separation-of-concerns

To separate business logic from UI and data access, you must enforce strict layer ownership where the presentation layer handles rendering, the domain layer manages rules, and the repository layer manages persistence without overlap.

Separation of concerns is an architectural principle ensuring each module or layer addresses exactly one well-defined concern, preventing the mixing of UI, business logic, data access, and cross-cutting concerns for better maintainability.

Refactoring a module with mixed concerns involves reorganizing the code into distinct presentation, domain, and infrastructure layers, moving business rules out of the UI and centralizing cross-cutting concerns for easier testing.

Common violations include embedding business rules in the UI or mixing data access with domain logic. Fixes involve moving rules to the domain layer and separating persistence into dedicated repository components.

Apply separation of concerns during code review when writing or modifying features to ensure each module owns a single concern, checking that presentation, domain, repository, and infrastructure code remain strictly layered.

Separation of concerns works effectively for modular architecture refactoring by outlining layer ownership and providing structural guidance for presentation, domain, repository, and infrastructure code to maintain clean boundaries.