I actually working on an agent library in golang and this is exactly the thought process I've come up with. If we have comprehensive logging we can actual reconstruct the agents state at any position. Allowing for replays etc. You just need the timestamp(endpoint) and the parent run and you can build children/branched runs after that.

Through the use of both a map that holds a context tree and a database we can purge old sessions and then reconstruct them from the database when needed (for instance an async agent session with user input required).

We also don't have to hold individual objects for the agents/workflows/tools we just make them stateless in a map and can refernce the pointers through an id as needed. Then we have a stateful object that holds the previous actions/steps/"context".

To make sure the agents/workflows are consistent we can hash the output agent/workflow (as these are serializable in my system)

I have only implemented basic Agent/tools though and the logging/reconstruction/cancellation logic has not actually been done yet.