CORRECT (Payload v3 pattern):

handler: async (req) => {
  const data = await req.json()
  return Response.json({ success: true }, { status: 200 })
}

Alternative using helper:

import { addDataAndFileToRequest } from 'payload'

handler: async (req) => {
  await addDataAndFileToRequest(req)
  const data = req.data  // now available
  return Response.json({ success: true })
}

CORRECT:

return Response.json({ message: 'success' }, { status: 200 })
return Response.json({ message: 'success' })  // defaults to 200

Error responses:

return Response.json({ error: 'Not found' }, { status: 404 })
return Response.json({ error: 'Unauthorized' }, { status: 401 })

CORRECT:

const cookieHeader = req.headers.get('cookie')
const cookies = parseCookies(cookieHeader)
const token = cookies.token

CORRECT:

handler: async (req) => { ... }
// or with PayloadRequest type
handler: async (req: PayloadRequest) => { ... }

WRONG:

req.payload.logger.info('User created', { userId: 123 })
req.payload.logger.error('Failed to save:', error)

CORRECT:

req.payload.logger.info({ userId: 123 }, 'User created')
req.payload.logger.error({ error: String(error) }, 'Failed to save')

For simple messages (no object):

req.payload.logger.info('Operation completed')  // This is fine

export const myEndpoint: Endpoint = { path: '/my-endpoint', method: 'post', handler: async (req: PayloadRequest) => { try { const data = await req.json()

  // Access payload
  const result = await req.payload.find({
    collection: 'users',
    where: { email: { equals: data.email } }
  })

  req.payload.logger.info({ count: result.totalDocs }, 'Found users')

  return Response.json({
    success: true,
    data: result
  })
} catch (error) {
  req.payload.logger.error({ error: String(error) }, 'Endpoint failed')
  return Response.json({ error: 'Internal error' }, { status: 500 })
}

} }

</pattern>

</critical_patterns>

<common_errors>
| Error | Cause | Fix |
|-------|-------|-----|
| `req.data is undefined` | Using v2 pattern | Use `await req.json()` |
| `req.cookies is undefined` | Using v2 pattern | Parse from `req.headers.get('cookie')` |
| `res.json is not a function` | Handler has wrong signature | Return `Response.json()` |
| `TS2769: No overload matches` on logger | Wrong argument order | Put object first, message second |
| `Type 'string \| string[]' not assignable` | relationTo can be array | Use `Array.isArray(x) ? x[0] : x` |
</common_errors>

<quick_reference>
```typescript
// Request body
const data = await req.json()

// Response
return Response.json({ data }, { status: 200 })

// Logger
req.payload.logger.info({ key: value }, 'Message')
req.payload.logger.error({ error: String(e) }, 'Error message')

// Handler signature
handler: async (req: PayloadRequest) => { ... }

</quick_reference>

<success_criteria>

All endpoints use await req.json() for body access
All responses use Response.json()
All logger calls have object first, message second
Handler signature is (req) not (req, res)
TypeScript compiles without errors </success_criteria>

payload-v3-endpoints