The `@authdog/tanstack-start` SDK provides a callback loader, HttpOnly cookie handling, and a small React URL-cleanup provider.

## Install

```package-install
@authdog/tanstack-start
```

Requires `@tanstack/react-start ^1` and React 18 or 19. Set `PK_AUTHDOG` (your environment's public key, `pk_...`) on the server.

## Wrap the app

Wrap the root component with `AuthdogProvider`. When `?token=` is present, it removes the parameter and reloads. It does not validate or persist the token, so the server loader must process the original request first:

```tsx
import { AuthdogProvider } from "@authdog/tanstack-start/client"

function RootLayout({ children }: { children: React.ReactNode }) {
  return <AuthdogProvider>{children}</AuthdogProvider>
}
```

## Handle the callback on the server

`identityLoader()` accepts a standard `Request` and returns a standard `Response`. It validates callback and cookie credentials through Authdog userinfo. Return its `Response` unchanged from the server route that receives the hosted sign-in redirect:

```ts
import { identityLoader } from "@authdog/tanstack-start"

const loadIdentity = identityLoader()

export async function handleAuthdogRequest(request: Request): Promise<Response> {
  return loadIdentity({ request })
}
```

Wire `handleAuthdogRequest` into a TanStack Start server route matched by the callback URL. Do not call `response.json()` and return only its body: that drops the two `Set-Cookie` headers. The loader reports `{ user, isAuthenticated, signinUri }`; it does not redirect or deny access, so protected handlers must check `isAuthenticated` and apply [authorization](/docs/concepts/authorization).

## Sign out

`logoutLoader` is a server loader and returns a 302 `Response` that clears the session cookies. Return it unchanged from a server route:

```ts
import { logoutLoader } from "@authdog/tanstack-start"
export const logout = logoutLoader
```

`AuthdogProvider` is presentational callback cleanup, not an authentication provider or route guard.

## Next steps

- [Component reference](/docs/components): the `@authdog/react-elements` UI.
- [Backend requests](/docs/backend): the verification model, in depth.
- [Quickstarts](/docs/quickstarts): the five-minute path.