"all the work is investigation and debugging" - Yes! Exactly you can ask the AI a bunch of questions first and really dig into what the codebase currently does. Then spend the time crafting that prompt that explains how to surgically do what needs to be done. If you are watching it every min like a hawk you are doing it wrong. You need to watch it more like a VERY smart junior dev and trust but verify. I'm not saying it's easy to get good at these new skill sets. But simply throwing your hands up and saying "I'll just walk everywhere vs using a bicycle" isn't a strategy that's going to work well.