lean-codelisted

# Lean Code The cheapest code to maintain is the code you did not write. This skill runs **before** you type. For cleaning up code that already exists, use a simplification pass instead — this does not duplicate it. ## The search-first rule Before writing any new helper, type, hook, or component, **spend one search proving it does not already exist.** The answer is very often yes. Check, every time: - The shared utilities directory named in `CONVENTIONS.md`. - The canonical reference module — whatever it does, it probably does this too. - The transport or client layer. **Never hand-roll a fetch wrapper or a URL concatenation** when the project has a sanctioned one. - Any component library the project already ships. Check before building a dialog, table shell, or form field from scratch. If something similar exists but does not quite fit, **prefer extending it over cloning it** — but say so, since widening a shared helper affects its other callers. ## Questions to pass before adding code **Does this need to exist?** Not "is it nice" — does removing it break a stated requirement? Speculative flexibility for a future nobody specified is the most common source of bulk. **Is this the third time?** Two similar call sites do not justify an abstraction. **Duplication is cheaper than the wrong abstraction**, and the right shape is usually only visible on the third use. **Can an existing type carry this?** A new type that is an existing type plus one field is usually a fi