Engineering-craft practices for building, testing, and structuring code at the implementation and component level — distilled from gold-standard open-source codebases. Covers testing and correctness, error and failure handling, extensibility and module/plugin boundaries, backpressure and resource control, observability, API and backward-compatibility discipline, and implementation simplicity. Use whenever the user asks how to build, structure, or test a component; the best-practice or "how do the best codebases do it" approach for a code-level concern (testing, error handling, flow control, logging/metrics, API stability); for a craft-level review; or to distill engineering practices from a repository — even if they don't say "craft". Do NOT use for system-level architecture decisions — service boundaries, monolith-vs-microservices, distributed transactions, consistency models, bounded contexts, ADRs, or team topology — the software-architect skill owns those; hand off to it.
2026-06-20