Any advice on how to get Opus to not bullshit me and hallucinate the opposite of the correct answer? This is less about code, but more about best practices and functionality of applications (e.g. how do I do x y z with Github Desktop). It will often make up the perfectly wrong answer with total confidence and not budge even when pressured. I haven't had that issue with ChatGPT.

It's entirely possible that ChatGPT is behaving better because of the default beefy system prompt I'm using that asks it explicitly to not make stuff up and let me know when it's unsure, which unfortunately Claude doesn't seem to offer, requiring you to manually say that each time.