Why cant you just build a project document that outlines that prompt that you want to do? Or have claude save your progress in memory so you can pick it up later? Thats what I do. It seems abhorrent to expect to have a running prompt that left idle for long periods of time just so you can pick up at a moments whim...
You know that memory goes back into a prompt as context that wasn't cached, so... that just adds work.
Granted, the "memory" can be available across session, as can docs...
recursive-mode does just that: https://recursive-mode.dev/introduction