ui: QR sharing overlay + Share My QR header on Contacts tab

Adds an lxma://<hash>:<pubkey> QR overlay reachable from Settings and
from a new header row at the top of the Contacts tab. Including the
public key lets Columba/Sideband skip the PENDING_IDENTITY round-trip.

Contacts list stays visible even with no saved contacts so the header
row is always reachable; the empty-state floats above it.

lv_conf.h

@@ -63,14 +63,15 @@ extern const lv_font_t lv_font_ratdeck_14;
 #define LV_USE_ROLLER     1
 #define LV_USE_TABLE      0
 #define LV_USE_TABVIEW    0
-#define LV_USE_IMG        1
+#define LV_USE_IMG        1   // required by LV_USE_CANVAS / LV_USE_QRCODE
 #define LV_USE_LINE       0
 #define LV_USE_ARC        0
 #define LV_USE_SPINNER    0
 #define LV_USE_MSGBOX     0
 #define LV_USE_KEYBOARD   0
 #define LV_USE_CHECKBOX   0
-#define LV_USE_CANVAS     1
+#define LV_USE_CANVAS     1   // required by LV_USE_QRCODE
+#define LV_USE_QRCODE     1
 
 // Layouts
 #define LV_USE_FLEX 1

src/main.cpp

@@ -33,6 +33,7 @@
 #include "ui/screens/LvContactsScreen.h"
 #include "ui/screens/LvSettingsScreen.h"
 #include "ui/screens/LvHelpOverlay.h"
+#include "ui/screens/LvQrOverlay.h"
 // Map screen removed
 #include "ui/screens/LvNameInputScreen.h"
 #include "ui/screens/LvTimezoneScreen.h"
@@ -117,6 +118,7 @@ LvContactsScreen lvContactsScreen;
 LvMessageView lvMessageView;
 LvSettingsScreen lvSettingsScreen;
 LvHelpOverlay lvHelpOverlay;
+LvQrOverlay lvQrOverlay;
 // LvMapScreen removed
 LvNameInputScreen lvNameInputScreen;
 LvTimezoneScreen lvTimezoneScreen;
@@ -1071,8 +1073,22 @@ void setup() {
     });
 #endif
 
+    auto showQr = []() {
+        // Encode `lxma://<destHash>:<publicKey>` so Columba/Sideband
+        // scanners get a full identity (no PENDING_IDENTITY round-trip).
+        String destHex = rns.destinationHashHex();
+        String pubHex;
+        if (auto identity = rns.destination().identity()) {
+            pubHex = String(identity.get_public_key().toHex().c_str());
+        }
+        lvQrOverlay.show(destHex, pubHex);
+    };
+    lvSettingsScreen.setShowQrCallback(showQr);
+    lvContactsScreen.setShowQrCallback(showQr);
+
     // LVGL help overlay
     lvHelpOverlay.create();
+    lvQrOverlay.create();
 
     // Tab bar callbacks — LVGL
     lvTabScreens[LvTabBar::TAB_HOME]     = &lvHomeScreen;
@@ -1250,6 +1266,10 @@ void loop() {
         if (lvHelpOverlay.isVisible()) {
             lvHelpOverlay.handleKey(evt);
         }
+        // QR overlay also dismisses on any keypress while visible
+        else if (lvQrOverlay.isVisible()) {
+            lvQrOverlay.handleKey(evt);
+        }
         else {
             // Screen-local input owns the keyboard. This keeps message and
             // settings text entry from being preempted by global shortcuts.

src/ui/screens/LvContactsScreen.cpp

@@ -156,14 +156,55 @@ void LvContactsScreen::rebuildList() {
     _lastContactCount = count;
     _avatarBuffers.reserve(count);
 
-    if (count == 0) {
-        if (_emptyState) lv_obj_clear_flag(_emptyState, LV_OBJ_FLAG_HIDDEN);
-        lv_obj_add_flag(_list, LV_OBJ_FLAG_HIDDEN);
-        return;
+    // Keep list visible even with no contacts so the QR header row is reachable.
+    lv_obj_clear_flag(_list, LV_OBJ_FLAG_HIDDEN);
+    if (_emptyState) {
+        if (count == 0) {
+            lv_obj_clear_flag(_emptyState, LV_OBJ_FLAG_HIDDEN);
+            lv_obj_move_foreground(_emptyState);
+        } else {
+            lv_obj_add_flag(_emptyState, LV_OBJ_FLAG_HIDDEN);
+        }
     }
 
-    if (_emptyState) lv_obj_add_flag(_emptyState, LV_OBJ_FLAG_HIDDEN);
-    lv_obj_clear_flag(_list, LV_OBJ_FLAG_HIDDEN);
+    {
+        lv_obj_t* qrRow = lv_obj_create(_list);
+        lv_obj_set_size(qrRow, Theme::CONTENT_W, 28);
+        lv_obj_add_style(qrRow, LvTheme::styleListBtn(), 0);
+        lv_obj_add_style(qrRow, LvTheme::styleListBtnFocused(), LV_STATE_FOCUSED);
+        lv_obj_set_style_bg_color(qrRow, lv_color_hex(Theme::PRIMARY_SUBTLE), 0);
+        lv_obj_set_style_bg_opa(qrRow, LV_OPA_COVER, 0);
+        lv_obj_set_style_border_side(qrRow, LV_BORDER_SIDE_BOTTOM, 0);
+        lv_obj_set_style_border_width(qrRow, 1, 0);
+        lv_obj_set_style_border_color(qrRow, lv_color_hex(Theme::BORDER), 0);
+        lv_obj_set_style_pad_all(qrRow, 0, 0);
+        lv_obj_clear_flag(qrRow, LV_OBJ_FLAG_SCROLLABLE);
+        lv_obj_add_flag(qrRow, LV_OBJ_FLAG_CLICKABLE);
+        // Sentinel marks this as not-a-contact for handleLongPress().
+        lv_obj_set_user_data(qrRow, (void*)(intptr_t)-1);
+
+        lv_obj_add_event_cb(qrRow, [](lv_event_t* e) {
+            auto* self = (LvContactsScreen*)lv_event_get_user_data(e);
+            if (self->_showQrCb) self->_showQrCb();
+        }, LV_EVENT_CLICKED, this);
+
+        lv_group_add_obj(LvInput::group(), qrRow);
+        lv_obj_add_event_cb(qrRow, [](lv_event_t* e) {
+            lv_obj_scroll_to_view(lv_event_get_target(e), LV_ANIM_ON);
+        }, LV_EVENT_FOCUSED, nullptr);
+
+        lv_obj_t* qrLbl = lv_label_create(qrRow);
+        lv_obj_set_style_text_font(qrLbl, &lv_font_ratdeck_14, 0);
+        lv_obj_set_style_text_color(qrLbl, lv_color_hex(Theme::ACCENT), 0);
+        lv_label_set_text(qrLbl, "Share My QR");
+        lv_obj_align(qrLbl, LV_ALIGN_LEFT_MID, 12, 0);
+
+        lv_obj_t* hintLbl = lv_label_create(qrRow);
+        lv_obj_set_style_text_font(hintLbl, &lv_font_ratdeck_10, 0);
+        lv_obj_set_style_text_color(hintLbl, lv_color_hex(Theme::TEXT_MUTED), 0);
+        lv_label_set_text(hintLbl, "Enter");
+        lv_obj_align(hintLbl, LV_ALIGN_RIGHT_MID, -12, 0);
+    }
 
     unsigned long now = millis();
 

src/ui/screens/LvContactsScreen.h

@@ -18,6 +18,7 @@ public:
 
     void setAnnounceManager(AnnounceManager* am) { _am = am; }
     void setNodeSelectedCallback(NodeSelectedCallback cb) { _onSelect = cb; }
+    void setShowQrCallback(std::function<void()> cb) { _showQrCb = cb; }
     void setUIManager(class UIManager* ui) { _ui = ui; }
     bool handleLongPress() override;
 
@@ -29,6 +30,7 @@ private:
     AnnounceManager* _am = nullptr;
     class UIManager* _ui = nullptr;
     NodeSelectedCallback _onSelect;
+    std::function<void()> _showQrCb;
     bool _confirmDelete = false;
     bool _focusActive = false;
     int _deleteIdx = -1;

src/ui/screens/LvQrOverlay.cpp

@@ -0,0 +1,82 @@
+#include "LvQrOverlay.h"
+#include "ui/Theme.h"
+#include "ui/LvTheme.h"
+#include <lvgl.h>
+#include "fonts/fonts.h"
+
+void LvQrOverlay::create() {
+    if (_overlay) return;
+    _overlay = lv_obj_create(lv_layer_top());
+    lv_obj_set_size(_overlay, Theme::SCREEN_W, Theme::SCREEN_H);
+    lv_obj_align(_overlay, LV_ALIGN_TOP_LEFT, 0, 0);
+    lv_obj_set_style_bg_color(_overlay, lv_color_hex(Theme::BG), 0);
+    lv_obj_set_style_bg_opa(_overlay, LV_OPA_COVER, 0);
+    lv_obj_set_style_border_width(_overlay, 0, 0);
+    lv_obj_set_style_pad_all(_overlay, 6, 0);
+    lv_obj_set_style_pad_row(_overlay, 4, 0);
+    lv_obj_set_layout(_overlay, LV_LAYOUT_FLEX);
+    lv_obj_set_flex_flow(_overlay, LV_FLEX_FLOW_COLUMN);
+    lv_obj_set_flex_align(_overlay, LV_FLEX_ALIGN_CENTER, LV_FLEX_ALIGN_CENTER, LV_FLEX_ALIGN_CENTER);
+    lv_obj_clear_flag(_overlay, LV_OBJ_FLAG_SCROLLABLE);
+
+    lv_obj_t* title = lv_label_create(_overlay);
+    lv_obj_set_style_text_font(title, &lv_font_ratdeck_14, 0);
+    lv_obj_set_style_text_color(title, lv_color_hex(Theme::ACCENT), 0);
+    lv_label_set_text(title, "Scan to add me");
+
+    // 180px; dark-on-light for standard scanner contrast on 320x240.
+    _qr = lv_qrcode_create(_overlay,
+                           180,
+                           lv_color_hex(0x000000),
+                           lv_color_hex(0xFFFFFF));
+
+    _lblAddr = lv_label_create(_overlay);
+    lv_obj_set_style_text_font(_lblAddr, &lv_font_ratdeck_10, 0);
+    lv_obj_set_style_text_color(_lblAddr, lv_color_hex(Theme::TEXT_MUTED), 0);
+    lv_label_set_long_mode(_lblAddr, LV_LABEL_LONG_WRAP);
+    lv_obj_set_width(_lblAddr, Theme::SCREEN_W - 12);
+    lv_obj_set_style_text_align(_lblAddr, LV_TEXT_ALIGN_CENTER, 0);
+    lv_label_set_text(_lblAddr, "");
+
+    lv_obj_t* hint = lv_label_create(_overlay);
+    lv_obj_set_style_text_font(hint, &lv_font_ratdeck_10, 0);
+    lv_obj_set_style_text_color(hint, lv_color_hex(Theme::TEXT_MUTED), 0);
+    lv_label_set_text(hint, "Any key to close");
+
+    lv_obj_add_flag(_overlay, LV_OBJ_FLAG_HIDDEN);
+}
+
+void LvQrOverlay::show(const String& destHashHex, const String& publicKeyHex) {
+    if (!_overlay) create();
+
+    // lxma://<hash>:<pubkey> — Columba/Sideband format; pubkey skips
+    // the PENDING_IDENTITY round-trip on the scanning end.
+    String payload = "lxma://" + destHashHex;
+    if (publicKeyHex.length() > 0) {
+        payload += ":" + publicKeyHex;
+    }
+
+    if (_qr) {
+        if (lv_qrcode_update(_qr, payload.c_str(), payload.length()) != LV_RES_OK) {
+            return;
+        }
+    }
+    if (_lblAddr) {
+        lv_label_set_text(_lblAddr, destHashHex.c_str());
+    }
+
+    lv_obj_clear_flag(_overlay, LV_OBJ_FLAG_HIDDEN);
+    _visible = true;
+}
+
+void LvQrOverlay::hide() {
+    if (_overlay) lv_obj_add_flag(_overlay, LV_OBJ_FLAG_HIDDEN);
+    _visible = false;
+}
+
+bool LvQrOverlay::handleKey(const KeyEvent& event) {
+    if (!_visible) return false;
+    (void)event;
+    hide();
+    return true;
+}

src/ui/screens/LvQrOverlay.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include "ui/UIManager.h"
+
+// Fullscreen QR overlay — encodes lxma://<hash>:<pubkey> for Columba/Sideband.
+class LvQrOverlay {
+public:
+    void create();
+    void show(const String& destHashHex, const String& publicKeyHex);
+    void hide();
+    bool isVisible() const { return _visible; }
+    bool handleKey(const KeyEvent& event);
+
+private:
+    lv_obj_t* _overlay = nullptr;
+    lv_obj_t* _qr = nullptr;
+    lv_obj_t* _lblAddr = nullptr;
+    bool _visible = false;
+};

src/ui/screens/LvSettingsScreen.cpp

@@ -957,6 +957,18 @@ void LvSettingsScreen::buildItems() {
         _items.push_back(announceItem);
         idx++;
     }
+    {
+        SettingItem showQrItem;
+        showQrItem.label = "Show QR Code";
+        showQrItem.type = SettingType::ACTION;
+        showQrItem.formatter = [](int) { return String("[Enter]"); };
+        showQrItem.action = [this]() {
+            if (_showQrCb) _showQrCb();
+            else if (_ui) _ui->lvStatusBar().showToast("QR not available");
+        };
+        _items.push_back(showQrItem);
+        idx++;
+    }
     {
         SettingItem initSD;
         initSD.label = "Format SD Card";

src/ui/screens/LvSettingsScreen.h

@@ -80,6 +80,7 @@ public:
     void setSaveCallback(std::function<bool()> cb) { _saveCallback = cb; }
     void setTCPChangeCallback(std::function<void()> cb) { _tcpChangeCb = cb; }
     void setGPSChangeCallback(std::function<void(bool enabled)> cb) { _gpsChangeCb = cb; }
+    void setShowQrCallback(std::function<void()> cb) { _showQrCb = cb; }
 
     const char* title() const override { return "Settings"; }
 
@@ -136,6 +137,7 @@ private:
     std::function<bool()> _saveCallback;
     std::function<void()> _tcpChangeCb;
     std::function<void(bool)> _gpsChangeCb;
+    std::function<void()> _showQrCb;
     bool _gpsSnapEnabled = true;
 
     SettingsView _view = SettingsView::CATEGORY_LIST;