Have you tried the "use red/green TDD" trick?

I believe that increases the chances of one-shot code working, though it's also possible that it did that against Opus 4.5 and isn't necessary against Opus 4.7 but I haven't spotted the difference yet.

Yeah this is the way. Thinking about how it will verify that it has done the right thing is the key. This been be set up at the AGENTS.md level.

Very simple things like: "Write tests and make sure they pass." "Run lint after each change." "Write API docs in XYZ format."

In my experience, they are very good at fixing things they've done wrong after discovering them during those kinds of steps.