refactor-safely

Recipe for restructuring code without changing behaviour - establish a behavioural safety net first, write characterisation tests where coverage is thin, work in small reversible steps, keep one kind of change per commit, keep tests green at every step, never mix behaviour changes into a refactor, measure when performance is the motive, apply stop criteria, and know how to roll back. Names the skills to apply at each step, the exit check, and what to hand forward. Load when asked to refactor, restructure, rename, extract, simplify, or clean up existing code.