refactor(companion): unify screen save-on-exit via UITask::savePrefsIfDirty()

The "_dirty bool, then if (_dirty) the_mesh.savePrefs() on exit" pattern was
duplicated across 9 screens with subtle divergence: some cleared the flag
after saving, some left it set and relied on onShow() to reset. Replace all
12 exit sites with a single _task->savePrefsIfDirty(flag) helper that saves
once only if dirty and always clears the flag, so the "did we touch flash?"
answer lives in one place and the reset is consistent.

Edit sites still mark the flag manually (inherent to change tracking); only
the persist-on-exit boilerplate is centralised.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

examples/companion_radio/ui-new/AutoAdvertScreen.h

@@ -51,7 +51,7 @@ public:
 
   bool handleInput(char c) override {
     if (c == KEY_CANCEL || c == KEY_CONTEXT_MENU) {
-      if (_dirty) the_mesh.savePrefs();
+      _task->savePrefsIfDirty(_dirty);
       _task->gotoToolsScreen();
       return true;
     }

examples/companion_radio/ui-new/BotScreen.h

@@ -141,7 +141,7 @@ public:
     }
 
     if (cancel) {
-      if (_dirty) the_mesh.savePrefs();
+      _task->savePrefsIfDirty(_dirty);
       _task->gotoToolsScreen();
       return true;
     }

examples/companion_radio/ui-new/DashboardConfigScreen.h

@@ -65,7 +65,7 @@ public:
 
   bool handleInput(char c) override {
     if (c == KEY_CANCEL || c == KEY_CONTEXT_MENU) {
-      if (_dirty) the_mesh.savePrefs();
+      _task->savePrefsIfDirty(_dirty);
       _task->gotoHomeScreen();
       return true;
     }

examples/companion_radio/ui-new/LiveShareScreen.h

@@ -161,7 +161,7 @@ public:
 
   bool handleInput(char c) override {
     if (c == KEY_CANCEL || c == KEY_CONTEXT_MENU) {
-      if (_dirty) { the_mesh.savePrefs(); _dirty = false; }
+      _task->savePrefsIfDirty(_dirty);
       _task->gotoToolsScreen();
       return true;
     }

examples/companion_radio/ui-new/LocatorScreen.h

@@ -293,7 +293,7 @@ public:
       return true;
     }
     if (c == KEY_CANCEL || c == KEY_CONTEXT_MENU) {
-      if (_dirty) { the_mesh.savePrefs(); _dirty = false; }   // engine re-seeded per edit
+      _task->savePrefsIfDirty(_dirty);   // engine re-seeded per edit
       _task->gotoToolsScreen();
       return true;
     }

examples/companion_radio/ui-new/QuickMsgScreen.h

@@ -1606,9 +1606,7 @@ public:
             // sel == 1 (Notif) and sel == 2 (Melody): already cycled via LEFT/RIGHT; ENTER just closes.
           }
         }
-        if (res != PopupMenu::NONE && _ctx_dirty) {
+        if (res != PopupMenu::NONE) _task->savePrefsIfDirty(_ctx_dirty);
-          the_mesh.savePrefs(); _ctx_dirty = false;
-        }
         return true;
       }
       if (c == KEY_CANCEL) { _room_mode = false; _phase = MODE_SELECT; return true; }
@@ -1718,9 +1716,7 @@ public:
           }
           // sel 1/2/3 already handled by LEFT/RIGHT; ENTER just closes.
         }
-        if (res != PopupMenu::NONE && _ctx_dirty) {
+        if (res != PopupMenu::NONE) _task->savePrefsIfDirty(_ctx_dirty);
-          the_mesh.savePrefs(); _ctx_dirty = false;
-        }
         return true;
       }
       if (c == KEY_CANCEL) { _phase = MODE_SELECT; return true; }

examples/companion_radio/ui-new/RepeaterScreen.h

@@ -211,7 +211,7 @@ public:
     }
 
     if (c == KEY_CANCEL || c == KEY_CONTEXT_MENU) {
-      if (_dirty) the_mesh.savePrefs();
+      _task->savePrefsIfDirty(_dirty);
       _task->gotoToolsScreen();
       return true;
     }

examples/companion_radio/ui-new/SettingsScreen.h

@@ -754,7 +754,7 @@ public:
     }
 
     if (c == KEY_CANCEL) {
-      if (_dirty) the_mesh.savePrefs();
+      _task->savePrefsIfDirty(_dirty);
       _task->gotoHomeScreen();
       return true;
     }

examples/companion_radio/ui-new/TrailScreen.h

@@ -192,16 +192,16 @@ public:
           case ACT_EXPORT:        handleExport();      break;
           case ACT_EXPORT_SAVED:  handleExportSaved(); break;
         }
-        if (_cfg_dirty) { the_mesh.savePrefs(); _cfg_dirty = false; }
+        _task->savePrefsIfDirty(_cfg_dirty);
       } else if (res == PopupMenu::CANCELLED) {
-        if (_cfg_dirty) { the_mesh.savePrefs(); _cfg_dirty = false; }
+        _task->savePrefsIfDirty(_cfg_dirty);
         if (_menu_level != ML_MAIN) buildMainMenu();   // Cancel backs out of a submenu
       }
       return true;
     }
 
     if (c == KEY_CANCEL) {
-      if (_cfg_dirty) { the_mesh.savePrefs(); _cfg_dirty = false; }
+      _task->savePrefsIfDirty(_cfg_dirty);
       if (_return_home) _task->gotoHomeScreen();
       else              _task->gotoToolsScreen();
       return true;

examples/companion_radio/ui-new/UITask.cpp

@@ -1758,6 +1758,13 @@ void UITask::setCurrScreen(UIScreen* c) {
   _next_refresh = 100;
 }
 
+bool UITask::savePrefsIfDirty(bool& dirty) {
+  if (!dirty) return false;
+  the_mesh.savePrefs();
+  dirty = false;
+  return true;
+}
+
 /*
   hardware-agnostic pre-shutdown activity should be done here
 */

examples/companion_radio/ui-new/UITask.h

@@ -355,6 +355,11 @@ public:
   void applyPowerSave();   // hardware duty-cycle RX on/off from prefs
   void applyApc();         // Adaptive Power Control on/off from prefs
   void applyRadioParams(); // freq/bw/sf/cr from prefs (radio preset change)
+  // Save-on-exit helper for the screen `_dirty` pattern: persists NodePrefs once
+  // only if `dirty`, then clears the flag. Standardises the screens' exit paths
+  // (some used to leave the flag set, relying on onShow() to reset it) and keeps
+  // the "did we touch flash?" answer in one place. Returns whether it saved.
+  bool savePrefsIfDirty(bool& dirty);
   void applyFont();
   void applyRotation();
   void applyFullRefreshInterval();