(defun rust-compile-send-input ()
"Read string from minibuffer and send it to the rust process of the current
(let ((input (read-from-minibuffer "Send input to rust process: "))
(proc (get-buffer-process (current-buffer)))
What I've got here works with iTerm2 3.3.11 + tmux 3.0a + Emacs 26.3 and is a combination of some previous answers here with a couple of tweaks.
The biggest problem I had was that despite them matching the CSI u spec, the codes in tarsius' answer did not support case-sensitive chords. I confirmed by going into sed -n l and trying out various key combinations ...