Google open-sources Stitch's DESIGN.md for brand-consistent AI agent design

What changed

Google released the DESIGN.md file from its Stitch project as an open-source resource. The document is a structured framework for capturing brand identity, visual guidelines, and tone of voice in a format that AI agents can read and follow during generation tasks.

Why it matters

For solo makers using Cursor, Claude Code, Lovable, or v0 to ship products, the failure mode is the same: prompts drift, output looks generic, and every new component requires re-explaining the brand. A persistent constraints file in the repo root is the fix, and DESIGN.md is now a battle-tested version of that file. It turns one-off prompts into a system that compounds across iterations.

What to watch for

Fork the schema, fill it with your actual brand rules, and reference it in your agent's project instructions. Test it by regenerating a component you already have and comparing the output. If the brand alignment improves, expand it to cover voice, layout grids, and component patterns. Treat it as a living spec that gets sharper every time you ship.