Thanks for the pointers. I forgot to mention that in my example, the firstName and lastName fields are not mutable, and the combination of these fields is guaranteed to be unique (i.e., there can only be one John Smith). The age field, however, is mutable. Given this constraint, I believe there could be a more elegant sync approach than the "Create duplicates in CloudKit and delete one" method if only it would be possible for me to set recordName as I wish.

Yes, my usage of word "daemon" was a little ambiguous. I meant it in context of anything that runs without UI. Whether launchd daemon or launchd agent. But CKSyncEngine has following event hook - accountChange(CKSyncEngine.Event.AccountChange) - wouldn't presence of this hook imply that CKSyncEngine (and hence also CloudKit subscriptions) could in theory work also from launchd daemon? At least when particular user signs in on MacOs?

Yes, my usage of word "daemon" was a little ambiguous. I meant it in context of anything that runs without UI. Whether launchd daemon or launchd agent. But CKSyncEngine has following event hook - accountChange(CKSyncEngine.Event.AccountChange) - wouldn't presence of this hook imply that CKSyncEngine (and hence also CloudKit subscriptions) could in theory work also from launchd daemon? At least when user signs in on MacOs?

That did work, Thank you! However, would CloudKit change notifications work too from Command Line app too?