diff --git a/tools/chatgui/src/user_activity_monitor.cpp b/tools/chatgui/src/user_activity_monitor.cpp
new file mode 100644
index 00000000..72b96033
--- /dev/null
+++ b/tools/chatgui/src/user_activity_monitor.cpp
@@ -0,0 +1,213 @@
+#include "user_activity_monitor.h"
+#include "debug_ui.h"
+
+#include <QApplication>
+#include <QEvent>
+#include <QGuiApplication>
+#include <cmath>
+#include <limits>
+
+#ifdef UTUN_ACTIVITY_DBUS
+#include <QDBusConnection>
+#include <QDBusMessage>
+#include <QDBusPendingCallWatcher>
+#include <QDBusPendingReply>
+#endif
+#ifdef UTUN_ACTIVITY_KIDLETIME
+#include <KIdleTime>
+#endif
+#ifdef Q_OS_WIN
+#include <qt_windows.h>
+#elif defined(Q_OS_MACOS)
+#include <ApplicationServices/ApplicationServices.h>
+#elif defined(UTUN_ACTIVITY_X11)
+#include <X11/Xlib.h>
+#include <X11/extensions/scrnsaver.h>
+#undef KeyPress
+#undef KeyRelease
+#endif
+
+UserActivityMonitor::UserActivityMonitor(QObject* parent) : QObject(parent) {
+    m_pollTimer.setInterval(250);
+    connect(&m_pollTimer, &QTimer::timeout, this, &UserActivityMonitor::poll);
+}
+
+UserActivityMonitor::~UserActivityMonitor() {
+    stop();
+#ifdef UTUN_ACTIVITY_X11
+    if (m_display) XCloseDisplay(static_cast<Display*>(m_display));
+#endif
+    GUI_DEBUG("activity: monitor destroyed");
+}
+
+void UserActivityMonitor::start() {
+    stop();
+    m_watching = true;
+    m_elapsed.start();
+    qApp->installEventFilter(this);
+    const QString platform = QGuiApplication::platformName();
+    const bool wayland = platform.startsWith("wayland") ||
+        (platform == "xcb" && qEnvironmentVariable("XDG_SESSION_TYPE") == "wayland");
+#ifdef UTUN_ACTIVITY_DBUS
+    if (wayland && !m_gnomeUnavailable) {
+        m_useGnome = true;
+        m_pollTimer.start();
+        poll();
+        return;
+    }
+#endif
+    if (wayland) { startWaylandFallback(); return; }
+    if (systemIdleTime() >= 0) {
+        GUI_DEBUG("activity: watching system input platform=%s poll_ms=%d", qPrintable(platform), m_pollTimer.interval());
+        m_pollTimer.start();
+    } else useLocalActivity();
+}
+
+void UserActivityMonitor::stop() {
+    ++m_generation;
+    m_pollTimer.stop();
+    if (m_watching && qApp) qApp->removeEventFilter(this);
+#ifdef UTUN_ACTIVITY_KIDLETIME
+    if (m_useKIdleTime) KIdleTime::instance()->stopCatchingResumeEvent();
+#endif
+    m_watching = false;
+    m_dbusPending = false;
+    m_useGnome = false;
+    m_useKIdleTime = false;
+}
+
+bool UserActivityMonitor::eventFilter(QObject*, QEvent* event) {
+    if (!m_watching || !event->spontaneous()) return false;
+    switch (event->type()) {
+    case QEvent::MouseMove:
+    case QEvent::MouseButtonPress:
+    case QEvent::Wheel:
+    case QEvent::KeyPress:
+    case QEvent::TouchBegin:
+    case QEvent::TouchUpdate:
+    case QEvent::TabletMove:
+    case QEvent::TabletPress:
+        GUI_DEBUG("activity: application input event=%d elapsed_ms=%lld", int(event->type()), (long long)m_elapsed.elapsed());
+        stop();
+        emit activity();
+        break;
+    default:
+        break;
+    }
+    return false;
+}
+
+void UserActivityMonitor::checkIdleTime(qint64 idleMs, qint64 elapsedMs) {
+    if (!m_watching || idleMs < 0 || idleMs >= elapsedMs) return;
+    GUI_DEBUG("activity: system input idle_ms=%lld elapsed_ms=%lld", (long long)idleMs, (long long)elapsedMs);
+    stop();
+    emit activity();
+}
+
+void UserActivityMonitor::poll() {
+#ifdef UTUN_ACTIVITY_DBUS
+    if (m_useGnome) {
+        if (m_dbusPending) return;
+        auto message = QDBusMessage::createMethodCall("org.gnome.Mutter.IdleMonitor", "/org/gnome/Mutter/IdleMonitor/Core",
+                                                     "org.gnome.Mutter.IdleMonitor", "GetIdletime");
+        message.setAutoStartService(false);
+        auto* watcher = new QDBusPendingCallWatcher(QDBusConnection::sessionBus().asyncCall(message, 1000), this);
+        const quint64 generation = m_generation;
+        const qint64 elapsedMs = m_elapsed.elapsed();
+        m_dbusPending = true;
+        connect(watcher, &QDBusPendingCallWatcher::finished, this, [this, watcher, generation, elapsedMs] {
+            QDBusPendingReply<qulonglong> reply = *watcher;
+            watcher->deleteLater();
+            if (!m_watching || generation != m_generation) return;
+            m_dbusPending = false;
+            if (reply.isError()) {
+                GUI_WARN("activity: GNOME idle monitor unavailable: %s", qPrintable(reply.error().message()));
+                m_gnomeUnavailable = true;
+                m_useGnome = false;
+                m_pollTimer.stop();
+                startWaylandFallback();
+                return;
+            }
+            if (elapsedMs == 0) GUI_DEBUG("activity: GNOME system idle monitor ready");
+            if (reply.value() <= qulonglong(std::numeric_limits<qint64>::max())) checkIdleTime(qint64(reply.value()), elapsedMs);
+            else GUI_WARN("activity: GNOME idle time out of range: %llu", (unsigned long long)reply.value());
+        });
+        return;
+    }
+#endif
+    const qint64 elapsedMs = m_elapsed.elapsed();
+    const qint64 idleMs = systemIdleTime();
+    if (idleMs < 0) { m_pollTimer.stop(); useLocalActivity(); return; }
+    checkIdleTime(idleMs, elapsedMs);
+}
+
+void UserActivityMonitor::startWaylandFallback() {
+#ifdef UTUN_ACTIVITY_KIDLETIME
+    if (QGuiApplication::platformName().startsWith("wayland")) {
+        auto* idle = KIdleTime::instance();
+        const int timeout = idle->addIdleTimeout(0);
+        if (timeout) {
+            idle->removeIdleTimeout(timeout);
+            connect(idle, &KIdleTime::resumingFromIdle, this, [this] {
+                if (!m_watching || !m_useKIdleTime) return;
+                GUI_DEBUG("activity: Wayland compositor reported user activity");
+                stop();
+                emit activity();
+            });
+            m_useKIdleTime = true;
+            idle->catchNextResumeEvent();
+            GUI_DEBUG("activity: watching Wayland resume through KIdleTime (subject to compositor idle inhibitors)");
+            return;
+        }
+        GUI_WARN("activity: KIdleTime has no available compositor backend");
+    }
+#endif
+    useLocalActivity();
+}
+
+void UserActivityMonitor::useLocalActivity() {
+    if (!m_localWarningLogged) {
+        GUI_WARN("activity: global input unavailable platform=%s session=%s; using ChatGUI input and manual dismissal",
+                 qPrintable(QGuiApplication::platformName()), qPrintable(qEnvironmentVariable("XDG_SESSION_TYPE")));
+        m_localWarningLogged = true;
+    }
+}
+
+qint64 UserActivityMonitor::systemIdleTime() {
+#ifdef Q_OS_WIN
+    LASTINPUTINFO info = {sizeof(info), 0};
+    if (!GetLastInputInfo(&info)) { GUI_WARN("activity: GetLastInputInfo failed error=%lu", GetLastError()); return -1; }
+    return DWORD(GetTickCount() - info.dwTime);
+#elif defined(Q_OS_MACOS)
+    const double seconds = CGEventSourceSecondsSinceLastEventType(kCGEventSourceStateCombinedSessionState, kCGAnyInputEventType);
+    if (!std::isfinite(seconds) || seconds < 0 || seconds > double(std::numeric_limits<qint64>::max() / 1000)) {
+        GUI_WARN("activity: invalid macOS idle time seconds=%g", seconds);
+        return -1;
+    }
+    return qint64(seconds * 1000);
+#elif defined(UTUN_ACTIVITY_X11)
+    if (QGuiApplication::platformName() != "xcb") return -1;
+    if (!m_x11Checked) {
+        m_x11Checked = true;
+        auto* display = XOpenDisplay(nullptr);
+        int eventBase = 0, errorBase = 0;
+        if (!display) { GUI_WARN("activity: cannot open X11 display"); return -1; }
+        if (!XScreenSaverQueryExtension(display, &eventBase, &errorBase)) {
+            GUI_WARN("activity: X11 screen saver extension unavailable");
+            XCloseDisplay(display);
+            return -1;
+        }
+        m_display = display;
+    }
+    if (!m_display) return -1;
+    auto* display = static_cast<Display*>(m_display);
+    XScreenSaverInfo info{};
+    if (!XScreenSaverQueryInfo(display, DefaultRootWindow(display), &info)) {
+        GUI_WARN("activity: XScreenSaverQueryInfo failed");
+        return -1;
+    }
+    return qint64(info.idle);
+#else
+    return -1;
+#endif
+}
diff --git a/tools/chatgui/src/user_activity_monitor.h b/tools/chatgui/src/user_activity_monitor.h
new file mode 100644
index 00000000..dc8b6186
--- /dev/null
+++ b/tools/chatgui/src/user_activity_monitor.h
@@ -0,0 +1,41 @@
+/* Первая активность после start(): системный idle time или события приложения при ограничениях ОС.
+ * stop() отменяет наблюдение и запоздалые D-Bus ответы. Все вызовы и сигнал — в GUI-потоке. */
+#pragma once
+
+#include <QObject>
+#include <QElapsedTimer>
+#include <QTimer>
+
+class UserActivityMonitor : public QObject {
+    Q_OBJECT
+public:
+    explicit UserActivityMonitor(QObject* parent = nullptr);
+    ~UserActivityMonitor() override;
+    void start();
+    void stop();
+
+signals:
+    void activity();
+
+protected:
+    bool eventFilter(QObject* object, QEvent* event) override;
+    virtual qint64 systemIdleTime();
+
+private:
+    void poll();
+    void checkIdleTime(qint64 idleMs, qint64 elapsedMs);
+    void useLocalActivity();
+    void startWaylandFallback();
+
+    QTimer m_pollTimer;
+    QElapsedTimer m_elapsed;
+    bool m_watching = false;
+    bool m_localWarningLogged = false;
+    bool m_dbusPending = false;
+    bool m_useGnome = false;
+    bool m_gnomeUnavailable = false;
+    bool m_useKIdleTime = false;
+    quint64 m_generation = 0;
+    void* m_display = nullptr;
+    bool m_x11Checked = false;
+};