{
  "data": {
    "id": "m1a2b3c4d5e6f7g8h9i0j",
    "x_user_id": "944883311",
    "username": "founderhandle",
    "name": "Founder Name",
    "avatar_url": "https://pbs.twimg.com/profile_images/...",
    "added_at": "2026-06-25T11:00:00.000Z"
  },
  "duplicate": true
}

{
  "data": {
    "id": "m1a2b3c4d5e6f7g8h9i0j",
    "x_user_id": "944883311",
    "username": "founderhandle",
    "name": "Founder Name",
    "avatar_url": "https://pbs.twimg.com/profile_images/...",
    "added_at": "2026-07-08T10:00:00.000Z"
  }
}

{
  "error": {
    "code": "system_list_read_only",
    "message": "System lists are managed automatically and can't be edited."
  }
}

{
  "error": {
    "code": "invalid_api_key",
    "message": "Unknown or revoked API key"
  }
}

{
  "error": {
    "code": "insufficient_scope",
    "message": "This API key is read-only. Create a key with the write scope to use this endpoint."
  }
}

{
  "error": {
    "code": "user_not_found",
    "message": "No X account matches that handle."
  }
}

{
  "error": {
    "code": "rate_limited",
    "message": "Rate limit exceeded for the Pro plan (30 requests/min). Upgrade for higher limits.",
    "retry_after": 42
  }
}

{
  "error": {
    "code": "upstream_error",
    "message": "Failed to fetch scheduled posts. Try again shortly."
  }
}

{
  "error": {
    "code": "upstream_unavailable",
    "message": "The scheduling service is temporarily unavailable. Retry with the same Idempotency-Key."
  }
}