This is a very interesting idea and I really should consider Aider in the "scriptable" sense more, I only use interactively.
I might add another step after each PR is created where another agent(s?) review and compare the results (maybe have the other 2 agents review the first agents code?).
Thanks, and having another step for reviewing each other's code is a really cool extension to this, I'll give it a shot :) Whether it works or it doesn't it could be really interesting for a future post!
Wonder if you could have the reviewer characterize any mistakes and feed those back into the coding prompt: “be sure to… be sure not to…”