Clerk Setup Agent Skill

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.

Quick Reference

| 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 | https://clerk.com/docs/remix/getting-started/quickstart |

| astro | Astro | https://clerk.com/docs/astro/getting-started/quickstart |

| nuxt | Nuxt | https://clerk.com/docs/nuxt/getting-started/quickstart |

| react-router | React Router | https://clerk.com/docs/react-router/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 "Claim your application" popover
• No manual key setup required—keys are created and injected automatically
• 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

• 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

• 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

• 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

| Level | Issue | Solution |

|-------|-------|----------|

| CRITICAL | Missing await on auth() | In Next.js 15+, auth() is async: const { userId } = await auth() |

| CRITICAL | Exposing CLERK_SECRET_KEY | Never use secret key in client code; only NEXT_PUBLIC_* keys are safe |

| HIGH | Missing middleware matcher | Include API routes: matcher: ['/((?!.*\\..*|_next).*)', '/'] |

| HIGH | ClerkProvider placement | Must be inside <body> in root layout (Core 2: could wrap <html>) |

| HIGH | Auth routes not public | Allow /sign-in, /sign-up in middleware config |

| HIGH | Landing page requires auth | To keep "/" public, exclude it: matcher: ['/((?!.*\\..*|_next|^/$).*)', '/api/(.*)'] |

| MEDIUM | Wrong import path | Server code uses @clerk/nextjs/server, client uses @clerk/nextjs |

| MEDIUM | 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