yuno-errors-and-testing

Guides error handling and testing for Yuno payments: reading payment status and sub_status, interpreting transaction response_code and hard/soft declines, using Merchant Advice Codes and AVS/CVV verification results, applying idempotency correctly, and testing in sandbox with the Yuno Testing Gateway and 3DS frictionless/challenge test cards. Use when the developer says "Yuno payment failed", "payment is PENDING forever", "what does DECLINED_BY_BANK mean", "should I retry this decline", "hard vs soft decline", "X-Idempotency-Key", "IDEMPOTENCY_DUPLICATED", "REQUEST_IN_PROCESS", "Yuno test cards", "test 3DS", "challenge flow", "sandbox not working", "sdk_action_required", "continuePayment", "AVS", "CVV check", "chargeback webhook", or when debugging any non-SUCCEEDED Yuno payment.