feat(ui): Favourites phase 3 — in-place pin picker on empty tile

Enter on an empty Favourites slot opens a PopupMenu listing candidate
contacts. Sourced first from upstream-favourited chat contacts (those
flagged with c.flags & 0x01), then from recent DM contacts (resolved
from the 4-byte _dm_hist prefix to a full 6-byte pub_key via the contact
list), deduped against the favourites list. Capped at 12 entries.

Selection writes the chosen 6-byte prefix into the target slot; if the
contact is already pinned elsewhere, the previous slot is vacated first
(one contact per dial, per the agreed pin-only semantics). savePrefs
commits to flash and a brief alert confirms.

Plumbing:
- New QuickMsgScreen::getRecentDMContacts() resolves recent DM senders
  to 6-byte pub_key prefixes, deduped, newest first
- UITask::getRecentDMContacts() wraps it so HomeScreen doesn't reach
  into the QuickMsg screen directly
- HomeScreen gains its own PopupMenu + per-entry pub_key / label buffers
  (12 × 6 B keys + 12 × 22 B labels), no shared state with QuickMsg's
  Contact-options menu

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

examples/companion_radio/ui-new/QuickMsgScreen.h

@@ -475,6 +475,32 @@ public:
     _viewing_max_seen = 0;
   }
 
+  // Recent DM contacts, newest first, deduped. Resolves the 4-byte
+  // _dm_hist prefix to a 6-byte pub_key prefix by walking the contact
+  // list once per unique sender. Returns the number filled.
+  int getRecentDMContacts(uint8_t out[][NodePrefs::FAVOURITE_PREFIX_LEN], int max) const {
+    int n = 0;
+    for (int i = _dm_hist_count - 1; i >= 0 && n < max; i--) {
+      int pos = (_dm_hist_head + i) % DM_HIST_MAX;
+      const uint8_t* p4 = _dm_hist[pos].prefix;
+      // Skip if already collected.
+      bool dup = false;
+      for (int j = 0; j < n; j++) if (memcmp(out[j], p4, 4) == 0) { dup = true; break; }
+      if (dup) continue;
+      // Find a real contact whose pub_key starts with this 4-byte prefix.
+      for (int idx = 0; ; idx++) {
+        ContactInfo c;
+        if (!the_mesh.getContactByIdx(idx, c)) break;
+        if (memcmp(c.id.pub_key, p4, 4) == 0) {
+          memcpy(out[n], c.id.pub_key, NodePrefs::FAVOURITE_PREFIX_LEN);
+          n++;
+          break;
+        }
+      }
+    }
+    return n;
+  }
+
   // Jump straight into a contact's DM history (used by the Favourites dial).
   // Caller must have already reset() the screen. Marks the entry so KEY_CANCEL
   // from DM_HIST returns to the home screen instead of falling back through

examples/companion_radio/ui-new/UITask.cpp

@@ -143,6 +143,58 @@ class HomeScreen : public UIScreen {
   // Selected slot on the Favourites page (0..FAVOURITES_COUNT - 1).
   uint8_t _fav_sel = 0;
 
+  // Build the in-place pin picker list for an empty slot. Favourited chat
+  // contacts first (`c.flags & 0x01`), then recent DM contacts deduped
+  // against the favourites list. Up to PIN_PICKER_MAX.
+  void buildPinPicker(int slot) {
+    _pin_target_slot = slot;
+    _pin_count = 0;
+    // 1) Upstream-favourited chat contacts.
+    for (int idx = 0; _pin_count < PIN_PICKER_MAX; idx++) {
+      ContactInfo c;
+      if (!the_mesh.getContactByIdx(idx, c)) break;
+      if (c.type != ADV_TYPE_CHAT) continue;
+      if (!(c.flags & 0x01)) continue;
+      memcpy(_pin_keys[_pin_count], c.id.pub_key, NodePrefs::FAVOURITE_PREFIX_LEN);
+      DisplayDriver::translateUTF8Static(_pin_labels[_pin_count], c.name, sizeof(_pin_labels[_pin_count]));
+      _pin_count++;
+    }
+    // 2) Recent DM contacts (deduped).
+    uint8_t recent[PIN_PICKER_MAX][NodePrefs::FAVOURITE_PREFIX_LEN];
+    int rn = _task->getRecentDMContacts(recent, PIN_PICKER_MAX);
+    for (int i = 0; i < rn && _pin_count < PIN_PICKER_MAX; i++) {
+      bool dup = false;
+      for (int j = 0; j < _pin_count; j++)
+        if (memcmp(_pin_keys[j], recent[i], NodePrefs::FAVOURITE_PREFIX_LEN) == 0) { dup = true; break; }
+      if (dup) continue;
+      for (int idx = 0; ; idx++) {
+        ContactInfo c;
+        if (!the_mesh.getContactByIdx(idx, c)) break;
+        if (memcmp(c.id.pub_key, recent[i], NodePrefs::FAVOURITE_PREFIX_LEN) == 0) {
+          memcpy(_pin_keys[_pin_count], recent[i], NodePrefs::FAVOURITE_PREFIX_LEN);
+          DisplayDriver::translateUTF8Static(_pin_labels[_pin_count], c.name, sizeof(_pin_labels[_pin_count]));
+          _pin_count++;
+          break;
+        }
+      }
+    }
+    if (_pin_count == 0) {
+      _task->showAlert("No contacts available", 1000);
+      _pin_target_slot = -1;
+      return;
+    }
+    _pin_menu.begin("Pick contact", 3);
+    for (int i = 0; i < _pin_count; i++) _pin_menu.addItem(_pin_labels[i]);
+  }
+
+  // In-place pin picker (opens when Enter hits an empty Favourites tile).
+  static const int PIN_PICKER_MAX = 12;
+  PopupMenu _pin_menu;
+  uint8_t   _pin_keys[PIN_PICKER_MAX][NodePrefs::FAVOURITE_PREFIX_LEN];
+  char      _pin_labels[PIN_PICKER_MAX][22];
+  int       _pin_count = 0;
+  int       _pin_target_slot = -1;
+
   UITask* _task;
   mesh::RTCClock* _rtc;
   SensorManager* _sensors;
@@ -811,6 +863,7 @@ public:
         }
         if (sel) display.setColor(DisplayDriver::LIGHT);
       }
+      if (_pin_menu.active) _pin_menu.render(display);
     } else if (_page == HomePage::SHUTDOWN) {
       display.setColor(DisplayDriver::LIGHT);
       display.setTextSize(1);
@@ -850,6 +903,25 @@ public:
     // left column and RIGHT at the right column fall through to page nav so the
     // user can still leave the page sideways.
     if (_page == HomePage::FAVOURITES) {
+      // Pin picker consumes all input while open.
+      if (_pin_menu.active) {
+        auto res = _pin_menu.handleInput(c);
+        if (res == PopupMenu::SELECTED && _pin_target_slot >= 0) {
+          int idx = _pin_menu.selectedIndex();
+          if (idx >= 0 && idx < _pin_count) {
+            // If this contact is already pinned elsewhere, vacate that slot first.
+            int existing = _task->findFavouriteSlot(_pin_keys[idx]);
+            if (existing >= 0 && existing != _pin_target_slot) _task->clearFavouriteSlot(existing);
+            _task->setFavouriteSlot(_pin_target_slot, _pin_keys[idx]);
+            the_mesh.savePrefs();
+            char alert[24];
+            snprintf(alert, sizeof(alert), "Pinned to slot %d", _pin_target_slot + 1);
+            _task->showAlert(alert, 800);
+          }
+        }
+        if (res != PopupMenu::NONE) _pin_target_slot = -1;
+        return true;
+      }
       DisplayDriver* d = _task->getDisplay();
       const int cols = (d && d->isLandscape()) ? 3 : 2;
       const int rows = NodePrefs::FAVOURITES_COUNT / cols;
@@ -879,7 +951,8 @@ public:
           }
           _task->showAlert("Contact not found", 800);
         } else {
-          _task->showAlert("Pin from contact options", 1000);
+          // Empty slot → open in-place pin picker.
+          buildPinPicker(_fav_sel);
         }
         return true;
       }
@@ -1071,6 +1144,10 @@ void UITask::openContactDM(const ContactInfo& ci) {
   setCurrScreen(quick_msg);
 }
 
+int UITask::getRecentDMContacts(uint8_t out[][NodePrefs::FAVOURITE_PREFIX_LEN], int max) const {
+  return ((QuickMsgScreen*)quick_msg)->getRecentDMContacts(out, max);
+}
+
 void UITask::addChannelMsg(uint8_t channel_idx, const char* text) {
   _last_notif_ch_idx = (int)channel_idx;
   ((QuickMsgScreen*)quick_msg)->addChannelMsg(channel_idx, text);

examples/companion_radio/ui-new/UITask.h

@@ -110,6 +110,7 @@ public:
   void gotoSettingsScreen();
   void gotoQuickMsgScreen();
   void openContactDM(const ContactInfo& ci);
+  int  getRecentDMContacts(uint8_t out[][NodePrefs::FAVOURITE_PREFIX_LEN], int max) const;
   void gotoToolsScreen();
   void gotoRingtoneEditor(int slot = 0);
   void gotoBotScreen();