defense-in-depth

To prevent invalid data failures, implement multi-layer data validation across entry points, business logic, environment guards, and debugging contexts to ensure data integrity and predictable failures.

Defense-in-depth is an architecture pattern enforcing multi-layer data validation to stop bugs caused by invalid data propagating silently across structural components, guaranteeing improved software reliability.

Implement layered validation by defining checks in design-documentation across four layers: API boundaries, business rules, environment constraints, and debugging contexts to cover common failure paths.

Multi-layer validation reduces the risk of defects slipping through due to refactors or mocks across components by enforcing structural checks at every layer of your architecture.

You should avoid a layered validation strategy for simple scripts lacking distinct architectural layers, as the overhead of implementing four separate validation checks provides no structural benefit.