External persistence hook during CleanupJob.ExecuteAsync

[DanielMPries]

I'd like to consider the option to externally persist or move a workflow in the retention policy when its ready to be cleaned up. The idea being that I'd like to keep the execution database clean and performant but I may need to audit workflow and activity state.

I'm leaning towards an Action<WorkflowInstance> or a Func<WorkflowInstance, T> in the retention policy options to allow the mechanism of that capture, to be up to the users needs. A database could be fine if auditing is via the designer; however, firing off an HTTP message to another server of the serialized workflow could be enough as well.

In either sense, being able to move completed or faulted flows out of the execution context would enable performance while also ensuring auditability. Thoughts?