Cascade
Architecture

One Rust core, six native shells

Cascade is a waterfall white-noise player for focus and sleep, and an architecture kata. A single headless Rust core owns every behavior - state, timers, volume, sessions, settings - and each platform is a thin native UI over one JSON boundary. The core never touches an audio API, the filesystem, or the clock.

Cascade architecture: the cascade-core Rust crate at the center, dispatching Commands and returning a Snapshot and Effects, with web, Android, macOS, iOS, watchOS, and Windows shells bound around it.
cascade-core at the center; every shell is a thin UI over the same JSON boundary.

The boundary

Every interaction is one call: dispatch(Command) -> Update { Snapshot, Effects }. The UI sends Commands (Play, SetVolume, Tick). The core returns a Snapshot to render and a list of Effects the shell performs - start playback, set platform volume, persist settings. Platform events, like audio starting or a tick of wall-clock time, fold back in as Commands. No chatty getters cross the boundary, and time is an input the UI supplies rather than something the core reads.

One core, many shells

The same commands, effects, and snapshots serialize over each platform's binding:

Open the player Get the app Source on GitHub