who-built-this-before-me

Check whether a project, tool, library, or product idea has already been built before the user invests time in it. Find existing solutions, extract standard patterns, benchmark the user's angle against prior art, and deliver a clear verdict (build / fork / contribute / use existing / investigate why it failed). Use this skill whenever the user describes something they're thinking of building, making, shipping, launching, or coding — especially phrases like "I want to build…", "I'm thinking of making…", "should I build X…", "is there already a…", "my idea is…", or when the user is scoping a new side project, startup, library, or tool. Trigger even if the user doesn't explicitly ask for prior art research — if they're about to build something, they should check first.