All of the "solo green field projects" I let LLMs mostly write, despite supplying the scaffolding, structure and specific implementation details as code, prompts or context, I can't tell you much about 6+ months later, except for the parts I did write.

It's like I never wrote them, because I didn't. I've got the gist of them, but it's the same way I get the gist of something like Numpy: I know how it works theoretically, but certainly not specifically enough to jump in and write some working Fortran that fixes bugs or adds features.

I now have a bunch of stalled projects I'm not very familiar with. I no longer do solo green field projects that way.