TCP scaling, GUI pooling, dev mode, protocol improvements

- TCP: wider drain budgets, TCP_NODELAY, no flush, PSRAM buffers, queue announces until hub ID
- GUI: object pool Messages/Contacts screens, partial MessageView status, targeted tab refresh
- LVGL throttled to 5fps when dimmed, non-blocking RSSI monitor, bounded I2S writes
- LXMF batch drain, BLE frame mutex, LoRa interrupt-driven RX, name cache cap 300
- Developer mode in settings: custom radio params (freq/txp/SF/BW/CR/preamble) behind warning

src/ui/LvTabBar.cpp

@@ -60,22 +60,28 @@ void LvTabBar::cycleTab(int direction) {
 
 void LvTabBar::setUnreadCount(int tab, int count) {
     if (tab < 0 || tab >= TAB_COUNT) return;
+    if (_unread[tab] == count) return;  // No change
     _unread[tab] = count;
-    refreshTabs();
+    refreshTab(tab);
+}
+
+void LvTabBar::refreshTab(int idx) {
+    if (idx < 0 || idx >= TAB_COUNT || !_tabs[idx]) return;
+    bool active = (idx == _activeTab);
+    lv_obj_set_style_text_color(_tabs[idx],
+        lv_color_hex(active ? Theme::TAB_ACTIVE : Theme::TAB_INACTIVE), 0);
+
+    char buf[24];
+    if (_unread[idx] > 0) {
+        snprintf(buf, sizeof(buf), "%s(%d)", TAB_NAMES[idx], _unread[idx]);
+    } else {
+        snprintf(buf, sizeof(buf), "%s", TAB_NAMES[idx]);
+    }
+    lv_label_set_text(_tabs[idx], buf);
 }
 
 void LvTabBar::refreshTabs() {
     for (int i = 0; i < TAB_COUNT; i++) {
-        bool active = (i == _activeTab);
-        lv_obj_set_style_text_color(_tabs[i],
-            lv_color_hex(active ? Theme::TAB_ACTIVE : Theme::TAB_INACTIVE), 0);
-
-        char buf[24];
-        if (_unread[i] > 0) {
-            snprintf(buf, sizeof(buf), "%s(%d)", TAB_NAMES[i], _unread[i]);
-        } else {
-            snprintf(buf, sizeof(buf), "%s", TAB_NAMES[i]);
-        }
-        lv_label_set_text(_tabs[i], buf);
+        refreshTab(i);
     }
 }

src/ui/LvTabBar.h

@@ -21,6 +21,7 @@ public:
 
 private:
     void refreshTabs();
+    void refreshTab(int idx);
 
     lv_obj_t* _bar = nullptr;
     lv_obj_t* _tabs[TAB_COUNT] = {};

src/ui/screens/LvContactsScreen.cpp

@@ -28,6 +28,31 @@ void LvContactsScreen::createUI(lv_obj_t* parent) {
     lv_obj_set_layout(_list, LV_LAYOUT_FLEX);
     lv_obj_set_flex_flow(_list, LV_FLEX_FLOW_COLUMN);
 
+    // Pre-allocate row pool
+    const lv_font_t* font = &lv_font_montserrat_14;
+    for (int i = 0; i < ROW_POOL_SIZE; i++) {
+        lv_obj_t* row = lv_obj_create(_list);
+        lv_obj_set_size(row, Theme::CONTENT_W, 28);
+        lv_obj_set_style_bg_color(row, lv_color_hex(Theme::BG), 0);
+        lv_obj_set_style_bg_opa(row, LV_OPA_COVER, 0);
+        lv_obj_set_style_border_color(row, lv_color_hex(Theme::BORDER), 0);
+        lv_obj_set_style_border_width(row, 1, 0);
+        lv_obj_set_style_border_side(row, LV_BORDER_SIDE_BOTTOM, 0);
+        lv_obj_set_style_pad_all(row, 0, 0);
+        lv_obj_set_style_radius(row, 0, 0);
+        lv_obj_clear_flag(row, LV_OBJ_FLAG_SCROLLABLE);
+        lv_obj_add_flag(row, LV_OBJ_FLAG_HIDDEN);
+
+        lv_obj_t* lbl = lv_label_create(row);
+        lv_obj_set_style_text_font(lbl, font, 0);
+        lv_obj_set_style_text_color(lbl, lv_color_hex(Theme::ACCENT), 0);
+        lv_label_set_text(lbl, "");
+        lv_obj_align(lbl, LV_ALIGN_LEFT_MID, 8, 0);
+
+        _poolRows[i] = row;
+        _poolNameLabels[i] = lbl;
+    }
+
     _lastContactCount = -1;
     rebuildList();
 }
@@ -35,6 +60,7 @@ void LvContactsScreen::createUI(lv_obj_t* parent) {
 void LvContactsScreen::onEnter() {
     _lastContactCount = -1;
     _selectedIdx = 0;
+    _viewportStart = 0;
     rebuildList();
 }
 
@@ -48,20 +74,13 @@ void LvContactsScreen::refreshUI() {
 }
 
 void LvContactsScreen::updateSelection(int oldIdx, int newIdx) {
-    if (oldIdx >= 0 && oldIdx < (int)_rows.size()) {
-        lv_obj_set_style_bg_color(_rows[oldIdx], lv_color_hex(Theme::BG), 0);
-    }
-    if (newIdx >= 0 && newIdx < (int)_rows.size()) {
-        lv_obj_set_style_bg_color(_rows[newIdx], lv_color_hex(Theme::SELECTION_BG), 0);
-        lv_obj_scroll_to_view(_rows[newIdx], LV_ANIM_OFF);
-    }
+    syncVisibleRows();
 }
 
 void LvContactsScreen::rebuildList() {
     if (!_am || !_list) return;
     _rows.clear();
     _contactIndices.clear();
-    lv_obj_clean(_list);
 
     const auto& nodes = _am->nodes();
     for (int i = 0; i < (int)nodes.size(); i++) {
@@ -73,6 +92,7 @@ void LvContactsScreen::rebuildList() {
     if (count == 0) {
         lv_obj_clear_flag(_lblEmpty, LV_OBJ_FLAG_HIDDEN);
         lv_obj_add_flag(_list, LV_OBJ_FLAG_HIDDEN);
+        for (int i = 0; i < ROW_POOL_SIZE; i++) lv_obj_add_flag(_poolRows[i], LV_OBJ_FLAG_HIDDEN);
         return;
     }
 
@@ -82,32 +102,47 @@ void LvContactsScreen::rebuildList() {
     if (_selectedIdx >= count) _selectedIdx = count - 1;
     if (_selectedIdx < 0) _selectedIdx = 0;
 
-    const lv_font_t* font = &lv_font_montserrat_14;
+    syncVisibleRows();
+}
 
-    for (int i = 0; i < count; i++) {
-        const auto& node = nodes[_contactIndices[i]];
-        bool selected = (i == _selectedIdx);
+void LvContactsScreen::syncVisibleRows() {
+    if (!_am || !_list) return;
+    int count = (int)_contactIndices.size();
+    const auto& nodes = _am->nodes();
 
-        lv_obj_t* row = lv_obj_create(_list);
-        lv_obj_set_size(row, Theme::CONTENT_W, 28);
-        lv_obj_set_style_bg_color(row, lv_color_hex(
-            selected ? Theme::SELECTION_BG : Theme::BG), 0);
-        lv_obj_set_style_bg_opa(row, LV_OPA_COVER, 0);
-        lv_obj_set_style_border_color(row, lv_color_hex(Theme::BORDER), 0);
-        lv_obj_set_style_border_width(row, 1, 0);
-        lv_obj_set_style_border_side(row, LV_BORDER_SIDE_BOTTOM, 0);
-        lv_obj_set_style_pad_all(row, 0, 0);
-        lv_obj_set_style_radius(row, 0, 0);
-        lv_obj_clear_flag(row, LV_OBJ_FLAG_SCROLLABLE);
+    if (count == 0) {
+        for (int i = 0; i < ROW_POOL_SIZE; i++) lv_obj_add_flag(_poolRows[i], LV_OBJ_FLAG_HIDDEN);
+        return;
+    }
 
-        // Display name only
-        lv_obj_t* lbl = lv_label_create(row);
-        lv_obj_set_style_text_font(lbl, font, 0);
-        lv_obj_set_style_text_color(lbl, lv_color_hex(Theme::ACCENT), 0);
-        lv_label_set_text(lbl, node.name.c_str());
-        lv_obj_align(lbl, LV_ALIGN_LEFT_MID, 8, 0);
+    // Compute viewport centered on selection
+    int halfPool = ROW_POOL_SIZE / 2;
+    _viewportStart = _selectedIdx - halfPool;
+    if (_viewportStart < 0) _viewportStart = 0;
+    if (_viewportStart + ROW_POOL_SIZE > count) {
+        _viewportStart = count - ROW_POOL_SIZE;
+        if (_viewportStart < 0) _viewportStart = 0;
+    }
 
-        _rows.push_back(row);
+    for (int i = 0; i < ROW_POOL_SIZE; i++) {
+        int contactIdx = _viewportStart + i;
+        if (contactIdx >= count) {
+            lv_obj_add_flag(_poolRows[i], LV_OBJ_FLAG_HIDDEN);
+            continue;
+        }
+
+        lv_obj_clear_flag(_poolRows[i], LV_OBJ_FLAG_HIDDEN);
+        int nodeIdx = _contactIndices[contactIdx];
+        if (nodeIdx < 0 || nodeIdx >= (int)nodes.size()) {
+            lv_obj_add_flag(_poolRows[i], LV_OBJ_FLAG_HIDDEN);
+            continue;
+        }
+        const auto& node = nodes[nodeIdx];
+        bool isSelected = (contactIdx == _selectedIdx);
+
+        lv_obj_set_style_bg_color(_poolRows[i], lv_color_hex(
+            isSelected ? Theme::SELECTION_BG : Theme::BG), 0);
+        lv_label_set_text(_poolNameLabels[i], node.name.c_str());
     }
 }
 
@@ -148,17 +183,15 @@ bool LvContactsScreen::handleKey(const KeyEvent& event) {
 
     if (event.up) {
         if (_selectedIdx > 0) {
-            int prev = _selectedIdx;
             _selectedIdx--;
-            updateSelection(prev, _selectedIdx);
+            syncVisibleRows();
         }
         return true;
     }
     if (event.down) {
         if (_selectedIdx < count - 1) {
-            int prev = _selectedIdx;
             _selectedIdx++;
-            updateSelection(prev, _selectedIdx);
+            syncVisibleRows();
         }
         return true;
     }

src/ui/screens/LvContactsScreen.h

@@ -25,6 +25,7 @@ public:
 
 private:
     void rebuildList();
+    void syncVisibleRows();
     void updateSelection(int oldIdx, int newIdx);
 
     AnnounceManager* _am = nullptr;
@@ -33,9 +34,15 @@ private:
     bool _confirmDelete = false;
     int _lastContactCount = -1;
     int _selectedIdx = 0;
+    int _viewportStart = 0;
     std::vector<int> _contactIndices; // Maps row -> node index in _am->nodes()
 
     lv_obj_t* _list = nullptr;
     lv_obj_t* _lblEmpty = nullptr;
     std::vector<lv_obj_t*> _rows;
+
+    // Object pool
+    static constexpr int ROW_POOL_SIZE = 10;
+    lv_obj_t* _poolRows[ROW_POOL_SIZE] = {};
+    lv_obj_t* _poolNameLabels[ROW_POOL_SIZE] = {};
 };

src/ui/screens/LvMessageView.cpp

@@ -111,14 +111,14 @@ void LvMessageView::onEnter() {
         _lxmf->markRead(_peerHex);
         // Update unread badge on Messages tab
         if (_ui) _ui->lvTabBar().setUnreadCount(LvTabBar::TAB_MSGS, _lxmf->unreadCount());
-        // Register status callback — update cached message status in-place
+        // Register status callback — partial update without full rebuild
         std::string peer = _peerHex;
         _lxmf->setStatusCallback([this, peer](const std::string& peerHex, double, LXMFStatus newStatus) {
             if (peerHex != peer) return;
             for (int i = _cachedMsgs.size() - 1; i >= 0; i--) {
                 if (!_cachedMsgs[i].incoming && _cachedMsgs[i].status == LXMFStatus::QUEUED) {
                     _cachedMsgs[i].status = newStatus;
-                    rebuildMessages();
+                    updateMessageStatus(i, newStatus);
                     break;
                 }
             }
@@ -174,6 +174,8 @@ void LvMessageView::rebuildMessages() {
     _lastMsgCount = (int)_cachedMsgs.size();
     _lastRefreshMs = millis();
     lv_obj_clean(_msgScroll);
+    _statusLabels.clear();
+    _textLabels.clear();
 
     const lv_font_t* font = &lv_font_montserrat_12;
     int maxBubbleW = Theme::CONTENT_W * 3 / 4;
@@ -229,7 +231,7 @@ void LvMessageView::rebuildMessages() {
         lv_obj_set_width(lbl, maxBubbleW - 14);
         lv_label_set_text(lbl, msg.content.c_str());
 
-        // Status indicator for outgoing
+        // Status indicator for outgoing (tracked for partial updates)
         if (!msg.incoming) {
             const char* ind = "~";
             uint32_t indColor = Theme::MUTED;
@@ -243,6 +245,11 @@ void LvMessageView::rebuildMessages() {
             lv_obj_set_style_text_color(statusLbl, lv_color_hex(indColor), 0);
             lv_label_set_text(statusLbl, ind);
             lv_obj_align(statusLbl, LV_ALIGN_BOTTOM_RIGHT, 0, 0);
+            _statusLabels.push_back(statusLbl);
+            _textLabels.push_back(lbl);
+        } else {
+            _statusLabels.push_back(nullptr);
+            _textLabels.push_back(nullptr);
         }
 
         // Timestamp below bubble
@@ -269,6 +276,35 @@ void LvMessageView::rebuildMessages() {
     lv_obj_scroll_to_y(_msgScroll, LV_COORD_MAX, LV_ANIM_OFF);
 }
 
+void LvMessageView::updateMessageStatus(int msgIdx, LXMFStatus status) {
+    if (msgIdx < 0 || msgIdx >= (int)_statusLabels.size()) return;
+    lv_obj_t* statusLbl = _statusLabels[msgIdx];
+    lv_obj_t* textLbl = _textLabels[msgIdx];
+    if (!statusLbl) return;  // Incoming message, no status label
+
+    // Update status indicator
+    const char* ind = "~";
+    uint32_t indColor = Theme::MUTED;
+    if (status == LXMFStatus::SENT || status == LXMFStatus::DELIVERED) {
+        ind = "*"; indColor = Theme::ACCENT;
+    } else if (status == LXMFStatus::FAILED) {
+        ind = "!"; indColor = Theme::ERROR_CLR;
+    }
+    lv_obj_set_style_text_color(statusLbl, lv_color_hex(indColor), 0);
+    lv_label_set_text(statusLbl, ind);
+
+    // Update text color to match status
+    if (textLbl) {
+        uint32_t textColor = Theme::PRIMARY;
+        if (status == LXMFStatus::QUEUED || status == LXMFStatus::SENDING) {
+            textColor = Theme::WARNING_CLR;
+        } else if (status == LXMFStatus::FAILED) {
+            textColor = Theme::ERROR_CLR;
+        }
+        lv_obj_set_style_text_color(textLbl, lv_color_hex(textColor), 0);
+    }
+}
+
 void LvMessageView::sendCurrentMessage() {
     if (!_lxmf || _peerHex.empty() || _inputText.empty()) return;
 

src/ui/screens/LvMessageView.h

@@ -43,6 +43,8 @@ private:
     unsigned long _lastRefreshMs = 0;
     std::vector<LXMFMessage> _cachedMsgs;
 
+    void updateMessageStatus(int msgIdx, LXMFStatus status);
+
     // LVGL widgets
     lv_obj_t* _header = nullptr;
     lv_obj_t* _lblHeader = nullptr;
@@ -51,5 +53,9 @@ private:
     lv_obj_t* _textarea = nullptr;
     lv_obj_t* _btnSend = nullptr;
 
+    // Per-message status labels for partial updates (avoids full rebuild)
+    std::vector<lv_obj_t*> _statusLabels;
+    std::vector<lv_obj_t*> _textLabels;
+
     static constexpr unsigned long REFRESH_INTERVAL_MS = 2000;  // Check for new messages every 2s
 };

src/ui/screens/LvMessagesScreen.cpp

@@ -32,6 +32,62 @@ void LvMessagesScreen::createUI(lv_obj_t* parent) {
     lv_obj_set_layout(_list, LV_LAYOUT_FLEX);
     lv_obj_set_flex_flow(_list, LV_FLEX_FLOW_COLUMN);
 
+    // Pre-allocate row pool (following LvNodesScreen pattern)
+    const lv_font_t* nameFont = &lv_font_montserrat_14;
+    const lv_font_t* smallFont = &lv_font_montserrat_12;
+
+    for (int i = 0; i < ROW_POOL_SIZE; i++) {
+        lv_obj_t* row = lv_obj_create(_list);
+        lv_obj_set_size(row, Theme::CONTENT_W, 38);
+        lv_obj_set_style_bg_color(row, lv_color_hex(Theme::BG), 0);
+        lv_obj_set_style_bg_opa(row, LV_OPA_COVER, 0);
+        lv_obj_set_style_border_color(row, lv_color_hex(Theme::BORDER), 0);
+        lv_obj_set_style_border_width(row, 1, 0);
+        lv_obj_set_style_border_side(row, LV_BORDER_SIDE_BOTTOM, 0);
+        lv_obj_set_style_pad_all(row, 0, 0);
+        lv_obj_set_style_radius(row, 0, 0);
+        lv_obj_clear_flag(row, LV_OBJ_FLAG_SCROLLABLE);
+        lv_obj_add_flag(row, LV_OBJ_FLAG_HIDDEN);
+
+        // Unread dot
+        lv_obj_t* dot = lv_obj_create(row);
+        lv_obj_set_size(dot, 6, 6);
+        lv_obj_set_style_radius(dot, 3, 0);
+        lv_obj_set_style_bg_color(dot, lv_color_hex(Theme::PRIMARY), 0);
+        lv_obj_set_style_bg_opa(dot, LV_OPA_COVER, 0);
+        lv_obj_set_style_border_width(dot, 0, 0);
+        lv_obj_set_style_pad_all(dot, 0, 0);
+        lv_obj_set_pos(dot, 5, 8);
+        lv_obj_add_flag(dot, LV_OBJ_FLAG_HIDDEN);
+
+        // Name label (line 1)
+        lv_obj_t* nameLbl = lv_label_create(row);
+        lv_obj_set_style_text_font(nameLbl, nameFont, 0);
+        lv_obj_set_style_text_color(nameLbl, lv_color_hex(Theme::PRIMARY), 0);
+        lv_label_set_text(nameLbl, "");
+        lv_obj_align(nameLbl, LV_ALIGN_TOP_LEFT, 14, 2);
+
+        // Time label (line 1, right)
+        lv_obj_t* timeLbl = lv_label_create(row);
+        lv_obj_set_style_text_font(timeLbl, &lv_font_montserrat_10, 0);
+        lv_obj_set_style_text_color(timeLbl, lv_color_hex(Theme::MUTED), 0);
+        lv_label_set_text(timeLbl, "");
+        lv_obj_align(timeLbl, LV_ALIGN_TOP_RIGHT, -4, 4);
+
+        // Preview label (line 2)
+        lv_obj_t* prevLbl = lv_label_create(row);
+        lv_obj_set_style_text_font(prevLbl, smallFont, 0);
+        lv_obj_set_style_text_color(prevLbl, lv_color_hex(Theme::MUTED), 0);
+        lv_label_set_text(prevLbl, "");
+        lv_obj_align(prevLbl, LV_ALIGN_BOTTOM_LEFT, 14, -4);
+
+        _poolRows[i] = row;
+        _poolDots[i] = dot;
+        _poolNameLabels[i] = nameLbl;
+        _poolTimeLabels[i] = timeLbl;
+        _poolPreviewLabels[i] = prevLbl;
+    }
+
     _lastConvCount = -1;
     rebuildList();
 }
@@ -39,6 +95,7 @@ void LvMessagesScreen::createUI(lv_obj_t* parent) {
 void LvMessagesScreen::onEnter() {
     _lastConvCount = -1;
     _selectedIdx = 0;
+    _viewportStart = 0;
     rebuildList();
 }
 
@@ -51,15 +108,9 @@ void LvMessagesScreen::refreshUI() {
     }
 }
 
-// Update only the selection highlight without rebuilding widgets
+// Update only the selection highlight via pool sync
 void LvMessagesScreen::updateSelection(int oldIdx, int newIdx) {
-    if (oldIdx >= 0 && oldIdx < (int)_rows.size()) {
-        lv_obj_set_style_bg_color(_rows[oldIdx], lv_color_hex(Theme::BG), 0);
-    }
-    if (newIdx >= 0 && newIdx < (int)_rows.size()) {
-        lv_obj_set_style_bg_color(_rows[newIdx], lv_color_hex(Theme::SELECTION_BG), 0);
-        lv_obj_scroll_to_view(_rows[newIdx], LV_ANIM_OFF);
-    }
+    syncVisibleRows();
 }
 
 void LvMessagesScreen::rebuildList() {
@@ -69,30 +120,21 @@ void LvMessagesScreen::rebuildList() {
     int count = (int)convs.size();
     _lastConvCount = count;
     _lastUnreadTotal = _lxmf->unreadCount();
-    _rows.clear();
     _sortedPeers.clear();
-    lv_obj_clean(_list);
+    _sortedConvs.clear();
 
     if (count == 0) {
         lv_obj_clear_flag(_lblEmpty, LV_OBJ_FLAG_HIDDEN);
         lv_obj_add_flag(_list, LV_OBJ_FLAG_HIDDEN);
+        for (int i = 0; i < ROW_POOL_SIZE; i++) lv_obj_add_flag(_poolRows[i], LV_OBJ_FLAG_HIDDEN);
         return;
     }
 
     lv_obj_add_flag(_lblEmpty, LV_OBJ_FLAG_HIDDEN);
     lv_obj_clear_flag(_list, LV_OBJ_FLAG_HIDDEN);
 
-    // Build conversation info for sorting by most recent
-    struct ConvInfo {
-        std::string peerHex;
-        double lastTs = 0;
-        std::string preview;
-        bool hasUnread = false;
-    };
-
-    std::vector<ConvInfo> sorted;
-    sorted.reserve(count);
-
+    // Build sorted conversation info
+    _sortedConvs.reserve(count);
     for (int i = 0; i < count; i++) {
         ConvInfo ci;
         ci.peerHex = convs[i];
@@ -102,85 +144,85 @@ void LvMessagesScreen::rebuildList() {
             ci.preview = s->lastPreview;
             ci.hasUnread = s->unreadCount > 0;
         }
-        sorted.push_back(ci);
+        // Resolve display name
+        std::string peerName;
+        if (_am) peerName = _am->lookupName(ci.peerHex);
+        ci.displayName = !peerName.empty() ? peerName.substr(0, 15) : ci.peerHex.substr(0, 12);
+        _sortedConvs.push_back(ci);
     }
 
-    std::sort(sorted.begin(), sorted.end(), [](const ConvInfo& a, const ConvInfo& b) {
+    std::sort(_sortedConvs.begin(), _sortedConvs.end(), [](const ConvInfo& a, const ConvInfo& b) {
         return a.lastTs > b.lastTs;
     });
 
-    for (auto& ci : sorted) _sortedPeers.push_back(ci.peerHex);
+    for (auto& ci : _sortedConvs) _sortedPeers.push_back(ci.peerHex);
 
     if (_selectedIdx >= count) _selectedIdx = count - 1;
     if (_selectedIdx < 0) _selectedIdx = 0;
 
-    const lv_font_t* nameFont = &lv_font_montserrat_14;
-    const lv_font_t* smallFont = &lv_font_montserrat_12;
+    syncVisibleRows();
+}
 
-    for (int i = 0; i < (int)sorted.size(); i++) {
-        const auto& ci = sorted[i];
+void LvMessagesScreen::syncVisibleRows() {
+    if (!_list) return;
+    int count = (int)_sortedConvs.size();
 
-        lv_obj_t* row = lv_obj_create(_list);
-        lv_obj_set_size(row, Theme::CONTENT_W, 38);
-        lv_obj_set_style_bg_color(row, lv_color_hex(
-            i == _selectedIdx ? Theme::SELECTION_BG : Theme::BG), 0);
-        lv_obj_set_style_bg_opa(row, LV_OPA_COVER, 0);
-        lv_obj_set_style_border_color(row, lv_color_hex(Theme::BORDER), 0);
-        lv_obj_set_style_border_width(row, 1, 0);
-        lv_obj_set_style_border_side(row, LV_BORDER_SIDE_BOTTOM, 0);
-        lv_obj_set_style_pad_all(row, 0, 0);
-        lv_obj_set_style_radius(row, 0, 0);
-        lv_obj_clear_flag(row, LV_OBJ_FLAG_SCROLLABLE);
+    if (count == 0) {
+        for (int i = 0; i < ROW_POOL_SIZE; i++) lv_obj_add_flag(_poolRows[i], LV_OBJ_FLAG_HIDDEN);
+        return;
+    }
 
-        // Green dot for unread
-        if (ci.hasUnread) {
-            lv_obj_t* dot = lv_obj_create(row);
-            lv_obj_set_size(dot, 6, 6);
-            lv_obj_set_style_radius(dot, 3, 0);
-            lv_obj_set_style_bg_color(dot, lv_color_hex(Theme::PRIMARY), 0);
-            lv_obj_set_style_bg_opa(dot, LV_OPA_COVER, 0);
-            lv_obj_set_style_border_width(dot, 0, 0);
-            lv_obj_set_style_pad_all(dot, 0, 0);
-            lv_obj_set_pos(dot, 5, 8);
+    // Compute viewport centered on selection
+    int halfPool = ROW_POOL_SIZE / 2;
+    _viewportStart = _selectedIdx - halfPool;
+    if (_viewportStart < 0) _viewportStart = 0;
+    if (_viewportStart + ROW_POOL_SIZE > count) {
+        _viewportStart = count - ROW_POOL_SIZE;
+        if (_viewportStart < 0) _viewportStart = 0;
+    }
+
+    for (int i = 0; i < ROW_POOL_SIZE; i++) {
+        int convIdx = _viewportStart + i;
+        if (convIdx >= count) {
+            lv_obj_add_flag(_poolRows[i], LV_OBJ_FLAG_HIDDEN);
+            continue;
         }
 
-        // Peer name (line 1)
-        std::string peerName;
-        if (_am) peerName = _am->lookupName(ci.peerHex);
-        std::string displayName = !peerName.empty() ?
-            peerName.substr(0, 15) : ci.peerHex.substr(0, 12);
+        lv_obj_clear_flag(_poolRows[i], LV_OBJ_FLAG_HIDDEN);
+        const auto& ci = _sortedConvs[convIdx];
+        bool isSelected = (convIdx == _selectedIdx);
 
-        lv_obj_t* nameLbl = lv_label_create(row);
-        lv_obj_set_style_text_font(nameLbl, nameFont, 0);
-        lv_obj_set_style_text_color(nameLbl, lv_color_hex(Theme::PRIMARY), 0);
-        lv_label_set_text(nameLbl, displayName.c_str());
-        lv_obj_align(nameLbl, LV_ALIGN_TOP_LEFT, 14, 2);
+        // Selection highlight
+        lv_obj_set_style_bg_color(_poolRows[i], lv_color_hex(
+            isSelected ? Theme::SELECTION_BG : Theme::BG), 0);
 
-        // Timestamp (line 1, right)
+        // Unread dot
+        if (ci.hasUnread) {
+            lv_obj_clear_flag(_poolDots[i], LV_OBJ_FLAG_HIDDEN);
+        } else {
+            lv_obj_add_flag(_poolDots[i], LV_OBJ_FLAG_HIDDEN);
+        }
+
+        // Name
+        lv_label_set_text(_poolNameLabels[i], ci.displayName.c_str());
+
+        // Time
         if (ci.lastTs > 1700000000) {
             time_t t = (time_t)ci.lastTs;
             struct tm* tm = localtime(&t);
             if (tm) {
                 char timeBuf[8];
                 snprintf(timeBuf, sizeof(timeBuf), "%02d:%02d", tm->tm_hour, tm->tm_min);
-                lv_obj_t* timeLbl = lv_label_create(row);
-                lv_obj_set_style_text_font(timeLbl, &lv_font_montserrat_10, 0);
-                lv_obj_set_style_text_color(timeLbl, lv_color_hex(Theme::MUTED), 0);
-                lv_label_set_text(timeLbl, timeBuf);
-                lv_obj_align(timeLbl, LV_ALIGN_TOP_RIGHT, -4, 4);
+                lv_label_set_text(_poolTimeLabels[i], timeBuf);
+            } else {
+                lv_label_set_text(_poolTimeLabels[i], "");
             }
+        } else {
+            lv_label_set_text(_poolTimeLabels[i], "");
         }
 
-        // Preview (line 2)
-        if (!ci.preview.empty()) {
-            lv_obj_t* prevLbl = lv_label_create(row);
-            lv_obj_set_style_text_font(prevLbl, smallFont, 0);
-            lv_obj_set_style_text_color(prevLbl, lv_color_hex(Theme::MUTED), 0);
-            lv_label_set_text(prevLbl, ci.preview.c_str());
-            lv_obj_align(prevLbl, LV_ALIGN_BOTTOM_LEFT, 14, -4);
-        }
-
-        _rows.push_back(row);
+        // Preview
+        lv_label_set_text(_poolPreviewLabels[i], ci.preview.c_str());
     }
 }
 
@@ -276,7 +318,7 @@ bool LvMessagesScreen::handleKey(const KeyEvent& event) {
         if (_selectedIdx > 0) {
             int prev = _selectedIdx;
             _selectedIdx--;
-            updateSelection(prev, _selectedIdx);
+            syncVisibleRows();
         }
         return true;
     }
@@ -284,7 +326,7 @@ bool LvMessagesScreen::handleKey(const KeyEvent& event) {
         if (_selectedIdx < count - 1) {
             int prev = _selectedIdx;
             _selectedIdx++;
-            updateSelection(prev, _selectedIdx);
+            syncVisibleRows();
         }
         return true;
     }

src/ui/screens/LvMessagesScreen.h

@@ -27,6 +27,7 @@ public:
 
 private:
     void rebuildList();
+    void syncVisibleRows();
     void updateSelection(int oldIdx, int newIdx);
 
     LXMFManager* _lxmf = nullptr;
@@ -36,6 +37,7 @@ private:
     int _lastConvCount = -1;
     int _lastUnreadTotal = 0;
     int _selectedIdx = 0;
+    int _viewportStart = 0;
     std::vector<std::string> _sortedPeers;
     enum LongPressState { LP_NONE, LP_MENU, LP_CONFIRM_DELETE };
     LongPressState _lpState = LP_NONE;
@@ -44,4 +46,22 @@ private:
     lv_obj_t* _list = nullptr;
     lv_obj_t* _lblEmpty = nullptr;
     std::vector<lv_obj_t*> _rows;
+
+    // Object pool for conversation rows
+    static constexpr int ROW_POOL_SIZE = 10;
+    lv_obj_t* _poolRows[ROW_POOL_SIZE] = {};
+    lv_obj_t* _poolNameLabels[ROW_POOL_SIZE] = {};
+    lv_obj_t* _poolPreviewLabels[ROW_POOL_SIZE] = {};
+    lv_obj_t* _poolTimeLabels[ROW_POOL_SIZE] = {};
+    lv_obj_t* _poolDots[ROW_POOL_SIZE] = {};
+
+    // Cached sorted conversation data
+    struct ConvInfo {
+        std::string peerHex;
+        double lastTs = 0;
+        std::string preview;
+        std::string displayName;
+        bool hasUnread = false;
+    };
+    std::vector<ConvInfo> _sortedConvs;
 };

src/ui/screens/LvSettingsScreen.cpp

@@ -165,6 +165,39 @@ void LvSettingsScreen::buildItems() {
         _items.push_back(newId);
         idx++;
     }
+    {
+        SettingItem devModeItem;
+        devModeItem.label = "Developer Mode";
+        devModeItem.type = SettingType::ACTION;
+        devModeItem.formatter = [&s](int) { return s.devMode ? String("ON") : String("OFF"); };
+        devModeItem.action = [this, &s]() {
+            if (s.devMode) {
+                // Already on — just turn it off
+                s.devMode = false;
+                _confirmingDevMode = false;
+                applyAndSave();
+                buildItems();
+                enterCategory(_categoryIdx);
+                if (_ui) _ui->lvStatusBar().showToast("Developer mode OFF", 1200);
+                return;
+            }
+            if (!_confirmingDevMode) {
+                _confirmingDevMode = true;
+                if (_ui) _ui->lvStatusBar().showToast("WARNING: KNOW YOUR LAWS! Enter=Enable", 5000);
+                rebuildItemList();
+                return;
+            }
+            // Confirmed
+            _confirmingDevMode = false;
+            s.devMode = true;
+            applyAndSave();
+            buildItems();
+            enterCategory(_categoryIdx);
+            if (_ui) _ui->lvStatusBar().showToast("Developer mode ON", 1200);
+        };
+        _items.push_back(devModeItem);
+        idx++;
+    }
     _categories.push_back({"Device", devStart, idx - devStart,
         [&s]() { return s.displayName.isEmpty() ? String("(unnamed)") : s.displayName; }});
 
@@ -202,48 +235,47 @@ void LvSettingsScreen::buildItems() {
         _items.push_back(presetItem);
         idx++;
     }
-    _items.push_back({"Frequency", SettingType::ENUM_CHOICE,
-        [&s]() {
-            if (s.loraFrequency <= 868000000) return 0;
-            if (s.loraFrequency <= 906000000) return 1;
-            if (s.loraFrequency <= 915000000) return 2;
-            return 3;
-        },
-        [&s](int v) {
-            static const uint32_t freqs[] = {868000000, 906000000, 915000000, 923000000};
-            s.loraFrequency = freqs[constrain(v, 0, 3)];
-        },
-        nullptr, 0, 3, 1, {"868 MHz", "906 MHz", "915 MHz", "923 MHz"}});
-    idx++;
-    _items.push_back({"TX Power", SettingType::INTEGER,
-        [&s]() { return s.loraTxPower; }, [&s](int v) { s.loraTxPower = v; },
-        [](int v) { return String(v) + " dBm"; }, -9, 22, 1});
-    idx++;
-    _items.push_back({"Spread Factor", SettingType::INTEGER,
-        [&s]() { return s.loraSF; }, [&s](int v) { s.loraSF = v; },
-        [](int v) { return String("SF") + String(v); }, 5, 12, 1});
-    idx++;
-    _items.push_back({"Bandwidth", SettingType::ENUM_CHOICE,
-        [&s]() {
-            if (s.loraBW <= 62500)  return 0;
-            if (s.loraBW <= 125000) return 1;
-            if (s.loraBW <= 250000) return 2;
-            return 3;
-        },
-        [&s](int v) {
-            static const uint32_t bws[] = {62500, 125000, 250000, 500000};
-            s.loraBW = bws[constrain(v, 0, 3)];
-        },
-        nullptr, 0, 3, 1, {"62.5k", "125k", "250k", "500k"}});
-    idx++;
-    _items.push_back({"Coding Rate", SettingType::INTEGER,
-        [&s]() { return s.loraCR; }, [&s](int v) { s.loraCR = v; },
-        [](int v) { return String("4/") + String(v); }, 5, 8, 1});
-    idx++;
-    _items.push_back({"Preamble", SettingType::INTEGER,
-        [&s]() { return (int)s.loraPreamble; }, [&s](int v) { s.loraPreamble = v; },
-        [](int v) { return String(v); }, 6, 65, 1});
-    idx++;
+    // Custom radio parameters — only visible in Developer Mode
+    if (s.devMode) {
+        _items.push_back({"Frequency", SettingType::INTEGER,
+            [&s]() { return (int)(s.loraFrequency / 1000); },
+            [&s](int v) { s.loraFrequency = (uint32_t)v * 1000; },
+            [](int v) -> String {
+                char buf[16]; snprintf(buf, sizeof(buf), "%d.%03d MHz", v / 1000, v % 1000);
+                return String(buf);
+            },
+            137000, 1020000, 125});
+        idx++;
+        _items.push_back({"TX Power", SettingType::INTEGER,
+            [&s]() { return s.loraTxPower; }, [&s](int v) { s.loraTxPower = v; },
+            [](int v) { return String(v) + " dBm"; }, -9, 22, 1});
+        idx++;
+        _items.push_back({"Spread Factor", SettingType::INTEGER,
+            [&s]() { return s.loraSF; }, [&s](int v) { s.loraSF = v; },
+            [](int v) { return String("SF") + String(v); }, 5, 12, 1});
+        idx++;
+        _items.push_back({"Bandwidth", SettingType::ENUM_CHOICE,
+            [&s]() {
+                if (s.loraBW <= 62500)  return 0;
+                if (s.loraBW <= 125000) return 1;
+                if (s.loraBW <= 250000) return 2;
+                return 3;
+            },
+            [&s](int v) {
+                static const uint32_t bws[] = {62500, 125000, 250000, 500000};
+                s.loraBW = bws[constrain(v, 0, 3)];
+            },
+            nullptr, 0, 3, 1, {"62.5k", "125k", "250k", "500k"}});
+        idx++;
+        _items.push_back({"Coding Rate", SettingType::INTEGER,
+            [&s]() { return s.loraCR; }, [&s](int v) { s.loraCR = v; },
+            [](int v) { return String("4/") + String(v); }, 5, 8, 1});
+        idx++;
+        _items.push_back({"Preamble", SettingType::INTEGER,
+            [&s]() { return (int)s.loraPreamble; }, [&s](int v) { s.loraPreamble = v; },
+            [](int v) { return String(v); }, 6, 65, 1});
+        idx++;
+    }
     _categories.push_back({"Radio", radioStart, idx - radioStart,
         [this]() { int p = detectPreset(); return (p >= 0) ? String(LV_PRESETS[p].name) : String("Custom"); }});
 
@@ -590,6 +622,7 @@ void LvSettingsScreen::onEnter() {
     _editing = false;
     _textEditing = false;
     _confirmingReset = false;
+    _confirmingDevMode = false;
     rebuildCategoryList();
 }
 
@@ -901,6 +934,7 @@ void LvSettingsScreen::exitToCategories() {
     _editing = false;
     _textEditing = false;
     _confirmingReset = false;
+    _confirmingDevMode = false;
     rebuildCategoryList();
 }
 

src/ui/screens/LvSettingsScreen.h

@@ -130,6 +130,7 @@ private:
     bool _textEditing = false;
     String _editText;
     bool _confirmingReset = false;
+    bool _confirmingDevMode = false;
 
     // WiFi picker
     std::vector<WiFiInterface::ScanResult> _wifiResults;