Transversal software-engineering principles for any code in any language, frontend or backend. Use when writing new code, implementing a feature, refactoring, reviewing code, naming things, deciding where logic belongs, splitting or merging classes/modules/components, introducing an abstraction, or judging whether code is "good enough" — even when the user doesn't name a principle explicitly (e.g. "clean this up", "does this look right?", "where should this go?"). It encodes SOLID, simple design, clean code, code smells, and complexity management — applied with judgment, not dogma: rules are signals to weigh, and a minor duplication beats a wrong abstraction.
