const options = {
  method: 'PATCH',
  headers: {'x-spree-api-key': '<api-key>', Authorization: 'Bearer <token>'}
};

fetch('http://{defaultHost}/api/v3/admin/stock_transfers/{id}/mark_ready', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

curl --request PATCH \
  --url http://{defaultHost}/api/v3/admin/stock_transfers/{id}/mark_ready \
  --header 'Authorization: Bearer <token>' \
  --header 'x-spree-api-key: <api-key>'

{
  "id": "st_UkLWZg9DAJ",
  "number": "T1001",
  "reference": "Weekly restock",
  "created_at": "2026-01-15T12:00:00.000Z",
  "updated_at": "2026-01-15T12:00:00.000Z",
  "source_location_id": "sloc_UkLWZg9DAJ",
  "destination_location_id": "sloc_gbHJdmfrXB",
  "status": "ready_to_ship",
  "notes": null,
  "metadata": {},
  "close_reason": null,
  "items_count": 1,
  "quantity_received_total": 0,
  "quantity_rejected_total": 0,
  "shipped_at": null,
  "received_at": null,
  "closed_short_at": null,
  "deleted_at": null,
  "closed_short": false,
  "quantity_shipped_total": 10,
  "editable": false
}