Use FFDQ and some form of persistence mechanism to preserve the original data values of records passed between actors. Messages between actors should be immutable to avoid intermittent ConcurrentModification exceptions and to better reason about communication and dependencies between actors. Also important to think about coupling of actors in terms of the workflow builder and integration between different types of actors.

A messaging system approach using Kafka is a good fit for preserving the messages passed and has the added benefit of decoupling actors. Akka persistence is also a possible approach if we would also like to persist actor internal state at different stages of processing (comments, curation status).