A foldable phone can impress people in a demo and still confuse them in daily use. The screen opens, the canvas expands, apps rearrange, controls move, and the user has to trust that nothing has been lost along the way. That is the real challenge for Apple’s first foldable concept, the iPhone Duo. The hardware idea is clear: a 5.4-inch outer Super Retina XDR display for quick tasks, paired with a 7.6-inch inner screen for reading, creating, watching, and multitasking. The har