Skip loading clerk-ui when headless variants are used #7570

nikosdouvlis · 2026-01-09T11:34:16Z

Description

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pnpm test runs as expected.
pnpm build runs as expected.
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(If applicable) Documentation has been updated

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Summary by CodeRabbit

New Features
- Added headless variant support across Next.js, Astro, React, and Vue, allowing configuration via environment variables to load only the Clerk JS core without the UI layer.
Tests
- Added integration test to verify headless variant behavior and script injection.

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why: when using clerkJSVariant='headless', applications only need control components and don't require the full UI bundle. loading the unnecessary @clerk/ui script adds overhead without providing value. what changed: - clerk-script.tsx: conditionally render clerk-ui script tag only when clerkJSVariant !== 'headless' - integration template: read NEXT_PUBLIC_CLERK_JS_VARIANT env var and pass to ClerkProvider users can now set NEXT_PUBLIC_CLERK_JS_VARIANT='headless' to skip loading the ~100KB @clerk/ui bundle when using only control components.

why: when using clerkJSVariant='headless', applications only need control components and don't require the full UI bundle. loading the unnecessary @clerk/ui script adds overhead without providing value. what changed: - build-clerk-hotload-script: skip generating clerk-ui script tag when clerkJsVariant === 'headless' - create-clerk-instance: getClerkUiEntryChunk returns undefined for headless variant to skip client-side hot-loading users can now set clerkJSVariant='headless' to skip loading the ~100KB @clerk/ui bundle when using only control components.

why: when using clerkJSVariant='headless', applications only need control components and don't require the full UI bundle. loading the unnecessary @clerk/ui script adds overhead without providing value. what changed: isomorphicClerk's getClerkUiEntryChunk method now returns undefined when clerkJSVariant === 'headless', skipping the loadClerkUiScript call entirely. users can now set clerkJSVariant='headless' to skip loading the ~100KB @clerk/ui bundle when using only control components.

why: when using clerkJSVariant='headless', applications only need control components and don't require the full UI bundle. loading the unnecessary @clerk/ui script adds overhead without providing value. what changed: clerkPlugin now checks if clerkJSVariant === 'headless' and skips the loadClerkUiScript call, resolving the clerkUiCtorPromise to undefined instead. users can now set clerkJSVariant='headless' to skip loading the ~100KB @clerk/ui bundle when using only control components.

why: verify that the headless variant correctly skips clerk-ui script injection across the full integration stack (env var → prop → script rendering). what changed: created headless-variant.test.ts that sets CLERK_JS_VARIANT='headless' and asserts clerk-ui script is absent while clerk-js script is present.

changeset-bot · 2026-01-09T11:34:21Z

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vercel · 2026-01-09T11:34:21Z

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Project	Deployment	Review	Updated (UTC)
clerk-js-sandbox	Ready	Preview, Comment	Jan 9, 2026 11:34am

pkg-pr-new · 2026-01-09T11:37:25Z

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commit: a2e16cd

coderabbitai · 2026-01-09T11:37:31Z

📝 Walkthrough

Walkthrough

This pull request introduces support for a headless variant of Clerk JS across multiple frameworks and packages. The changes add conditional logic to skip loading the Clerk UI layer when clerkJSVariant is set to 'headless', allowing only the core Clerk JS library to be loaded. Updates span Next.js, Astro, React, and Vue packages, modifying script generation and component initialization to respect the headless variant flag. A new integration test verifies that the Clerk JS script is injected while the Clerk UI script is not injected when the headless variant is enabled. The change maintains backward compatibility by preserving existing behavior when the headless variant is not specified.

🚥 Pre-merge checks | ✅ 2 | ❌ 1

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Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 25.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
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Title check	✅ Passed	The title 'Skip loading clerk-ui when headless variants are used' directly and accurately summarizes the main objective of the PR, which is to conditionally avoid loading the @clerk/ui bundle when the headless variant is enabled across multiple framework integrations.

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📒 Files selected for processing (7)

integration/templates/next-app-router/src/app/layout.tsx
integration/tests/headless-variant.test.ts
packages/astro/src/internal/create-clerk-instance.ts
packages/astro/src/server/build-clerk-hotload-script.ts
packages/nextjs/src/utils/clerk-script.tsx
packages/react/src/isomorphicClerk.ts
packages/vue/src/plugin.ts

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packages/astro/src/server/build-clerk-hotload-script.ts
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packages/react/src/isomorphicClerk.ts
integration/tests/headless-variant.test.ts
integration/templates/next-app-router/src/app/layout.tsx
packages/nextjs/src/utils/clerk-script.tsx

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packages/vue/src/plugin.ts
packages/astro/src/server/build-clerk-hotload-script.ts
packages/astro/src/internal/create-clerk-instance.ts
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packages/vue/src/plugin.ts
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integration/tests/headless-variant.test.ts
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integration/templates/next-app-router/src/app/layout.tsx
packages/nextjs/src/utils/clerk-script.tsx

🧬 Code graph analysis (3)

packages/astro/src/server/build-clerk-hotload-script.ts (1)

packages/astro/src/server/get-safe-env.ts (1)

getSafeEnv (61-61)

packages/react/src/isomorphicClerk.ts (1)

packages/shared/src/ui/types.ts (1)

ClerkUiConstructor (33-41)

integration/tests/headless-variant.test.ts (2)

integration/models/application.ts (1)

Application (10-10)

integration/presets/index.ts (1)

appConfigs (14-30)

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🔇 Additional comments (2)

integration/templates/next-app-router/src/app/layout.tsx (1)

15-15: LGTM!

The conditional prop correctly reads the Next.js environment variable and maps the headless variant appropriately.

packages/react/src/isomorphicClerk.ts (1)

511-515: LGTM!

The early return for headless variant correctly prevents loading the Clerk UI bundle while preserving the core authentication functionality. The return type is properly updated to reflect the optional nature of the UI constructor.

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nikosdouvlis added 5 commits January 9, 2026 13:15

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Skip loading clerk-ui when headless variants are used #7570

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