Clerk Tanstack Patterns Agent Skill

TanStack React Start auth patterns with @clerk/tanstack-react-start auth, createServerFn clerk, beforeLoad protection, TanStack Start middleware.'

5k tokens

context cost

the whole folder, loaded on every use

files

ships runnable scripts

copies elsewhere

how many repositories repackaged it

stars on the repo

on the repository, not the skill itself

Install

one command, takes just this skill from the repository

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

What comes with it

15 966 bytes besides the instruction

evals/evals.json

references/loaders.md

references/router-guards.md

references/server-functions.md

references/vinxi-server.md

templates/tanstack-basic-auth/package.json

templates/tanstack-basic-auth/src/router.tsx

templates/tanstack-basic-auth/src/routes/__root.tsx

templates/tanstack-basic-auth/src/routes/index.tsx

templates/tanstack-basic-auth/src/start.ts

templates/tanstack-basic-auth/tsconfig.json

templates/tanstack-basic-auth/vite.config.ts

What it tells the agent to use

found in the instruction text

WebFetch fetches pages from the network

The instruction itself

9 sections, as written by the author

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 |

Docs

TanStack React Start SDK

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How to use it

Copy the folder

Take clerk/clerk-tanstack-patterns from the repository into ~/.claude/skills for personal use, or into .claude/skills inside a project.

Check the name does not clash

The agent identifies a skill by the name field in its header. Two skills with the same name cannot sit side by side — one of them will be ignored.

Install what it needs

The instructions reference npm. Without those the skill loads but fails at the first command.