Smart rule when a new document is synced?

I’ve got a synced database on two machines. I’m trying to trigger an action via Smart Rule when a new (synced) document from machine A ‘shows up’ on machine B. There doesn’t seem to be a direct way to do that? I could use “On synchronization” and then tag (or even remove) processed documents. But is there a standardized way to trigger an action on “when a new document appears in synced database”?

Have you tried After Synchronization?

Yes, but it keeps triggering every time the database is synchronized. I think the workaround is to add a tag on machine A before synchronization and remove that tag after synchronization on machine B? Or can it be done more efficient?

What location are you targeting with the smart rule?

The database on machine B with Any Kind of document

Then a tag applied on machine A and removed on B would be a good criterion IMHO.