✨ Power-off confirm / beep options (#22191)

Marlin/Configuration.h

 //#define PSU_NAME "Power Supply"
 
 #if ENABLED(PSU_CONTROL)
+  //#define PS_OFF_CONFIRM          // Confirm dialog when power off
+  //#define PS_OFF_SOUND            // Beep 1s when power off
   #define PSU_ACTIVE_STATE LOW      // Set 'LOW' for ATX, 'HIGH' for X-Box
 
   //#define PSU_DEFAULT_OFF         // Keep power off until enabled directly with M80

Marlin/src/gcode/control/M80_M81.cpp

     #endif
   #endif
 
+  #if ENABLED(PS_OFF_SOUND)
+    BUZZ(1000, 659);
+  #endif
+
   safe_delay(1000); // Wait 1 second before switching off
 
   #if HAS_SUICIDE

Marlin/src/lcd/marlinui.cpp

     TERN_(HAS_LCD_MENU, return_to_status());
   }
 
+  #if BOTH(PSU_CONTROL, PS_OFF_CONFIRM)
+    void MarlinUI::poweroff() {
+      queue.inject_P(PSTR("M81"));
+      goto_previous_screen();
+    }
+  #endif
+
   void MarlinUI::flow_fault() {
     LCD_ALERTMESSAGEPGM(MSG_FLOWMETER_FAULT);
     TERN_(HAS_BUZZER, buzz(1000, 440));

Marlin/src/lcd/marlinui.h

     static void resume_print();
     static void flow_fault();
 
+    #if BOTH(PSU_CONTROL, PS_OFF_CONFIRM)
+      static void poweroff();
+    #endif
+
     #if HAS_WIRED_LCD
 
       static millis_t next_button_update_ms;

Marlin/src/lcd/menu/menu_main.cpp

   //
   #if ENABLED(PSU_CONTROL)
     if (powersupply_on)
-      GCODES_ITEM(MSG_SWITCH_PS_OFF, PSTR("M81"));
+      #if ENABLED(PS_OFF_CONFIRM)
+        CONFIRM_ITEM(MSG_SWITCH_PS_OFF,
+          MSG_YES, MSG_NO,
+          ui.poweroff, ui.goto_previous_screen,
+          GET_TEXT(MSG_SWITCH_PS_OFF), (const char *)nullptr, PSTR("?")
+        );
+      #else
+        GCODES_ITEM(MSG_SWITCH_PS_OFF, PSTR("M81"));
+      #endif
     else
       GCODES_ITEM(MSG_SWITCH_PS_ON, PSTR("M80"));
   #endif

buildroot/tests/rambo

            SKEW_CORRECTION SKEW_CORRECTION_FOR_Z SKEW_CORRECTION_GCODE \
            BACKLASH_COMPENSATION BACKLASH_GCODE BAUD_RATE_GCODE BEZIER_CURVE_SUPPORT \
            FWRETRACT ARC_P_CIRCLES CNC_WORKSPACE_PLANES CNC_COORDINATE_SYSTEMS \
-           PSU_CONTROL AUTO_POWER_CONTROL POWER_LOSS_RECOVERY POWER_LOSS_PIN POWER_LOSS_STATE POWER_LOSS_RECOVER_ZHOME POWER_LOSS_ZHOME_POS \
+           PSU_CONTROL PS_OFF_CONFIRM PS_OFF_SOUND AUTO_POWER_CONTROL \
+           POWER_LOSS_RECOVERY POWER_LOSS_PIN POWER_LOSS_STATE POWER_LOSS_RECOVER_ZHOME POWER_LOSS_ZHOME_POS \
            SLOW_PWM_HEATERS THERMAL_PROTECTION_CHAMBER LIN_ADVANCE EXTRA_LIN_ADVANCE_K \
            HOST_ACTION_COMMANDS HOST_PROMPT_SUPPORT PINS_DEBUGGING MAX7219_DEBUG M114_DETAIL
 opt_add DEBUG_POWER_LOSS_RECOVERY