Workflow-driven skill that builds the chargeback / dispute test suite: canonical reason codes (Visa 10.4 fraud, 13.1 services-not-provided; Mastercard MCC 4855), per-gateway dispute APIs (Stripe Disputes, Adyen Chargeback notifications, PayPal Disputes), the evidence-submission flow + window, and disposition outcomes (won / lost / accepted). Use when designing dispute coverage; for refunds use refund-test-matrix-builder, for webhook redelivery + idempotency use payment-webhook-replay, and for the lifecycle state model use payment-flow-states-reference.