If people start using the Claude Max plans with other agent harnesses that don't use the same kinds of optimizations the economics may no longer have worked out.
(But I also buy that they're going for horizontal control of the stack here and banning other agent harnesses was a competitive move to support that.)
I've had a similar experience with opencode, but I find that works better with my local models anyway.
(There probably is, but I found it very hard to make sense of the UI and how everything works. Hard to change models, no chat history etc.?)