1. Fetch README (BLOCKING)
   ├── Extract package name from install command
   └── README is source of truth for ALL code patterns

2. Detect directory structure
   ├── src/ (TanStack Start v1.132+, default)
   └── app/ (legacy vinxi-based projects)

3. Follow README install/setup exactly
   └── Do not invent commands or patterns

src/
├── start.ts              # Middleware config (CRITICAL)
├── router.tsx            # Router setup
├── routes/
│   ├── __root.tsx        # Root layout
│   ├── api.auth.callback.tsx  # OAuth callback (flat route)
│   └── ...

app/
├── start.ts or router.tsx
├── routes/
│   └── api/auth/callback.tsx  # OAuth callback (nested route)

ls src/routes 2>/dev/null && echo "Modern (src/)" || echo "Legacy (app/)"

import { authkitMiddleware } from '@workos/authkit-tanstack-react-start';

export default {
  requestMiddleware: [authkitMiddleware()],
};

import { createStart } from '@tanstack/react-start';
import { authkitMiddleware } from '@workos/authkit-tanstack-react-start';

export default createStart({
  requestMiddleware: [authkitMiddleware()],
});

import { createFileRoute } from '@tanstack/react-router';
import { handleCallbackRoute } from '@workos/authkit-tanstack-react-start';

export const Route = createFileRoute('/api/auth/callback')({
  server: {
    handlers: {
      GET: handleCallbackRoute(),
    },
  },
});

import { createFileRoute, redirect } from '@tanstack/react-router';
import { getAuth, getSignInUrl } from '@workos/authkit-tanstack-react-start';

export const Route = createFileRoute('/dashboard')({
  loader: async () => {
    const { user } = await getAuth();
    if (!user) {
      const signInUrl = await getSignInUrl();
      throw redirect({ href: signInUrl });
    }
    return { user };
  },
  component: Dashboard,
});

import { createFileRoute, redirect } from '@tanstack/react-router';
import { signOut } from '@workos/authkit-tanstack-react-start';

export const Route = createFileRoute('/signout')({
  loader: async () => {
    await signOut();
    throw redirect({ href: '/' });
  },
});

// src/routes/__root.tsx
import { AuthKitProvider } from '@workos/authkit-tanstack-react-start/client';

function RootComponent() {
  return (
    <AuthKitProvider>
      <Outlet />
    </AuthKitProvider>
  );
}

import { useAuth } from '@workos/authkit-tanstack-react-start/client';

function Profile() {
  const { user, isLoading } = useAuth();
  // ...
}