curl --request POST \
  --url https://api.kie.ai/api/v1/generate/extend \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "defaultParamFlag": true,
  "audioId": "5c79****be8e",
  "prompt": "用更多放松的音符和一个柔和的过渡段延长音乐",
  "style": "Classical",
  "title": "Peaceful Piano Extended",
  "continueAt": 60,
  "model": "V3_5",
  "callBackUrl": "https://api.example.com/callback",
  "negativeTags": "重金属, 快节奏鼓点"
}'

{
  "code": 200,
  "msg": "success",
  "data": {
    "taskId": "5c79****be8e"
  }
}