🚸 Restore active tool after ABL G29 (#23692)

Co-authored-by: Scott Lahteine <thinkyhead@users.noreply.github.com>

Marlin/src/feature/bedlevel/ubl/ubl_G29.cpp

@@ -316,7 +316,7 @@ void unified_bed_leveling::G29() {
     planner.synchronize();
     // Send 'N' to force homing before G29 (internal only)
     if (axes_should_home() || parser.seen_test('N')) gcode.home_all_axes();
-    TERN_(HAS_MULTI_HOTEND, if (active_extruder) tool_change(0));
+    TERN_(HAS_MULTI_HOTEND, if (active_extruder != 0) tool_change(0, true));
   }
 
   // Invalidate one or more nearby mesh points, possibly all.
@@ -663,7 +663,7 @@ void unified_bed_leveling::G29() {
     UNUSED(probe_deployed);
   #endif
 
-  TERN_(HAS_MULTI_HOTEND, tool_change(old_tool_index));
+  TERN_(HAS_MULTI_HOTEND, if (old_tool_index != 0) tool_change(old_tool_index));
   return;
 }
 

Marlin/src/gcode/bedlevel/G35.cpp

@@ -155,7 +155,7 @@ void GcodeSuite::G35() {
 
   // Restore the active tool after homing
   #if HAS_MULTI_HOTEND
-    tool_change(old_tool_index, DISABLED(PARKING_EXTRUDER)); // Fetch previous toolhead if not PARKING_EXTRUDER
+    if (old_tool_index != 0) tool_change(old_tool_index, DISABLED(PARKING_EXTRUDER)); // Fetch previous toolhead if not PARKING_EXTRUDER
   #endif
 
   #if BOTH(HAS_LEVELING, RESTORE_LEVELING_AFTER_G35)

Marlin/src/gcode/bedlevel/abl/G29.cpp

@@ -93,6 +93,10 @@ public:
   bool      dryrun,
             reenable;
 
+  #if HAS_MULTI_HOTEND
+    uint8_t tool_index;
+  #endif
+
   #if EITHER(PROBE_MANUALLY, AUTO_BED_LEVELING_LINEAR)
     int abl_probe_index;
   #endif
@@ -263,7 +267,10 @@ G29_TYPE GcodeSuite::G29() {
    */
   if (!g29_in_progress) {
 
-    TERN_(HAS_MULTI_HOTEND, if (active_extruder) tool_change(0));
+    #if HAS_MULTI_HOTEND
+      abl.tool_index = active_extruder;
+      if (active_extruder != 0) tool_change(0, true);
+    #endif
 
     #if EITHER(PROBE_MANUALLY, AUTO_BED_LEVELING_LINEAR)
       abl.abl_probe_index = -1;
@@ -891,6 +898,8 @@ G29_TYPE GcodeSuite::G29() {
 
   TERN_(HAS_DWIN_E3V2_BASIC, DWIN_CompletedLeveling());
 
+  TERN_(HAS_MULTI_HOTEND, if (abl.tool_index != 0) tool_change(abl.tool_index));
+
   report_current_position();
 
   TERN_(FULL_REPORT_TO_HOST_FEATURE, set_and_report_grblstate(M_IDLE));