BeatFit

Expo with strict TypeScript and the New Architecture, with no backend: everything is stored in SQLite with Drizzle, and the UI never touches the database directly. The workout engine is a pure reducer that receives the current time with each action, so every transition is deterministic and can be tested without real timers.

It can be controlled by voice (“next”, “pause”) in Spanish, English and Portuguese, and its sounds lower the music’s volume instead of cutting it. In the background, a notification with a native countdown follows the workout. Timed steps are scheduled ahead, but a set by reps breaks that chain, since there’s no knowing when it ends. Premium features go through RevenueCat, behind an interface with a development implementation.