fix(ui): Ensure cssLayerName from appearance is preserved during updateProps

[alexcarpenter]

Description

Fix cssLayerName from theme not being applied after initial mount. When ClerkProvider re-renders, the updateProps handler overwrote the extracted cssLayerName with the raw appearance object, causing Clerk's runtime CSS to not be wrapped in @layer. This broke Tailwind utility overrides when using themes like shadcn that set cssLayerName: 'components'.

Checklist

• pnpm test runs as expected.
• pnpm build runs as expected.
• (If applicable) JSDoc comments have been added or updated for any package exports
• (If applicable) Documentation has been updated

Type of change

• 🐛 Bug fix
• 🌟 New feature
• 🔨 Breaking change
• 📖 Refactoring / dependency upgrade / documentation
• other:

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Project	Deployment	Actions	Updated (UTC)
clerk-js-sandbox	Ready	Preview, Comment	May 6, 2026 6:38pm

[changeset-bot]

🦋 Changeset detected

Latest commit: a675237

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@clerk/ui	Patch
@clerk/chrome-extension	Patch

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository YAML (base), Organization UI (inherited)

Review profile: CHILL

Plan: Pro

Run ID: 6b73d146-9346-4888-8e64-8a488da2be31

📥 Commits

Reviewing files that changed from the base of the PR and between 556b0f6 and a675237.

📒 Files selected for processing (1)

• packages/ui/src/utils/__tests__/extractCssLayerNameFromAppearance.test.ts

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📝 Walkthrough

Walkthrough

This PR patches @clerk/ui to prevent losing cssLayerName during runtime prop updates. It adds normalization in updateProps to extract a cssLayerName from appearance (including theme arrays) and promote it to the appearance level before merging state. A new unit test file exercises extraction from single-theme and theme-array inputs, preserves explicit appearance-level values, and reproduces the original buggy merge versus the fixed merge behavior.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately and concisely describes the main fix: ensuring cssLayerName preservation during updateProps in the UI package.
Description check	✅ Passed	The description clearly explains the bug, root cause, and impact related to cssLayerName not being applied after initial mount during ClerkProvider re-renders.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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commit: a675237