A design system is an operating decision, not a deliverable. It changes who is allowed to make what change, and how long that change takes to reach the people it affects. We build systems only where that tradeoff is worth making, which is roughly where more than one team is shipping interface work.

The build covers tokens, components in the technologies the client actually uses, documentation with the reasoning visible, and the governance: who can add a component, what evidence is required, how a deprecation is handled. Half the effort goes into the parts that are not code.

We measure success by whether the client team extends the system without us. That means we stay for the first months after launch, reviewing contributions, and then we stop, which is the part most engagements get wrong.