Constrain the decision, not the review

The failure mode of a design system is not inconsistency. Inconsistency is cheap and visible, and somebody always spots it. What is expensive is who spots it, and when. Every decision the system has not already made gets re-invented, then corrected at review. The correction is the cost, and it repeats.

The scale was already there, unwritten

I own the design system across the applications and embedded experiences at Aria. Before proposing anything, I went to measure what the code was already doing.

The correction that came back most often was spacing. The code held many arbitrary dimension values, silently drifting from our system. A scale existed. Nobody had written it down, so it was re-decided per instance and argued about afterwards.

Move the constraint upstream of the review

None of that argues for stricter review. Review is where the cost already lands. The constraint has to sit where the decision is made: designers and agents build experiences based on predefined decisions that are enforced at the development step.

It starts by ensuring one token definition is consumed by every application, and a written size and spacing scale extracted from what was already there rather than invented. I can change the system and merge it without an engineer writing the change.

Exceptions are allowed, and each one states a reason. That is what we count: overrules, not lint hits. A violation caught before merge is the system working.

The rules are the part that is left

What I am building now is the rules themselves, for the engineers and for the agents they build with. Not only sizes and tokens: which input a form field should use, when a drawer beats a modal, how a button label or an error message is written. Someone decides those on every screen, and re-argues them whenever nobody wrote them down.

None of that can be generated. What the system contains comes from the source and cannot go stale, but what to reach for and when is judgement, and judgement is written once, by whoever has it. Everyone building after that starts from it rather than from nothing, agents included.