概要
This skill provides expert guidance for developers integrating PayPal's robust payment ecosystem into their applications. It covers the full lifecycle of transaction management, from setting up client-side Smart Payment Buttons and server-side REST API order creation to handling complex asynchronous events like Instant Payment Notifications (IPN) and managing recurring billing plans. Whether you are building a simple one-time checkout or a sophisticated subscription-based platform, this skill offers production-ready patterns for secure, international payment processing and error handling.