Pure-reference catalog of payment lifecycle state machines across Stripe, Adyen, PayPal, and Braintree: canonical states (created / requires_action / processing / succeeded / requires_capture / canceled / failed), authorisation vs capture, asynchronous webhook states, and refund / dispute / chargeback transitions. Use when designing tests for payment flows or auditing state-handling code; this is the state model, not a builder - to author suites on it use refund-test-matrix-builder (refunds), chargeback-flow-test-author (disputes), or payment-webhook-replay (webhook replay).