John Ternus walked onto the stage for the first time as Apple's chief executive and immediately made clear that he had no intention of playing it safe. The device he held up — thin, hinged, folding cleanly in half like a travel document — was the iPhone Duo, and it drew a sharp line between everything Apple has built for the past 18 years and whatever comes next. The Duo is the most radical redesign of the iPhone since Steve Jobs unveiled the original model in January 2007. Where every iPhone since then has followed the same fundamental logic — a single flat glass slab — the Duo breaks that shape entirely.

Folded, it fits into a shirt pocket or a small clutch bag. Unfolded, it opens into a larger display that Apple says rivals a compact tablet. The hinge, which the company spent years engineering, is designed to leave no visible crease on the inner screen, a persistent weakness that has plagued rival foldable phones from Samsung in South Korea and Huawei in China. Ternus did not arrive at this moment by accident.

He led Apple's hardware engineering division for years before being appointed CEO, and the Duo is widely regarded inside the company as his defining project. Analysts in Tokyo, London, and São Paulo have already begun revising their forecasts upward, with several predicting that the foldable category — long dominated by Android manufacturers — could shift decisively toward Apple within two product cycles.