This technique is pretty similar to Operational Transformations, except that it requires an authority for serialization and must re-apply any state which is out of sync.
Reflect is based on Server Reconciliation: https://www.gabrielgambetta.com/client-side-prediction-serve....
The critical difference is that Reflect doesn't need to know the operations up front. That is what allows developers to provide their own operations, or as we call them "mutators".