Good Architecture Is a Function of Time

Cate Huston, who led the rebuild of Twill, a recruiting platform, says a design system and a strict permissions model paid off once her team built with AI agents.

Cate Huston is the part-time chief technology officer of Twill, a platform where members, candidates and recruiters each see the same data in different ways. Her team rebuilt Twill in four months with tight scope, but she paid for a design system and a central model of who may see what. She writes that neither would have been worth it before AI agents wrote code, and that both caused far fewer problems than expected.

• Huston argues that architecture makes good decisions easier over a period a team can reason about. A start-up can rarely see that far ahead, so good architecture is often too expensive for it to justify.
• Her permissions model makes it easy to add a new type of user, and granting a permission takes one line in a table. She chose it because Twill's roles kept changing and because security depends on who can see what.
• When she noticed architectural problems emerging elsewhere, she added more work of the same kind, such as replacing hand-written database queries with generated ones.
• She argues that AI agents talk about time without experiencing it, so judging what is likely to change remains a human responsibility.

An engineering team that builds with AI agents may find that shared structure it once could not justify now pays for itself. Huston gives no numbers, and the application beyond Twill is an inference and is not the author's claim.

Derived by Working Surface from the article. Source line: Neither of these choices would have been justifiable in a pre-agentic-development world.

29 September 2026: when AI tools do the making, a team has to keep some of the old steps on purpose.