Throw tmux in and this is my exact setup as well. I'm looking into finding ways to orchestrate entire workflows across multiple agents in a harness-agnostic way (locally at first).

I forgot to say, I use Tmux + Workmux

https://github.com/raine/workmux

Cmux is rather fancy if you still like a UI. Used to love iTerm but Cmux was perfect for tons of ClaudeCode/Codex instances.

Maybe you're interested in https://github.com/RivoLink/leaf. If so, I'd appreciate your feedback.