Built-in skill — behaviour-preserving refactoring.
Injects a system-prompt section requiring the model to understand existing behaviour first, keep the external API and observable effects identical, work in independently verifiable steps drawn from a named catalogue (extract function, rename, simplify conditionals, remove dead code, reduce coupling, improve data structures), and re-run tests after each one — with an explicit ban on mixing in features or bug fixes.
Activates on prompts containing "refactor", "clean up", "simplify" or
"restructure". Group :coding; tags :refactor, :cleanup, :improvement.