概要
The Defense-in-Depth skill provides a robust architectural framework for software reliability by enforcing the principle of validating data at every layer it passes through. Instead of relying on a single entry check that could be bypassed by mocks, refactoring, or alternate code paths, this skill guides you through implementing four critical layers: entry point validation, business logic checks, environment guards, and debug instrumentation. This comprehensive approach makes bugs structurally impossible to reproduce by ensuring that data integrity is maintained from the API boundary down to the low-level execution environment.
