Error Codes

// Every 4xx/5xx is a FLAT envelope — never nested under "detail".
{
  "code": "INSUFFICIENT_MARGIN",
  "message": "Insufficient margin: need 47,500 cents, have 12,300 free.",
  "request_id": "9cb4ae023baa"
}

// Some codes carry structured extras under "details" (plural). E.g. a
// leverage cap rejection (HTTP 422):
{
  "code": "INVALID_LEVERAGE",
  "message": "requested leverage 50x exceeds account cap 40x",
  "request_id": "9cb4ae023baa",
  "details": { "requested_leverage": 50, "effective_leverage": 40 }
}

// For order rejections (HTTP 200, status REJECTED):
{
  "order_id": "…",
  "status": "REJECTED",
  "reject_reason": "INSUFFICIENT_MARGIN",
  "reject_message": "Insufficient margin: need 47,500 cents, have 12,300 free.",
  "filled_qty": 0,
  "remaining_qty": 0,
  …
}