Overview

The parts of VitaSync and what talks to what.

VitaSync is an app on your phone with an optional cloud backup behind it. This tab explains the mechanism for curious users and beta testers. It names methods where that helps.

Three ideas the design rests on

Local first. Every log is written to the phone at once. The app works with no connection. Cloud backup is a background copy, never a step in logging. See Local first.

The day is the unit. All your data hangs off one record per calendar day. Storage, backup and merging all work on days. See A day of data.

Nothing leaves the phone unasked. Uploading needs one recorded choice, made on this phone. That choice is never copied to the cloud, so restoring a backup cannot switch uploading back on. See Privacy.

What is where

Part	Where it runs	What it holds
VitaSync app	Your phone	Logging, Insights, Health Connect reading
Local store	Your phone	Every entry and setting, encrypted
Your account	Our server (Supabase)	A private copy of entries and settings, only once cloud backup is on
Food database	Open Food Facts	Foods and barcodes. It receives your search term, nothing else