> But yeah spinning up a green fields project in an extensively solved area (ledgers) is going to be something an AI shines at.

I couldn't disagree with this more. It's impressive at building demos, but asking it to build the foundation for a long-term project has been disastrous in my experience.

When you have an established project and you're asking it to color between the lines it can do that well (most of the time), but when you give it a blank canvas and a lot of autonomy it will likely end up generating crap code at a staggering pace. It becomes a constant fight against entropy where every mess you don't clean up immediately gets picked up as "the way things should be done" the next time.

Before someone asks, this is my experience with both Claude Code (Sonnet/Opus 4.6) and Codex (GPT 5.4).