chatgui: track read position via debounced scroll, only fully visible msgs are read

- Debounce timer (300ms) advances lastReadMsgId only when message is fully in viewport
- Unread badge no longer resets on channel select — only when actual scroll reads msgs
- saveChannelState() uses tracked m_lastReadMsgId instead of viewport bottom
- getChannels() reads lastReadMsgId from ui_state (was reading unused channels column)

tools/chatgui/db/db_manager.cpp

@@ -117,6 +117,10 @@ QList<ChannelRow> DbManager::getChannels() const {
     }
     sqlite3_finalize(stmt);
     for (auto& ch : list) {
+        ch.lastReadMsgId = getUiStateInt64(
+            QStringLiteral("ch_%1_last_read").arg(ch.channelId), 0);
+        ch.lastPosMsgId = getUiStateInt64(
+            QStringLiteral("ch_%1_last_pos").arg(ch.channelId), 0);
         ch.unreadCount = getUnreadCount(ch.channelId, ch.lastReadMsgId);
     }
     return list;

tools/chatgui/src/mainwindow.cpp

@@ -212,7 +212,6 @@ void MainWindow::setupConnects() {
             this, [this](const QString& channelId) {
                 QSettings().setValue("last_channel_id", channelId);
                 m_currentChannelId = channelId;
-                m_channelList->setChannelUnreadCount(channelId, 0);
                 m_messageList->loadChannel(channelId);
                 m_accountList->setChannel(channelId);
                 QByteArray cidBA = channelId.toUtf8();
@@ -223,6 +222,13 @@ void MainWindow::setupConnects() {
     connect(m_channelList, &ChannelList::joinRequested,       this, &MainWindow::showJoinDialog);
     connect(m_channelList, &ChannelList::createGroupRequested, this, &MainWindow::onCreateGroupRequested);
     connect(m_channelList, &ChannelList::settingsRequested,   this, &MainWindow::showSettings);
+    connect(m_messageList, &MessageList::readPositionChanged,
+            this, [this](const QString& channelId, qint64 lastReadMsgId) {
+                Q_UNUSED(lastReadMsgId);
+                if (m_channelList && m_db)
+                    m_channelList->setChannelUnreadCount(channelId,
+                        m_db->getUnreadCount(channelId, lastReadMsgId));
+            });
 }
 
 void MainWindow::setupTray() {

tools/chatgui/src/messagelist.cpp

@@ -12,6 +12,7 @@
 #include <QPixmap>
 #include <QDateTime>
 #include <QFile>
+#include <QScrollBar>
 #include <QApplication>
 #include <QDebug>
 #include <vector>
@@ -163,6 +164,13 @@ MessageList::MessageList(DbManager* db, QWidget *parent)
         if (!wasActive && m_animHoverActive) AnimTimer::instance()->activate();
         else if (wasActive && !m_animHoverActive) AnimTimer::instance()->deactivate();
     });
+
+    m_readDebounce = new QTimer(this);
+    m_readDebounce->setSingleShot(true);
+    m_readDebounce->setInterval(300);
+    connect(m_readDebounce, &QTimer::timeout, this, &MessageList::updateReadPosition);
+    connect(m_view->verticalScrollBar(), &QScrollBar::valueChanged,
+            m_readDebounce, QOverload<>::of(&QTimer::start));
 }
 
 void MessageList::loadChannel(const QString& channelId) {
@@ -175,6 +183,9 @@ void MessageList::loadChannel(const QString& channelId) {
     m_model->clear();
     m_avatarCache.clear();
     m_currentChannelId = channelId;
+    m_readDebounce->stop();
+    m_lastReadMsgId = m_db->getUiStateInt64(
+        QStringLiteral("ch_%1_last_read").arg(channelId), 0);
     if (!m_db || !m_db->isOpen()) return;
 
     auto msgs = m_db->getMessages(channelId, 100);
@@ -247,18 +258,12 @@ void MessageList::saveChannelState() {
 
     int vpHeight = m_view->viewport()->height();
     QModelIndex topIdx = m_view->indexAt(QPoint(0, 0));
-    QModelIndex bottomIdx = m_view->indexAt(QPoint(0, vpHeight - 1));
 
-    qint64 lastReadMsgId = 0;
     qint64 lastPosMsgId  = 0;
-
     if (topIdx.isValid())
         lastPosMsgId = topIdx.data(MsgIdRole).toLongLong();
-    if (bottomIdx.isValid())
-        lastReadMsgId = bottomIdx.data(MsgIdRole).toLongLong();
-    else if (m_model->rowCount() > 0)
-        lastReadMsgId = m_model->item(m_model->rowCount() - 1)->data(MsgIdRole).toLongLong();
 
+    qint64 lastReadMsgId = m_lastReadMsgId;
     if (lastReadMsgId == 0 && lastPosMsgId == 0) return;
 
     QByteArray cid = m_currentChannelId.toUtf8();
@@ -298,3 +303,44 @@ void MessageList::restoreScrollPosition(const QString& channelId) {
 
     m_view->scrollToBottom();
 }
+
+void MessageList::updateReadPosition() {
+    if (m_currentChannelId.isEmpty() || m_model->rowCount() == 0) return;
+
+    int vpHeight = m_view->viewport()->height();
+    int lastFullyVisibleRow = -1;
+    qint64 newReadMsgId = m_lastReadMsgId;
+
+    for (int row = m_model->rowCount() - 1; row >= 0; --row) {
+        QModelIndex idx = m_model->index(row, 0);
+        QRect vr = m_view->visualRect(idx);
+        if (vr.isValid() && vr.bottom() <= vpHeight) {
+            lastFullyVisibleRow = row;
+            break;
+        }
+    }
+
+    if (lastFullyVisibleRow >= 0) {
+        qint64 msgId = m_model->item(lastFullyVisibleRow)->data(MsgIdRole).toLongLong();
+        if (msgId > m_lastReadMsgId)
+            newReadMsgId = msgId;
+    }
+
+    if (newReadMsgId > m_lastReadMsgId) {
+        m_lastReadMsgId = newReadMsgId;
+
+        QByteArray cid = m_currentChannelId.toUtf8();
+        QByteArray key = "ch_" + cid + "_last_read";
+        QByteArray valStr = QByteArray::number(m_lastReadMsgId);
+        size_t klen = key.size(), vlen = valStr.size();
+        size_t total = klen + 1 + vlen + 1;
+        if (total <= 256) {
+            void* arg = u_malloc(total);
+            memcpy(arg, key.constData(), klen + 1);
+            memcpy((char*)arg + klen + 1, valStr.constData(), vlen + 1);
+            gui_bridge_post_uasync_fn(chat_core_save_ui_state_trampoline, arg);
+        }
+
+        emit readPositionChanged(m_currentChannelId, m_lastReadMsgId);
+    }
+}

tools/chatgui/src/messagelist.h

@@ -3,11 +3,13 @@
 #include <QWidget>
 #include <QStandardItemModel>
 #include <QHash>
+#include <QTimer>
 
 class ChatView;
 class InputBar;
 class EmojiPanel;
 class DbManager;
+class ChannelList;
 
 class MessageList : public QWidget {
     Q_OBJECT
@@ -19,6 +21,9 @@ public:
     void addMessage(const QString& channelId, quint64 authorNodeId,
                     const QByteArray& content, qint64 timestamp);
 
+signals:
+    void readPositionChanged(const QString& channelId, qint64 lastReadMsgId);
+
 private:
     ChatView           *m_view;
     QStandardItemModel *m_model;
@@ -28,7 +33,10 @@ private:
     QString              m_currentChannelId;
     bool                 m_animHoverActive = false;
     QHash<quint64, QColor> m_avatarCache;
+    qint64                m_lastReadMsgId = 0;
+    QTimer*               m_readDebounce;
 
     void saveChannelState();
     void restoreScrollPosition(const QString& channelId);
+    void updateReadPosition();
 };