Adding Clerk

Version: Check package.json for the SDK version — see clerk skill for the version table. Core 2 differences are noted inline with > **Core 2 ONLY (skip if current SDK):** callouts.

This skill sets up Clerk for authentication by following the official quickstart documentation. For agents, the clerk CLI handles most of this end to end — see the next section.

Agent-first: Provision via CLI

The clerk CLI replaces most Dashboard clicks. Three scenarios cover almost everything:

Scenario A — New project, new Clerk app

clerk init --framework <next|react|vue|nuxt|astro|react-router|tanstack-react-start|expressjs|fastify|expo> -y

clerk init creates the Clerk app via PLAPI, links the project, writes the framework-specific publishable + secret keys to the right env file (e.g. .env.local for Next.js, .env for Vite-based projects), and installs the SDK package.

Scenario B — Existing project, existing Clerk app

clerk auth login                      # one-time OAuth (skip if already logged in)
clerk link                            # autolinks if a CLERK_PUBLISHABLE_KEY is in your .env
clerk link --app app_xxx              # explicit form, required in agent mode
clerk env pull                        # writes the framework-detected env vars

Scenario C — Existing project, new Clerk app

clerk auth login
clerk apps create "My App" --json     # returns the new app_id
clerk link --app app_xxx
clerk env pull

Daily ops

clerk env pull                        # refresh keys (uses linked profile)
clerk env pull --instance prod        # production keys
clerk doctor --json                   # framework integration health check

Rotate the secret key (replaces Dashboard rotation)

PLAPI exposes secret-key rotation directly. Use raw clerk api until the friendly wrapper ships:

clerk api --platform POST /v1/platform/applications/<app_id>/rotate_secret_keys \
  -d '{"delay_old_secrets_expiration_hours": 24, "reason": "scheduled rotation"}'

delay_old_secrets_expiration_hours keeps the old key valid for the grace period so deploys can roll forward without downtime.

Notes for agents

• clerk link (no flags) only autolinks when a CLERK_PUBLISHABLE_KEY is already in .env / .env.local. Without it, agent mode errors out: "Cannot select an application in agent mode." When that happens, run clerk apps list --json, and ask the user which app_id to link rather than guessing.
• Pass --json on apps list/create, users create, and doctor for parseable output.
• The CLI auto-detects framework env var names (VITE_CLERK_PUBLISHABLE_KEY for Vite, NEXT_PUBLIC_CLERK_PUBLISHABLE_KEY for Next.js, etc.) and target file (.env.development.local > .env.local > .env).

Quick Reference (Dashboard fallback)

If the CLI isn't an option (sandboxed environments, docs walkthroughs), here's the manual Dashboard path:

Step	Action
1. Detect framework	Check package.json dependencies
2. Fetch quickstart	Use WebFetch on the appropriate docs URL
3. Follow instructions	Execute steps; create proxy.ts (Next.js <=15: middleware.ts)
4. Get API keys	From dashboard.clerk.com

If the project has components.json (shadcn/ui), apply the shadcn theme after setup. See clerk-custom-ui skill → shadcn Theme.

Framework Detection

Check package.json to identify the framework:

Dependency	Framework	Quickstart URL
next	Next.js	https://clerk.com/docs/nextjs/getting-started/quickstart
@remix-run/react	Remix (deprecated)	Migrate to React Router v7 — use the React Router quickstart below
react-router	React Router (v7+)	https://clerk.com/docs/react-router/getting-started/quickstart
astro	Astro	https://clerk.com/docs/astro/getting-started/quickstart
nuxt	Nuxt	https://clerk.com/docs/nuxt/getting-started/quickstart
@tanstack/react-start	TanStack Start	https://clerk.com/docs/tanstack-react-start/getting-started/quickstart
react (no framework)	React SPA	https://clerk.com/docs/react/getting-started/quickstart
vue	Vue	https://clerk.com/docs/vue/getting-started/quickstart
express	Express	https://clerk.com/docs/expressjs/getting-started/quickstart
fastify	Fastify	https://clerk.com/docs/fastify/getting-started/quickstart
expo	Expo	https://clerk.com/docs/expo/getting-started/quickstart

For other platforms:

• Chrome Extension: https://clerk.com/docs/chrome-extension/getting-started/quickstart
• Android: https://clerk.com/docs/android/getting-started/quickstart
• iOS: https://clerk.com/docs/ios/getting-started/quickstart
• Vanilla JavaScript: https://clerk.com/docs/js-frontend/getting-started/quickstart

Decision Tree

User Request: "Add Clerk" / "Add authentication"
    │
    ├─ Read package.json
    │
    ├─ Existing auth detected?
    │   ├─ YES → Audit → Migration plan
    │   └─ NO → Fresh install
    │
    ├─ Identify framework → WebFetch quickstart → Follow instructions
    │   └─ Next.js? → Create proxy.ts (Next.js <=15: middleware.ts)
    │
    └─ components.json exists? → YES → Apply shadcn theme (see clerk-custom-ui)

Setup Process

1. Detect the Framework

Read the project's package.json and match dependencies to the table above.

2. Fetch the Quickstart Guide

Use WebFetch to retrieve the official quickstart for the detected framework:

WebFetch: https://clerk.com/docs/{framework}/getting-started/quickstart
Prompt: "Extract the complete setup instructions including all code snippets, file paths, and configuration steps."

3. Follow the Instructions

Execute each step from the quickstart guide:

• Install the required packages
• Set up environment variables
• Add the provider and proxy/middleware
• Create sign-in/sign-up routes if needed
• Test the integration

Next.js: Create proxy.ts (Next.js <=15: middleware.ts). See the clerk-nextjs-patterns skill for middleware strategies.

shadcn/ui detected (components.json exists): ALWAYS apply the shadcn theme. See clerk-custom-ui skill → shadcn Theme section.

4. Get API Keys

Two paths for development API keys:

Keyless (Automatic)

• On first SDK initialization, Clerk auto-generates dev keys and shows a "Configure your application" button in the bottom right of the running app
• No manual key setup required, keys are created and injected automatically
• Selecting "Configure your application" associates the auto-generated app with your Clerk account so you can edit it from the Dashboard
• Simplest path for new projects

Manual (Dashboard)

• Get keys from dashboard.clerk.com if Keyless doesn't trigger
• Publishable Key: Starts with pk_test_ or pk_live_
• Secret Key: Starts with sk_test_ or sk_live_
• Set as environment variables: NEXT_PUBLIC_CLERK_PUBLISHABLE_KEY and CLERK_SECRET_KEY

Migrating from Another Auth Provider

If the project already has authentication, create a migration plan before replacing it.

Detect Existing Auth

Check package.json for existing auth libraries:

• next-auth / @auth/core → NextAuth/Auth.js
• @supabase/supabase-js → Supabase Auth
• firebase / firebase-admin → Firebase Auth
• @aws-amplify/auth → AWS Cognito
• auth0 / @auth0/nextjs-auth0 → Auth0
• passport → Passport.js
• Custom JWT/session implementation

Migration Process

1. Audit current auth - Identify all auth touchpoints:

   • Sign-in/sign-up pages
   • Session/token handling
   • Protected routes and middleware
   • User data storage (database tables, external IDs)
   • OAuth providers configured

2. Create migration plan - Consider:

   • User data export - Export users and import via Clerk's Backend API
   • Password hashes - Clerk can upgrade hashes to Bcrypt transparently
   • External IDs - Store legacy user IDs as external_id in Clerk
   • Session handling - Existing sessions will terminate on switch

3. Choose migration strategy:

   • Big bang - Switch all users at once (simpler, requires maintenance window)
   • Trickle migration - Run both systems temporarily (lower risk, higher complexity)

Migration Reference

• Migration Overview: https://clerk.com/docs/guides/development/migrating/overview

SDK Notes

Package Names

Package	Install
Next.js	@clerk/nextjs
React	@clerk/react
Expo	@clerk/expo
React Router	@clerk/react-router
TanStack Start	@clerk/tanstack-react-start

Core 2 ONLY (skip if current SDK): React and Expo packages have different names: @clerk/clerk-react and @clerk/clerk-expo (with clerk- prefix).

ClerkProvider Placement (Next.js)

ClerkProvider must be placed inside <body>, not wrapping <html>:

// root layout.tsx
export default function RootLayout({ children }) {
  return (
    <html>
      <body>
        <ClerkProvider>{children}</ClerkProvider>
      </body>
    </html>
  )
}

Core 2 ONLY (skip if current SDK): ClerkProvider can wrap <html> directly.

Dynamic Rendering (Next.js)

For dynamic rendering with auth data, use the dynamic prop:

<ClerkProvider dynamic>{children}</ClerkProvider>

Node.js Requirement

Requires Node.js 20.9.0 or higher.

Core 2 ONLY (skip if current SDK): Minimum Node.js 18.17.0.

Themes Package

Themes are installed from @clerk/ui:

npm install @clerk/ui

Core 2 ONLY (skip if current SDK): Themes are from @clerk/themes instead of @clerk/ui.

shadcn Theme

If the project uses shadcn/ui (check for components.json in the project root), apply the shadcn theme so Clerk components match the app's design system:

npm install @clerk/ui

import { shadcn } from '@clerk/ui/themes'

<ClerkProvider appearance={{ theme: shadcn }}>{children}</ClerkProvider>

Also import the shadcn CSS in your global styles:

@import 'tailwindcss';
@import '@clerk/ui/themes/shadcn.css';

Core 2 ONLY (skip if current SDK): Import from @clerk/themes and @clerk/themes/shadcn.css instead.

Common Pitfalls

Run clerk doctor first. It checks framework integration, env vars, middleware presence, and SDK install status. Fixes a lot of these in one shot.

Issue	Solution
Missing await on auth()	In Next.js 15+, auth() is async: const { userId } = await auth()
Exposing CLERK_SECRET_KEY	Never use the secret key in client code; only NEXT_PUBLIC_* keys are safe
Missing middleware matcher	Include API routes: `matcher: ['/((?!.\..
ClerkProvider placement	Must be inside <body> in root layout (Core 2: could wrap <html>)
Auth routes not public	Allow /sign-in, /sign-up in middleware config
Landing page requires auth	To keep "/" public, exclude it: `matcher: ['/((?!.\..
Wrong import path	Server code uses @clerk/nextjs/server, client uses @clerk/nextjs
Wrong package name	Use @clerk/react not @clerk/clerk-react (Core 2 naming)

See Also

• clerk-custom-ui - Custom sign-in/up components
• clerk-nextjs-patterns - Advanced Next.js patterns
• clerk-react-patterns - React SPA patterns
• clerk-react-router-patterns - React Router patterns
• clerk-vue-patterns - Vue patterns
• clerk-nuxt-patterns - Nuxt patterns
• clerk-astro-patterns - Astro patterns
• clerk-tanstack-patterns - TanStack Start patterns
• clerk-expo-patterns - Expo patterns
• clerk-chrome-extension-patterns - Chrome Extension patterns
• clerk-orgs - B2B multi-tenant organizations
• clerk-webhooks - Webhook → database sync
• clerk-testing - E2E testing setup
• clerk-swift - Native iOS auth
• clerk-android - Native Android auth
• clerk-backend-api - Backend REST API explorer

Documentation

• Quickstart Overview: https://clerk.com/docs/getting-started/quickstart/overview
• Migration Guide: https://clerk.com/docs/guides/development/migrating/overview
• Full Documentation: https://clerk.com/docs