clerk-tanstack-patterns

TanStack React Start auth patterns with @clerk/tanstack-react-start

npx skills add https://github.com/clerk/skills --skill clerk-tanstack-patterns

TanStack React Start Patterns

What Do You Need?

Task	Reference
Protect routes with beforeLoad	references/router-guards.md
Auth in createServerFn	references/server-functions.md
Pass auth to loaders	references/loaders.md
Configure Vite + Clerk middleware	references/server-setup.md

References

Reference	Description
`references/router-guards.md`	beforeLoad auth redirect
`references/server-functions.md`	createServerFn with auth()
`references/loaders.md`	Auth context in loaders
`references/server-setup.md`	Vite and request middleware setup

Setup

npm install @clerk/tanstack-react-start

.env:

VITE_CLERK_PUBLISHABLE_KEY=pk_...
CLERK_SECRET_KEY=sk_...

src/start.ts (request middleware):

import { clerkMiddleware } from '@clerk/tanstack-react-start/server'
import { createCsrfMiddleware, createStart } from '@tanstack/react-start'

const csrfMiddleware = createCsrfMiddleware({
  filter: (ctx) => ctx.handlerType === 'serverFn',
})

export const startInstance = createStart(() => {
  return {
    requestMiddleware: [csrfMiddleware, clerkMiddleware()],
  }
})

src/routes/__root.tsx — wrap with <ClerkProvider>:

import { ClerkProvider } from '@clerk/tanstack-react-start'

function RootDocument({ children }: { children: React.ReactNode }) {
  return (
    <html lang="en">
      <body>
        <ClerkProvider>{children}</ClerkProvider>
      </body>
    </html>
  )
}

Mental Model

TanStack Start uses the tanstackStart() Vite plugin. Register CSRF protection before Clerk request middleware in src/start.ts; auth then flows through two layers:

Server layer — createServerFn + auth() from @clerk/tanstack-react-start/server
Router layer — beforeLoad on route definitions, throws redirect for unauthenticated

Both layers are server-executed. Client hooks (useAuth, useUser) are React hooks for the browser side.

Minimal Pattern

import { createFileRoute, redirect } from '@tanstack/react-router'
import { createServerFn } from '@tanstack/react-start'
import { auth } from '@clerk/tanstack-react-start/server'

const authStateFn = createServerFn().handler(async () => {
  const { isAuthenticated, userId } = await auth()
  if (!isAuthenticated) {
    throw redirect({ to: '/sign-in' })
  }
  return { userId }
})

export const Route = createFileRoute('/dashboard')({
  beforeLoad: async () => await authStateFn(),
})

Common Pitfalls

Symptom	Cause	Fix
`auth()` throws "without configuring the middleware"	Missing `clerkMiddleware` in start.ts	Add it after CSRF middleware in `requestMiddleware`
`redirect` not thrown	Using `return` instead of `throw`	`throw redirect(...)` in TanStack
Wrong import for `auth`	Mixing client/server imports	Server: `@clerk/tanstack-react-start/server`
Loader context missing userId	Not passing from beforeLoad	Return from beforeLoad, access via `context`
`ClerkProvider` missing	Forgot root wrapping	Add to `__root.tsx` shell component