code-reuselisted

# Code reuse Before writing a function, hook, component, or script, assume it already exists somewhere in the repo. Go find it. ## Search before you write - Grep for the *concept*, not the name you were about to give it - the existing function probably isn't called what you'd call it. - Check the project's existing dependencies before hand-rolling something a library already does. - When you report the change, name the search you actually ran. "Grepped for `debounce`, `throttle`; found none" is a claim someone can check. "Nothing else did this" is not. ## Extend, do not fork - A near-duplicate function with one different line is a sign the original needs a parameter, not a sibling. - Exception: a boolean flag that switches between two behaviors is two functions wearing one name. Splitting them is not the duplication this skill is about - see `architect-review`'s flag-parameter rule. ## Rule of three, both directions - Don't abstract at two instances - a two-case abstraction usually fits neither case well. - Don't tolerate a third copy - by copy three, the shared shape is real. This is `architect-review`'s rule; this skill exists to catch the moment before copy two. ## What is not reuse - A wrapper around one call site that will only ever have one call site. - A re-export with no added behavior. - Reaching into a `utils.ts` grab-bag because it's *there*, when nothing in it is related to the problem. - Pulling in a new dependency to save five lines you could write dire