tmux by itself lets you create any number of sessions, windows and panes. You can arrange them for anything you want to do.

Having a pane dedicated to some LLM prompt split side by side with your code editor doesn't require additional tools, it's just a tmux hotkey to split a pane.

There's also plugins like tmux resurrect that lets you save and restore everything, including across reboots. I've been using this set up for like 6-7 years, here's a video from ~5 years ago but it still applies today https://www.youtube.com/watch?v=sMbuGf2g7gc&t=315s. I like this approach because you can use tmux normally, there's no layout config file you need to define.

It lets me switch between projects in 2 seconds and everything I need is immediately available.