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+;;; system-commands.el --- System power and session management -*- lexical-binding: t; coding: utf-8; -*-
+;; author: Craig Jennings <c@cjennings.net>
+;;
+;;; Commentary:
+;;
+;; System commands for logout, lock, suspend, shutdown, reboot, and Emacs
+;; exit/restart. Provides both a keymap (C-; !) and a completing-read menu.
+;;
+;; Commands include:
+;; - Logout (terminate user session)
+;; - Lock screen (slock)
+;; - Suspend (systemctl suspend)
+;; - Shutdown (systemctl poweroff)
+;; - Reboot (systemctl reboot)
+;; - Exit Emacs (kill-emacs)
+;; - Restart Emacs (via systemctl --user restart emacs.service)
+;;
+;; Dangerous commands (logout, suspend, shutdown, reboot) require confirmation.
+;;
+;;; Code:
+
+(eval-when-compile (require 'keybindings))
+(eval-when-compile (require 'subr-x))
+(require 'rx)
+
+;; ------------------------------ System Commands ------------------------------
+
+(defun cj/system-cmd--resolve (cmd)
+  "Return (values symbol-or-nil command-string label) for CMD."
+  (cond
+   ((symbolp cmd)
+    (let ((val (and (boundp cmd) (symbol-value cmd))))
+      (unless (and (stringp val) (not (string-empty-p val)))
+        (user-error "Variable %s is not a non-empty string" cmd))
+      (list cmd val (symbol-name cmd))))
+   ((stringp cmd)
+    (let ((s (string-trim cmd)))
+      (when (string-empty-p s) (user-error "Command string is empty"))
+      (list nil s "command")))
+   (t (user-error "Error: cj/system-cmd expects a string or a symbol"))))
+
+(defun cj/system-cmd (cmd)
+  "Run CMD (string or symbol naming a string) detached via the shell.
+Shell expansions like $(...) are supported. Output is silenced.
+If CMD is deemed dangerous, ask for confirmation."
+  (interactive (list (read-shell-command "System command: ")))
+  (pcase-let ((`(,sym ,cmdstr ,label) (cj/system-cmd--resolve cmd)))
+    (when (and sym (get sym 'cj/system-confirm)
+               (memq (read-char-choice
+                      (format "Run %s now (%s)? (Y/n) " label cmdstr)
+                      '(?y ?Y ?n ?N ?\r ?\n ?\s))
+                     '(?n ?N)))
+      (user-error "Aborted"))
+    (let ((proc (start-process-shell-command "cj/system-cmd" nil
+                                             (format "nohup %s >/dev/null 2>&1 &" cmdstr))))
+      (set-process-query-on-exit-flag proc nil)
+      (set-process-sentinel proc #'ignore)
+      (message "Running %s..." label))))
+
+(defmacro cj/defsystem-command (name var cmdstr &optional confirm)
+  "Define VAR with CMDSTR and interactive command NAME to run it.
+If CONFIRM is non-nil, mark VAR to always require confirmation."
+  (declare (indent defun))
+  `(progn
+     (defvar ,var ,cmdstr)
+     ,(when confirm `(put ',var 'cj/system-confirm t))
+     (defun ,name ()
+       ,(format "Run %s via `cj/system-cmd'." var)
+       (interactive)
+       (cj/system-cmd ',var))))
+
+;; Define system commands
+(cj/defsystem-command cj/system-cmd-logout   logout-cmd "loginctl terminate-user $(whoami)" t)
+(cj/defsystem-command cj/system-cmd-lock     lockscreen-cmd "slock")
+(cj/defsystem-command cj/system-cmd-suspend  suspend-cmd "systemctl suspend" t)
+(cj/defsystem-command cj/system-cmd-shutdown shutdown-cmd "systemctl poweroff" t)
+(cj/defsystem-command cj/system-cmd-reboot   reboot-cmd "systemctl reboot" t)
+
+(defun cj/system-cmd-exit-emacs ()
+  "Exit Emacs server and all clients."
+  (interactive)
+  (when (memq (read-char-choice
+               "Exit Emacs? (Y/n) "
+               '(?y ?Y ?n ?N ?\r ?\n ?\s))
+              '(?n ?N))
+    (user-error "Aborted"))
+  (kill-emacs))
+
+(defun cj/system-cmd-restart-emacs ()
+  "Restart Emacs server after saving buffers."
+  (interactive)
+  (when (memq (read-char-choice
+               "Restart Emacs? (Y/n) "
+               '(?y ?Y ?n ?N ?\r ?\n ?\s))
+              '(?n ?N))
+    (user-error "Aborted"))
+  (save-some-buffers)
+  ;; Start the restart process before killing Emacs
+  (run-at-time 0.5 nil
+               (lambda ()
+                 (call-process-shell-command
+                  "systemctl --user restart emacs.service && emacsclient -c"
+                  nil 0)))
+  (run-at-time 1 nil #'kill-emacs)
+  (message "Restarting Emacs..."))
+
+(defvar-keymap cj/system-command-map
+  :doc "Keymap for system commands."
+  "L" #'cj/system-cmd-logout
+  "r" #'cj/system-cmd-reboot
+  "s" #'cj/system-cmd-shutdown
+  "S" #'cj/system-cmd-suspend
+  "l" #'cj/system-cmd-lock
+  "E" #'cj/system-cmd-exit-emacs
+  "e" #'cj/system-cmd-restart-emacs)
+(keymap-set cj/custom-keymap "!" cj/system-command-map)
+
+(defun cj/system-command-menu ()
+  "Present system commands via \='completing-read\='."
+  (interactive)
+  (let* ((commands '(("Logout System"   . cj/system-cmd-logout)
+                     ("Lock Screen"     . cj/system-cmd-lock)
+                     ("Suspend System"  . cj/system-cmd-suspend)
+                     ("Shutdown System" . cj/system-cmd-shutdown)
+                     ("Reboot System"   . cj/system-cmd-reboot)
+                     ("Exit Emacs"      . cj/system-cmd-exit-emacs)
+                     ("Restart Emacs"   . cj/system-cmd-restart-emacs)))
+         (choice (completing-read "System command: " commands nil t)))
+    (when-let ((cmd (alist-get choice commands nil nil #'equal)))
+      (call-interactively cmd))))
+
+(keymap-set cj/custom-keymap "!" #'cj/system-command-menu)
+
+(with-eval-after-load 'which-key
+  (which-key-add-key-based-replacements "C-; !" "system commands"))
+
+(provide 'system-commands)
+;;; system-commands.el ends here