A record a new device creates by default must carry the oldest timestamp, or last-writer-wins sync spreads it over the real one

Fact

In last-writer-wins (LWW) sync, the copy with the newer change timestamp wins. A device that starts without the user's data usually creates a placeholder (a random name, default settings) and stamps it now(), which is newer than every real edit, so the first sync replaces the user's real record with the placeholder, on every device.

Why it matters

Signing in on a second device, reinstalling, or clearing storage silently resets the user's profile everywhere. Nothing fails: the placeholder simply looks like the latest edit.

How to apply

• Stamp generated defaults with 0 ("never edited") and set the timestamp only when the user edits the record.
• Bump it only for fields the user edits (a name, an avatar), not for counters or flags the app updates by itself, or every device always looks newest.
• Merge accumulating fields monotonically instead of by LWW (a union of earned items keeping the earliest date, the maximum of each counter), so no device loses progress whichever side wins.
• When a device signs in to an existing account, seed its local record from the server's copy before the first sync, not from local defaults.
• Test that merging a fresh default with an older real record yields the real record, in both argument orders.