You can write a config that points your claude code at any anthropic-compatible endpoint, and replace opus and sonnet with whatever you want. Things like deepseek and glm in there do not feel at all like they do in more minimal harnesses, but neither do they convincingly act like claude models. It's very stark and frankly they run like shit this way. Try it.
it's almost like the harness was specifically designed for their model and not others :)