Each stack frame has its own isolated context. This pushes the token pressure down the stack. The top level conversation can go on for days in this arrangement. There is no need for summarization or other tricks.
Is this related to the paper on Recursive Language Models? I remember it mentioned something similar about "symbolic recursion", but the way you describe it makes it sound too simple, why is there an entire paper about it?
The RLM paper did inspire me to try it. This is where the term comes from. "Symbolic" should be taken to mean "deterministic" or "out of band" in this context. A lot of other recursive LLM schemes rely on the recursion being in the token stream (i.e.. "make believe you have a call stack and work through this problem recursively"). Clearly this pales in comparison to actual recursion with a real stack.