Protocol·Engineering notes

How Protocol works, from the code

Long-form explanations of the mechanics behind the product: how data gets in, how it's stored, and how a number on the screen was chosen. Each doc is written from the repository and lists the files to confirm it against.

Sync

How data gets from wearables, Apple Health, and the cloud into Protocol, and how a day's canonical number is chosen when sources disagree.

Sync

How Protocol syncs, stores, and reconciles Steps

Apple Health steps are pushed from the phone; Oura steps are pulled from the cloud; WHOOP has none. The 365-day backfill, the 14-day rolling window, foreground vs background, the silent push wake, and the highest-value merge rule.

Updated September 3, 2026