For most of computing history, designers have been the authors of the visible world. They shaped the screens we tap, the icons we recognize, the patterns we repeat until they feel second nature. From Xerox PARC to Apple's Human Interface Guidelines, nearly every interface worth designing has already been designed. The metaphors of interaction: the desktop, folders, windows, menu, tap, swipe, are now complete, endlessly iterated but rarely reinvented.

But we are entering a new frontier. For the first time, the interface itself thinks. And when it thinks, the rules change.

Today's most profound design problems don't live on the screen at all. They live in the invisible substrate beneath it: how models behave, how they reason, and how their decisions are constrained or liberated.