Resend

# Resend Email API Emulator

Fully stateful Resend API emulation. Emails, domains, API keys, audiences, and contacts persist in memory. Sent emails are captured and viewable through the inbox UI or the REST API.

No real emails are sent. Every call to `POST /emails` stores the message locally so you can inspect it programmatically or in the browser.

## Start

```bash
# Resend only
npx emulate --service resend

# Default port (when run alone)
# http://localhost:4000
```

Or programmatically:

```typescript
import { createEmulator } from 'emulate'

const resend = await createEmulator({ service: 'resend', port: 4000 })
// resend.url === 'http://localhost:4000'
```

## Auth

Pass tokens as `Authorization: Bearer <token>`. Any `re_` prefixed token is accepted.

```bash
curl http://localhost:4000/emails \
  -H "Authorization: Bearer re_test_key"
```

When no token is provided, requests fall back to the default user.

## Pointing Your App at the Emulator

### Environment Variable (Resend SDK)

The official Resend Node.js SDK reads `RESEND_BASE_URL` at module load time. Set it to the emulator URL and the SDK works without any code changes:

```bash
RESEND_BASE_URL=http://localhost:4000
```

```typescript
import { Resend } from 'resend'

// No baseUrl argument needed; the SDK reads RESEND_BASE_URL automatically.
const resend = new Resend('re_test_key')

await resend.emails.send({
  from: 'hello@example.com',
  to: 'user@example.com',
  subject: 'Hello',
  html: '<p>It works!</p>',
})
```

### Embedded in Next.js (adapter-next)

When using `@emulators/adapter-next`, the emulator runs inside your Next.js app at `/emulate/resend`. Set `RESEND_BASE_URL` via `next.config.ts`:

```typescript
// next.config.ts
import { withEmulate } from '@emulators/adapter-next'

export default withEmulate({
  env: {
    RESEND_BASE_URL: `http://localhost:${process.env.PORT ?? '3000'}/emulate/resend`,
  },
})
```

```typescript
// app/emulate/[...path]/route.ts
import { createEmulateHandler } from '@emulators/adapter-next'
import * as resend from '@emulators/resend'

export const { GET, POST, PUT, PATCH, DELETE } = createEmulateHandler({
  services: {
    resend: {
      emulator: resend,
      seed: {
        domains: [{ name: 'example.com' }],
      },
    },
  },
})
```

### Direct fetch

If you cannot use the SDK or env var, call the emulator directly:

```typescript
await fetch('http://localhost:4000/emails', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
    'Authorization': 'Bearer re_test_key',
  },
  body: JSON.stringify({
    from: 'hello@example.com',
    to: 'user@example.com',
    subject: 'Hello',
    html: '<p>It works!</p>',
  }),
})
```

## Seed Config

```yaml
resend:
  domains:
    - name: example.com
      region: us-east-1
  contacts:
    - email: test@example.com
      first_name: Test
      last_name: User
      audience: Default
```

## Retrieving Sent Emails

This is the key differentiator of the emulator: every email sent via `POST /emails` is stored and queryable.

### Inbox UI

Browse sent emails in the browser:

```
http://localhost:4000/inbox
```

### REST API

```bash
# List all sent emails
curl http://localhost:4000/emails \
  -H "Authorization: Bearer re_test_key"

# Get a single email by ID
curl http://localhost:4000/emails/<id> \
  -H "Authorization: Bearer re_test_key"
```

### Extracting Data from Emails (tes