Cycle tracking apps tend to hand you either a calendar or a horoscope. Meridian, an app I built with AI, is an attempt at a third thing: it takes the ritual and narrative people actually come to these apps for and puts real structure underneath it.
The spine is four cycles turning at different speeds: the lunar month, your own cycle, the Ayurvedic day and the Chinese organ clock. They nest cleanly — twelve organ hours divide exactly into six dosha periods — so the home screen is one dial with all four rings, and everything else falls out of where those rings currently sit.
Traditional Chinese Medicine and Ayurveda agree more than they disagree: both say warm and cooked while you’re bleeding, light and green while you’re building, cool and bitter at ovulation, and protect digestion in the luteal phase. The app is built on that overlap.
The rule for motion was that it should feel like breathing. Everything eases on sine and soft cubic curves, nothing moves at a constant speed, and opacity runs on a curve of its own so a fade is actually seen. Each arrival plays once, when you land on a screen, and not again until you come back.