Clean Architecture

This walks you through implementing Clean Architecture and Hexagonal Architecture patterns in Spring Boot 3.5+ apps, focusing on keeping your domain logic completely framework-free. You get concrete package structures, instructions for organizing domain entities and value objects separate from JPA entities, and guidance on setting up ports and adapters so infrastructure stays swappable. The skill emphasizes putting business logic in rich domain models rather than anemic services, using Java records for immutable value objects, and includes ArchUnit tests to enforce the dependency rules. It's opinionated about transaction boundaries and includes a validation checklist to grep for Spring annotations leaking into your domain layer, which honestly feels necessary given how easy it is to let framework concerns creep inward.