yuno-payments/yuno

Authoritative guide to Yuno API credentials, the Sandbox/Production split, and the confirmation ritual required before any money-moving operation. Use whenever authenticating to the Yuno API, choosing or creating API keys, wiring the Yuno MCP server, switching between Test Mode and Live Mode, setting up a sandbox, or picking a base URL. Use BEFORE creating, authorizing, capturing, cancelling or refunding a payment, creating a payment link, creating or cancelling a subscription, creating a customer or recipient, or calling any Yuno MCP tool that writes. Also use for key rotation, allowed-IP restrictions, leaked or committed credentials, and 3DS or test-card setup.

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.

Guides integration with Yuno's Payments API: the object chain (customer, session, payment, transaction), payment and transaction status lifecycles, authorization vs capture, cancel and refund semantics, tokenization, and 3D Secure. Use when creating a payment, choosing between the SDK checkout, a direct server-to-server integration or a payment link, integrating Yuno's checkout session, handling authorization and capture, capturing or canceling an authorization, issuing a full or partial refund, reading a payment status / sub_status, debugging a PENDING or WAITING_ADDITIONAL_STEP payment, working with one-time, vaulted or network tokens, enrolling a payment method, or wiring up 3DS challenge redirects.

Guides correct installation, initialization, and version upgrades of Yuno's client SDKs (Web, iOS, Android, Flutter, React Native), the Yuno MCP server, and the Yuno Agent Toolkit, plus generating an API client from Yuno's OpenAPI spec. Use when the developer says "add Yuno to my app", "install the Yuno SDK", "set up Yuno checkout", "initialize Yuno", "Yuno.initialize", "mount checkout", "startCheckout", "@yuno-payments/sdk-web", "YunoSDK", "com.yuno.payments", "yuno pub add", "Yuno React Native", "which Yuno SDK version", "upgrade the Yuno SDK", "Yuno breaking change", "Yuno OpenAPI", "generate a Yuno client", "Yuno MCP server", or "Yuno agent toolkit". Also use before writing any Yuno integration code, to confirm the package name and version rather than guessing.

Guides building and hardening a Yuno webhook receiver: the delivery contract and retry schedule, the event catalog across payments, refunds, chargebacks, subscriptions, payouts, enrollments and onboarding, HMAC-SHA256 signature verification, and endpoint configuration in the Yuno dashboard. Use when setting up a webhook endpoint, verifying the x-hmac-signature header, handling payment status notifications, reacting to payment.purchase or payment.chargeback, tracking subscription renewals, debugging missed or duplicated events, making a handler idempotent, deciding which events to subscribe to, or figuring out why Yuno keeps retrying a delivery.