Clerk Sdk Patterns

---
name: clerk-sdk-patterns
description: |
  Common Clerk SDK patterns and best practices.
  Use when implementing authentication flows, accessing user data,
  or integrating Clerk SDK methods in your application.
  Trigger with phrases like "clerk SDK", "clerk patterns",
  "clerk best practices", "clerk API usage".
allowed-tools: Read, Write, Edit, Grep
version: 1.0.0
license: MIT
author: Jeremy Longshore <jeremy@intentsolutions.io>
---

# Clerk SDK Patterns

## Overview
Learn common patterns and best practices for using the Clerk SDK effectively.

## Prerequisites
- Clerk SDK installed and configured
- Basic understanding of React/Next.js
- ClerkProvider wrapping application

## Instructions

### Pattern 1: Server-Side Authentication
```typescript
// app/api/protected/route.ts
import { auth, currentUser } from '@clerk/nextjs/server'

export async function GET() {
  // Quick auth check
  const { userId, sessionId, orgId } = await auth()

  if (!userId) {
    return Response.json({ error: 'Unauthorized' }, { status: 401 })
  }

  // Full user data when needed
  const user = await currentUser()

  return Response.json({
    userId,
    sessionId,
    orgId,
    email: user?.primaryEmailAddress?.emailAddress
  })
}
```

### Pattern 2: Client-Side Hooks
```typescript
'use client'
import { useUser, useAuth, useClerk, useSession } from '@clerk/nextjs'

export function AuthenticatedComponent() {
  // User data and loading state
  const { user, isLoaded, isSignedIn } = useUser()

  // Auth utilities
  const { userId, getToken, signOut } = useAuth()

  // Full Clerk instance
  const clerk = useClerk()

  // Session info
  const { session } = useSession()

  // Get JWT token for API calls
  const callExternalAPI = async () => {
    const token = await getToken({ template: 'supabase' }) // or custom template
    const res = await fetch('https://api.example.com', {
      headers: { Authorization: `Bearer ${token}` }
    })
  }

  if (!isLoaded) return <div>Loading...</div>
  if (!isSignedIn) return <div>Please sign in</div>

  return <div>Welcome, {user.firstName}</div>
}
```

### Pattern 3: Protected Routes with Middleware
```typescript
// middleware.ts
import { clerkMiddleware, createRouteMatcher } from '@clerk/nextjs/server'

const isPublicRoute = createRouteMatcher([
  '/',
  '/sign-in(.*)',
  '/sign-up(.*)',
  '/api/webhooks(.*)'
])

const isProtectedRoute = createRouteMatcher([
  '/dashboard(.*)',
  '/api/protected(.*)'
])

export default clerkMiddleware(async (auth, request) => {
  if (isProtectedRoute(request)) {
    await auth.protect()
  }
})

export const config = {
  matcher: ['/((?!.*\\..*|_next).*)', '/', '/(api|trpc)(.*)']
}
```

### Pattern 4: Organization-Aware Queries
```typescript
import { auth } from '@clerk/nextjs/server'

export async function GET() {
  const { userId, orgId, orgRole } = await auth()

  // Check organization membership
  if (!orgId) {
    return Response.json({ error: 'No organization selected' }, { status: 400 })
  }

  // Check role-based access
  if (orgRole !== 'org:admin') {
    return Response.json({ error: 'Admin access required' }, { status: 403 })
  }

  // Query with organization scope
  const data = await db.query.resources.findMany({
    where: eq(resources.organizationId, orgId)
  })

  return Response.json(data)
}
```

### Pattern 5: Custom JWT Templates
```typescript
// Use custom JWT claims for external services
const { getToken } = useAuth()

// Standard Clerk token
const clerkToken = await getToken()

// Custom template for Supabase
const supabaseToken = await getToken({ template: 'supabase' })

// Custom template for Hasura
const hasuraToken = await getToken({ template: 'hasura' })
```

## Output
- Server and client authentication patterns
- Protected route middleware
- Organization-aware queries
- Custom JWT tokens for integrations

## Error Handling
| Error | Cause | Solution |
|-------|-------|----------|
| auth() returns null | Not in server context | Use in Server Components or API routes |
| useUser() not updating | Component not re-rendering | Check ClerkProvider placement |
| getToken() fails | Template not configured | Configure JWT template in dashboard |
| orgId is null | No organization selected | Prompt user to select organization |

## Examples

### Complete Protected Page Pattern
```typescript
// app/dashboard/page.tsx
import { auth, currentUser } from '@clerk/nextjs/server'
import { redirect } from 'next/navigation'

export default async function DashboardPage() {
  const { userId } = await auth()

  if (!userId) {
    redirect('/sign-in')
  }

  const user = await currentUser()

  return (
    <main>
      <h1>Dashboard</h1>
      <UserProfile user={user} />
      <DashboardContent userId={userId} />
    </main>
  )
}
```

### Typed User Metadata
```typescript
// types/clerk.d.ts
interface UserPublicMetadata {
  tier: 'free' | 'pro' | 'enterprise'
  onboarded: boolean
}

interface UserPrivateMetadata {
  stripeCustomerId?: string
}

// Usage
const user = await currentUser()
const tier = user?.publicMetadata?.tier ?? 'free'
```

## Resources
- [Clerk SDK Reference](https://clerk.com/docs/references/nextjs/overview)
- [Authentication Patterns](https://clerk.com/docs/references/nextjs/auth)
- [JWT Templates](https://clerk.com/docs/backend-requests/making/jwt-templates)

## Next Steps
Proceed to `clerk-core-workflow-a` for user sign-up and sign-in flows.