I hope this is an implementation detail and that the technology can, in the future, maintain the role playing across really long conversations.
As the context windows of Claude/GPT-4 etc increase, I think this will be less of an issue, but for now it's a pretty effective workaround.
Here's an example of the prompts I'm using (from an activity I just did with my world history class): https://docs.google.com/document/d/1sLRsUVJ_KSPtjrO83ko2MSFf...
And my writeup of an earlier version: https://resobscura.substack.com/p/simulating-history-with-ch...
There are vector database solutions that address the forgetting of context. Oobabooga has superbooga (chromadb), SillyTavern requires the headache of the Extras service but will let you use chromadb, Google or OpenAI. Koboldcpp doesn't do vectorization, but does have a clunky autogenerate-summary feature that injects a summary of events so far into the prompt.
Relatedly, when editing past prompts, I've found that it sometimes reuses things that were in the original branch of the conversation, even though they're not in the logical flow of the current conversation.