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TanStack React Start auth patterns with @clerk/tanstack-react-start - createServerFn, beforeLoad guards, loaders, Vinxi server. Triggers on: TanStack auth,…
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 Vinxi + clerkMiddleware
references/vinxi-server.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/vinxi-server.md
clerkMiddleware() setup
Setup
npm install @clerk/tanstack-react-start
.env:
CLERK_PUBLISHABLE_KEY=pk_...
CLERK_SECRET_KEY=sk_...
src/start.ts (Vinxi entry):
import { clerkMiddleware } from '@clerk/tanstack-react-start/server'
import { createStart } from '@tanstack/react-start'
export const startInstance = createStart(() => {
return {
requestMiddleware: [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 runs on Vinxi. Auth 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() returns empty
Missing clerkMiddleware in start.ts
Add to requestMiddleware array
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
See Also
clerk-setup - Initial Clerk install
clerk-custom-ui - Custom flows & appearance
clerk-orgs - B2B organizations
Docs
TanStack React Start SDK
1f:["$don't have the plugin yet? install it then click "run inline in claude" again.