defense-in-depth

To prevent invalid input propagation, apply defense-in-depth validation by enforcing entry-point checks at API boundaries, business-logic assertions, and environment guards to produce deterministic errors and forensic logs.

Defense-in-depth validation is a technique that validates data across system layers to prevent failures caused by invalid inputs, turning sporadic bugs into structurally impossible errors through multi-layer data checks and assertions.

To stop accidental git operations in tests, validate projectDir at creation, apply environment guards in git init, refuse dangerous operations in non-temporary contexts, and capture stack logs before risky actions.

Yes, you can use environment guards to refuse dangerous operations in test or non-temporary contexts, capturing contextual logs and stacks for forensics to ensure risky actions are blocked before execution.

The best way to validate data at API boundaries is implementing entry-point validation to reject obviously invalid inputs early, ensuring quick failures and reducing noisy error states before data reaches business logic.

Business logic validation catches edge cases that entry checks miss by ensuring data makes sense for the specific operation, applying assertions deeper in the system where business rules are enforced.