What I learned building a Claude Code plugin for MV3 Chrome extensions

Claude Code writes extension code fine. That was never the problem. Ask it for a content script that highlights matched text, or a background service worker that debounces a fetch, and it produces something reasonable on the first try. Where it trips is everything around the code: the Manifest V3 rules, the permission model, the content security policy, and the unwritten expectations of Chrome Web Store review. Those are the parts that fail late, at install, at build, or three weeks after you t...