When Apple executives publicly compare a foldable iPhone to the iPad mini, it's a reminder that device boundaries are blurring. Users expect the same app to follow them from a phone in the morning to a tablet at lunch to a watch on the move — with the experience adjusting, not breaking.
Adaptive UI is the discipline of building one codebase that respects each context. Bigger screens earn richer layouts and multitasking; smaller ones get focus and speed. We treat the size class as a design input from day one, so growth to a new device is a setting, not a rewrite.