Code got cheap, decisions didn't. Building a design system with AI agents

Alexander Ostrovsky is a Staff iOS Engineer at TradingView. He's building a design system for its iOS app, his third; AI agents write most of its documents and code. In ten years of iOS he has built apps from scratch and led a mobile team; before that, he wrote C++ for flight simulators. TradingView is a large product with a long history, and we're bringing a design system to its mobile apps. I lead the iOS side, from the architecture and the first components to moving the whole app onto them. AI agents write most of the documents and the code; I review and decide. Code turned out to be the cheap part: a working prototype with alternatives takes hours. Two things stayed expensive, and agents can't do them for you. One is decisions: in three weeks we made more than 200. The other is reaching agreement with everyone the design system affects. In this talk: - where the time actually goes when code is nearly free; - how cheap prototypes make it cheap to change your mind; - how to keep track of decisions so you don't make them twice.