curl --request POST \
  --url https://your-instance.example.com/api/pipelines/stages/reassign \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "sourceStageId": "67f0a0b0c0d0e0f0a0b0c0d0",
  "targetStageId": "67f0a0b0c0d0e0f0a0b0c0d1"
}
'

{
  "success": true,
  "recordsTransferred": 7,
  "sourceStage": {
    "id": "67f0a0b0c0d0e0f0a0b0c0d0",
    "name": "New"
  },
  "targetStage": {
    "id": "67f0a0b0c0d0e0f0a0b0c0d1",
    "name": "Qualified"
  }
}