StumpWM + spatial groups + Emacs-per-group-z-index = bliss.

init.lisp

;;;
;;; We run a server per z-index.
;;;
(defparameter *xdg-runtime-dir* (getenv "XDG_RUNTIME_DIR"))
(defparameter *emacs-socket-dir* (concatenate 'string *xdg-runtime-dir* "/emacs/"))

(defun cur-z ()
  (third (split-string (group-name (current-group)) ",")))
(defun cur-socket ()
  (concatenate 'string *emacs-socket-dir* (cur-z)))
(defun maybe-start-emacs-server ()
  (unless (probe-file (cur-socket))
    (run-shell-command (concatenate 'string "emacs --bg-daemon=" (cur-z)))
    (echo "Started Emacs server, sleeping a bit before starting client...")
    (sleep 10)
    (echo "Starting client")))

(defcommand emacs () ()
   "Start Emacs client with a z-index specific server"
   (maybe-start-emacs-server)
   (run-shell-command (concatenate 'string "emacsclient -c -s " (cur-socket))))