refactor: one place each for "in view" and the keyboard's backspace

ui-new's messagesInView() and ui-lvgl's threadInView() hold the
lit-and-unlocked test the viewing checks repeated; the keyboard's three
copies of the backspace call deleteBeforeCursor(). A stale comment on the
cursor-mode hint goes, onDisplayOn() sits after the view helpers it calls.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

examples/companion_radio/MyMesh.cpp

@@ -3469,8 +3469,9 @@ void MyMesh::loop() {
   if ((dirty_contacts_expiry && millisHasNowPassed(dirty_contacts_expiry))
       || (dirty_paths_expiry && millisHasNowPassed(dirty_paths_expiry))) {
     if (millis() - _last_input_ms < USER_QUIET_MILLIS) {
-      if (dirty_contacts_expiry) dirty_contacts_expiry = futureMillis(LAZY_CONTACTS_WRITE_DELAY);
-      if (dirty_paths_expiry) dirty_paths_expiry = futureMillis(LAZY_CONTACTS_WRITE_DELAY);
+      unsigned long later = futureMillis(LAZY_CONTACTS_WRITE_DELAY);
+      if (dirty_contacts_expiry) dirty_contacts_expiry = later;
+      if (dirty_paths_expiry) dirty_paths_expiry = later;
     } else {
       saveContacts();
       dirty_contacts_expiry = dirty_paths_expiry = 0;

examples/companion_radio/ui-lvgl/UITask.cpp

@@ -1914,12 +1914,16 @@ void UITask::onMessageArrived(const UiEvent& ev) {
 }
 
 // On screen: a conversation left open under the lock or a dark display isn't read.
+bool UITask::threadInView() const {
+  return !_asleep && !locked() && _screen == SCR_THREAD;
+}
+
 bool UITask::isViewingChannel(uint8_t channel_idx) {
-  return !_asleep && !locked() && _screen == SCR_THREAD && _thread_is_channel && _thread_channel == channel_idx;
+  return threadInView() && _thread_is_channel && _thread_channel == channel_idx;
 }
 
 bool UITask::isViewingDM(const uint8_t* pub_key) {
-  return !_asleep && !locked() && _screen == SCR_THREAD && !_thread_is_channel && memcmp(_thread_key, pub_key, 4) == 0;
+  return threadInView() && !_thread_is_channel && memcmp(_thread_key, pub_key, 4) == 0;
 }
 
 // ── Status bar + toast (top layer, over every screen) ─────────────────────────

examples/companion_radio/ui-lvgl/UITask.h

@@ -430,6 +430,7 @@ private:
   void buildThread();
   void threadOpenAt(int first);
   void reopenThreadIfUnread();
+  bool threadInView() const;   // a thread on a lit, unlocked screen
   void refreshThread();
   void refreshThreadAges();
   uint32_t threadSignature() const;

examples/companion_radio/ui-new/KeyboardWidget.h

@@ -546,6 +546,7 @@ struct KeyboardWidget {
     return p;
   }
 
+  // Backspace: the codepoint before the cursor.
   void deleteBeforeCursor() {
     t9_cell = -1;
     if (cursor_pos <= 0) return;
@@ -600,9 +601,7 @@ struct KeyboardWidget {
     // Compact mode only ever draws 2 short hint lines (no grid, no status line
     // -- see below), but reserves at least as much height as the smallest real
     // grid (T9's 3 rows) would need, rather than shrinking to just those 2
-    // lines: cursor_mode's own 3-line hint (drawn in this same region,
-    // regardless of Compact, for a physical-button user) already relies on
-    // that floor and would otherwise get clipped.
+    // lines, so the preview keeps the same height whichever mode is on.
     // A tall screen (the 4.2" panel: 20 lines) gives the keys half a line more each.
     const int key_lh    = display.height() >= 18 * lh ? lh * 3 / 2 : lh;
     const int kb_h      = compact_ui ? (KB_T9_ROWS + 1) * lh : (rows + 1) * key_lh;
@@ -1077,13 +1076,7 @@ struct KeyboardWidget {
     // no ambiguity to resolve at this layer -- pollCardKB() already decided.
     if (c == KEY_KB_ENTER) return DONE;
     if (c == 0x08) {
-      t9_cell = -1;   // invalidate any pending T9 cycle -- see the grid paths below
-      if (cursor_pos > 0) {
-        int n = kbUtf8LastCharBytes(buf, cursor_pos);
-        memmove(buf + cursor_pos - n, buf + cursor_pos, len - cursor_pos);
-        len -= n; cursor_pos -= n;
-        buf[len] = '\0';
-      }
+      deleteBeforeCursor();   // also ends any pending T9 cycle -- see the grid paths below
       return NONE;
     }
     if (c >= 0x20 && c <= 0x7E) {
@@ -1140,13 +1133,7 @@ struct KeyboardWidget {
         }
         // special row
         if (col == 0) {
-          t9_cell = -1;
-          if (cursor_pos > 0) {
-            int n = kbUtf8LastCharBytes(buf, cursor_pos);
-            memmove(buf + cursor_pos - n, buf + cursor_pos, len - cursor_pos);
-            len -= n; cursor_pos -= n;
-            buf[len] = '\0';
-          }
+          deleteBeforeCursor();
         } else if (col == 1) {
           pin_mode = false;   // ABC switch: the user's own layout
           row = col = 0;
@@ -1304,14 +1291,7 @@ struct KeyboardWidget {
               buf[len] = '\0';
             }
             break;
-          case 2:
-            if (cursor_pos > 0) {
-              int n = kbUtf8LastCharBytes(buf, cursor_pos);
-              memmove(buf + cursor_pos - n, buf + cursor_pos, len - cursor_pos);
-              len -= n; cursor_pos -= n;
-              buf[len] = '\0';
-            }
-            break;
+          case 2: deleteBeforeCursor(); break;
           case 3:
             openPlaceholders();
             break;

examples/companion_radio/ui-new/MessagesScreen.h

@@ -1063,13 +1063,6 @@ public:
     _dm_hist_scroll = 0;
     _dm_fs.active = false;
   }
-  // The display came back on over a conversation: what was filed while it was
-  // dark is unread -- read on from its first message, as on opening.
-  void onDisplayOn() {
-    if (_ctx_menu.active) return;
-    if (_phase == CHANNEL_HIST && !_fs.active && _history.chUnread(_sel_channel_idx) > 0) beginChannelView(_sel_channel_idx);
-    else if (_phase == DM_HIST && !_dm_fs.active && _task->getDMUnread(_sel_contact.id.pub_key) > 0) beginDmView();
-  }
   void beginChannelView(uint8_t channel_idx) {
     _sel_channel_idx = channel_idx;
     _unread_at_entry = (int)_history.chUnread(channel_idx);
@@ -1081,6 +1074,13 @@ public:
     _hist_sel = _new_idx >= 0 ? _new_idx : _history.histCountForChannel(channel_idx) > 0 ? 0 : -1;
     _fs.active = false;
   }
+  // The display came back on over a conversation: what was filed while it was
+  // dark is unread -- read on from its first message, as on opening.
+  void onDisplayOn() {
+    if (_ctx_menu.active) return;
+    if (_phase == CHANNEL_HIST && !_fs.active && _history.chUnread(_sel_channel_idx) > 0) beginChannelView(_sel_channel_idx);
+    else if (_phase == DM_HIST && !_dm_fs.active && _task->getDMUnread(_sel_contact.id.pub_key) > 0) beginDmView();
+  }
 
   // On the first unread (sel), opening: the scroll showing it highest with
   // "New" above it (stack(s) lays out from s, sets div_y when "New" fits).

examples/companion_radio/ui-new/UITask.cpp

@@ -2280,13 +2280,14 @@ void UITask::pickBotRoomTarget() {
 MyMesh::Listener* UITask::meshListener() { return _core; }
 
 // On screen: a conversation left open under the lock or a dark display isn't read.
+bool UITask::messagesInView() const {
+  return curr == messages_screen && _display && _display->isOn() && !_locked;
+}
 bool UITask::isViewingChannel(uint8_t channel_idx) {
-  return curr == messages_screen && _display && _display->isOn() && !_locked
-      && ((MessagesScreen*)messages_screen)->isViewingChannel(channel_idx);
+  return messagesInView() && ((MessagesScreen*)messages_screen)->isViewingChannel(channel_idx);
 }
 bool UITask::isViewingDM(const uint8_t* pub_key) {
-  return curr == messages_screen && _display && _display->isOn() && !_locked
-      && ((MessagesScreen*)messages_screen)->isViewingDM(pub_key);
+  return messagesInView() && ((MessagesScreen*)messages_screen)->isViewingDM(pub_key);
 }
 void UITask::onViewedHistoryGrew(bool channel) {
   ((MessagesScreen*)messages_screen)->onViewedHistoryGrew(channel);
@@ -3170,8 +3171,8 @@ void UITask::loop() {
   pollConnection();   // BLE link state -> hasConnection() (see UITaskBase)
   drainCoreEvents();  // react to what the Core filed during mesh processing (alerts, wake, sounds)
   {  // a conversation in view again (display on, unlocked): on to what came in meanwhile
-    bool on = _display && _display->isOn() && !_locked;
-    if (on && !_display_was_on && curr == messages_screen) ((MessagesScreen*)messages_screen)->onDisplayOn();
+    bool on = messagesInView();
+    if (on && !_display_was_on) ((MessagesScreen*)messages_screen)->onDisplayOn();
     _display_was_on = on;
   }
   if (status_screen) ((StatusScreen*)status_screen)->sample();   // Status history lines, once a minute

examples/companion_radio/ui-new/UITask.h

@@ -60,10 +60,11 @@ class UITask : public UITaskBase, public UiCoreHost {
   GenericVibration vibration;
 #endif
   unsigned long _next_refresh, _auto_off;
-  bool _display_was_on = true;   // loop(): the display back on and unlocked
+  bool _display_was_on = true;   // loop(): messagesInView() last time round
   NodePrefs* _node_prefs;
   bool _locked;
   bool _tool_from_home = false;
+  bool messagesInView() const;   // Messages on a lit, unlocked display
   unsigned long _lock_wake_until;  // when to blank screen again after locked wake (5s)
   int  _lock_seq_count;            // Enter presses while Back held (lock/unlock sequence)
   unsigned long _lock_seq_ms;      // millis() of last lock-sequence press (for timeout)