Lewis Mills
Notes on building Coach Yu and other projects.
One Login, Two Roles — and the Seven Bugs In Between
2026-08-04Merging Coach Yu's separate athlete and coach accounts into one identity: why admin was deliberately left out of the merge, and the seven bugs — from passkey collisions to a silent role-array footgun — that building and shipping it surfaced.
Building Something That Didn't Exist: A Phone-Only VBT System for Olympic Weightlifting
2026-07-28How Coach Yu computes velocity, force, power, and phase-by-phase lift breakdowns from ordinary phone video — no transducer, no dedicated camera — and the Mac debug harness (VBT Lab) that made building the pipeline possible.
Building CoachYu's Bar Path Tracker: A YOLO-Powered Microservice for Weightlifting Analysis
2026-07-28Why bar-path tracking runs server-side rather than on-device, how a YOLO-based Python microservice picks the right plate to track across auto and locked modes, and what changed working in Python for AI serving for the first time.
Reverse-Engineering My Glucose Meter's Bluetooth Protocol (and Building an App Around It)
2026-07-28How badblood talks to a Contour glucose meter over the standard Bluetooth SIG Glucose Profile — decoding IEEE-11073 SFLOAT readings, a Python prototype before Swift, and the sync/reconnect decisions behind the real app.