Building an iOS golf performance app that connects rounds, swings, clubs and putting into one coaching system for the club golfer. I work across the whole stack: React Native and Expo on iOS, Supabase and Postgres behind it, on-device computer vision for swing and club analysis, and the marketing site and beta programme around it. The interesting part is the measurement. Turning phone video into numbers a golfer can act on means knowing when a reading is real and when it's an artefact of the camera, the frame rate or the landmark model — and being willing to suppress a feature that measures the wrong thing rather than ship a confident number. Most of the work is building the evidence to tell those apart.