Product design grows up. Taste in people's heads doesn't scale. Written decisions do.

A CTO I follow wrote that AI is helping programming grow up. It's moving closer to engineering and further from craft.

The phrase that stayed with me is "grows up." Product design has been trying to grow up for about fifteen years.

We built design systems, ran research ops, wrote principles and drew maturity models with five neat steps. In most teams I've worked in, each designer still had their own way of doing things. Decisions lived in someone's head or in a Figma comment. Quality depended on who was on the squad that quarter.

At Koa, we audited the product and found that only about 15% of the components were shared. Every team had been crafting carefully, and nobody was building one product. Getting to 95% didn't need better designers. It needed decisions that were written down, agreed and reusable. That was the maturity step. It was boring, and it changed everything after it.

AI makes that step mandatory. An agent can't read the room or ask the senior designer what they meant. It works from what you have made explicit, and nothing else. If your product design practice only exists as taste spread across five people, the agent will produce five products.

So, to me, maturity in product design looks like this:

• Decisions you can explain without the person who made them
• Rules that hold when the data is messy and the user is an expert
• Quality that doesn't depend on who happens to be in the room
• Being judged on outcomes, not on how good the file looks

None of this kills craft. Immature craft depends on heroes. Mature craft is something other people can pick up and continue.

Engineering is going through this now because it has to. Product design gets the same chance. The difference is that this time it isn't optional.