Clean Architecture

Clean Architecture organizes code into concentric rings—entities, use cases, interface adapters, frameworks—with dependencies pointing inward. Use cases orchestrate application-specific rules; entities hold enterprise-wide invariants. Frameworks and drivers stay at the outer edge as replaceable details.

On interviews: explain the dependency rule and where DTOs live. Contrast ceremonial folder trees with teams that achieve the same rule via modules.

Common pitfalls: renaming folders without changing dependencies; use cases that are pass-through CRUD; skipping boundaries in small scripts then copying structure blindly.

The trade-off is flexibility versus complexity—know when the simpler path is enough.

Checklist:

• Inner rings never import outer rings.
• Use case classes map to application workflows.
• Mappers translate at adapter boundaries.
• Architecture tests enforce forbidden imports.