Question: What is Vivaldi’s implementation of Sync based on? When enabled, is it going to pick up the data from one of the synced clients and overwrite the others with the data, or is it going to collect the data from all the synced clients into a server and so not going to overwrite any of the existing data?
Answer: Vivaldi Sync is based on the Chromium sync code with some modification and uses the same protocol. The data to be synced is encrypted, then sent to a central server from which it can be requested from all other Vivaldi instances from the same user. Some merging then takes place on the client to ensure that everything remains consistent.
The answer didn't really fully explain how consistency is maintained without risk of stuff getting wrongly overwritten.
Example: There's entry #1234 on the sever (I'm guessing entries get a non-shown database key). On the server it has a last-updated timestamp of "Jan. 1". It gets updated independently by two clients, while they're offline: on Client A on Feb. 1 and on Client B on Feb. 2, each updating the bookmark to have a different changed address field. Upon reconnecting to the server, do the clients communicate to the server that each entry was changed with a "previous synched change: Jan. 1", so that the server knows to resolve the conflict by splitting Entry #1234 into two database entries, the existing #1234 and a new bookmark #5678?
Or will the server just go with with the most recent (Feb. 2) one? (That wouldn't be good, IMO.)