clean-architecture

Structure software using clean architecture by separating code into domain-first layers: entities, use cases, interface adapters, and frameworks. This approach enforces dependency direction rules, prevents framework leakage, and improves testability across the codebase.

Dependency direction rules in clean architecture mandate that inner layers like entities and use cases must not depend on outer layers like interface adapters or frameworks. Enforcing these boundaries prevents domain logic leakage and maintains strict separation of concerns.

Refactor a legacy codebase into domain-first layers by applying clean architecture principles during code reviews. Reorganize existing logic into entities, use cases, and adapters, establishing boundaries that isolate core domain rules from external framework dependencies.

The best way to make architectural decisions for partial versus full boundaries is to evaluate modularity and testing needs. Use partial boundaries for simpler domain isolation or full boundaries when strict separation of concerns and independent testability are critical.

You need a composition-root main to enforce clean architecture by centralizing dependency injection. This setup configures and wires dependencies at application startup, ensuring inner layers remain completely unaware of external frameworks and interface adapters.

You should not use clean architecture for system design when a project is too small to justify domain-first layers, as enforcing strict boundaries and dependency direction rules on simple codebases introduces unnecessary overhead without meaningful modularity or testability gains.