api-routes

## When to Use API Routes

Use API routes when you need:

- **Server-side secrets** — API keys, database credentials, or tokens that must never reach the client
- **Database operations** — Direct database queries that shouldn't be exposed
- **Third-party API proxies** — Hide API keys when calling external services (OpenAI, Stripe, etc.)
- **Server-side validation** — Validate data before database writes
- **Webhook endpoints** — Receive callbacks from services like Stripe or GitHub
- **Rate limiting** — Control access at the server level
- **Heavy computation** — Offload processing that would be slow on mobile

## When NOT to Use API Routes

Avoid API routes when:

- **Data is already public** — Use direct fetch to public APIs instead
- **No secrets required** — Static data or client-safe operations
- **Real-time updates needed** — Use WebSockets or services like Supabase Realtime
- **Simple CRUD** — Consider Firebase, Supabase, or Convex for managed backends
- **File uploads** — Use direct-to-storage uploads (S3 presigned URLs, Cloudflare R2)
- **Authentication only** — Use Clerk, Auth0, or Firebase Auth instead

## File Structure

API routes live in the `app` directory with `+api.ts` suffix:

```
app/
  api/
    hello+api.ts          → GET /api/hello
    users+api.ts          → /api/users
    users/[id]+api.ts     → /api/users/:id
  (tabs)/
    index.tsx
```

## Basic API Route

```ts
// app/api/hello+api.ts
export function GET(request: Request) {
  return Response.json({ message: "Hello from Expo!" });
}
```

## HTTP Methods

Export named functions for each HTTP method:

```ts
// app/api/items+api.ts
export function GET(request: Request) {
  return Response.json({ items: [] });
}

export async function POST(request: Request) {
  const body = await request.json();
  return Response.json({ created: body }, { status: 201 });
}

export async function PUT(request: Request) {
  const body = await request.json();
  return Response.json({ updated: body });
}

export asyn