The web docs say the revisions are saved every 10 minutes. Is that the only criterion?
I've lost some notes because of a plugin, and I don't see them in history. I've made sure to save everything and sync and even restart Joplin before enabling the plugin; I didn't do a backup, relying on the history feature. But there are no revisions. I'd expected a revision to be saved when syncing, or before modification after startup, or something like that.
So my question is: is this the intended behavior? In the future, can I somehow force the creation of a revision? Or is waiting 10 minutes the only way?
Not directly an answer to your question but I assembled a guide on restoring deleted notes which you could also use just to double check if your data is actually gone.
To check - you say that you "lost some notes" - do you mean that the entire note has gone or that changes made to a (still existing) note have been lost? The second case is the only one covered by the "in app" note revisions whereas the first requires somewhat more of a manual intervention (as per the guide).
As for backups, I honestly can't recommend the simple backup plugin enough.
No, it just deleted parts of note texts, not the notes themselves. I've been able to recreate the content since then. (And yes, I do use the backup plugin.)
This is not some major data loss; I'm just curious if I can improve my use of history.