Skill Claude CodeCodex
Drive feature development using Outside-In TDD with Hexagonal Architecture. Design emerges through inline code, in-memory fakes, interface extraction, and deferred I/O. Use when building features, writing tests, or structuring backend services. Triggers on: TDD, outside-in, hexagonal, ports and adapters, emergent…
Skill Claude CodeCodex
Find where a codebase actually costs time by mining its git history (Tornhill hotspot analysis). Produces ranked refactoring targets with evidence, change-coupling seams, and a do-not-refactor list; re-run after refactoring to verify it paid off.
Skill Claude CodeCodex
Refactoring process. Invoke immediately when user or document mentions refactoring, or proactively when code gets too complex or messy.
Skill Claude CodeCodex
Iterative refinement through multiple passes. Use when the user asks to 'meditate on', 'distill', 'refine', or 'iterate on' something, or proactively when a problem benefits from multiple passes rather than a single attempt.
Skill Claude CodeCodex
Writes approval tests (snapshot/golden master testing) for Python, JavaScript/TypeScript, or Java. Use when verifying complex output, characterization testing legacy code, testing combinations, or working with .approved/.received files.
Skill Claude CodeCodex
Scannable BDD tests written in domain language. Use when doing BDD.
Skill Claude CodeCodex
Nullables — testing technique alternative to using mocking libraries. Use when writing unit tests, when code touches external I/O or state (HTTP, databases, files, clock, random) anywhere in its dependency chain, when making a system testable, or when tests are slow or flaky.
Skill Claude CodeCodex
Test-driven development (TDD) process used when writing code. Use whenever you are adding any new code, unless the user explicitly asks to skip TDD or the code is exploratory/spike.