Claude Code, Fable 5, xhigh reasoning, allow it to run the full CI, end to end and benchmark, it will not make silly mistakes (or only occasionally). Also, be able to state what you desire. Have any docs or materials in the same directory so the model can reference it. For even better results: turn on speech recognition and braindump what you know about the system, its goals, its context, history anything relevant, any gotchas you'd explain to a new employee or intern. Talk for 5-10 minutes. This is optional, "make it faster" can already get a large part of the job done.
And if it doesn't work well, describe what you dislike in its solution and tell it. Even just one extra iteration can make things work.
(I guess GPT-5.6 can be similarly good, I use Claude)
I feel like some people are emotionally invested in it not working and subconsciously sabotage their own effective use of the tool.
I mean yeah, that's mostly what I'm saying?
The only parts where I would disagree are that capabilities are spiky, and also the fact that they're a bit prone to losing the forest for the trees without guidance (the macro/micro distinction). But yeah, by default I don't write code by hand.