Knowledge in both places Diagram

Both sides add

merged = base − removed here − removed there + added here + added there
A photo added to an event here and a name given in the cloud both survive

A real disagreement

Two values for a fact that has one: a date, an event type, a name, a summary in one language
That is a conflict: nothing is written, and the person picks mine or theirs

Checked on every write

The edge validates the merged graph before it writes anything
The cloud runs the same shapes and the sensitive-number guard for every writer
A save based on an old version gets 409 and the current graph, and the edge merges again

What crosses

Statements about people, pets, events, places and things, and which items they are in
Never face vectors or crops; face boxes go separately, through /media/faces