If you’re not building something fully decentralized, you may be able to loosen some of the constraints CRDTs require. As an example, if you can guarantee that all clients have received changes later than X date, you can safely drop any operations from before that date.
Could you also make it fully decentralized but require clients to come online within a deadline (1 day, week) or risk losing their local changes? This would also allowing trimming history but with loss of some functionality to sync.
