Yeah so I've been working with Claude on that. Typically it greps to find what it's looking for and that can be a lot of tokens. So I created something halfway between rag and that (semantic search), and overall it lowers token usage a bit, but even if it optimistically reduces tokens 20%, Claude is hungry for docs.
There is automatic compaction, but I typically want to control that myself when I change focus (if I don't just /clear it). Still I'd say almost all of the stuff I do runs north of 100k tokens.