CLI: Remove deprecated componentSubtitle

[valentinpalkovic]

Closes #

What I did

parameters.componentSubtitle has been deprecated for a while, and the Subtitle block still fell back to it.
Storybook 11 removes that fallback.
A new component-subtitle automigration moves the value to parameters.docs.subtitle, in the preview and in story metas.

This is a real run on twentyhq/twenty's twenty-ui Storybook (1 main.ts, 1 preview.tsx, 105 story files), with componentSubtitle added to four metas, one of them built from a spread:

 const meta: Meta<typeof ButtonGroup> = {
-  parameters: { componentSubtitle: 'Injected subtitle' },
+  parameters: {
+    docs: {
+      subtitle: 'Injected subtitle',
+    },
+  },
   title: 'UI/Input/Button/ButtonGroup',

What changes for users:

• parameters.componentSubtitle no longer renders a subtitle, and its deprecation warning is gone.
• A docs.subtitle in the preview used to win over a componentSubtitle in a meta. After the migration the meta value wins, like any other parameter. MIGRATION.md asks users with a preview-level docs.subtitle to check their Docs pages.
• A componentSubtitle on a single story stays where it is, since the block never read it there.

Checklist for Contributors

Testing

The changes in this PR are covered in the following automated tests:

• stories
• unit tests
• integration tests
• end-to-end tests

Manual testing

Caution

This section is mandatory for all contributions. If you believe no manual test is necessary, please state so explicitly. Thanks!

1. Generate a sandbox: yarn task sandbox --template react-vite/default-ts --start-from auto.
2. In the sandbox, add parameters: { componentSubtitle: 'Legacy' } to the default export of .storybook/preview.ts and to the meta of one story file.
3. In a second story file's meta, add parameters: { ...shared, componentSubtitle: 'Unsafe' }, where shared is imported from another module.
4. Run npx storybook automigrate component-subtitle.
   Confirm that the preview and the first story file now use parameters.docs.subtitle, that the second story file is unchanged, and that the command reports 1 file that could not be migrated and points to automigrations-summary.md.
5. Open automigrations-summary.md in the project root and confirm it lists the second story file under component-subtitle.
6. Replace the spread in the second story file with parameters: { componentSubtitle: 'Fixed' } and run the command again.
   Confirm the second story file now uses parameters.docs.subtitle, automigrations-summary.md is gone, and the subtitles render on the Docs pages.

Documentation

• Add or update documentation reflecting your changes
• If you are deprecating/removing a feature, make sure to update
  MIGRATION.MD

Checklist for Maintainers

• When this PR is ready for testing, make sure to add ci:normal, ci:merged or ci:daily GH label to it to run a specific set of sandboxes. The particular set of sandboxes can be found in code/lib/cli-storybook/src/sandbox-templates.ts

• Declare whether manual QA will be needed for this PR during the next release, through qa:needed or qa:skip

• Make sure this PR contains one of the labels below:

  Available labels

  • bug: Internal changes that fixes incorrect behavior.
  • maintenance: User-facing maintenance tasks.
  • dependencies: Upgrading (sometimes downgrading) dependencies.
  • build: Internal-facing build tooling & test updates. Will not show up in release changelog.
  • cleanup: Minor cleanup style change. Will not show up in release changelog.
  • documentation: Documentation only changes. Will not show up in release changelog.
  • feature request: Introducing a new feature.
  • BREAKING CHANGE: Changes that break compatibility in some way with current major version.
  • other: Changes that don't fit in the above categories.

🦋 Canary release

This PR does not have a canary release associated. You can request a canary release of this pull request by mentioning the @storybookjs/core team here.

core team members can create a canary release here or locally with gh workflow run --repo storybookjs/storybook publish.yml --field pr=<PR_NUMBER>

🤖 Generated with Claude Code

[github-actions]

	Fails
🚫	PR is not labeled with one of: ["qa:needed","qa:skip","qa:success"]

	Warnings
⚠️	This PR targets refactor/automigrate-fix-files. The default branch for contributions is next. Please make sure you are targeting the correct branch.

Generated by 🚫 dangerJS against 3a8a33e

[storybook-app-bot]

Package Benchmarks

^{Commit: 3a8a33e, ran on 29 September 2026 at 09:58:57 UTC}

No significant changes detected, all good. 👏

[valentinpalkovic]

@copilot rebase and resolve conflicts

[Copilot]

@copilot rebase and resolve conflicts

Merged origin/next into the branch and resolved the conflicts in merge commit 153fc6aabbf.

[valentinpalkovic]

CSF mutation adoption pushed at 2b798ef7b32a6a809e86adfeeff62d46ab3b2732.

• Stacked on CSF: Add shared mutation API for stories and config files #36248 with a normal merge; no force-push.
• Story-file mutations now use CsfFile.objects() and its formatting-preserving move, transform, and remove operations for meta, CSF2 annotations, and CSF4 stories. Preview-config precedence policy remains in this migration.
• Added CSF2 and CSF4 regression coverage.
• Verified: vitest run --config code/lib/cli-storybook/vitest.config.ts ...component-subtitle.test.ts ...component-subtitle-run.test.ts — 37 passed; nx check cli passed; focused oxlint passed.

[valentinpalkovic]

@copilot resolve the merge conflicts in this pull request

[Copilot]

@copilot resolve the merge conflicts in this pull request

Resolved the merge conflicts with origin/next in merge commit 4b11ae43fd3. Focused component subtitle tests pass (45 tests).

[valentinpalkovic]

[AUTOMATED MESSAGE]

Component-subtitle migration: PASS for exact head 4b11ae43fd3c1edf1ad543d290a3b9931b716c10.

Both repositories upgraded through Storybook 9 and 10 to PR-built Storybook 11 packages with storybook@11.0.0-alpha.0 upgrade --yes --force --config-dir .storybook.

• fintraffic-design/fds-coreui-components: moved 14 componentSubtitle values to parameters.docs.subtitle. Headless Chromium rendered the migrated subtitle at desktop and mobile sizes; the popover interaction showed “Popover content.”
• excaliburjs/Excalibur: moved two subtitle values to parameters.docs.subtitle. Headless Chromium rendered the pointer-events story at desktop and mobile sizes; hover, pointer-down, and pointer-up produced distinct canvas states. Its config has no autodocs entry, so the subtitle was source-verified while the affected story was runtime-verified.

In both repositories, the installed runtime reported 11.0.0-alpha.0, no legacy subtitle keys remained, git diff --check passed, and a second automigrate component-subtitle found no applicable migration. The PR head still matched after verification.