Errors

Every failed response carries the same body:

{ "message": "Bu tarih/saat için çakışan randevu var", "code": "SLOT_CONFLICT" }

• code is stable; branch on it.
• message is for humans and may change. Messages from the store handlers are Turkish; the partner layer's own messages follow Accept-Language: en.
• Some errors carry extra fields (e.g. uncovered on SERVICE_AREA_NOT_COVERED, the existing escrow on ESCROW_EXISTS).

Validation errors

A body or query that does not fit the schema gets 400 VALIDATION_ERROR and a per-field list:

{
  "message": "The request failed validation.",
  "code": "VALIDATION_ERROR",
  "location": "body",
  "issues": [
    {
      "path": "items.0.quantity",
      "message": "Too big: expected number to be <=99",
      "code": "too_big"
    }
  ]
}

Status codes

Status	Meaning
400	Invalid request
401	Invalid key (PARTNER_KEY_INVALID)
403	Role or scope insufficient, or the record is not yours
404	Not found, or not visible to you
409	The record's state does not allow it (SLOT_CONFLICT, ESCROW_EXISTS…)
422	Unprocessable (SERVICE_AREA_NOT_COVERED…)
429	Rate limited (RATE_LIMITED)
5xx	Server or upstream error; you may retry

Each endpoint's possible codes are listed under its responses in the reference.