Nexity is an open source system for starting and growing AI-native websites on Next.js + Sanity. Coding agents read the project's rules before they build, so new sections stay consistent. - AGENTS.md, DESIGN.md, BRAND.md: how to build, how it looks, what it says - Claude Code skills for setup, new sections, link fixes, Sanity audits - Sanity Studio: about two dozen sections, click-to-edit preview, redirects editors manage themselves Used on 20+ client projects. Free and MIT.