what if this magical harness is just: experienced operator† + claude code + official plugins + opus 4.7 + max effort ?

† swe with practical experience, a code wrangler if you will

There you have a verifier though. As in you have test cases (which are written in JS and thus do not need to be translated). The moment you have a verifier signal LLMs become extremely reliable. Now of course they can reward hack your test cases but in a large codebase with many tests it becomes the only small thing you have to worry about.