Nothing fancy, just text as serialized json.
At run time there is a data structure with all the messages and lists.
When we send a prompt, it builds a payload with the current state and includes a whole bunch of context about whats happening in the sim/race, what people have been saying in chat, and of course the long/medium term memories as system messages.
When the system shuts down, it takes that whole data structure that represents its working memory, serializes it and saves it to disk. Then the next time it starts up it loads the previous state.
I save the current one to a file that always has the same name, but I also save a timestamped copy so I can go back and review what was in a particular previous state. I’ve also thought about including one or more previous long term memory chunks to include in the consolidation and may do experiments with that eventually.