DESIGN.md is an open format from Google Labs that describes a design system to AI coding agents. It pairs machine-readable design tokens (YAML front matter) with human-readable rationale (markdown prose), so an agent generates UI that matches your brand instead of generic defaults.
Why agents need it
Left alone, an AI coding agent draws on the most common patterns in its training data — generic blues, default fonts, arbitrary spacing. It has no way to know your design system unless you tell it, every single time. The result is UI that looks plausible but not like yours.
DESIGN.md removes the "every single time." You describe your visual identity once, in a file the agent reads before generating any UI.
Where it lives
