Design systems die in the handover, not in Figma

Every failed design system we have inherited failed at the same seam: the file was beautiful and the handover was a conversation. Six months later the codebase has four button variants that were never designed and two spacing scales.

What has to be in the file

• Every interactive state, drawn — not described in a comment
• Empty, loading, error and permission-denied states for anything that fetches
• Tokens exported as CSS custom properties, not hex values in a table
• Responsive behaviour written as rules, not implied by three artboards

The test

Hand the file to a developer who was not in the project. If they have to ask a question before they can build the card, the system is not finished.

The expensive part of a redesign is the ambiguity handed to engineering, not the pixels.