Developer Builds React-Inspired UI Architecture for RAM-Constrained Garmin Watches

A developer has introduced modern UI architecture principles — including unidirectional data flow and component separation — to Garmin smartwatch app development, where RAM is measured in kilobytes and CPU speeds hover around a few hundred megahertz. To work within these tight constraints, they built a custom Hooks-like library for Garmin's Monkey C language and adopted a Container/Presenter pattern alongside a Props Packing approach using arrays. Running the hooks library directly inside the render loop proved too CPU-intensive, so the architectural patterns were used instead to keep overhead to just 0.8ms per frame. The approach unlocked the ability to run headless UI integration tests and benchmarks without requiring a device emulator, significantly improving the development experience. The work was applied to YAMAKAGE, a released Garmin app that calculates true sunrise and sunset times by factoring in surrounding terrain elevation.