Tags: Remove undocumented x-only tags

MIGRATION.md

@@ -7,6 +7,7 @@
     - [Node.js 20.19+ or 22.12+ required](#nodejs-2019-or-2212-required)
     - [Require `tsconfig.json` `moduleResolution` set to value that supports `types` condition](#require-tsconfigjson-moduleresolution-set-to-value-that-supports-types-condition)
     - [`core.builder` configuration must be a fully resolved path](#corebuilder-configuration-must-be-a-fully-resolved-path)
+    - [Removed x-only builtin tags](#removed-x-only-builtin-tags)
 - [From version 8.x to 9.0.0](#from-version-8x-to-900)
   - [Core Changes and Removals](#core-changes-and-removals)
     - [Dropped support for legacy packages](#dropped-support-for-legacy-packages)
@@ -580,6 +581,10 @@ export const core = {
 };
 ```
 
+#### Removed x-only builtin tags
+During development of Storybook [Tags](https://storybook.js.org/docs/writing-stories/tags), we created `dev-only`, `docs-only`, and `test-only` built-in tags. These tags were never documented and superseded by the currently-documented `dev`, `autodocs`, and `test` tags which provide more precise control. The outdated `x-only` tags are removed in 10.0.
+During development of Storybook [Tags](https://storybook.js.org/docs/writing-stories/tags), we created `dev-only`, `docs-only`, and `test-only` built-in tags. These tags were never documented and superceded by the currently-documented `dev`, `autodocs`, and `test` tags which provide more precise control. The outdated `x-only` tags are removed in 10.0.
+
 ## From version 8.x to 9.0.0
 
 ### Core Changes and Removals
@@ -1806,7 +1811,7 @@ These sections explain the rationale, and the required changes you might have to
 
 ### Deprecated `@storybook/testing-library` package
 
- The `@storybook/testing-library` package has been deprecated with the release of Storybook 8.0, and we recommend using the `@storybook/test` package instead. If you're migrating manually, you'll need to install the new package and update your imports as follows:
+The `@storybook/testing-library` package has been deprecated with the release of Storybook 8.0, and we recommend using the `@storybook/test` package instead. If you're migrating manually, you'll need to install the new package and update your imports as follows:
 
 ```diff
 - import { userEvent } from '@storybook/testing-library';

code/core/src/core-server/presets/common-preset.ts

@@ -278,16 +278,6 @@ export const resolvedReact = async (existing: any) => {
   }
 };
 
-/** Set up `dev-only`, `docs-only`, `test-only` tags out of the box */
-export const tags = async (existing: any) => {
-  return {
-    ...existing,
-    'dev-only': { excludeFromDocsStories: true },
-    'docs-only': { excludeFromSidebar: true },
-    'test-only': { excludeFromSidebar: true, excludeFromDocsStories: true },
-  };
-};
-
 export const managerEntries = async (existing: any) => {
   return [
     pathe.join(resolvePackageDir('storybook'), 'dist/core-server/presets/common-manager.js'),

code/core/src/manager/components/sidebar/TagsFilter.tsx

@@ -12,15 +12,7 @@ import { TagsFilterPanel } from './TagsFilterPanel';
 
 const TAGS_FILTER = 'tags-filter';
 
-const BUILT_IN_TAGS_HIDE = new Set([
-  'dev',
-  'docs-only',
-  'test-only',
-  'autodocs',
-  'test',
-  'attached-mdx',
-  'unattached-mdx',
-]);
+const BUILT_IN_TAGS_HIDE = new Set(['dev', 'autodocs', 'test', 'attached-mdx', 'unattached-mdx']);
 
 const Wrapper = styled.div({
   position: 'relative',

code/core/src/manager/components/sidebar/TagsFilterPanel.tsx

@@ -20,9 +20,6 @@ import type { Link } from '../../../components/components/tooltip/TooltipLinkLis
 const BUILT_IN_TAGS = new Set([
   'dev',
   'test',
-  'dev-only',
-  'test-only',
-  'docs-only',
   'autodocs',
   'attached-mdx',
   'unattached-mdx',

code/e2e-tests/tags.spec.ts

@@ -10,24 +10,6 @@ test.describe('tags', () => {
     await new SbPage(page, expect).waitUntilLoaded();
   });
 
-  test('should correctly filter dev-only, docs-only, test-only stories', async ({ page }) => {
-    const sbPage = new SbPage(page, expect);
-
-    await sbPage.navigateToStory('core/tags-config', 'docs');
-
-    // Sidebar should include dev-only and exclude docs-only and test-only
-    await expect(page.locator('#core-tags-config--dev-only')).toHaveCount(1);
-    await expect(page.locator('#core-tags-config--docs-only')).toHaveCount(0);
-    await expect(page.locator('#core-tags-config--test-only')).toHaveCount(0);
-
-    // Autodocs should include docs-only and exclude dev-only and test-only
-    const preview = sbPage.previewRoot();
-
-    await expect(preview.locator('#anchor--core-tags-config--dev-only')).toHaveCount(0);
-    await expect(preview.locator('#anchor--core-tags-config--docs-only')).toHaveCount(1);
-    await expect(preview.locator('#anchor--core-tags-config--test-only')).toHaveCount(0);
-  });
-
   test('should correctly add dev, autodocs, test stories', async ({ page }) => {
     const sbPage = new SbPage(page, expect);