Design a choreography-based Saga pattern for a complex e-commerce checkout process involving Inventory, Payment, and Shipping services. Define the specific events each service publishes and listens to (e.g., 'PaymentAuthorized', 'InventoryReserved'). Detail the compensating transaction logic for every step in case of a failure (e.g., 'PaymentFailed'). Discuss how to handle transactional isolation issues (e.g., phantom reads) without distributed locks.