A designer in 2024 who wanted to turn a sentence into a usable app design ended up with a pretty single screen and a long to-do list. A designer in 2026 who tries the same thing — with the right tool and the right prompt — gets a connected, multi-screen flow with navigation, states, and content placeholders that roughly match the brief. The shift from "one prompt, one screen" to "one prompt, one product" is the single largest productivity move in the design category this decade. The tools that make this possible are real, but they are not interchangeable, and the prompt that makes them sing is very different from the prompt most people type on the first try. This playbook maps what the category actually produces in 2026, how to write a prompt that yields a usable multi-screen output, the five tools worth trying, and the failure modes to expect and recover from.…