         environment: 'jsdom'
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }));"
+    `);
+  });
+  it('supports mergeConfig without defineConfig calls', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig } from 'vite'
+      import viteConfig from './vite.config'
+
+      export default mergeConfig(
+        viteConfig,
+        {
+          plugins: [react()],
+          test: {
+            environment: 'jsdom',
+          }
+        }
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig } from 'vite';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { defineConfig } from 'vitest/config';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, {
+          plugins: [react()],
+          test: {
+        
+      -     environment: 'jsdom'
+      - 
+      +     workspace: [{
+      +       extends: true,
+      +       test: {
+      +         environment: 'jsdom'
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        });"
+    `);
+  });
+
+  it('supports mergeConfig without config containing test property', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig } from 'vite'
+      import { defineConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      export default mergeConfig(
+        viteConfig,
+        defineConfig({
+          plugins: [react()],
+        })
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig } from 'vite';
+        import { defineConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, defineConfig({
+        
+      -   plugins: [react()]
+      - 
+      +   plugins: [react()],
+      +   test: {
+      +     workspace: [{
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      +   }
+      + 
+        }));"
+    `);
+  });
+
+  it('supports mergeConfig with defineConfig pattern using projects (Vitest 3.2+)', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      /// <reference types="vitest/config" />
+      import { mergeConfig, defineConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      // https://vite.dev/config/
+      export default mergeConfig(
+        viteConfig,
+        defineConfig({
+          test: {
+            globals: true,
+          },
+        })
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  ...
+        import viteConfig from './vite.config';
+        
+        // https://vite.dev/config/
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, defineConfig({
+          test: {
+        
+      -     globals: true
+      - 
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         globals: true
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }));"
+    `);
+  });
+
+  it('appends storybook project to existing test.projects array (no double nesting)', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig, defineConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      export default mergeConfig(
+        viteConfig,
+        defineConfig({
+          test: {
+            expect: { requireAssertions: true },
+            projects: [
+              {
+                extends: "./vite.config.ts",
+                test: { name: "client" },
+              },
+              {
+                extends: "./vite.config.ts",
+                test: { name: "server" },
+              },
+            ],
+          },
+        })
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly (storybook project appended to existing projects, no double nesting)
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig, defineConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, defineConfig({
+          test: {
+            expect: {
+              requireAssertions: true
+      ...
+              test: {
+                name: "server"
+              }
+        
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      + 
+            }]
+          }
+        }));"
+    `);
+  });
+
+  it('extracts coverage config and keeps it at top level when using workspace', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig, defineConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      export default mergeConfig(
+        viteConfig,
+        defineConfig({
+          test: {
+            name: 'node',
+            environment: 'happy-dom',
+            include: ['**/*.test.ts'],
+            coverage: {
+              exclude: [
+                'storybook.setup.ts',
+                '**/*.stories.*',
+              ],
+            },
+          },
+        })
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    // Coverage should stay at the top level, not moved into the workspace
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig, defineConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, defineConfig({
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts'],
+      - 
+            coverage: {
+              exclude: ['storybook.setup.ts', '**/*.stories.*']
+        
+      -     }
+      - 
+      +     },
+      +     workspace: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }));"
+    `);
+  });
+
+  it('extracts coverage config and keeps it at top level when using projects', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.3.2.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig, defineConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      export default mergeConfig(
+        viteConfig,
+        defineConfig({
+          test: {
+            name: 'node',
+            environment: 'happy-dom',
+            include: ['**/*.test.ts'],
+            coverage: {
+              exclude: [
+                'storybook.setup.ts',
+                '**/*.stories.*',
+              ],
+            },
+          },
+        })
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    // Coverage should stay at the top level, not moved into the projects
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig, defineConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, defineConfig({
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts'],
+      - 
+            coverage: {
+              exclude: ['storybook.setup.ts', '**/*.stories.*']
+        
+      -     }
+      - 
+      +     },
+      +     projects: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }));"
+    `);
+  });
+
+  it('supports defineConfig wrapping mergeConfig', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { defineConfig, mergeConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      export default defineConfig(mergeConfig(viteConfig, {
+        test: {
+          name: 'node',
+          environment: 'happy-dom',
+          include: ['**/*.test.ts'],
+        },
+      }))
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { defineConfig, mergeConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default defineConfig(mergeConfig(viteConfig, {
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts']
+      - 
+      +     workspace: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }));"
+    `);
+  });
+
+  it('supports defineConfig wrapping mergeConfig with satisfies operator', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { defineConfig, mergeConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+      import type { ViteUserConfig } from 'vitest/config'
+
+      export default defineConfig(
+        mergeConfig(viteConfig, {
+          test: {
+            name: 'node',
+            environment: 'happy-dom',
+            include: ['**/*.test.ts'],
+          },
+        }) satisfies ViteUserConfig
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { defineConfig, mergeConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        import type { ViteUserConfig } from 'vitest/config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default defineConfig(mergeConfig(viteConfig, {
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts']
+      - 
+      +     workspace: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }) satisfies ViteUserConfig);"
+    `);
+  });
+
+  it('supports mergeConfig with as operator (TSAsExpression)', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+      import type { ViteUserConfig } from 'vitest/config'
+
+      export default mergeConfig(viteConfig, {
+        test: {
+          name: 'node',
+          environment: 'happy-dom',
+          include: ['**/*.test.ts'],
+        },
+      }) as ViteUserConfig
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        import type { ViteUserConfig } from 'vitest/config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { defineConfig } from 'vitest/config';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, {
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts']
+      - 
+      +     workspace: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }) as ViteUserConfig;"
+    `);
+  });
+
+  it('supports mergeConfig with test defined as a constant (shorthand property)', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      const test = {
+        name: 'node',
+        environment: 'happy-dom',
+        include: ['**/*.test.ts'],
+      }
+
+      export default mergeConfig(viteConfig, { test })
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { defineConfig } from 'vitest/config';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        const test = {
+          name: 'node',
+          environment: 'happy-dom',
+          include: ['**/*.test.ts']
+        };
+        export default mergeConfig(viteConfig, {
+        
+      -   test
+      - 
+      +   test: {
+      +     workspace: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      +   }
+      + 
+        });"
+    `);
+  });
+
+  it('supports const defined config re-exported (export default config)', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { defineConfig, mergeConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      const config = mergeConfig(
+        viteConfig,
+        defineConfig({
+          test: {
+            name: 'node',
+            environment: 'happy-dom',
+            include: ['**/*.test.ts'],
+          },
+        })
+      )
+
+      export default config
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { defineConfig, mergeConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        const config = mergeConfig(viteConfig, defineConfig({
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts']
+      - 
+      +     workspace: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }));
+        export default config;"
+    `);
+  });
+
+  it('supports defineProject instead of defineConfig', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { defineProject } from 'vitest/config'
+
+      export default defineProject({
+        test: {
+          name: 'node',
+          environment: 'happy-dom',
+          include: ['**/*.test.ts'],
+        },
+      })
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { defineProject } from 'vitest/config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { defineConfig } from 'vitest/config';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default defineProject({
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts']
+      - 
+      +     workspace: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        });"
+    `);
+  });
+
+  it('supports export const config re-exported as default (ExportNamedDeclaration)', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { defineConfig, mergeConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      export const config = mergeConfig(
+        viteConfig,
+        defineConfig({
+          test: {
+            name: 'node',
+            environment: 'happy-dom',
+            include: ['**/*.test.ts'],
+          },
+        })
+      )
+
+      export default config
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { defineConfig, mergeConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export const config = mergeConfig(viteConfig, defineConfig({
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts']
+      - 
+      +     workspace: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }));
+        export default config;"
+    `);
+  });
+
+  it('supports mergeConfig with config object as an exported constant (ExportNamedDeclaration)', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      export const vitestConfig = {
+        test: {
+          name: 'node',
+          environment: 'happy-dom',
+          include: ['**/*.test.ts'],
+        }
+      }
+
+      export default mergeConfig(viteConfig, vitestConfig)
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { defineConfig } from 'vitest/config';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export const vitestConfig = {
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts']
+      - 
+      +     workspace: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        };
+        export default mergeConfig(viteConfig, vitestConfig);"
+    `);
+  });
+
+  it('supports mergeConfig with config object as a constant variable', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      const vitestConfig = {
+        test: {
+          name: 'node',
+          environment: 'happy-dom',
+          include: ['**/*.test.ts'],
+        }
+      }
+
+      export default mergeConfig(viteConfig, vitestConfig)
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { defineConfig } from 'vitest/config';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        const vitestConfig = {
+          test: {
+        
+      -     name: 'node',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts']
+      - 
+      +     workspace: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'node',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts']
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        };
+        export default mergeConfig(viteConfig, vitestConfig);"
+    `);
+  });
+
+  it('keeps coverage at top level instead of moving into workspace', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.config.template', {
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { mergeConfig, defineConfig } from 'vitest/config'
+      import viteConfig from './vite.config'
+
+      export default mergeConfig(
+        viteConfig,
+        defineConfig({
+          test: {
+            name: 'unit',
+            environment: 'happy-dom',
+            include: ['**/*.test.ts'],
+            env: { CI: 'true' },
+            pool: 'forks',
+            maxWorkers: 4,
+            coverage: {
+              provider: 'v8',
+              exclude: ['**/*.stories.*'],
+            },
+          },
+        })
+      )
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateConfigFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+    expect(after).not.toBe(before);
+
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { mergeConfig, defineConfig } from 'vitest/config';
+        import viteConfig from './vite.config';
+        
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + 
+        export default mergeConfig(viteConfig, defineConfig({
+          test: {
+        
+      -     name: 'unit',
+      -     environment: 'happy-dom',
+      -     include: ['**/*.test.ts'],
+      -     env: {
+      -       CI: 'true'
+      -     },
+      -     pool: 'forks',
+      -     maxWorkers: 4,
+      - 
+            coverage: {
+              provider: 'v8',
+              exclude: ['**/*.stories.*']
+        
+      -     }
+      - 
+      +     },
+      +     workspace: [{
+      +       extends: true,
+      +       test: {
+      +         name: 'unit',
+      +         environment: 'happy-dom',
+      +         include: ['**/*.test.ts'],
+      +         env: {
+      +           CI: 'true'
+      +         },
+      +         pool: 'forks',
+      +         maxWorkers: 4
+      +       }
+      +     }, {
+      +       extends: true,
+      +       plugins: [
+      +       // The plugin will run tests for the stories defined in your Storybook config
+      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +       storybookTest({
+      +         configDir: path.join(dirname, '.storybook')
+      +       })],
+      +       test: {
+      +         name: 'storybook',
+      +         browser: {
+      +           enabled: true,
+      +           headless: true,
+      +           provider: 'playwright',
+      +           instances: [{
+      +             browser: 'chromium'
+      +           }]
+      +         }
+      +       }
+      +     }]
+      + 
+          }
+        }));"
+    `);
+  });
+});
diff --git a/code/addons/vitest/src/updateVitestFile.config.workspace.test.ts b/code/addons/vitest/src/updateVitestFile.config.workspace.test.ts
new file mode 100644
index 000000000000..5f5784816d21
--- /dev/null
+++ b/code/addons/vitest/src/updateVitestFile.config.workspace.test.ts
@@ -0,0 +1,135 @@
+import { join } from 'node:path';
+
+import { describe, expect, it, vi } from 'vitest';
+
+import * as babel from 'storybook/internal/babel';
+
+import { getDiff } from '../../../core/src/core-server/utils/save-story/getDiff';
+import { loadTemplate, updateWorkspaceFile } from './updateVitestFile';
+
+vi.mock('storybook/internal/node-logger', () => ({
+  logger: {
+    info: vi.fn(),
+    warn: vi.fn(),
+    error: vi.fn(),
+  },
+}));
+
+vi.mock('../../../core/src/shared/utils/module', () => ({
+  resolvePackageDir: vi.fn().mockImplementation(() => join(__dirname, '..')),
+}));
+
+describe('updateWorkspaceFile', () => {
+  it('updates vitest workspace file using array syntax', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.workspace.template', {
+        EXTENDS_WORKSPACE: '',
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      export default ['packages/*']
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateWorkspaceFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "- export default ['packages/*'];
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { defineWorkspace } from 'vitest/config';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + export default ['packages/*', 'ROOT_CONFIG', {
+      +   extends: '.',
+      +   plugins: [
+      +   // The plugin will run tests for the stories defined in your Storybook config
+      +   // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +   storybookTest({
+      +     configDir: path.join(dirname, '.storybook')
+      +   })],
+      +   test: {
+      +     name: 'storybook',
+      +     browser: {
+      +       enabled: true,
+      +       headless: true,
+      +       provider: 'playwright',
+      +       instances: [{
+      +         browser: 'chromium'
+      +       }]
+      +     }
+      +   }
+      + }];"
+    `);
+  });
+
+  it('updates vitest workspace file using defineWorkspace syntax', async () => {
+    const source = babel.babelParse(
+      await loadTemplate('vitest.workspace.template', {
+        EXTENDS_WORKSPACE: '',
+        CONFIG_DIR: '.storybook',
+        BROWSER_CONFIG: "{ provider: 'playwright' }",
+        SETUP_FILE: '../.storybook/vitest.setup.ts',
+      })
+    );
+    const target = babel.babelParse(`
+      import { defineWorkspace } from 'vitest/config'
+
+      export default defineWorkspace(['packages/*'])
+    `);
+
+    const before = babel.generate(target).code;
+    const updated = updateWorkspaceFile(source, target);
+    expect(updated).toBe(true);
+
+    const after = babel.generate(target).code;
+
+    // check if the code was updated at all
+    expect(after).not.toBe(before);
+
+    // check if the code was updated correctly
+    expect(getDiff(before, after)).toMatchInlineSnapshot(`
+      "  import { defineWorkspace } from 'vitest/config';
+        
+      - export default defineWorkspace(['packages/*']);
+      + import path from 'node:path';
+      + import { fileURLToPath } from 'node:url';
+      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+      + 
+      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+      + export default defineWorkspace(['packages/*', 'ROOT_CONFIG', {
+      +   extends: '.',
+      +   plugins: [
+      +   // The plugin will run tests for the stories defined in your Storybook config
+      +   // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      +   storybookTest({
+      +     configDir: path.join(dirname, '.storybook')
+      +   })],
+      +   test: {
+      +     name: 'storybook',
+      +     browser: {
+      +       enabled: true,
+      +       headless: true,
+      +       provider: 'playwright',
+      +       instances: [{
+      +         browser: 'chromium'
+      +       }]
+      +     }
+      +   }
+      + }]);"
+    `);
+  });
+});
diff --git a/code/addons/vitest/src/updateVitestFile.test.ts b/code/addons/vitest/src/updateVitestFile.test.ts
index 9ff9385b80ab..321918e77221 100644
--- a/code/addons/vitest/src/updateVitestFile.test.ts
+++ b/code/addons/vitest/src/updateVitestFile.test.ts
@@ -2,10 +2,7 @@ import { join } from 'node:path';
 
 import { describe, expect, it, vi } from 'vitest';
 
-import * as babel from 'storybook/internal/babel';
-
-import { getDiff } from '../../../core/src/core-server/utils/save-story/getDiff';
-import { loadTemplate, updateConfigFile, updateWorkspaceFile } from './updateVitestFile';
+import { loadTemplate } from './updateVitestFile';
 
 vi.mock('storybook/internal/node-logger', () => ({
   logger: {
@@ -19,1315 +16,6 @@ vi.mock('../../../core/src/shared/utils/module', () => ({
   resolvePackageDir: vi.fn().mockImplementation(() => join(__dirname, '..')),
 }));
 
-describe('updateConfigFile', () => {
-  it('updates vite config file', async () => {
-    const source = babel.babelParse(
-      await loadTemplate('vitest.config.template', {
-        CONFIG_DIR: '.storybook',
-        BROWSER_CONFIG: "{ provider: 'playwright' }",
-        SETUP_FILE: '../.storybook/vitest.setup.ts',
-      })
-    );
-    const target = babel.babelParse(`
-      /// <reference types="vitest/config" />
-      import { defineConfig } from 'vite'
-      import react from '@vitejs/plugin-react'
-
-      // https://vite.dev/config/
-      export default defineConfig({
-        plugins: [react()],
-        test: {
-          globals: true,
-          workspace: ['packages/*']
-        },
-      })
-    `);
-
-    const before = babel.generate(target).code;
-    const updated = updateConfigFile(source, target);
-    expect(updated).toBe(true);
-
-    const after = babel.generate(target).code;
-
-    // check if the code was updated at all
-    expect(after).not.toBe(before);
-
-    // check if the code was updated correctly
-    expect(getDiff(before, after)).toMatchInlineSnapshot(`
-      "  ...
-        import react from '@vitejs/plugin-react';
-        
-        // https://vite.dev/config/
-        
-      + import path from 'node:path';
-      + import { fileURLToPath } from 'node:url';
-      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
-      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
-      + 
-      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
-      + 
-        export default defineConfig({
-          plugins: [react()],
-          test: {
-            globals: true,
-        
-      -     workspace: ['packages/*']
-      - 
-      +     workspace: ['packages/*', {
-      +       extends: true,
-      +       plugins: [
-      +       // The plugin will run tests for the stories defined in your Storybook config
-      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
-      +       storybookTest({
-      +         configDir: path.join(dirname, '.storybook')
-      +       })],
-      +       test: {
-      +         name: 'storybook',
-      +         browser: {
-      +           enabled: true,
-      +           headless: true,
-      +           provider: 'playwright',
-      +           instances: [{
-      +             browser: 'chromium'
-      +           }]
-      +         }
-      +       }
-      +     }]
-      + 
-          }
-        });"
-    `);
-  });
-
-  it('supports object notation without defineConfig', async () => {
-    const source = babel.babelParse(
-      await loadTemplate('vitest.config.template', {
-        CONFIG_DIR: '.storybook',
-        BROWSER_CONFIG: "{ provider: 'playwright' }",
-        SETUP_FILE: '../.storybook/vitest.setup.ts',
-      })
-    );
-    const target = babel.babelParse(`
-      /// <reference types="vitest/config" />
-      import react from '@vitejs/plugin-react'
-
-      // https://vite.dev/config/
-      export default {
-        plugins: [react()],
-        test: {
-          globals: true,
-          workspace: ['packages/*']
-        },
-      }
-    `);
-
-    const before = babel.generate(target).code;
-    const updated = updateConfigFile(source, target);
-    expect(updated).toBe(true);
-
-    const after = babel.generate(target).code;
-
-    // check if the code was updated at all
-    expect(after).not.toBe(before);
-
-    // check if the code was updated correctly
-    expect(getDiff(before, after)).toMatchInlineSnapshot(`
-      "  ...
-        import react from '@vitejs/plugin-react';
-        
-        // https://vite.dev/config/
-        
-      + import path from 'node:path';
-      + import { fileURLToPath } from 'node:url';
-      + import { defineConfig } from 'vitest/config';
-      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
-      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
-      + 
-      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
-      + 
-        export default {
-          plugins: [react()],
-          test: {
-            globals: true,
-        
-      -     workspace: ['packages/*']
-      - 
-      +     workspace: ['packages/*', {
-      +       extends: true,
-      +       plugins: [
-      +       // The plugin will run tests for the stories defined in your Storybook config
-      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
-      +       storybookTest({
-      +         configDir: path.join(dirname, '.storybook')
-      +       })],
-      +       test: {
-      +         name: 'storybook',
-      +         browser: {
-      +           enabled: true,
-      +           headless: true,
-      +           provider: 'playwright',
-      +           instances: [{
-      +             browser: 'chromium'
-      +           }]
-      +         }
-      +       }
-      +     }]
-      + 
-          }
-        };"
-    `);
-  });
-
-  it('does not support function notation', async () => {
-    const source = babel.babelParse(
-      await loadTemplate('vitest.config.template', {
-        CONFIG_DIR: '.storybook',
-        BROWSER_CONFIG: "{ provider: 'playwright' }",
-        SETUP_FILE: '../.storybook/vitest.setup.ts',
-      })
-    );
-    const target = babel.babelParse(`
-      /// <reference types="vitest/config" />
-      import react from '@vitejs/plugin-react'
-
-      // https://vite.dev/config/
-      export default defineConfig(() => ({
-        plugins: [react()],
-        test: {
-          globals: true,
-          workspace: ['packages/*']
-        },
-      }))
-    `);
-
-    const before = babel.generate(target).code;
-    const updated = updateConfigFile(source, target);
-    expect(updated).toBe(false);
-
-    const after = babel.generate(target).code;
-
-    // check if the code was NOT updated
-    expect(after).toBe(before);
-  });
-
-  it('adds projects property to test config', async () => {
-    const source = babel.babelParse(
-      await loadTemplate('vitest.config.3.2.template', {
-        CONFIG_DIR: '.storybook',
-        BROWSER_CONFIG: "{ provider: 'playwright' }",
-        SETUP_FILE: '../.storybook/vitest.setup.ts',
-      })
-    );
-    const target = babel.babelParse(`
-      /// <reference types="vitest/config" />
-      import { defineConfig } from 'vite'
-      import react from '@vitejs/plugin-react'
-
-      // https://vite.dev/config/
-      export default defineConfig({
-        plugins: [react()],
-        test: {
-          globals: true,
-        },
-      })
-    `);
-
-    const before = babel.generate(target).code;
-    const updated = updateConfigFile(source, target);
-    expect(updated).toBe(true);
-
-    const after = babel.generate(target).code;
-
-    // check if the code was updated at all
-    expect(after).not.toBe(before);
-
-    // check if the code was updated correctly
-    expect(getDiff(before, after)).toMatchInlineSnapshot(`
-      "  ...
-        import react from '@vitejs/plugin-react';
-        
-        // https://vite.dev/config/
-        
-      + import path from 'node:path';
-      + import { fileURLToPath } from 'node:url';
-      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
-      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
-      + 
-      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
-      + 
-        export default defineConfig({
-          plugins: [react()],
-          test: {
-        
-      -     globals: true
-      - 
-      +     globals: true,
-      +     projects: [{
-      +       extends: true,
-      +       plugins: [
-      +       // The plugin will run tests for the stories defined in your Storybook config
-      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
-      +       storybookTest({
-      +         configDir: path.join(dirname, '.storybook')
-      +       })],
-      +       test: {
-      +         name: 'storybook',
-      +         browser: {
-      +           enabled: true,
-      +           headless: true,
-      +           provider: 'playwright',
-      +           instances: [{
-      +             browser: 'chromium'
-      +           }]
-      +         }
-      +       }
-      +     }]
-      + 
-          }
-        });"
-    `);
-  });
-
-  it('updates config which is not exported immediately', async () => {
-    const source = babel.babelParse(
-      await loadTemplate('vitest.config.3.2.template', {
-        CONFIG_DIR: '.storybook',
-        BROWSER_CONFIG: "{ provider: 'playwright' }",
-        SETUP_FILE: '../.storybook/vitest.setup.ts',
-      })
-    );
-    const target = babel.babelParse(`
-      import { defineConfig } from 'vite'
-      import viteReact from '@vitejs/plugin-react'
-      import { fileURLToPath, URL } from 'url'
-
-      const config = defineConfig({
-        resolve: {
-          preserveSymlinks: true,
-          alias: {
-            '@': fileURLToPath(new URL('./src', import.meta.url)),
-          },
-        },
-        plugins: [
-          viteReact(),
-        ],
-      })
-
-      export default config
-    `);
-
-    const before = babel.generate(target).code;
-    const updated = updateConfigFile(source, target);
-    expect(updated).toBe(true);
-
-    const after = babel.generate(target).code;
-
-    expect(getDiff(before, after)).toMatchInlineSnapshot(`
-  "  import { defineConfig } from 'vite';
-    import viteReact from '@vitejs/plugin-react';
-    import { fileURLToPath, URL } from 'url';
-    
-  + import path from 'node:path';
-  + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
-  + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
-  + 
-  + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
-  + 
-    const config = defineConfig({
-      resolve: {
-        preserveSymlinks: true,
-        alias: {
-          '@': fileURLToPath(new URL('./src', import.meta.url))
-        }
-      },
-    
-  -   plugins: [viteReact()]
-  - 
-  +   plugins: [viteReact()],
-  +   test: {
-  +     projects: [{
-  +       extends: true,
-  +       plugins: [
-  +       // The plugin will run tests for the stories defined in your Storybook config
-  +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
-  +       storybookTest({
-  +         configDir: path.join(dirname, '.storybook')
-  +       })],
-  +       test: {
-  +         name: 'storybook',
-  +         browser: {
-  +           enabled: true,
-  +           headless: true,
-  +           provider: 'playwright',
-  +           instances: [{
-  +             browser: 'chromium'
-  +           }]
-  +         }
-  +       }
-  +     }]
-  +   }
-  + 
-    });
-    export default config;"
-`);
-  });
-
-  it('edits projects property of test config', async () => {
-    const source = babel.babelParse(
-      await loadTemplate('vitest.config.3.2.template', {
-        CONFIG_DIR: '.storybook',
-        BROWSER_CONFIG: "{ provider: 'playwright' }",
-        SETUP_FILE: '../.storybook/vitest.setup.ts',
-      })
-    );
-    const target = babel.babelParse(`
-      /// <reference types="vitest/config" />
-      import { defineConfig } from 'vite'
-      import react from '@vitejs/plugin-react'
-
-      // https://vite.dev/config/
-      export default defineConfig({
-        plugins: [react()],
-        test: {
-          globals: true,
-          projects: ['packages/*', {some: 'config'}]
-        }
-      })
-    `);
-
-    const before = babel.generate(target).code;
-    const updated = updateConfigFile(source, target);
-    expect(updated).toBe(true);
-
-    const after = babel.generate(target).code;
-
-    // check if the code was updated at all
-    expect(after).not.toBe(before);
-
-    // check if the code was updated correctly
-    expect(getDiff(before, after)).toMatchInlineSnapshot(`
-      "  ...
-        import react from '@vitejs/plugin-react';
-        
-        // https://vite.dev/config/
-        
-      + import path from 'node:path';
-      + import { fileURLToPath } from 'node:url';
-      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
-      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
-      + 
-      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
-      + 
-        export default defineConfig({
-          plugins: [react()],
-          test: {
-            globals: true,
-            projects: ['packages/*', {
-              some: 'config'
-        
-      +     }, {
-      +       extends: true,
-      +       plugins: [
-      +       // The plugin will run tests for the stories defined in your Storybook config
-      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
-      +       storybookTest({
-      +         configDir: path.join(dirname, '.storybook')
-      +       })],
-      +       test: {
-      +         name: 'storybook',
-      +         browser: {
-      +           enabled: true,
-      +           headless: true,
-      +           provider: 'playwright',
-      +           instances: [{
-      +             browser: 'chromium'
-      +           }]
-      +         }
-      +       }
-      + 
-            }]
-          }
-        });"
-    `);
-  });
-
-  it('adds workspace property to test config', async () => {
-    const source = babel.babelParse(
-      await loadTemplate('vitest.config.template', {
-        CONFIG_DIR: '.storybook',
-        BROWSER_CONFIG: "{ provider: 'playwright' }",
-        SETUP_FILE: '../.storybook/vitest.setup.ts',
-      })
-    );
-    const target = babel.babelParse(`
-      /// <reference types="vitest/config" />
-      import { defineConfig } from 'vite'
-      import react from '@vitejs/plugin-react'
-
-      // https://vite.dev/config/
-      export default defineConfig({
-        plugins: [react()],
-        test: {
-          globals: true,
-        },
-      })
-    `);
-
-    const before = babel.generate(target).code;
-    const updated = updateConfigFile(source, target);
-    expect(updated).toBe(true);
-
-    const after = babel.generate(target).code;
-
-    // check if the code was updated at all
-    expect(after).not.toBe(before);
-
-    // check if the code was updated correctly
-    expect(getDiff(before, after)).toMatchInlineSnapshot(`
-      "  ...
-        import react from '@vitejs/plugin-react';
-        
-        // https://vite.dev/config/
-        
-      + import path from 'node:path';
-      + import { fileURLToPath } from 'node:url';
-      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
-      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
-      + 
-      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
-      + 
-        export default defineConfig({
-          plugins: [react()],
-          test: {
-        
-      -     globals: true
-      - 
-      +     globals: true,
-      +     workspace: [{
-      +       extends: true,
-      +       plugins: [
-      +       // The plugin will run tests for the stories defined in your Storybook config
-      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
-      +       storybookTest({
-      +         configDir: path.join(dirname, '.storybook')
-      +       })],
-      +       test: {
-      +         name: 'storybook',
-      +         browser: {
-      +           enabled: true,
-      +           headless: true,
-      +           provider: 'playwright',
-      +           instances: [{
-      +             browser: 'chromium'
-      +           }]
-      +         }
-      +       }
-      +     }]
-      + 
-          }
-        });"
-    `);
-  });
-
-  it('adds test property to vite config', async () => {
-    const source = babel.babelParse(
-      await loadTemplate('vitest.config.template', {
-        CONFIG_DIR: '.storybook',
-        BROWSER_CONFIG: "{ provider: 'playwright' }",
-        SETUP_FILE: '../.storybook/vitest.setup.ts',
-      })
-    );
-    const target = babel.babelParse(`
-      /// <reference types="vitest/config" />
-      import { defineConfig } from 'vite'
-      import react from '@vitejs/plugin-react'
-
-      // https://vite.dev/config/
-      export default defineConfig({
-        plugins: [react()],
-      })
-    `);
-
-    const before = babel.generate(target).code;
-    const updated = updateConfigFile(source, target);
-    expect(updated).toBe(true);
-
-    const after = babel.generate(target).code;
-
-    // check if the code was updated at all
-    expect(after).not.toBe(before);
-
-    // check if the code was updated correctly
-    expect(getDiff(before, after)).toMatchInlineSnapshot(`
-      "  ...
-        import react from '@vitejs/plugin-react';
-        
-        // https://vite.dev/config/
-        
-      + import path from 'node:path';
-      + import { fileURLToPath } from 'node:url';
-      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
-      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
-      + 
-      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
-      + 
-        export default defineConfig({
-        
-      -   plugins: [react()]
-      - 
-      +   plugins: [react()],
-      +   test: {
-      +     workspace: [{
-      +       extends: true,
-      +       plugins: [
-      +       // The plugin will run tests for the stories defined in your Storybook config
-      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
-      +       storybookTest({
-      +         configDir: path.join(dirname, '.storybook')
-      +       })],
-      +       test: {
-      +         name: 'storybook',
-      +         browser: {
-      +           enabled: true,
-      +           headless: true,
-      +           provider: 'playwright',
-      +           instances: [{
-      +             browser: 'chromium'
-      +           }]
-      +         }
-      +       }
-      +     }]
-      +   }
-      + 
-        });"
-    `);
-  });
-
-  it('supports mergeConfig with multiple defineConfig calls, finding the one with test', async () => {
-    const source = babel.babelParse(
-      await loadTemplate('vitest.config.template', {
-        CONFIG_DIR: '.storybook',
-        BROWSER_CONFIG: "{ provider: 'playwright' }",
-        SETUP_FILE: '../.storybook/vitest.setup.ts',
-      })
-    );
-    const target = babel.babelParse(`
-      import { mergeConfig } from 'vite'
-      import { defineConfig } from 'vitest/config'
-      import viteConfig from './vite.config'
-
-      export default mergeConfig(
-        viteConfig,
-        defineConfig({
-          plugins: [react()],
-        }),
-        defineConfig({
-          test: {
-            environment: 'jsdom',
-          }
-        })
-      )
-    `);
-
-    const before = babel.generate(target).code;
-    const updated = updateConfigFile(source, target);
-    expect(updated).toBe(true);
-
-    const after = babel.generate(target).code;
-
-    // check if the code was updated at all
-    expect(after).not.toBe(before);
-
-    // check if the code was updated correctly
-    expect(getDiff(before, after)).toMatchInlineSnapshot(`
-      "  import { mergeConfig } from 'vite';
-        import { defineConfig } from 'vitest/config';
-        import viteConfig from './vite.config';
-        
-      + import path from 'node:path';
-      + import { fileURLToPath } from 'node:url';
-      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
-      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
-      + 
-      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
-      + 
-        export default mergeConfig(viteConfig, defineConfig({
-          plugins: [react()]
-        }), defineConfig({
-          test: {
-        
-      -     environment: 'jsdom'
-      - 
-      +     workspace: [{
-      +       extends: true,
-      +       test: {
-      +         environment: 'jsdom'
-      +       }
-      +     }, {
-      +       extends: true,
-      +       plugins: [
-      +       // The plugin will run tests for the stories defined in your Storybook config
-      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
-      +       storybookTest({
-      +         configDir: path.join(dirname, '.storybook')
-      +       })],
-      +       test: {
-      +         name: 'storybook',
-      +         browser: {
-      +           enabled: true,
-      +           headless: true,
-      +           provider: 'playwright',
-      +           instances: [{
-      +             browser: 'chromium'
-      +           }]
-      +         }
-      +       }
-      +     }]
-      + 
-          }
-        }));"
-    `);
-  });
-  it('supports mergeConfig without defineConfig calls', async () => {
-    const source = babel.babelParse(
-      await loadTemplate('vitest.config.template', {
-        CONFIG_DIR: '.storybook',
-        BROWSER_CONFIG: "{ provider: 'playwright' }",
-        SETUP_FILE: '../.storybook/vitest.setup.ts',
-      })
-    );
-    const target = babel.babelParse(`
-      import { mergeConfig } from 'vite'
-      import viteConfig from './vite.config'
-
-      export default mergeConfig(
-        viteConfig,
-        {
-          plugins: [react()],
-          test: {
-            environment: 'jsdom',
-          }
-        }
-      )
-    `);
-
-    const before = babel.generate(target).code;
-    const updated = updateConfigFile(source, target);
-    expect(updated).toBe(true);
-
-    const after = babel.generate(target).code;
-
-    // check if the code was updated at all
-    expect(after).not.toBe(before);
-
-    // check if the code was updated correctly
-    expect(getDiff(before, after)).toMatchInlineSnapshot(`
-      "  import { mergeConfig } from 'vite';
-        import viteConfig from './vite.config';
-        
-      + import path from 'node:path';
-      + import { fileURLToPath } from 'node:url';
-      + import { defineConfig } from 'vitest/config';
-      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
-      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
-      + 
-      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
-      + 
-        export default mergeConfig(viteConfig, {
-          plugins: [react()],
-          test: {
-        
-      -     environment: 'jsdom'
-      - 
-      +     workspace: [{
-      +       extends: true,
-      +       test: {
-      +         environment: 'jsdom'
-      +       }
-      +     }, {
-      +       extends: true,
-      +       plugins: [
-      +       // The plugin will run tests for the stories defined in your Storybook config
-      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
-      +       storybookTest({
-      +         configDir: path.join(dirname, '.storybook')
-      +       })],
-      +       test: {
-      +         name: 'storybook',
-      +         browser: {
-      +           enabled: true,
-      +           headless: true,
-      +           provider: 'playwright',
-      +           instances: [{
-      +             browser: 'chromium'
-      +           }]
-      +         }
-      +       }
-      +     }]
-      + 
-          }
-        });"
-    `);
-  });
-
-  it('supports mergeConfig without config containing test property', async () => {
-    const source = babel.babelParse(
-      await loadTemplate('vitest.config.template', {
-        CONFIG_DIR: '.storybook',
-        BROWSER_CONFIG: "{ provider: 'playwright' }",
-        SETUP_FILE: '../.storybook/vitest.setup.ts',
-      })
-    );
-    const target = babel.babelParse(`
-      import { mergeConfig } from 'vite'
-      import { defineConfig } from 'vitest/config'
-      import viteConfig from './vite.config'
-
-      export default mergeConfig(
-        viteConfig,
-        defineConfig({
-          plugins: [react()],
-        })
-      )
-    `);
-
-    const before = babel.generate(target).code;
-    const updated = updateConfigFile(source, target);
-    expect(updated).toBe(true);
-
-    const after = babel.generate(target).code;
-
-    // check if the code was updated at all
-    expect(after).not.toBe(before);
-
-    // check if the code was updated correctly
-    expect(getDiff(before, after)).toMatchInlineSnapshot(`
-      "  import { mergeConfig } from 'vite';
-        import { defineConfig } from 'vitest/config';
-        import viteConfig from './vite.config';
-        
-      + import path from 'node:path';
-      + import { fileURLToPath } from 'node:url';
-      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
-      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
-      + 
-      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
-      + 
-        export default mergeConfig(viteConfig, defineConfig({
-        
-      -   plugins: [react()]
-      - 
-      +   plugins: [react()],
-      +   test: {
-      +     workspace: [{
-      +       extends: true,
-      +       plugins: [
-      +       // The plugin will run tests for the stories defined in your Storybook config
-      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
-      +       storybookTest({
-      +         configDir: path.join(dirname, '.storybook')
-      +       })],
-      +       test: {
-      +         name: 'storybook',
-      +         browser: {
-      +           enabled: true,
-      +           headless: true,
-      +           provider: 'playwright',
-      +           instances: [{
-      +             browser: 'chromium'
-      +           }]
-      +         }
-      +       }
-      +     }]
-      +   }
-      + 
-        }));"
-    `);
-  });
-
-  it('supports mergeConfig with defineConfig pattern using projects (Vitest 3.2+)', async () => {
-    const source = babel.babelParse(
-      await loadTemplate('vitest.config.3.2.template', {
-        CONFIG_DIR: '.storybook',
-        BROWSER_CONFIG: "{ provider: 'playwright' }",
-        SETUP_FILE: '../.storybook/vitest.setup.ts',
-      })
-    );
-    const target = babel.babelParse(`
-      /// <reference types="vitest/config" />
-      import { mergeConfig, defineConfig } from 'vitest/config'
-      import viteConfig from './vite.config'
-
-      // https://vite.dev/config/
-      export default mergeConfig(
-        viteConfig,
-        defineConfig({
-          test: {
-            globals: true,
-          },
-        })
-      )
-    `);
-
-    const before = babel.generate(target).code;
-    const updated = updateConfigFile(source, target);
-    expect(updated).toBe(true);
-
-    const after = babel.generate(target).code;
-
-    // check if the code was updated at all
-    expect(after).not.toBe(before);
-
-    // check if the code was updated correctly
-    expect(getDiff(before, after)).toMatchInlineSnapshot(`
-      "  ...
-        import viteConfig from './vite.config';
-        
-        // https://vite.dev/config/
-        
-      + import path from 'node:path';
-      + import { fileURLToPath } from 'node:url';
-      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
-      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
-      + 
-      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
-      + 
-        export default mergeConfig(viteConfig, defineConfig({
-          test: {
-        
-      -     globals: true
-      - 
-      +     projects: [{
-      +       extends: true,
-      +       test: {
-      +         globals: true
-      +       }
-      +     }, {
-      +       extends: true,
-      +       plugins: [
-      +       // The plugin will run tests for the stories defined in your Storybook config
-      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
-      +       storybookTest({
-      +         configDir: path.join(dirname, '.storybook')
-      +       })],
-      +       test: {
-      +         name: 'storybook',
-      +         browser: {
-      +           enabled: true,
-      +           headless: true,
-      +           provider: 'playwright',
-      +           instances: [{
-      +             browser: 'chromium'
-      +           }]
-      +         }
-      +       }
-      +     }]
-      + 
-          }
-        }));"
-    `);
-  });
-
-  it('appends storybook project to existing test.projects array (no double nesting)', async () => {
-    const source = babel.babelParse(
-      await loadTemplate('vitest.config.3.2.template', {
-        CONFIG_DIR: '.storybook',
-        BROWSER_CONFIG: "{ provider: 'playwright' }",
-        SETUP_FILE: '../.storybook/vitest.setup.ts',
-      })
-    );
-    const target = babel.babelParse(`
-      import { mergeConfig, defineConfig } from 'vitest/config'
-      import viteConfig from './vite.config'
-
-      export default mergeConfig(
-        viteConfig,
-        defineConfig({
-          test: {
-            expect: { requireAssertions: true },
-            projects: [
-              {
-                extends: "./vite.config.ts",
-                test: { name: "client" },
-              },
-              {
-                extends: "./vite.config.ts",
-                test: { name: "server" },
-              },
-            ],
-          },
-        })
-      )
-    `);
-
-    const before = babel.generate(target).code;
-    const updated = updateConfigFile(source, target);
-    expect(updated).toBe(true);
-
-    const after = babel.generate(target).code;
-
-    // check if the code was updated at all
-    expect(after).not.toBe(before);
-
-    // check if the code was updated correctly (storybook project appended to existing projects, no double nesting)
-    expect(getDiff(before, after)).toMatchInlineSnapshot(`
-      "  import { mergeConfig, defineConfig } from 'vitest/config';
-        import viteConfig from './vite.config';
-        
-      + import path from 'node:path';
-      + import { fileURLToPath } from 'node:url';
-      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
-      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
-      + 
-      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
-      + 
-        export default mergeConfig(viteConfig, defineConfig({
-          test: {
-            expect: {
-              requireAssertions: true
-      ...
-              test: {
-                name: "server"
-              }
-        
-      +     }, {
-      +       extends: true,
-      +       plugins: [
-      +       // The plugin will run tests for the stories defined in your Storybook config
-      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
-      +       storybookTest({
-      +         configDir: path.join(dirname, '.storybook')
-      +       })],
-      +       test: {
-      +         name: 'storybook',
-      +         browser: {
-      +           enabled: true,
-      +           headless: true,
-      +           provider: 'playwright',
-      +           instances: [{
-      +             browser: 'chromium'
-      +           }]
-      +         }
-      +       }
-      + 
-            }]
-          }
-        }));"
-    `);
-  });
-
-  it('extracts coverage config and keeps it at top level when using workspace', async () => {
-    const source = babel.babelParse(
-      await loadTemplate('vitest.config.template', {
-        CONFIG_DIR: '.storybook',
-        BROWSER_CONFIG: "{ provider: 'playwright' }",
-        SETUP_FILE: '../.storybook/vitest.setup.ts',
-      })
-    );
-    const target = babel.babelParse(`
-      import { mergeConfig, defineConfig } from 'vitest/config'
-      import viteConfig from './vite.config'
-
-      export default mergeConfig(
-        viteConfig,
-        defineConfig({
-          test: {
-            name: 'node',
-            environment: 'happy-dom',
-            include: ['**/*.test.ts'],
-            coverage: {
-              exclude: [
-                'storybook.setup.ts',
-                '**/*.stories.*',
-              ],
-            },
-          },
-        })
-      )
-    `);
-
-    const before = babel.generate(target).code;
-    const updated = updateConfigFile(source, target);
-    expect(updated).toBe(true);
-
-    const after = babel.generate(target).code;
-
-    // check if the code was updated at all
-    expect(after).not.toBe(before);
-
-    // check if the code was updated correctly
-    // Coverage should stay at the top level, not moved into the workspace
-    expect(getDiff(before, after)).toMatchInlineSnapshot(`
-      "  import { mergeConfig, defineConfig } from 'vitest/config';
-        import viteConfig from './vite.config';
-        
-      + import path from 'node:path';
-      + import { fileURLToPath } from 'node:url';
-      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
-      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
-      + 
-      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
-      + 
-        export default mergeConfig(viteConfig, defineConfig({
-          test: {
-        
-      -     name: 'node',
-      -     environment: 'happy-dom',
-      -     include: ['**/*.test.ts'],
-      - 
-            coverage: {
-              exclude: ['storybook.setup.ts', '**/*.stories.*']
-        
-      -     }
-      - 
-      +     },
-      +     workspace: [{
-      +       extends: true,
-      +       test: {
-      +         name: 'node',
-      +         environment: 'happy-dom',
-      +         include: ['**/*.test.ts']
-      +       }
-      +     }, {
-      +       extends: true,
-      +       plugins: [
-      +       // The plugin will run tests for the stories defined in your Storybook config
-      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
-      +       storybookTest({
-      +         configDir: path.join(dirname, '.storybook')
-      +       })],
-      +       test: {
-      +         name: 'storybook',
-      +         browser: {
-      +           enabled: true,
-      +           headless: true,
-      +           provider: 'playwright',
-      +           instances: [{
-      +             browser: 'chromium'
-      +           }]
-      +         }
-      +       }
-      +     }]
-      + 
-          }
-        }));"
-    `);
-  });
-
-  it('extracts coverage config and keeps it at top level when using projects', async () => {
-    const source = babel.babelParse(
-      await loadTemplate('vitest.config.3.2.template', {
-        CONFIG_DIR: '.storybook',
-        BROWSER_CONFIG: "{ provider: 'playwright' }",
-        SETUP_FILE: '../.storybook/vitest.setup.ts',
-      })
-    );
-    const target = babel.babelParse(`
-      import { mergeConfig, defineConfig } from 'vitest/config'
-      import viteConfig from './vite.config'
-
-      export default mergeConfig(
-        viteConfig,
-        defineConfig({
-          test: {
-            name: 'node',
-            environment: 'happy-dom',
-            include: ['**/*.test.ts'],
-            coverage: {
-              exclude: [
-                'storybook.setup.ts',
-                '**/*.stories.*',
-              ],
-            },
-          },
-        })
-      )
-    `);
-
-    const before = babel.generate(target).code;
-    const updated = updateConfigFile(source, target);
-    expect(updated).toBe(true);
-
-    const after = babel.generate(target).code;
-
-    // check if the code was updated at all
-    expect(after).not.toBe(before);
-
-    // check if the code was updated correctly
-    // Coverage should stay at the top level, not moved into the projects
-    expect(getDiff(before, after)).toMatchInlineSnapshot(`
-      "  import { mergeConfig, defineConfig } from 'vitest/config';
-        import viteConfig from './vite.config';
-        
-      + import path from 'node:path';
-      + import { fileURLToPath } from 'node:url';
-      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
-      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
-      + 
-      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
-      + 
-        export default mergeConfig(viteConfig, defineConfig({
-          test: {
-        
-      -     name: 'node',
-      -     environment: 'happy-dom',
-      -     include: ['**/*.test.ts'],
-      - 
-            coverage: {
-              exclude: ['storybook.setup.ts', '**/*.stories.*']
-        
-      -     }
-      - 
-      +     },
-      +     projects: [{
-      +       extends: true,
-      +       test: {
-      +         name: 'node',
-      +         environment: 'happy-dom',
-      +         include: ['**/*.test.ts']
-      +       }
-      +     }, {
-      +       extends: true,
-      +       plugins: [
-      +       // The plugin will run tests for the stories defined in your Storybook config
-      +       // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
-      +       storybookTest({
-      +         configDir: path.join(dirname, '.storybook')
-      +       })],
-      +       test: {
-      +         name: 'storybook',
-      +         browser: {
-      +           enabled: true,
-      +           headless: true,
-      +           provider: 'playwright',
-      +           instances: [{
-      +             browser: 'chromium'
-      +           }]
-      +         }
-      +       }
-      +     }]
-      + 
-          }
-        }));"
-    `);
-  });
-});
-
-describe('updateWorkspaceFile', () => {
-  it('updates vitest workspace file using array syntax', async () => {
-    const source = babel.babelParse(
-      await loadTemplate('vitest.workspace.template', {
-        EXTENDS_WORKSPACE: '',
-        CONFIG_DIR: '.storybook',
-        BROWSER_CONFIG: "{ provider: 'playwright' }",
-        SETUP_FILE: '../.storybook/vitest.setup.ts',
-      })
-    );
-    const target = babel.babelParse(`
-      export default ['packages/*']
-    `);
-
-    const before = babel.generate(target).code;
-    const updated = updateWorkspaceFile(source, target);
-    expect(updated).toBe(true);
-
-    const after = babel.generate(target).code;
-
-    // check if the code was updated at all
-    expect(after).not.toBe(before);
-
-    // check if the code was updated correctly
-    expect(getDiff(before, after)).toMatchInlineSnapshot(`
-      "- export default ['packages/*'];
-      + import path from 'node:path';
-      + import { fileURLToPath } from 'node:url';
-      + import { defineWorkspace } from 'vitest/config';
-      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
-      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
-      + 
-      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
-      + export default ['packages/*', 'ROOT_CONFIG', {
-      +   extends: '.',
-      +   plugins: [
-      +   // The plugin will run tests for the stories defined in your Storybook config
-      +   // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
-      +   storybookTest({
-      +     configDir: path.join(dirname, '.storybook')
-      +   })],
-      +   test: {
-      +     name: 'storybook',
-      +     browser: {
-      +       enabled: true,
-      +       headless: true,
-      +       provider: 'playwright',
-      +       instances: [{
-      +         browser: 'chromium'
-      +       }]
-      +     }
-      +   }
-      + }];"
-    `);
-  });
-
-  it('updates vitest workspace file using defineWorkspace syntax', async () => {
-    const source = babel.babelParse(
-      await loadTemplate('vitest.workspace.template', {
-        EXTENDS_WORKSPACE: '',
-        CONFIG_DIR: '.storybook',
-        BROWSER_CONFIG: "{ provider: 'playwright' }",
-        SETUP_FILE: '../.storybook/vitest.setup.ts',
-      })
-    );
-    const target = babel.babelParse(`
-      import { defineWorkspace } from 'vitest/config'
-
-      export default defineWorkspace(['packages/*'])
-    `);
-
-    const before = babel.generate(target).code;
-    const updated = updateWorkspaceFile(source, target);
-    expect(updated).toBe(true);
-
-    const after = babel.generate(target).code;
-
-    // check if the code was updated at all
-    expect(after).not.toBe(before);
-
-    // check if the code was updated correctly
-    expect(getDiff(before, after)).toMatchInlineSnapshot(`
-      "  import { defineWorkspace } from 'vitest/config';
-        
-      - export default defineWorkspace(['packages/*']);
-      + import path from 'node:path';
-      + import { fileURLToPath } from 'node:url';
-      + import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
-      + const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
-      + 
-      + // More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
-      + export default defineWorkspace(['packages/*', 'ROOT_CONFIG', {
-      +   extends: '.',
-      +   plugins: [
-      +   // The plugin will run tests for the stories defined in your Storybook config
-      +   // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
-      +   storybookTest({
-      +     configDir: path.join(dirname, '.storybook')
-      +   })],
-      +   test: {
-      +     name: 'storybook',
-      +     browser: {
-      +       enabled: true,
-      +       headless: true,
-      +       provider: 'playwright',
-      +       instances: [{
-      +         browser: 'chromium'
-      +       }]
-      +     }
-      +   }
-      + }]);"
-    `);
-  });
-});
-
 describe('loadTemplate', () => {
   it('normalizes Windows paths to forward slashes', async () => {
     // Windows-style path with backslashes (need to escape them in JS strings)
diff --git a/code/addons/vitest/src/updateVitestFile.ts b/code/addons/vitest/src/updateVitestFile.ts
index ca9a01bffd9a..8aa792b52a1e 100644
--- a/code/addons/vitest/src/updateVitestFile.ts
+++ b/code/addons/vitest/src/updateVitestFile.ts
@@ -1,3 +1,4 @@
+import { resolveExpression } from 'storybook/internal/babel';
 import type { BabelFile, types as t } from 'storybook/internal/babel';
 
 import { normalize } from 'pathe';
@@ -69,56 +70,364 @@ const mergeProperties = (
 };
 
 /**
- * Resolves the target's default export to the actual config object expression we can merge into.
- * Handles: export default defineConfig({}), export default {}, and export default config (where
- * config is a variable holding defineConfig({}) or {}).
+ * Returns true if the identifier is a local alias for `defineConfig`/`defineProject` imported from
+ * either `vitest/config` or `vite`.
  */
-const getTargetConfigObject = (
-  target: BabelFile['ast'],
-  exportDefault: t.ExportDefaultDeclaration
+const isImportedDefineConfigLikeIdentifier = (localName: string, ast: BabelFile['ast']): boolean =>
+  ast.program.body.some(
+    (node): boolean =>
+      node.type === 'ImportDeclaration' &&
+      (node.source.value === 'vitest/config' || node.source.value === 'vite') &&
+      node.specifiers.some(
+        (specifier) =>
+          specifier.type === 'ImportSpecifier' &&
+          specifier.local.type === 'Identifier' &&
+          specifier.local.name === localName &&
+          specifier.imported.type === 'Identifier' &&
+          (specifier.imported.name === 'defineConfig' ||
+            specifier.imported.name === 'defineProject')
+      )
+  );
+
+/** Returns true if the call expression is a defineConfig or defineProject call (including aliases). */
+const isDefineConfigLike = (node: t.CallExpression, ast: BabelFile['ast']): boolean =>
+  node.callee.type === 'Identifier' &&
+  (node.callee.name === 'defineConfig' ||
+    node.callee.name === 'defineProject' ||
+    isImportedDefineConfigLikeIdentifier(node.callee.name, ast));
+
+/**
+ * Resolves a mergeConfig argument to a config object expression when possible. Supports both direct
+ * object args and wrapped forms like `defineConfig({ ... })`.
+ */
+const getConfigObjectFromMergeArg = (
+  arg: t.Expression,
+  ast: BabelFile['ast']
 ): t.ObjectExpression | null => {
-  const decl = exportDefault.declaration;
-  if (decl.type === 'ObjectExpression') {
-    return decl;
+  const resolved = resolveExpression(arg, ast);
+  if (!resolved) {
+    return null;
   }
-  if (
-    decl.type === 'CallExpression' &&
-    decl.callee.type === 'Identifier' &&
-    decl.callee.name === 'defineConfig' &&
-    decl.arguments[0]?.type === 'ObjectExpression'
-  ) {
-    return decl.arguments[0] as t.ObjectExpression;
+
+  if (resolved.type === 'ObjectExpression') {
+    return resolved;
+  }
+
+  if (resolved.type === 'CallExpression' && resolved.arguments[0]?.type === 'ObjectExpression') {
+    return resolved.arguments[0] as t.ObjectExpression;
+  }
+
+  return null;
+};
+
+/**
+ * Resolves the value of a `test` ObjectProperty to an ObjectExpression. Handles both inline objects
+ * and shorthand identifier references, e.g.: `{ test: { ... } }` → returns the inline
+ * ObjectExpression `const test = {...}; { test }` → resolves the identifier to its initializer
+ */
+const resolveTestPropValue = (
+  testProp: t.ObjectProperty,
+  ast: BabelFile['ast']
+): t.ObjectExpression | null => {
+  if (testProp.value.type === 'ObjectExpression') {
+    return testProp.value;
   }
-  if (decl.type === 'Identifier') {
-    const varName = decl.name;
-    const varDecl = target.program.body.find(
-      (n): n is t.VariableDeclaration =>
-        n.type === 'VariableDeclaration' &&
-        n.declarations.some((d) => d.id.type === 'Identifier' && d.id.name === varName)
+  const resolved = resolveExpression(testProp.value as t.Expression, ast);
+  return resolved?.type === 'ObjectExpression' ? resolved : null;
+};
+
+/** Finds a named ObjectProperty in an object expression's properties. */
+const findNamedProp = (
+  properties: t.ObjectExpression['properties'],
+  name: string
+): t.ObjectProperty | undefined =>
+  properties.find(
+    (p): p is t.ObjectProperty =>
+      p.type === 'ObjectProperty' && p.key.type === 'Identifier' && p.key.name === name
+  );
+
+/** Type guard for a property that is a `workspace` or `projects` key with an array value. */
+const isWorkspaceOrProjectsArrayProp = (
+  p: t.ObjectMethod | t.ObjectProperty | t.SpreadElement
+): p is t.ObjectProperty =>
+  p.type === 'ObjectProperty' &&
+  p.key.type === 'Identifier' &&
+  (p.key.name === 'workspace' || p.key.name === 'projects') &&
+  p.value.type === 'ArrayExpression';
+
+/**
+ * Appends storybook project(s) from template into an existing `test.workspace`/`test.projects`
+ * array, then merges any additional test-level options (e.g. coverage) that don't already exist.
+ */
+const appendToExistingProjectRefs = (
+  existingProjectRefsProp: t.ObjectProperty,
+  resolvedTestValue: t.ObjectExpression,
+  templateTestProp: t.ObjectProperty | undefined,
+  properties: t.ObjectExpression['properties'],
+  targetConfigObject: t.ObjectExpression
+) => {
+  const existingKeyName =
+    existingProjectRefsProp.key.type === 'Identifier' ? existingProjectRefsProp.key.name : null;
+
+  if (templateTestProp && templateTestProp.value.type === 'ObjectExpression') {
+    // Append template workspace/projects entries to existing workspace/projects array
+    const templateProjectRefsProp = templateTestProp.value.properties.find(
+      (p): p is t.ObjectProperty =>
+        isWorkspaceOrProjectsArrayProp(p) &&
+        (existingKeyName === null ||
+          (p.key.type === 'Identifier' && p.key.name === existingKeyName))
     );
-    if (!varDecl) {
-      return null;
+    if (templateProjectRefsProp && templateProjectRefsProp.value.type === 'ArrayExpression') {
+      (existingProjectRefsProp.value as t.ArrayExpression).elements.push(
+        ...(templateProjectRefsProp.value as t.ArrayExpression).elements
+      );
     }
-    const declarator = varDecl.declarations.find(
-      (d) => d.id.type === 'Identifier' && d.id.name === varName
+
+    // Merge other test-level options from template (e.g. coverage) that don't already exist
+    const existingTestPropNames = new Set(
+      resolvedTestValue.properties
+        .filter(
+          (p): p is t.ObjectProperty => p.type === 'ObjectProperty' && p.key.type === 'Identifier'
+        )
+        .map((p) => (p.key as t.Identifier).name)
     );
-    if (!declarator?.init) {
-      return null;
+    for (const templateProp of templateTestProp.value.properties) {
+      if (
+        templateProp.type === 'ObjectProperty' &&
+        templateProp.key.type === 'Identifier' &&
+        (templateProp.key as t.Identifier).name !== 'projects' &&
+        (templateProp.key as t.Identifier).name !== 'workspace' &&
+        !existingTestPropNames.has((templateProp.key as t.Identifier).name)
+      ) {
+        resolvedTestValue.properties.push(templateProp);
+      }
     }
-    const init = declarator.init;
+  }
+
+  // Merge only non-test properties from template
+  const otherTemplateProps = properties.filter(
+    (p) => !(p.type === 'ObjectProperty' && p.key.type === 'Identifier' && p.key.name === 'test')
+  );
+  if (otherTemplateProps.length > 0) {
+    mergeProperties(otherTemplateProps, targetConfigObject.properties);
+  }
+};
+
+/**
+ * Wraps the existing test config as one project entry inside the template's workspace/projects
+ * array, hoisting shared properties (coverage, env, pool, maxWorkers) to the top-level test
+ * object.
+ */
+const wrapTestConfigAsProject = (
+  resolvedTestValue: t.ObjectExpression,
+  existingTestProp: t.ObjectProperty,
+  templateTestProp: t.ObjectProperty,
+  properties: t.ObjectExpression['properties'],
+  targetConfigObject: t.ObjectExpression
+) => {
+  const workspaceOrProjectsProp =
+    templateTestProp.value.type === 'ObjectExpression'
+      ? (templateTestProp.value.properties.find(
+          (p) =>
+            p.type === 'ObjectProperty' &&
+            p.key.type === 'Identifier' &&
+            (p.key.name === 'workspace' || p.key.name === 'projects')
+        ) as t.ObjectProperty | undefined)
+      : undefined;
+
+  if (!workspaceOrProjectsProp || workspaceOrProjectsProp.value.type !== 'ArrayExpression') {
+    mergeProperties(properties, targetConfigObject.properties);
+    return;
+  }
+
+  // Properties that should stay at the top-level test object (shared across all projects)
+  const TOP_LEVEL_TEST_PROPERTIES = [
+    'shard',
+    'watch',
+    'run',
+    'cache',
+    'update',
+    'reporters',
+    'outputFile',
+    'teardownTimeout',
+    'silent',
+    'forceRerunTriggers',
+    'testNamePattern',
+    'ui',
+    'open',
+    'uiBase',
+    'snapshotFormat',
+    'resolveSnapshotPath',
+    'passWithNoTests',
+    'onConsoleLog',
+    'onStackTrace',
+    'dangerouslyIgnoreUnhandledErrors',
+    'slowTestThreshold',
+    'inspect',
+    'inspectBrk',
+    'coverage',
+    'watchTriggerPatterns',
+  ];
+
+  const topLevelProps = TOP_LEVEL_TEST_PROPERTIES.map((name) =>
+    findNamedProp(resolvedTestValue.properties, name)
+  ).filter(Boolean) as t.ObjectProperty[];
+
+  const topLevelPropSet = new Set(topLevelProps);
+  const projectTestProps = resolvedTestValue.properties.filter(
+    (p) => !topLevelPropSet.has(p as any)
+  );
+
+  // Create the existing test project: { extends: true, test: { ...projectTestProps } }
+  const existingTestProject: t.ObjectExpression = {
+    type: 'ObjectExpression',
+    properties: [
+      {
+        type: 'ObjectProperty',
+        key: { type: 'Identifier', name: 'extends' } as t.Identifier,
+        value: { type: 'BooleanLiteral', value: true } as t.BooleanLiteral,
+        computed: false,
+        shorthand: false,
+      } as t.ObjectProperty,
+      {
+        type: 'ObjectProperty',
+        key: { type: 'Identifier', name: 'test' } as t.Identifier,
+        value: {
+          type: 'ObjectExpression',
+          properties: projectTestProps,
+        } as t.ObjectExpression,
+        computed: false,
+        shorthand: false,
+      } as t.ObjectProperty,
+    ],
+  };
+
+  // Add the existing test project to the template's array
+  workspaceOrProjectsProp.value.elements.unshift(existingTestProject);
+
+  // Remove the existing test property from the target config (it's now in the array)
+  targetConfigObject.properties = targetConfigObject.properties.filter(
+    (p) => p !== existingTestProp
+  );
+
+  // Hoist top-level properties to the test object so they apply to all projects
+  if (topLevelProps.length > 0 && templateTestProp.value.type === 'ObjectExpression') {
+    templateTestProp.value.properties.unshift(...topLevelProps);
+  }
+
+  mergeProperties(properties, targetConfigObject.properties);
+};
+
+/**
+ * Merges template properties into a config object, handling Vitest `test.projects` migration
+ * semantics:
+ *
+ * - Append when projects already exists
+ * - Wrap existing test config as a project when template introduces projects/workspace
+ * - Otherwise perform a regular merge
+ */
+const mergeTemplateIntoConfigObject = (
+  targetConfigObject: t.ObjectExpression,
+  properties: t.ObjectExpression['properties'],
+  target: BabelFile['ast']
+) => {
+  const existingTestProp = findNamedProp(targetConfigObject.properties, 'test');
+  const resolvedTestValue = existingTestProp
+    ? resolveTestPropValue(existingTestProp, target)
+    : null;
+  const templateTestProp = findNamedProp(properties, 'test');
+
+  if (existingTestProp && resolvedTestValue !== null) {
+    const existingProjectRefsProp = resolvedTestValue.properties.find(
+      isWorkspaceOrProjectsArrayProp
+    );
+
+    if (existingProjectRefsProp) {
+      appendToExistingProjectRefs(
+        existingProjectRefsProp,
+        resolvedTestValue,
+        templateTestProp,
+        properties,
+        targetConfigObject
+      );
+      return;
+    }
+
+    if (templateTestProp && templateTestProp.value.type === 'ObjectExpression') {
+      wrapTestConfigAsProject(
+        resolvedTestValue,
+        existingTestProp,
+        templateTestProp,
+        properties,
+        targetConfigObject
+      );
+      return;
+    }
+  }
+
+  mergeProperties(properties, targetConfigObject.properties);
+};
+
+/**
+ * Extracts the effective mergeConfig call from a declaration, handling wrappers:
+ *
+ * - TypeScript type annotations (as X, satisfies X)
+ * - DefineConfig(mergeConfig(...)) outer wrapper
+ * - Variable references (export default config where config = mergeConfig(...))
+ */
+const getEffectiveMergeConfigCall = (
+  decl: t.Expression | t.Declaration,
+  ast: BabelFile['ast']
+): t.CallExpression | null => {
+  const resolved = resolveExpression(decl, ast);
+  if (!resolved || resolved.type !== 'CallExpression') {
+    return null;
+  }
+
+  // Handle defineConfig(mergeConfig(...)) – arg may itself be wrapped in a TS type expression
+  if (isDefineConfigLike(resolved, ast) && resolved.arguments.length > 0) {
+    const innerArg = resolveExpression(resolved.arguments[0] as t.Expression, ast);
     if (
-      init.type === 'CallExpression' &&
-      init.callee.type === 'Identifier' &&
-      init.callee.name === 'defineConfig' &&
-      init.arguments[0]?.type === 'ObjectExpression'
+      innerArg?.type === 'CallExpression' &&
+      innerArg.callee.type === 'Identifier' &&
+      innerArg.callee.name === 'mergeConfig'
     ) {
-      return init.arguments[0] as t.ObjectExpression;
-    }
-    if (init.type === 'ObjectExpression') {
-      return init;
+      return innerArg;
     }
+  }
+
+  // Handle mergeConfig(...) directly
+  if (resolved.callee.type === 'Identifier' && resolved.callee.name === 'mergeConfig') {
+    return resolved;
+  }
+
+  return null;
+};
+
+/**
+ * Resolves the target's default export to the actual config object expression we can merge into.
+ * Handles: export default defineConfig({}), export default defineProject({}), export default {},
+ * and export default config (where config is a variable holding one of those), as well as
+ * TypeScript type annotations on the declaration.
+ */
+const getTargetConfigObject = (
+  target: BabelFile['ast'],
+  exportDefault: t.ExportDefaultDeclaration
+): t.ObjectExpression | null => {
+  const resolved = resolveExpression(exportDefault.declaration, target);
+  if (!resolved) {
     return null;
   }
+  if (resolved.type === 'ObjectExpression') {
+    return resolved;
+  }
+  if (
+    resolved.type === 'CallExpression' &&
+    isDefineConfigLike(resolved, target) &&
+    resolved.arguments[0]?.type === 'ObjectExpression'
+  ) {
+    return resolved.arguments[0] as t.ObjectExpression;
+  }
   return null;
 };
 
@@ -165,50 +474,24 @@ export const updateConfigFile = (source: BabelFile['ast'], target: BabelFile['as
     return false;
   }
 
-  // Check if this is a function notation that we don't support
-  const rejectFunctionNotation = (decl: t.ExportDefaultDeclaration['declaration']) => {
-    if (
-      decl.type === 'CallExpression' &&
-      decl.callee.type === 'Identifier' &&
-      decl.callee.name === 'defineConfig' &&
-      decl.arguments.length > 0 &&
-      decl.arguments[0].type === 'ArrowFunctionExpression'
-    ) {
-      return true;
-    }
-    return false;
-  };
+  // Check if this is a function notation that we don't support (defineConfig(() => ({})))
+  // Resolve through TS type wrappers and variable references before checking.
+  const effectiveDecl = resolveExpression(targetExportDefault.declaration, target);
   if (
-    targetExportDefault.declaration.type === 'CallExpression' &&
-    rejectFunctionNotation(targetExportDefault.declaration)
+    effectiveDecl?.type === 'CallExpression' &&
+    isDefineConfigLike(effectiveDecl, target) &&
+    effectiveDecl.arguments.length > 0 &&
+    effectiveDecl.arguments[0].type === 'ArrowFunctionExpression'
   ) {
     return false;
   }
-  if (targetExportDefault.declaration.type === 'Identifier') {
-    const varName = targetExportDefault.declaration.name;
-    const varDecl = target.program.body.find(
-      (n): n is t.VariableDeclaration =>
-        n.type === 'VariableDeclaration' &&
-        n.declarations.some((d) => d.id.type === 'Identifier' && d.id.name === varName)
-    );
-    const declarator = varDecl?.declarations.find(
-      (d) => d.id.type === 'Identifier' && d.id.name === varName
-    );
-    if (declarator?.init?.type === 'CallExpression' && rejectFunctionNotation(declarator.init)) {
-      return false;
-    }
-  }
 
-  // Check if we can handle mergeConfig patterns (including export default config where config = defineConfig({}))
+  // Check if we can handle the config pattern (direct object, defineConfig/defineProject,
+  // mergeConfig, or any of these wrapped in TS type annotations / variable references)
   let canHandleConfig = false;
   if (getTargetConfigObject(target, targetExportDefault) !== null) {
     canHandleConfig = true;
-  } else if (
-    targetExportDefault.declaration.type === 'CallExpression' &&
-    targetExportDefault.declaration.callee.type === 'Identifier' &&
-    targetExportDefault.declaration.callee.name === 'mergeConfig' &&
-    targetExportDefault.declaration.arguments.length >= 2
-  ) {
+  } else if (getEffectiveMergeConfigCall(targetExportDefault.declaration, target) !== null) {
     canHandleConfig = true;
   }
 
@@ -258,196 +541,42 @@ export const updateConfigFile = (source: BabelFile['ast'], target: BabelFile['as
         const { properties } = sourceNode.declaration.arguments[0];
         const targetConfigObject = getTargetConfigObject(target, exportDefault);
         if (targetConfigObject !== null) {
-          mergeProperties(properties, targetConfigObject.properties);
+          mergeTemplateIntoConfigObject(targetConfigObject, properties, target);
           updated = true;
-        } else if (
-          exportDefault.declaration.type === 'CallExpression' &&
-          exportDefault.declaration.callee.type === 'Identifier' &&
-          exportDefault.declaration.callee.name === 'mergeConfig' &&
-          exportDefault.declaration.arguments.length >= 2
-        ) {
-          // We first collect all the potential config object nodes from mergeConfig, these can be:
-          // - defineConfig({ ... }) calls
-          // - plain object expressions { ... } without a defineConfig helper
-          const configObjectNodes: t.ObjectExpression[] = [];
-
-          for (const arg of exportDefault.declaration.arguments) {
-            if (
-              arg?.type === 'CallExpression' &&
-              arg.callee.type === 'Identifier' &&
-              arg.callee.name === 'defineConfig' &&
-              arg.arguments[0]?.type === 'ObjectExpression'
-            ) {
-              configObjectNodes.push(arg.arguments[0] as t.ObjectExpression);
-            } else if (arg?.type === 'ObjectExpression') {
-              configObjectNodes.push(arg);
-            }
-          }
-
-          // Prefer a config object that already contains a `test` property
-          const configObjectWithTest = configObjectNodes.find((obj) =>
-            obj.properties.some(
-              (p) =>
-                p.type === 'ObjectProperty' && p.key.type === 'Identifier' && p.key.name === 'test'
-            )
-          );
-
-          const targetConfigObject = configObjectWithTest || configObjectNodes[0];
-
-          if (!targetConfigObject) {
-            return false;
-          }
+        } else {
+          const mergeConfigCall = getEffectiveMergeConfigCall(exportDefault.declaration, target);
+          if (mergeConfigCall && mergeConfigCall.arguments.length >= 2) {
+            // Collect all potential config object nodes from mergeConfig arguments.
+            // Each argument may be a plain object, a wrapper call with object argument,
+            // an Identifier (variable reference), or wrapped in a TS type annotation.
+            const configObjectNodes: t.ObjectExpression[] = [];
 
-          // Check if there's already a test property in the target config
-          const existingTestProp = targetConfigObject.properties.find(
-            (p) =>
-              p.type === 'ObjectProperty' && p.key.type === 'Identifier' && p.key.name === 'test'
-          ) as t.ObjectProperty | undefined;
-
-          if (existingTestProp && existingTestProp.value.type === 'ObjectExpression') {
-            // Find the test property from the template (either workspace or projects)
-            const templateTestProp = properties.find(
-              (p) =>
-                p.type === 'ObjectProperty' && p.key.type === 'Identifier' && p.key.name === 'test'
-            ) as t.ObjectProperty | undefined;
-
-            const hasProjectsProp = (
-              p: t.ObjectMethod | t.ObjectProperty | t.SpreadElement
-            ): p is t.ObjectProperty =>
-              p.type === 'ObjectProperty' &&
-              p.key.type === 'Identifier' &&
-              p.key.name === 'projects' &&
-              p.value.type === 'ArrayExpression';
-
-            // Check if the existing config already uses a projects array (multi-project setup).
-            // If so, we must append the storybook project to that array instead of wrapping
-            // the entire test config as a single project (which would cause double nesting).
-            const existingProjectsProp = existingTestProp.value.properties.find(hasProjectsProp);
-
-            if (existingProjectsProp) {
-              // Existing config already has test.projects: append storybook project(s) to it
-              if (templateTestProp && templateTestProp.value.type === 'ObjectExpression') {
-                const templateProjectsProp =
-                  templateTestProp.value.properties.find(hasProjectsProp);
-                if (templateProjectsProp && templateProjectsProp.value.type === 'ArrayExpression') {
-                  const templateElements = (templateProjectsProp.value as t.ArrayExpression)
-                    .elements;
-                  (existingProjectsProp.value as t.ArrayExpression).elements.push(
-                    ...templateElements
-                  );
-                }
-                // Merge other test-level options from template (e.g. coverage) into existing test
-                for (const templateProp of templateTestProp.value.properties) {
-                  if (
-                    templateProp.type === 'ObjectProperty' &&
-                    templateProp.key.type === 'Identifier' &&
-                    (templateProp.key as t.Identifier).name !== 'projects'
-                  ) {
-                    const existingProp = existingTestProp.value.properties.find(
-                      (p) =>
-                        p.type === 'ObjectProperty' &&
-                        p.key.type === 'Identifier' &&
-                        (p.key as t.Identifier).name === (templateProp.key as t.Identifier).name
-                    );
-                    if (!existingProp && templateProp.type === 'ObjectProperty') {
-                      existingTestProp.value.properties.push(templateProp);
-                    }
-                  }
-                }
-              }
-              // Merge only non-test properties from template to avoid re-adding storybook project
-              const otherTemplateProps = properties.filter(
-                (p) =>
-                  !(
-                    p.type === 'ObjectProperty' &&
-                    p.key.type === 'Identifier' &&
-                    p.key.name === 'test'
-                  )
-              );
-              if (otherTemplateProps.length > 0) {
-                mergeProperties(otherTemplateProps, targetConfigObject.properties);
+            for (const arg of mergeConfigCall.arguments) {
+              const configObject = getConfigObjectFromMergeArg(arg as t.Expression, target);
+              if (configObject) {
+                configObjectNodes.push(configObject);
               }
-            } else if (templateTestProp && templateTestProp.value.type === 'ObjectExpression') {
-              // Existing test has no projects array: wrap entire test config as one project
-              const workspaceOrProjectsProp = templateTestProp.value.properties.find(
+            }
+
+            // Prefer the config object that already has an immediate `test` property.
+            const configObjectWithTest = configObjectNodes.find((obj) =>
+              obj.properties.some(
                 (p) =>
                   p.type === 'ObjectProperty' &&
                   p.key.type === 'Identifier' &&
-                  (p.key.name === 'workspace' || p.key.name === 'projects')
-              ) as t.ObjectProperty | undefined;
-
-              if (
-                workspaceOrProjectsProp &&
-                workspaceOrProjectsProp.value.type === 'ArrayExpression'
-              ) {
-                // Extract coverage config before creating the test project
-                const coverageProp = existingTestProp.value.properties.find(
-                  (p) =>
-                    p.type === 'ObjectProperty' &&
-                    p.key.type === 'Identifier' &&
-                    p.key.name === 'coverage'
-                ) as t.ObjectProperty | undefined;
-
-                // Create a new test config without the coverage property
-                const testPropsWithoutCoverage = existingTestProp.value.properties.filter(
-                  (p) => p !== coverageProp
-                );
-
-                const testConfigForProject: t.ObjectExpression = {
-                  type: 'ObjectExpression',
-                  properties: testPropsWithoutCoverage,
-                };
-
-                // Create the existing test project
-                const existingTestProject: t.ObjectExpression = {
-                  type: 'ObjectExpression',
-                  properties: [
-                    {
-                      type: 'ObjectProperty',
-                      key: { type: 'Identifier', name: 'extends' },
-                      value: { type: 'BooleanLiteral', value: true },
-                      computed: false,
-                      shorthand: false,
-                    },
-                    {
-                      type: 'ObjectProperty',
-                      key: { type: 'Identifier', name: 'test' },
-                      value: testConfigForProject,
-                      computed: false,
-                      shorthand: false,
-                    },
-                  ],
-                };
-
-                // Add the existing test project to the template's array
-                workspaceOrProjectsProp.value.elements.unshift(existingTestProject);
-
-                // Remove the existing test property from the target config since we're moving it to the array
-                targetConfigObject.properties = targetConfigObject.properties.filter(
-                  (p) => p !== existingTestProp
-                );
-
-                // If there was a coverage config, add it to the template's test config (at the top level of the test object)
-                // Insert it at the beginning so it appears before workspace/projects
-                if (coverageProp && templateTestProp.value.type === 'ObjectExpression') {
-                  templateTestProp.value.properties.unshift(coverageProp);
-                }
-
-                // Merge the template properties (which now include our existing test project in the array)
-                mergeProperties(properties, targetConfigObject.properties);
-              } else {
-                // Fallback to original behavior if template structure is unexpected
-                mergeProperties(properties, targetConfigObject.properties);
-              }
-            } else {
-              // Fallback to original behavior if template doesn't have expected structure
-              mergeProperties(properties, targetConfigObject.properties);
+                  p.key.name === 'test'
+              )
+            );
+
+            const targetConfigObject = configObjectWithTest || configObjectNodes[0];
+
+            if (!targetConfigObject) {
+              return false;
             }
-          } else {
-            // No existing test config, just merge normally
-            mergeProperties(properties, targetConfigObject.properties);
+
+            mergeTemplateIntoConfigObject(targetConfigObject, properties, target);
+            updated = true;
           }
-          updated = true;
         }
       }
     }
diff --git a/code/builders/builder-vite/package.json b/code/builders/builder-vite/package.json
index 46e7121bc2b4..72fe5453d036 100644
--- a/code/builders/builder-vite/package.json
+++ b/code/builders/builder-vite/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/builder-vite",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "A Storybook builder to dev and build with Vite",
   "keywords": [
     "storybook",
diff --git a/code/builders/builder-vite/src/plugins/storybook-optimize-deps-plugin.test.ts b/code/builders/builder-vite/src/plugins/storybook-optimize-deps-plugin.test.ts
index f42d94a5fe12..b9f1062943ba 100644
--- a/code/builders/builder-vite/src/plugins/storybook-optimize-deps-plugin.test.ts
+++ b/code/builders/builder-vite/src/plugins/storybook-optimize-deps-plugin.test.ts
@@ -1,6 +1,6 @@
 import { describe, expect, it } from 'vitest';
 
-import { escapeGlobPath } from './storybook-optimize-deps-plugin';
+import { escapeGlobPath, getMockRedirectIncludeEntries } from './storybook-optimize-deps-plugin';
 
 describe('escapeGlobPath', () => {
   it('should not modify a plain path without special characters', () => {
@@ -42,3 +42,35 @@ describe('escapeGlobPath', () => {
     );
   });
 });
+
+describe('getMockRedirectIncludeEntries', () => {
+  it('should include only manual mock redirect paths', () => {
+    expect(
+      getMockRedirectIncludeEntries([
+        { redirectPath: '/project/src/lib/__mocks__/db.ts' },
+        { redirectPath: null },
+      ])
+    ).toEqual(['/project/src/lib/__mocks__/db.ts']);
+  });
+
+  it('should escape special glob characters in redirect paths', () => {
+    expect(
+      getMockRedirectIncludeEntries([
+        { redirectPath: '/project/src/(group)/__mocks__/db.ts' },
+        { redirectPath: '/project/src/[id]/__mocks__/db.ts' },
+      ])
+    ).toEqual([
+      '/project/src/\\(group\\)/__mocks__/db.ts',
+      '/project/src/\\[id\\]/__mocks__/db.ts',
+    ]);
+  });
+
+  it('should dedupe redirect paths', () => {
+    expect(
+      getMockRedirectIncludeEntries([
+        { redirectPath: '/project/src/lib/__mocks__/db.ts' },
+        { redirectPath: '/project/src/lib/__mocks__/db.ts' },
+      ])
+    ).toEqual(['/project/src/lib/__mocks__/db.ts']);
+  });
+});
diff --git a/code/builders/builder-vite/src/plugins/storybook-optimize-deps-plugin.ts b/code/builders/builder-vite/src/plugins/storybook-optimize-deps-plugin.ts
index e75ab293dff1..cf3e2e8cc3f0 100644
--- a/code/builders/builder-vite/src/plugins/storybook-optimize-deps-plugin.ts
+++ b/code/builders/builder-vite/src/plugins/storybook-optimize-deps-plugin.ts
@@ -1,5 +1,6 @@
 import { loadPreviewOrConfigFile } from 'storybook/internal/common';
 import type { StoryIndexGenerator } from 'storybook/internal/core-server';
+import { babelParser, extractMockCalls, findMockRedirect } from 'storybook/internal/mocking-utils';
 import type { Options, PreviewAnnotation, StoryIndex } from 'storybook/internal/types';
 
 import { resolve } from 'pathe';
@@ -18,6 +19,20 @@ export function escapeGlobPath(filePath: string): string {
   return filePath.replace(/[()[\]{}!*?|+@]/g, '\\$&');
 }
 
+/** Converts extracted sb.mock calls into optimizeDeps include entries for manual **mocks** files. */
+export function getMockRedirectIncludeEntries(
+  mockCalls: Array<{ redirectPath: string | null }>
+): string[] {
+  return Array.from(
+    new Set(
+      mockCalls
+        .map((mockCall) => mockCall.redirectPath)
+        .filter((redirectPath): redirectPath is string => redirectPath !== null)
+        .map(escapeGlobPath)
+    )
+  );
+}
+
 /** A Vite plugin that configures dependency optimization for Storybook's dev server. */
 export function storybookOptimizeDepsPlugin(options: Options): Plugin {
   return {
@@ -41,6 +56,22 @@ export function storybookOptimizeDepsPlugin(options: Options): Plugin {
       // Include the user's preview file and all addon/framework/renderer preview annotations
       // as optimizer entries so Vite can discover all transitive CJS dependencies automatically.
       const previewOrConfigFile = loadPreviewOrConfigFile({ configDir: options.configDir });
+
+      const mockRedirectIncludeEntries = previewOrConfigFile
+        ? getMockRedirectIncludeEntries(
+            extractMockCalls(
+              {
+                previewConfigPath: previewOrConfigFile,
+                coreOptions: { disableTelemetry: true },
+                configDir: options.configDir,
+              },
+              babelParser,
+              projectRoot,
+              findMockRedirect
+            )
+          )
+        : [];
+
       const previewAnnotationEntries = [...previewAnnotations, previewOrConfigFile]
         .filter((path): path is PreviewAnnotation => path !== undefined)
         .map((path) => processPreviewAnnotation(path, projectRoot));
@@ -56,6 +87,7 @@ export function storybookOptimizeDepsPlugin(options: Options): Plugin {
             ...(typeof config.optimizeDeps?.entries === 'string'
               ? [config.optimizeDeps.entries]
               : (config.optimizeDeps?.entries ?? [])),
+            ...mockRedirectIncludeEntries,
             ...getUniqueImportPaths(index).map(escapeGlobPath),
             ...previewAnnotationEntries.map(escapeGlobPath),
           ],
diff --git a/code/builders/builder-webpack5/package.json b/code/builders/builder-webpack5/package.json
index 9dd1e2a94830..f5aa238d3694 100644
--- a/code/builders/builder-webpack5/package.json
+++ b/code/builders/builder-webpack5/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/builder-webpack5",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "A Storybook builder to dev and build with Webpack",
   "keywords": [
     "storybook",
diff --git a/code/core/package.json b/code/core/package.json
index 2956c06590ca..e9124f9a7b0d 100644
--- a/code/core/package.json
+++ b/code/core/package.json
@@ -1,6 +1,6 @@
 {
   "name": "storybook",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook: Develop, document, and test UI components in isolation",
   "keywords": [
     "storybook",
diff --git a/code/core/src/babel/expression-resolver.test.ts b/code/core/src/babel/expression-resolver.test.ts
new file mode 100644
index 000000000000..e1d5c93b681f
--- /dev/null
+++ b/code/core/src/babel/expression-resolver.test.ts
@@ -0,0 +1,150 @@
+import { describe, expect, it } from 'vitest';
+
+import * as parser from '@babel/parser';
+
+import { resolveExpression, unwrapTSExpression } from './expression-resolver';
+
+const parse = (code: string) =>
+  parser.parse(code, {
+    sourceType: 'module',
+    plugins: ['typescript'],
+  });
+
+describe('unwrapTSExpression', () => {
+  it('returns non-TS-wrapped expressions unchanged', () => {
+    const ast = parse('42');
+    const numLiteral = (ast.program.body[0] as any).expression;
+    expect(unwrapTSExpression(numLiteral)).toBe(numLiteral);
+  });
+
+  it('unwraps TSAsExpression', () => {
+    const ast = parse('foo as string');
+    const asExpr = (ast.program.body[0] as any).expression;
+    const result = unwrapTSExpression(asExpr);
+    expect(result.type).toBe('Identifier');
+    expect((result as any).name).toBe('foo');
+  });
+
+  it('unwraps TSSatisfiesExpression', () => {
+    const ast = parse('foo satisfies string');
+    const satisfiesExpr = (ast.program.body[0] as any).expression;
+    const result = unwrapTSExpression(satisfiesExpr);
+    expect(result.type).toBe('Identifier');
+    expect((result as any).name).toBe('foo');
+  });
+
+  it('unwraps TSTypeAssertion (<string>foo)', () => {
+    const ast = parser.parse('<string>foo', {
+      sourceType: 'module',
+      plugins: [['typescript', { dts: false }]],
+    });
+    const typeAssertion = (ast.program.body[0] as any).expression;
+    const result = unwrapTSExpression(typeAssertion);
+    expect(result.type).toBe('Identifier');
+    expect((result as any).name).toBe('foo');
+  });
+
+  it('unwraps nested TS wrappers', () => {
+    const ast = parse('(foo as any) satisfies string');
+    const outer = (ast.program.body[0] as any).expression;
+    const result = unwrapTSExpression(outer);
+    expect(result.type).toBe('Identifier');
+    expect((result as any).name).toBe('foo');
+  });
+});
+
+describe('resolveExpression', () => {
+  it('returns null for null/undefined input', () => {
+    const ast = parse('');
+    expect(resolveExpression(null, ast)).toBeNull();
+    expect(resolveExpression(undefined, ast)).toBeNull();
+  });
+
+  it('returns non-Identifier expressions directly', () => {
+    const ast = parse('42');
+    const numLiteral = (ast.program.body[0] as any).expression;
+    expect(resolveExpression(numLiteral, ast)).toBe(numLiteral);
+  });
+
+  it('resolves a bare VariableDeclaration', () => {
+    const ast = parse(`
+      const foo = { a: 1 };
+      export default foo;
+    `);
+    const defaultExport = ast.program.body[1] as any;
+    const result = resolveExpression(defaultExport.declaration, ast);
+    expect(result?.type).toBe('ObjectExpression');
+  });
+
+  it('resolves an exported const (ExportNamedDeclaration)', () => {
+    const ast = parse(`
+      export const config = { a: 1 };
+      export default config;
+    `);
+    const defaultExport = ast.program.body[1] as any;
+    const result = resolveExpression(defaultExport.declaration, ast);
+    expect(result?.type).toBe('ObjectExpression');
+  });
+
+  it('resolves a chain of variable references', () => {
+    const ast = parse(`
+      const inner = { a: 1 };
+      const outer = inner;
+      export default outer;
+    `);
+    const defaultExport = ast.program.body[2] as any;
+    const result = resolveExpression(defaultExport.declaration, ast);
+    expect(result?.type).toBe('ObjectExpression');
+  });
+
+  it('resolves through TSAsExpression', () => {
+    const ast = parse(`
+      const foo = { a: 1 };
+      export default foo as any;
+    `);
+    const defaultExport = ast.program.body[1] as any;
+    const result = resolveExpression(defaultExport.declaration, ast);
+    expect(result?.type).toBe('ObjectExpression');
+  });
+
+  it('resolves through TSSatisfiesExpression', () => {
+    const ast = parse(`
+      const foo = { a: 1 };
+      export default foo satisfies object;
+    `);
+    const defaultExport = ast.program.body[1] as any;
+    const result = resolveExpression(defaultExport.declaration, ast);
+    expect(result?.type).toBe('ObjectExpression');
+  });
+
+  it('returns the Identifier node when variable is not found', () => {
+    const ast = parse(`export default unknown;`);
+    const defaultExport = ast.program.body[0] as any;
+    const result = resolveExpression(defaultExport.declaration, ast);
+    expect(result?.type).toBe('Identifier');
+    expect((result as any).name).toBe('unknown');
+  });
+
+  it('returns the Identifier node when variable has no initializer', () => {
+    const ast = parse(`
+      let foo;
+      export default foo;
+    `);
+    const defaultExport = ast.program.body[1] as any;
+    const result = resolveExpression(defaultExport.declaration, ast);
+    expect(result?.type).toBe('Identifier');
+    expect((result as any).name).toBe('foo');
+  });
+
+  it('returns null when maxDepth is exceeded', () => {
+    // Create a chain longer than maxDepth (default 10)
+    const lines = Array.from({ length: 12 }, (_, i) =>
+      i === 0 ? `const v0 = { a: 1 };` : `const v${i} = v${i - 1};`
+    ).join('\n');
+    const ast = parse(`${lines}\nexport default v11;`);
+    const defaultExport = ast.program.body[ast.program.body.length - 1] as any;
+    const result = resolveExpression(defaultExport.declaration, ast);
+    // Depth exceeded — returns null
+    expect(result).toBeNull();
+  });
+});
diff --git a/code/core/src/babel/expression-resolver.ts b/code/core/src/babel/expression-resolver.ts
new file mode 100644
index 000000000000..3b2ab1d4ca80
--- /dev/null
+++ b/code/core/src/babel/expression-resolver.ts
@@ -0,0 +1,60 @@
+import type * as t from '@babel/types';
+
+/** Recursively unwraps TypeScript type annotation expressions (as X, satisfies X, <X>expr). */
+export const unwrapTSExpression = (expr: t.Expression | t.Declaration): t.Expression => {
+  if (
+    expr.type === 'TSAsExpression' ||
+    expr.type === 'TSSatisfiesExpression' ||
+    expr.type === 'TSTypeAssertion'
+  ) {
+    return unwrapTSExpression(
+      (expr as t.TSAsExpression | t.TSSatisfiesExpression | t.TSTypeAssertion).expression
+    );
+  }
+  return expr as t.Expression;
+};
+
+/**
+ * Resolves an expression through variable references and TypeScript type annotations. Handles:
+ * Identifier (variable lookup), TSAsExpression, TSSatisfiesExpression, TSTypeAssertion. Limits
+ * recursion depth to prevent infinite loops on circular variable references.
+ */
+export const resolveExpression = (
+  expr: t.Expression | t.Declaration | null | undefined,
+  ast: t.File,
+  depth = 0,
+  maxDepth = 10
+): t.Expression | null => {
+  if (!expr || depth > maxDepth) {
+    return null;
+  }
+  const unwrapped = unwrapTSExpression(expr as t.Expression | t.Declaration);
+  if (unwrapped.type !== 'Identifier') {
+    return unwrapped;
+  }
+  const varName = (unwrapped as t.Identifier).name;
+  let declarator: t.VariableDeclarator | undefined;
+  for (const node of ast.program.body) {
+    let declarations: t.VariableDeclarator[] | undefined;
+    if (node.type === 'VariableDeclaration') {
+      declarations = node.declarations;
+    } else if (
+      node.type === 'ExportNamedDeclaration' &&
+      node.declaration?.type === 'VariableDeclaration'
+    ) {
+      declarations = node.declaration.declarations;
+    }
+    if (declarations) {
+      declarator = declarations.find(
+        (d) => d.id.type === 'Identifier' && (d.id as t.Identifier).name === varName
+      );
+      if (declarator) {
+        break;
+      }
+    }
+  }
+  if (!declarator?.init) {
+    return unwrapped;
+  }
+  return resolveExpression(declarator.init, ast, depth + 1, maxDepth);
+};
diff --git a/code/core/src/babel/index.ts b/code/core/src/babel/index.ts
index 8aee3d8f5391..79e6fdd08d73 100644
--- a/code/core/src/babel/index.ts
+++ b/code/core/src/babel/index.ts
@@ -14,6 +14,7 @@ import * as types from '@babel/types';
 import * as recast from 'recast';
 
 export * from './babelParse';
+export { unwrapTSExpression, resolveExpression } from './expression-resolver';
 
 // @ts-expect-error (needed due to it's use of `exports.default`)
 const traverse = (bt.default || bt) as typeof bt;
diff --git a/code/core/src/common/versions.ts b/code/core/src/common/versions.ts
index 9b89d803329b..45bc692645fb 100644
--- a/code/core/src/common/versions.ts
+++ b/code/core/src/common/versions.ts
@@ -1,45 +1,45 @@
 // auto generated file, do not edit
 export default {
-  '@storybook/addon-a11y': '10.3.0-beta.1',
-  '@storybook/addon-docs': '10.3.0-beta.1',
-  '@storybook/addon-links': '10.3.0-beta.1',
-  '@storybook/addon-onboarding': '10.3.0-beta.1',
-  'storybook-addon-pseudo-states': '10.3.0-beta.1',
-  '@storybook/addon-themes': '10.3.0-beta.1',
-  '@storybook/addon-vitest': '10.3.0-beta.1',
-  '@storybook/builder-vite': '10.3.0-beta.1',
-  '@storybook/builder-webpack5': '10.3.0-beta.1',
-  storybook: '10.3.0-beta.1',
-  '@storybook/angular': '10.3.0-beta.1',
-  '@storybook/ember': '10.3.0-beta.1',
-  '@storybook/html-vite': '10.3.0-beta.1',
-  '@storybook/nextjs': '10.3.0-beta.1',
-  '@storybook/nextjs-vite': '10.3.0-beta.1',
-  '@storybook/preact-vite': '10.3.0-beta.1',
-  '@storybook/react-native-web-vite': '10.3.0-beta.1',
-  '@storybook/react-vite': '10.3.0-beta.1',
-  '@storybook/react-webpack5': '10.3.0-beta.1',
-  '@storybook/server-webpack5': '10.3.0-beta.1',
-  '@storybook/svelte-vite': '10.3.0-beta.1',
-  '@storybook/sveltekit': '10.3.0-beta.1',
-  '@storybook/vue3-vite': '10.3.0-beta.1',
-  '@storybook/web-components-vite': '10.3.0-beta.1',
-  sb: '10.3.0-beta.1',
-  '@storybook/cli': '10.3.0-beta.1',
-  '@storybook/codemod': '10.3.0-beta.1',
-  '@storybook/core-webpack': '10.3.0-beta.1',
-  'create-storybook': '10.3.0-beta.1',
-  '@storybook/csf-plugin': '10.3.0-beta.1',
-  'eslint-plugin-storybook': '10.3.0-beta.1',
-  '@storybook/react-dom-shim': '10.3.0-beta.1',
-  '@storybook/preset-create-react-app': '10.3.0-beta.1',
-  '@storybook/preset-react-webpack': '10.3.0-beta.1',
-  '@storybook/preset-server-webpack': '10.3.0-beta.1',
-  '@storybook/html': '10.3.0-beta.1',
-  '@storybook/preact': '10.3.0-beta.1',
-  '@storybook/react': '10.3.0-beta.1',
-  '@storybook/server': '10.3.0-beta.1',
-  '@storybook/svelte': '10.3.0-beta.1',
-  '@storybook/vue3': '10.3.0-beta.1',
-  '@storybook/web-components': '10.3.0-beta.1',
+  '@storybook/addon-a11y': '10.3.0-beta.2',
+  '@storybook/addon-docs': '10.3.0-beta.2',
+  '@storybook/addon-links': '10.3.0-beta.2',
+  '@storybook/addon-onboarding': '10.3.0-beta.2',
+  'storybook-addon-pseudo-states': '10.3.0-beta.2',
+  '@storybook/addon-themes': '10.3.0-beta.2',
+  '@storybook/addon-vitest': '10.3.0-beta.2',
+  '@storybook/builder-vite': '10.3.0-beta.2',
+  '@storybook/builder-webpack5': '10.3.0-beta.2',
+  storybook: '10.3.0-beta.2',
+  '@storybook/angular': '10.3.0-beta.2',
+  '@storybook/ember': '10.3.0-beta.2',
+  '@storybook/html-vite': '10.3.0-beta.2',
+  '@storybook/nextjs': '10.3.0-beta.2',
+  '@storybook/nextjs-vite': '10.3.0-beta.2',
+  '@storybook/preact-vite': '10.3.0-beta.2',
+  '@storybook/react-native-web-vite': '10.3.0-beta.2',
+  '@storybook/react-vite': '10.3.0-beta.2',
+  '@storybook/react-webpack5': '10.3.0-beta.2',
+  '@storybook/server-webpack5': '10.3.0-beta.2',
+  '@storybook/svelte-vite': '10.3.0-beta.2',
+  '@storybook/sveltekit': '10.3.0-beta.2',
+  '@storybook/vue3-vite': '10.3.0-beta.2',
+  '@storybook/web-components-vite': '10.3.0-beta.2',
+  sb: '10.3.0-beta.2',
+  '@storybook/cli': '10.3.0-beta.2',
+  '@storybook/codemod': '10.3.0-beta.2',
+  '@storybook/core-webpack': '10.3.0-beta.2',
+  'create-storybook': '10.3.0-beta.2',
+  '@storybook/csf-plugin': '10.3.0-beta.2',
+  'eslint-plugin-storybook': '10.3.0-beta.2',
+  '@storybook/react-dom-shim': '10.3.0-beta.2',
+  '@storybook/preset-create-react-app': '10.3.0-beta.2',
+  '@storybook/preset-react-webpack': '10.3.0-beta.2',
+  '@storybook/preset-server-webpack': '10.3.0-beta.2',
+  '@storybook/html': '10.3.0-beta.2',
+  '@storybook/preact': '10.3.0-beta.2',
+  '@storybook/react': '10.3.0-beta.2',
+  '@storybook/server': '10.3.0-beta.2',
+  '@storybook/svelte': '10.3.0-beta.2',
+  '@storybook/vue3': '10.3.0-beta.2',
+  '@storybook/web-components': '10.3.0-beta.2',
 };
diff --git a/code/core/src/manager-api/version.ts b/code/core/src/manager-api/version.ts
index a98b928e9511..66f11a256def 100644
--- a/code/core/src/manager-api/version.ts
+++ b/code/core/src/manager-api/version.ts
@@ -1 +1 @@
-export const version = '10.3.0-beta.1';
+export const version = '10.3.0-beta.2';
diff --git a/code/frameworks/angular/package.json b/code/frameworks/angular/package.json
index b328d0404069..122541a8fce3 100644
--- a/code/frameworks/angular/package.json
+++ b/code/frameworks/angular/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/angular",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook for Angular: Develop, document, and test UI components in isolation",
   "keywords": [
     "storybook",
diff --git a/code/frameworks/ember/package.json b/code/frameworks/ember/package.json
index 3dccd218d5bb..f555c1796679 100644
--- a/code/frameworks/ember/package.json
+++ b/code/frameworks/ember/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/ember",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook for Ember: Develop, document, and test UI components in isolation",
   "keywords": [
     "storybook",
diff --git a/code/frameworks/html-vite/package.json b/code/frameworks/html-vite/package.json
index 5d50fa1913cd..4dbfcb3a728f 100644
--- a/code/frameworks/html-vite/package.json
+++ b/code/frameworks/html-vite/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/html-vite",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook for HTML and Vite: Develop, document, and test UI components in isolation",
   "keywords": [
     "storybook",
diff --git a/code/frameworks/nextjs-vite/package.json b/code/frameworks/nextjs-vite/package.json
index 9dc52eaf04e6..3cfa847a20f7 100644
--- a/code/frameworks/nextjs-vite/package.json
+++ b/code/frameworks/nextjs-vite/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/nextjs-vite",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook for Next.js and Vite: Develop, document, and test UI components in isolation",
   "keywords": [
     "storybook",
diff --git a/code/frameworks/nextjs/package.json b/code/frameworks/nextjs/package.json
index 71315ad41a36..3fa3d4814091 100644
--- a/code/frameworks/nextjs/package.json
+++ b/code/frameworks/nextjs/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/nextjs",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook for Next.js: Develop, document, and test UI components in isolation",
   "keywords": [
     "storybook",
diff --git a/code/frameworks/preact-vite/package.json b/code/frameworks/preact-vite/package.json
index 0f9793e904d7..d4228939268b 100644
--- a/code/frameworks/preact-vite/package.json
+++ b/code/frameworks/preact-vite/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/preact-vite",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook for Preact and Vite: Develop, document, and test UI components in isolation",
   "keywords": [
     "storybook",
diff --git a/code/frameworks/react-native-web-vite/package.json b/code/frameworks/react-native-web-vite/package.json
index e9b7818c2add..3733ae36dbec 100644
--- a/code/frameworks/react-native-web-vite/package.json
+++ b/code/frameworks/react-native-web-vite/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/react-native-web-vite",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook for React Native Web and Vite: Develop, document, and test UI components in isolation",
   "keywords": [
     "storybook",
diff --git a/code/frameworks/react-vite/package.json b/code/frameworks/react-vite/package.json
index 69fa10365445..74c5f8a7f1b2 100644
--- a/code/frameworks/react-vite/package.json
+++ b/code/frameworks/react-vite/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/react-vite",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook for React and Vite: Develop, document, and test UI components in isolation",
   "keywords": [
     "storybook",
diff --git a/code/frameworks/react-webpack5/package.json b/code/frameworks/react-webpack5/package.json
index 155333dc1c34..22741dfb860a 100644
--- a/code/frameworks/react-webpack5/package.json
+++ b/code/frameworks/react-webpack5/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/react-webpack5",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook for React and Webpack: Develop, document, and test UI components in isolation",
   "keywords": [
     "storybook",
diff --git a/code/frameworks/server-webpack5/package.json b/code/frameworks/server-webpack5/package.json
index 004421483b70..48565ad717da 100644
--- a/code/frameworks/server-webpack5/package.json
+++ b/code/frameworks/server-webpack5/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/server-webpack5",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook for Server: View HTML snippets from a server in isolation with Hot Reloading.",
   "keywords": [
     "storybook",
diff --git a/code/frameworks/svelte-vite/package.json b/code/frameworks/svelte-vite/package.json
index 1de92680eab3..164e37c042c1 100644
--- a/code/frameworks/svelte-vite/package.json
+++ b/code/frameworks/svelte-vite/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/svelte-vite",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook for Svelte and Vite: Develop, document, and test UI components in isolation",
   "keywords": [
     "storybook",
diff --git a/code/frameworks/sveltekit/package.json b/code/frameworks/sveltekit/package.json
index 2f76e258ce9c..58c7f81bd1a4 100644
--- a/code/frameworks/sveltekit/package.json
+++ b/code/frameworks/sveltekit/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/sveltekit",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook for SvelteKit: Develop, document, and test UI components in isolation",
   "keywords": [
     "storybook",
diff --git a/code/frameworks/vue3-vite/package.json b/code/frameworks/vue3-vite/package.json
index 53e51c1c993c..2f0f62dc6f49 100644
--- a/code/frameworks/vue3-vite/package.json
+++ b/code/frameworks/vue3-vite/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/vue3-vite",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook for Vue3 and Vite: Develop, document, and test UI components in isolation",
   "keywords": [
     "storybook",
diff --git a/code/frameworks/web-components-vite/package.json b/code/frameworks/web-components-vite/package.json
index c1da46f0ecf4..b032ea34d703 100644
--- a/code/frameworks/web-components-vite/package.json
+++ b/code/frameworks/web-components-vite/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/web-components-vite",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook for Web Components and Vite: Develop, document, and test UI components in isolation",
   "keywords": [
     "storybook",
diff --git a/code/lib/cli-sb/package.json b/code/lib/cli-sb/package.json
index 013c03eaa7bc..f20e21705a55 100644
--- a/code/lib/cli-sb/package.json
+++ b/code/lib/cli-sb/package.json
@@ -1,6 +1,6 @@
 {
   "name": "sb",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook CLI: Develop, document, and test UI components in isolation",
   "keywords": [
     "storybook",
diff --git a/code/lib/cli-storybook/package.json b/code/lib/cli-storybook/package.json
index ec1e4bacec89..5c626a19e05e 100644
--- a/code/lib/cli-storybook/package.json
+++ b/code/lib/cli-storybook/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/cli",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook CLI: Develop, document, and test UI components in isolation",
   "keywords": [
     "storybook",
diff --git a/code/lib/codemod/package.json b/code/lib/codemod/package.json
index 70efb8ac4dbb..2096c61c3867 100644
--- a/code/lib/codemod/package.json
+++ b/code/lib/codemod/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/codemod",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "A collection of codemod scripts written with JSCodeshift",
   "keywords": [
     "storybook"
diff --git a/code/lib/core-webpack/package.json b/code/lib/core-webpack/package.json
index d3d901646f76..3133c2fe4fb5 100644
--- a/code/lib/core-webpack/package.json
+++ b/code/lib/core-webpack/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/core-webpack",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook framework-agnostic API",
   "keywords": [
     "storybook"
diff --git a/code/lib/create-storybook/package.json b/code/lib/create-storybook/package.json
index 9c4438f74adf..baee343d9bac 100644
--- a/code/lib/create-storybook/package.json
+++ b/code/lib/create-storybook/package.json
@@ -1,6 +1,6 @@
 {
   "name": "create-storybook",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook installer: Develop, document, and test UI components in isolation",
   "keywords": [
     "storybook",
diff --git a/code/lib/csf-plugin/package.json b/code/lib/csf-plugin/package.json
index bede0792fce9..9274198e3359 100644
--- a/code/lib/csf-plugin/package.json
+++ b/code/lib/csf-plugin/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/csf-plugin",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Enrich CSF files via static analysis",
   "keywords": [
     "storybook"
diff --git a/code/lib/eslint-plugin/package.json b/code/lib/eslint-plugin/package.json
index acec622cd26f..3a6bf8573f81 100644
--- a/code/lib/eslint-plugin/package.json
+++ b/code/lib/eslint-plugin/package.json
@@ -1,6 +1,6 @@
 {
   "name": "eslint-plugin-storybook",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook ESLint Plugin: Best practice rules for writing stories",
   "keywords": [
     "eslint",
diff --git a/code/lib/react-dom-shim/package.json b/code/lib/react-dom-shim/package.json
index f485171f4967..fc555fb3347a 100644
--- a/code/lib/react-dom-shim/package.json
+++ b/code/lib/react-dom-shim/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/react-dom-shim",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "",
   "keywords": [
     "storybook"
diff --git a/code/package.json b/code/package.json
index 01f43cf9050d..5dd7b74d414e 100644
--- a/code/package.json
+++ b/code/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/code",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "private": true,
   "description": "Storybook root",
   "homepage": "https://storybook.js.org/",
diff --git a/code/presets/create-react-app/package.json b/code/presets/create-react-app/package.json
index fd61d9120d3f..336299aaf27b 100644
--- a/code/presets/create-react-app/package.json
+++ b/code/presets/create-react-app/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/preset-create-react-app",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook for Create React App preset",
   "keywords": [
     "storybook"
diff --git a/code/presets/react-webpack/package.json b/code/presets/react-webpack/package.json
index 1048b0b4e2b6..c5b43cd46ddc 100644
--- a/code/presets/react-webpack/package.json
+++ b/code/presets/react-webpack/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/preset-react-webpack",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook for React: Develop React Component in isolation with Hot Reloading",
   "keywords": [
     "storybook"
diff --git a/code/presets/server-webpack/package.json b/code/presets/server-webpack/package.json
index 333b72f18eba..e48ddfd13e55 100644
--- a/code/presets/server-webpack/package.json
+++ b/code/presets/server-webpack/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/preset-server-webpack",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook for Server: View HTML snippets from a server in isolation with Hot Reloading.",
   "keywords": [
     "storybook"
diff --git a/code/renderers/html/package.json b/code/renderers/html/package.json
index 2ca19ef9b144..104105cd5b61 100644
--- a/code/renderers/html/package.json
+++ b/code/renderers/html/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/html",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook HTML renderer: Develop, document, and test UI components in isolation",
   "keywords": [
     "storybook",
diff --git a/code/renderers/preact/package.json b/code/renderers/preact/package.json
index 53bdf7a41b1c..2f2fbf5e1f85 100644
--- a/code/renderers/preact/package.json
+++ b/code/renderers/preact/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/preact",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook Preact renderer: Develop, document, and test UI components in isolation",
   "keywords": [
     "storybook",
diff --git a/code/renderers/react/package.json b/code/renderers/react/package.json
index 549506d071db..77feb03ccbd0 100644
--- a/code/renderers/react/package.json
+++ b/code/renderers/react/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/react",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook React renderer",
   "keywords": [
     "storybook"
diff --git a/code/renderers/server/package.json b/code/renderers/server/package.json
index 671a36f145f2..45d5400b2b5a 100644
--- a/code/renderers/server/package.json
+++ b/code/renderers/server/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/server",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook Server renderer: Develop, document, and test UI components in isolation",
   "keywords": [
     "storybook",
diff --git a/code/renderers/svelte/package.json b/code/renderers/svelte/package.json
index 92ffa38e6ccd..24ad267acaac 100644
--- a/code/renderers/svelte/package.json
+++ b/code/renderers/svelte/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/svelte",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook Svelte renderer: Develop, document, and test UI components in isolation.",
   "keywords": [
     "storybook",
diff --git a/code/renderers/vue3/package.json b/code/renderers/vue3/package.json
index e132d50f633b..718623906d34 100644
--- a/code/renderers/vue3/package.json
+++ b/code/renderers/vue3/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/vue3",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook Vue 3 renderer: Develop, document, and test UI components in isolation",
   "keywords": [
     "storybook",
diff --git a/code/renderers/web-components/package.json b/code/renderers/web-components/package.json
index 6bacf574ff7b..c694ba209e85 100644
--- a/code/renderers/web-components/package.json
+++ b/code/renderers/web-components/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@storybook/web-components",
-  "version": "10.3.0-beta.1",
+  "version": "10.3.0-beta.2",
   "description": "Storybook Web Components renderer: Develop, document, and test UI components in isolation",
   "keywords": [
     "storybook",
diff --git a/docs/versions/next.json b/docs/versions/next.json
index dca93cb3ae84..482f457d8234 100644
--- a/docs/versions/next.json
+++ b/docs/versions/next.json
@@ -1 +1 @@
-{"version":"10.3.0-beta.1","info":{"plain":"- Addon-Docs: Add React as optimizeDeps entry - [#34176](https://github.com/storybookjs/storybook/pull/34176), thanks @valentinpalkovic!\n- CLI: Avoid hanging of postinstall during init - [#34175](https://github.com/storybookjs/storybook/pull/34175), thanks @valentinpalkovic!"}}
\ No newline at end of file
+{"version":"10.3.0-beta.2","info":{"plain":"- UI: Hide addon panel Drag on pages without a panel - [#34162](https://github.com/storybookjs/storybook/pull/34162), thanks @Sidnioulz!\n- UI: Hide manifest tag for now - [#34165](https://github.com/storybookjs/storybook/pull/34165), thanks @Sidnioulz!\n- UI: Make disabled Buttons keyboard-focusable - [#34166](https://github.com/storybookjs/storybook/pull/34166), thanks @Sidnioulz!\n- UI: Use correct selector for addon panel focus check - [#34164](https://github.com/storybookjs/storybook/pull/34164), thanks @Sidnioulz!\n- Vue: Make globals reactive in decorators - [#34116](https://github.com/storybookjs/storybook/pull/34116), thanks @Sidnioulz!"}}
\ No newline at end of file
diff --git a/scripts/tasks/test-runner-build.ts b/scripts/tasks/test-runner-build.ts
index 9d3e070c52d0..85e07ac5db75 100644
--- a/scripts/tasks/test-runner-build.ts
+++ b/scripts/tasks/test-runner-build.ts
@@ -23,7 +23,7 @@ export const testRunnerBuild: Task & { port: number } = {
     const flags = [
       `--url http://localhost:${port}`,
       '--junit',
-      '--maxWorkers=2',
+      '--maxWorkers=1',
       '--failOnConsole',
       '--index-json',
     ];