How sync works under the hood — key, LWW, tombstones
You enter a sync key on a second computer and your rules are simply there. How it works under the hood — and why JustZix will not overwrite your work when you edit rules on two devices at once.
The sync key
Sync rests on a 25-character key. It is generated locally, on your device — the backend never sees it in plain form, it stores only a SHA-256 hash. That means even access to the server database does not reveal the key.
Conflict resolved per entity
You edit rule A on your laptop, rule B on your work computer, offline, at the same time. Once connected, both changes have to reconcile. JustZix resolves this per individual entity, not wholesale: there is no such thing as "overwrite all settings". Rule A and rule B are separate entities — both changes survive.
Last-Write-Wins with a Lamport clock
When the same entity changes in two places, the newer version wins — "last write wins". But "newer" cannot rely on the system clock (those drift). JustZix uses Lamport timestamps — a logical counter that increments on every change. That gives a consistent ordering of events whether or not the device clocks agree.
Tombstones — how a deletion propagates
Deletion is harder than editing. If a deleted rule simply "vanished", the other device, which never saw it disappear, would add it back on the next sync. So a deletion leaves a tombstone — a "this was deleted" marker. The tombstone propagates like any other change, so the deletion is permanent across all devices.
When the conflict is at login
You log in with a key on a new device that already has local rules. JustZix does not guess — it shows a resolution UI: use the server data, send the local data, or merge one with the other by the Last-Write-Wins rule. The decision is yours.
See also
- The folder hierarchy — what exactly gets synced
- Injected JS security — the JustZix trust model
- JustZix for a QA team — sync versus link sharing
Install JustZix — and have the same rules everywhere, with no lost work.
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