Vercel Launches design.md for On-Brand Pages

Vercel’s approach treats design consistency as an engineering feedback problem, not a prompting problem.

• –Seven fixed scenarios test reports, proposals, dashboards, and presentations across multiple models.
• –Deterministic checks handle mechanical failures, while humans judge hierarchy, composition, and usefulness.
• –Pages generated with `design.md` produced 39 known failures versus 91 without it—a 57% reduction, though the six-page sample remains small.
• –Separating judgment into Markdown and mechanics into CSS reduces model drift and context usage.
• –Weekly feedback from Slack, GitHub, and Figma turns recurring production complaints into new rules, primitives, or evals.