I've had the same experience and it has really put me off working on personal projects using AI quite a few times, though I keep coming back. My recent experience with Fable and the latest Sonnet have actually been very positive though. They seem to be capable of working for much longer stretches without constantly stopping and requiring further prompting to finish up large features. The place where I feel flow the most now is when I'm planning large feature sets and I use the Claude web app as a sounding board while doing this and prompt it to not write any code but focus only on asking questions and clarifying aspects that I haven't fully thought out. This results in a very detailed plan for implementation which seems to work very well with Fable or even Sonnet 5. I can then actually leave my computer and go do other things without the constant nagging feeling that I need to check if its stopped and needs nudging. After its done I review the changes and do QA and testing and then formulate a plan for the next set of tasks. It feels like this problem is getting solved, which is wonderful.