Vitals
A private iOS app that fuses Apple Health and Whoop into one record per day and lets an LLM reason over your trends — with anonymization guaranteed by the type system.
Overview
Vitals is small on purpose — one user, one device, no accounts — but it's where I proved out a way of building with AI I now trust.
It merges Apple Health and Whoop into a daily record (never averaging the two — different instruments, stored side by side, enforced by a test) and sends anonymized rollups to an LLM for correlations. Identity structurally cannot leave the device: rollup columns are typed so a cell can only be a number, and a test rejects any character that isn't one.
The real artifact is the verified-build loop — a single hard gate (compile, test, secret-scan), an independent read-only reviewer, and a state file that logs every real bug the gate caught. Discipline, not vibes.
Highlights
- A device-independent core, fully unit-tested; device code gated behind the same check.
- A domain invariant wired as a test, not a comment.
- A maker-checker loop that catches real defects — recorded, not hidden.