Comment by jb_hn

Re: open-source harnesses, ForgeCode appears to be pretty good (currently, #1 on Terminal Bench 2.0 -- https://www.tbench.ai/leaderboard/terminal-bench/2.0). Re: open models, Kimi K2.6 might be a good place to start, but admittedly I'm not too sure how it'd compare to Sonnet / Opus for your use case.