Build: Exempt @tailwindcss/turbopack from the sandbox age gate

[valentinpalkovic]

What I did

The Next.js prerelease sandbox does not generate at the moment. Sandbox generation applies a 7 day npm age gate, and create-next-app --tailwind pulls in @tailwindcss/turbopack, a package so new that ^4 has only ever matched a single release. That one release is inside the window, so the range has no installable version at all and the whole template dies:

❌ Failed to refresh Yarn 4 lockfile for prerelease template: Next.js Prerelease (Webpack | TypeScript)
   ➤ YN0016: @tailwindcss/turbopack@npm:^4: All versions satisfying "^4" are quarantined

Normally the generator works around that by narrowing the range to the newest release that clears the gate, inside the same major. Here there is nothing to narrow to, so it correctly refuses rather than dragging the template onto a different major. The only remaining lever is to let that one package past the gate:

-    minAgeGateExemptions: ['next', '@next/*', 'eslint-config-next'],
+    minAgeGateExemptions: ['next', '@next/*', 'eslint-config-next', '@tailwindcss/turbopack'],

The gate still applies to everything else in the template, and the canary line is unaffected. Generating it now succeeds with no ranges rewritten at all:

✅ Generated Next.js Prerelease (Webpack | TypeScript) (nextjs/prerelease) in 22 s

dependency	range after generation	resolved
next	16.3.1-canary.4	16.3.1-canary.4
eslint-config-next	16.3.1-canary.4	—
@tailwindcss/turbopack	^4 (untouched)	4.3.3
typescript	^5	—

One caveat worth stating plainly: this is a permanent entry for what is really a temporary condition. @tailwindcss/turbopack@4.3.3 was published on 2026-07-31, so it clears the 7 day window on its own on 2026-08-07, and once 4.x has a second release the range will always have an older candidate to fall back on. I would rather unblock generation now than wait a day for it, but the entry should come out again once that package has some history, and I noted that where it is declared.

Only one exemption was needed, by the way. I checked whether the rest of the family gets pulled in transitively, and it does not, so there is no reason to reach for a @tailwindcss/* glob here.

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

This is one entry in a template's config. There is no logic to unit test, and asserting the array contents back would just restate the change. The nightly sandbox generation is what actually exercises it.

Manual testing

command	what it does	run from
yarn generate-sandboxes --templates nextjs/prerelease	regenerates the affected sandbox	code/
yarn build-storybook --quiet	builds it	repros/nextjs/prerelease/after-storybook

1. Reproduce the failure on next first, so the change has something to prove:
   cd code && yarn generate-sandboxes --templates nextjs/prerelease
   It fails with All versions satisfying "^4" are quarantined for @tailwindcss/turbopack.
2. Switch to this branch and run the same command. It must print ✅ Generated Next.js Prerelease.
3. Check repros/nextjs/prerelease/before-storybook/package.json still tracks the canary: next and eslint-config-next on a -canary.N version, and @tailwindcss/turbopack still ^4 rather than a rewritten range.
4. Confirm the gate is still on for the rest of the template: repros/nextjs/prerelease/before-storybook/.yarnrc.yml must still contain npmMinimalAgeGate: 10080, with the four names under npmPreapprovedPackages.
5. Build it: cd repros/nextjs/prerelease/after-storybook && yarn build-storybook --quiet. Exit code must be 0.

Note

After 2026-08-07 step 1 will no longer reproduce, because the blocking release ages out of the window. That is expected, and is the same reason this entry should eventually be removed.

Documentation

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

Sandbox template config only, so there is nothing user facing to document.

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>

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• code/lib/cli-storybook/src/sandbox-templates.ts

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Walkthrough

The Next.js prerelease sandbox template now exempts @tailwindcss/turbopack from the minimum-age gate. Comments document the package-specific prerelease behavior.

Changes

Next.js prerelease template

Layer / File(s)	Summary
Tailwind Turbopack age-gate exemption code/lib/cli-storybook/src/sandbox-templates.ts	The template adds @tailwindcss/turbopack to minAgeGateExemptions and documents its Tailwind-driven prerelease gating behavior.

Possibly related PRs

• storybookjs/storybook#34852: Extends the same prerelease template exemption list.
• storybookjs/storybook#35770: Adds package-specific age-gate exemptions in the same file.
• storybookjs/storybook#35771: Updates framework-specific sandbox age-gate exemptions in the same file.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

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