I'm using "harness engineering" to do this: smaller tasks, well defined stop conditions, runs in a VM with --yolo-mode. I've worked up to this, and ended up rolling my own thing because nothing I found did what I wanted:

* agent fan-out * VM containment * full harnesses with test/exit conditions * runs fully unattended

I expend a lot more energy on plans, though. I've got a full "Karpathy knowledgebase" that's effectively my jumping off point, so some of my projects have literally dozens or hundreds of docs they can source to build plans.