# API Client Migration

For each breaking change, document:

- old endpoint
- new endpoint
- old request payload
- new request payload
- old response envelope
- new response envelope
- new authorization requirements
- sunset date
- migration notes

## Example

| Old | New | Notes |
|---|---|---|
| `GET /api/payments/file/{filename}` | `GET /api/v2/finance/payments/{payment}/file` | New route is payment-scoped and authorized. |
| legacy bulk send route | `/api/v2/communication/bulk-sends` | Requires `preview_id` and `confirmation_token`. |