Most AI agents don't have a cost problem on paper. They have a cost problem at the end of the month. More and more people use AI agents for real work now — not just writing code, but making slide decks, writing marketing plans, running competitor research, doing daily office automation. Use them for a while and everyone hits the same wall: the bill. A lot of well-known agents are structurally token-hungry. $30 for a single complete task isn't unusual. The model isn't to blame. It's the harness layer around it: cache design that doesn't hold up, tool sets that keep growing, compression that destroys cache prefixes, context windows rebuilt from scratch every few turns. Each layer quietly burns money, and the user only gets educated once — when the monthly invoice arrives. We decided from day one to treat "spend less" as a top-level harness design goal, not an optimization pass you bolt on later.…