feat(nextjs): throw missing-env error instead of keyless bootstrap

[djgould]

Description

Experiment: promote the CLI keyless flow over SDK keyless mode.

In development, when NEXT_PUBLIC_CLERK_PUBLISHABLE_KEY / CLERK_SECRET_KEY are missing, @clerk/nextjs no longer provisions a keyless application. All three bootstrap entry points (app-router server ClerkProvider, clerkMiddleware, createOrReadKeylessAction) now throw:

Clerk: Missing environment variables (NEXT_PUBLIC_CLERK_PUBLISHABLE_KEY and CLERK_SECRET_KEY).

To set up Clerk for this project, run:

  npx clerk@latest init

The error surfaces in both the dev server log and the dev error page. Configured keys, claimed keys, and production behavior are unchanged.

To test: run an app-router app with no Clerk env vars and hit any route.

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: experiment / RFC

🤖 Generated with Claude Code

[changeset-bot]

🦋 Changeset detected

Latest commit: a4ff714

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

This PR includes changesets to release 10 packages

Name	Type
@clerk/backend	Patch
@clerk/nextjs	Minor
@clerk/astro	Patch
@clerk/express	Patch
@clerk/fastify	Patch
@clerk/hono	Patch
@clerk/nuxt	Patch
@clerk/react-router	Patch
@clerk/tanstack-react-start	Patch
@clerk/testing	Patch

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Project	Deployment	Actions	Updated (UTC)
swingset	Ready	Preview	Aug 18, 2026 5:06pm

1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
clerk-js-sandbox	Skipped		Aug 18, 2026 5:06pm

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commit: a4ff714

[djgould]

Superseded by #9484 — restacked fresh off main as part 1 of the keyless→CLI stack (#9484 → #9485 → #9486).