This summer my team basically shut down when we hit a usage cap because we had recently pushed a decent portion of our devops workflow into agent skills. It had been done in such a way that it was difficult for humans to navigate. Relevant scripts turned out to be buggy and poorly documented, and nobody realized because these harnesses that are tuned to be absurdly tenacious about searching for workarounds had been quietly burning heaps of tokens on muddling through instead of raising any alerts about the horribly broken state of the system.
I do agree that home (or at least independently) grown harnesses might be the next logical step. Harness vendors who charge by the token have an inescapable conflict of interest here. Moderate, well-governed LLM usage isn't good for their revenue.