feat(notifications): QML and QWidget toasts with history drawer, folded repeats and sticky critical errors instead of modal error dialogs

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Kns5hgJ1MEXNfFeCuTESFP

bec_widgets/tests/fixtures.py

@@ -21,6 +21,7 @@ Requires ``bec_widgets[dev]`` (pytest-qt, fakeredis) and bec_lib's ``threads_che
 
 # pylint: disable=redefined-outer-name,unused-argument,wrong-import-position
 import os
+import sys
 
 # Keep ophyd on its dummy control layer, so importing it does not create a real EPICS CA context
 os.environ.setdefault("OPHYD_CONTROL_LAYER", "dummy")
@@ -159,6 +160,13 @@ def notification_broker_reset(bec_dispatcher):
     """Tear down the app-wide notification broker before the dispatcher it is bound to."""
     yield
     BECNotificationBroker.reset_singleton()
+    # the reworked notification hub is only reset if some test imported it
+    hub_module = sys.modules.get(
+        "bec_widgets.widgets.containers.main_window.addons.notification_center."
+        "notification_ux_common"
+    )
+    if hub_module is not None:
+        hub_module.NotificationHub.reset_instance()
 
 
 @pytest.fixture(autouse=True)

bec_widgets/utils/error_popups.py

@@ -111,7 +111,9 @@ def SafeProperty(
                 error_msg = traceback.format_exc()
 
                 if popup_error:
-                    ErrorPopupUtility().custom_exception_hook(*sys.exc_info(), popup_error=True)
+                    ErrorPopupUtility().custom_exception_hook(
+                        *sys.exc_info(), popup_error=True, source=py_getter.__qualname__
+                    )
                 logger.error(f"SafeProperty error in GETTER of '{prop_name}':\n{error_msg}")
                 return default
 
@@ -173,7 +175,7 @@ def SafeProperty(
 
                         if popup_error:
                             ErrorPopupUtility().custom_exception_hook(
-                                *sys.exc_info(), popup_error=True
+                                *sys.exc_info(), popup_error=True, source=setter_func.__qualname__
                             )
                         logger.error(f"SafeProperty error in SETTER of '{prop_name}':\n{error_msg}")
                         return
@@ -298,7 +300,9 @@ def SafeSlot(*slot_args, **slot_kwargs):  # pylint: disable=invalid-name
                 slot_name = f"{method.__module__}.{method.__qualname__}"
                 error_msg = traceback.format_exc()
                 if call_params["popup_error"]:
-                    ErrorPopupUtility().custom_exception_hook(*sys.exc_info(), popup_error=True)
+                    ErrorPopupUtility().custom_exception_hook(
+                        *sys.exc_info(), popup_error=True, source=method.__qualname__
+                    )
                 logger.error(f"SafeSlot error in slot '{slot_name}':\n{error_msg}")
                 if call_params["raise_error"]:
                     raise
@@ -308,6 +312,26 @@ def SafeSlot(*slot_args, **slot_kwargs):  # pylint: disable=invalid-name
     return error_managed
 
 
+def _notification_hub():
+    """Return the notification hub if a window shows notifications, else None.
+
+    When the reworked notification UI is attached to a window, errors and warnings become
+    toasts with a history entry instead of blocking message boxes.
+    """
+    # only look the module up: if nobody imported it, no window can show notifications, and
+    # importing it here would pull Qt Quick into every widget that reports an error
+    module = sys.modules.get(
+        "bec_widgets.widgets.containers.main_window.addons.notification_center."
+        "notification_ux_common"
+    )
+    if module is None:
+        return None
+    hub = module.NotificationHub._instance  # pylint: disable=protected-access
+    if hub is None or not shiboken6.isValid(hub) or not hub.has_hosts:
+        return None
+    return hub
+
+
 class WarningPopupUtility(QObject):
     """
     Utility class to show warning popups in the application.
@@ -315,6 +339,11 @@ class WarningPopupUtility(QObject):
 
     @SafeSlot(str, str, str, QWidget)
     def show_warning_message(self, title, message, detailed_text, widget):
+        hub = _notification_hub()
+        if hub is not None:
+            source = type(widget).__name__ if widget is not None else ""
+            hub.notify(title, message, "warning", details=detailed_text, source=source)
+            return
         msg = QMessageBox(widget)
         msg.setIcon(QMessageBox.Warning)
         msg.setWindowTitle(title)
@@ -415,12 +444,17 @@ class _ErrorPopupUtility(QObject):
     def get_error_message(self, exctype, value, tb):
         return "".join(traceback.format_exception(exctype, value, tb))
 
-    def custom_exception_hook(self, exctype, value, tb, popup_error=False):
+    def custom_exception_hook(self, exctype, value, tb, popup_error=False, source=None):
         if popup_error or self.enable_error_popup:
+            title = "Method error" if popup_error else "Application Error"
+            hub = _notification_hub()
+            if hub is not None:
+                hub.report_exception(
+                    title, self.get_error_message(exctype, value, tb), source=source or title
+                )
+                return
             self.error_occurred.emit(
-                "Method error" if popup_error else "Application Error",
-                self.get_error_message(exctype, value, tb),
-                self.parent(),
+                title, self.get_error_message(exctype, value, tb), self.parent()
             )
         else:
             sys.__excepthook__(exctype, value, tb)  # Call the original excepthook

bec_widgets/widgets/containers/main_window/addons/notification_center/notification_demo.py

@@ -0,0 +1,205 @@
+"""Demo window for the reworked notifications, used for screenshots and side-by-side checks.
+
+Run this module with ``--variant qml`` or ``--variant qwidget`` (``python -m
+bec_widgets.widgets.containers.main_window.addons.notification_center.notification_demo``).
+No BEC server is needed: the buttons post sample
+notifications and raise errors inside ``SafeSlot(popup_error=True)`` slots.
+"""
+
+from __future__ import annotations
+
+import argparse
+import sys
+import traceback
+
+import numpy as np
+import pyqtgraph as pg
+from qtpy.QtWidgets import (
+    QApplication,
+    QHBoxLayout,
+    QLabel,
+    QMainWindow,
+    QPushButton,
+    QToolBar,
+    QVBoxLayout,
+    QWidget,
+)
+
+from bec_widgets.utils.colors import apply_theme
+from bec_widgets.utils.error_popups import SafeSlot
+from bec_widgets.widgets.containers.main_window.addons.notification_center.notification_ux_common import (
+    NotificationHub,
+    Severity,
+)
+
+SAMPLE_TRACE = """Traceback (most recent call last):
+  File "/opt/bec/bec_server/device_server/devices/devicemanager.py", line 412, in stage
+    status = obj.stage()
+  File "/opt/bec/ophyd_devices/devices/eiger9m.py", line 233, in on_stage
+    self.cam.acquire.set(1).wait(timeout=10)
+  File "/opt/bec/ophyd/status.py", line 336, in wait
+    raise WaitTimeoutError(f"Status {self!r} has not completed yet.")
+ophyd.utils.errors.WaitTimeoutError: Status DeviceStatus(device=eiger9m_cam_acquire) has not completed yet.
+
+During handling of the above exception, another exception occurred:
+
+Traceback (most recent call last):
+  File "/opt/bec/bec_server/scan_server/scan_worker.py", line 289, in _stage_devices
+    self.device_manager.stage(devices, timeout=10)
+bec_lib.alarm_handler.DeviceTimeoutError: Device eiger9m did not respond within 10 s while staging."""
+
+
+def post_samples(hub: NotificationHub) -> None:
+    """Fill the hub with a realistic mix of notifications for screenshots."""
+    hub.notify(
+        "Scan 1042 finished",
+        "line_scan over samx, 101 points in 2 min 13 s.",
+        Severity.SUCCESS,
+        source="Scan queue",
+        scan_number=1042,
+    )
+    hub.notify(
+        "Profile saved",
+        "Workspace 'alignment' was saved to the beamline profiles.",
+        Severity.INFO,
+        source="Workspace",
+    )
+    hub.notify(
+        "Ring current low",
+        "Ring current dropped to 180 mA (threshold 200 mA). Data may be noisy.",
+        Severity.WARNING,
+        source="Beamline states",
+    )
+    trace = ""
+    try:
+        raise ValueError("Target 12.5 is outside the soft limits [-10, 10] of samx.")
+    except ValueError:
+        trace = traceback.format_exc()
+    for _ in range(3):
+        hub.report_exception("Method error", trace, source="PositionerBox.move")
+    hub.post_alarm(
+        {
+            "severity": 2,
+            "alarm_type": "DeviceTimeoutError",
+            "msg": SAMPLE_TRACE,
+            "info": {
+                "id": "demo-critical",
+                "error_message": SAMPLE_TRACE,
+                "compact_error_message": "Device eiger9m did not respond within 10 s while"
+                " staging. The scan was aborted.",
+                "exception_type": "DeviceTimeoutError",
+                "device": "eiger9m",
+            },
+        },
+        {"scan_number": 1043, "scan_id": "4f0d6c1e-7a51-4b0c-9a59-2f9a3d1c2b77"},
+    )
+
+
+class DemoWindow(QMainWindow):
+    """Window that looks like the BEC app, with buttons that produce notifications."""
+
+    def __init__(self, variant: str = "qwidget"):
+        super().__init__()
+        self.setWindowTitle(f"BEC notifications ({variant})")
+        self.resize(1180, 720)
+        self.menuBar().addMenu("File")
+        self.menuBar().addMenu("View")
+        self.menuBar().addMenu("Help")
+        toolbar = QToolBar("Main", self)
+        for label in ("Dock area", "Device manager", "Scan control"):
+            toolbar.addAction(label)
+        self.addToolBar(toolbar)
+
+        central = QWidget(self)
+        layout = QHBoxLayout(central)
+        controls = QVBoxLayout()
+        self.hub = NotificationHub.instance()
+        for label, slot in (
+            ("Info", lambda: self.hub.notify("Profile saved", "Workspace saved.", "info")),
+            ("Success", lambda: self.hub.notify("Scan finished", "101 points.", "success")),
+            ("Warning", lambda: self.hub.notify("Ring current low", "180 mA.", "warning")),
+            ("Error in a slot", self.failing_slot),
+            ("Critical alarm", self.critical),
+            ("Burst of 20 errors", self.burst),
+            ("Toggle theme", self.toggle_theme),
+        ):
+            button = QPushButton(label, central)
+            button.clicked.connect(slot)
+            controls.addWidget(button)
+        controls.addStretch(1)
+        layout.addLayout(controls)
+        plot = pg.PlotWidget(central)
+        x = np.linspace(-5, 5, 400)
+        plot.plot(x, np.exp(-(x**2) / 2) + 0.05 * np.sin(9 * x), pen=pg.mkPen("#3b82f6", width=2))
+        plot.showGrid(x=True, y=True, alpha=0.2)
+        layout.addWidget(plot, 1)
+        self.setCentralWidget(central)
+        self.statusBar().addWidget(QLabel("Ready · account p12345"))
+
+        if variant == "qml":
+            from bec_widgets.widgets.containers.main_window.addons.notification_center.notification_qml import (
+                NotificationHostQML as Host,
+            )
+        else:
+            from bec_widgets.widgets.containers.main_window.addons.notification_center.notification_qwidget import (
+                NotificationHostQWidget as Host,
+            )
+        self.notifications = Host(self)
+
+    @SafeSlot(popup_error=True)
+    def failing_slot(self):
+        """Raise inside a SafeSlot: shows a toast instead of a modal dialog."""
+        raise ValueError("Target 12.5 is outside the soft limits [-10, 10] of samx.")
+
+    def critical(self):
+        """Post a critical alarm with a long traceback."""
+        self.hub.post_alarm(
+            {
+                "severity": 2,
+                "alarm_type": "DeviceTimeoutError",
+                "msg": SAMPLE_TRACE,
+                "info": {
+                    "id": None,
+                    "error_message": SAMPLE_TRACE,
+                    "compact_error_message": "Device eiger9m did not respond within 10 s.",
+                    "exception_type": "DeviceTimeoutError",
+                    "device": "eiger9m",
+                },
+            },
+            {"scan_number": 1043},
+        )
+
+    def burst(self):
+        """Post many different errors at once; the stack shows three and counts the rest."""
+        for i in range(20):
+            self.hub.notify(f"Readback failed for motor{i}", "Timeout after 2 s.", "error")
+
+    def toggle_theme(self):
+        """Switch between the light and dark theme."""
+        theme = getattr(QApplication.instance(), "theme", None)
+        apply_theme("light" if theme is not None and theme.theme == "dark" else "dark")
+
+    def closeEvent(self, event):  # pylint: disable=invalid-name
+        """Detach the notification UI."""
+        self.notifications.cleanup()
+        super().closeEvent(event)
+
+
+def main(variant: str | None = None) -> None:  # pragma: no cover
+    """Start the demo."""
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("--variant", choices=("qml", "qwidget"), default=variant or "qwidget")
+    parser.add_argument("--theme", choices=("dark", "light"), default="dark")
+    parser.add_argument("--samples", action="store_true", help="start with sample notifications")
+    args = parser.parse_args()
+    app = QApplication(sys.argv)
+    apply_theme(args.theme)
+    window = DemoWindow(args.variant)
+    window.show()
+    if args.samples:
+        post_samples(window.hub)
+    sys.exit(app.exec())
+
+
+if __name__ == "__main__":  # pragma: no cover
+    main()

bec_widgets/widgets/containers/main_window/addons/notification_center/notification_qml.py

@@ -0,0 +1,177 @@
+"""Notification toasts, history drawer and bell rendered with Qt Quick (QML).
+
+Same UX as :mod:`notification_qwidget`; the state comes from
+:class:`~.notification_ux_common.NotificationHostBase`.
+"""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+from qtpy.QtCore import Property, QObject, Qt, Signal, Slot
+from qtpy.QtQuickWidgets import QQuickWidget
+
+from bec_widgets.utils.quick import DictListModel, create_quick_widget, release_quick_widget
+from bec_widgets.widgets.containers.main_window.addons.notification_center.notification_ux_common import (
+    NotificationHostBase,
+)
+
+QML_DIR = Path(__file__).parent / "qml"
+
+ROW_ROLES = [
+    "entryId",
+    "severity",
+    "severityLabel",
+    "icon",
+    "color",
+    "tint",
+    "title",
+    "body",
+    "details",
+    "hasDetails",
+    "source",
+    "meta",
+    "time",
+    "timeAbs",
+    "firstAbs",
+    "scan",
+    "count",
+    "unread",
+    "needsAck",
+    "critical",
+]
+
+
+class NotificationBackend(QObject):
+    """Bridge between :class:`NotificationHostQML` and its three QML views."""
+
+    changed = Signal()
+
+    def __init__(self, host: NotificationHostQML):
+        super().__init__(host)
+        self._host = host
+        self._state: dict = {}
+        self._toasts = DictListModel(ROW_ROLES, self)
+        self._rows = DictListModel(ROW_ROLES, self)
+
+    def update_from(self, state: dict) -> None:
+        """Take a new view state from the host."""
+        state = dict(state)
+        self._toasts.set_items(state.pop("toasts"))
+        self._rows.set_items(state.pop("rows"))
+        state["selected"] = state["selected"] or {}
+        self._state = state
+        self.changed.emit()
+
+    # pylint: disable=invalid-name,missing-function-docstring
+    @Slot()
+    def toggleDrawer(self) -> None:
+        self._host.toggle_drawer()
+
+    @Slot(bool)
+    def setDrawerOpen(self, open_: bool) -> None:
+        self._host.set_drawer_open(open_)
+
+    @Slot(str)
+    def openDetails(self, entry_id: str) -> None:
+        self._host.open_details(entry_id)
+
+    @Slot(str)
+    def select(self, entry_id: str) -> None:
+        self._host.select(entry_id or None)
+
+    @Slot(str)
+    def setFilter(self, key: str) -> None:
+        self._host.set_filter(key)
+
+    @Slot(str)
+    def setSearch(self, text: str) -> None:
+        self._host.set_search(text)
+
+    @Slot(str)
+    def acknowledge(self, entry_id: str) -> None:
+        self._host.acknowledge(entry_id)
+
+    @Slot(str)
+    def remove(self, entry_id: str) -> None:
+        self._host.remove(entry_id)
+
+    @Slot(str)
+    def dismissToast(self, entry_id: str) -> None:
+        self._host.dismiss_toast(entry_id)
+
+    @Slot(str, result=bool)
+    def copyDetails(self, entry_id: str) -> bool:
+        return self._host.copy_details(entry_id)
+
+    @Slot()
+    def markAllRead(self) -> None:
+        self._host.mark_all_read()
+
+    @Slot()
+    def clearHistory(self) -> None:
+        self._host.clear_history()
+
+    @Slot(bool)
+    def setHovered(self, hovered: bool) -> None:
+        self._host.set_toasts_hovered(hovered)
+
+    state = Property("QVariantMap", lambda self: self._state, notify=changed)
+    toasts = Property(QObject, lambda self: self._toasts, constant=True)
+    rows = Property(QObject, lambda self: self._rows, constant=True)
+
+
+class NotificationHostQML(NotificationHostBase):
+    """Notification UI rendered in QML. See :class:`NotificationHostBase`."""
+
+    def _create_views(self) -> None:
+        self.backend = NotificationBackend(self)
+        props = {"backend": self.backend}
+        # toasts float over the window content: a transparent view stacked on top
+        self.toasts = create_quick_widget(self.window, QML_DIR / "NotificationToasts.qml", props)
+        self.toasts.setAttribute(Qt.WidgetAttribute.WA_AlwaysStackOnTop, True)
+        self.toasts.setAttribute(Qt.WidgetAttribute.WA_TranslucentBackground, True)
+        self.toasts.setClearColor(Qt.GlobalColor.transparent)
+        self.toasts.hide()
+        self.drawer = create_quick_widget(self.window, QML_DIR / "NotificationDrawer.qml", props)
+        self.drawer.hide()
+        self.bell = None
+        if self.status_bar is not None:
+            self.bell = create_quick_widget(
+                self.status_bar, QML_DIR / "NotificationBell.qml", props
+            )
+            self.bell.setFixedSize(36, 24)
+            self.bell.setResizeMode(QQuickWidget.ResizeMode.SizeRootObjectToView)
+            self.status_bar.addPermanentWidget(self.bell)
+        root = self.toasts.rootObject()
+        if root is not None:
+            root.implicitHeightChanged.connect(self._place_views)
+
+    def _sync_views(self, state: dict) -> None:
+        self.backend.update_from(state)
+        self.toasts.setVisible(bool(state["toasts"]))
+        self.drawer.setVisible(state["drawerOpen"])
+
+    def _place_views(self, *_args) -> None:
+        if self.drawer.isVisible():
+            self.drawer.setGeometry(self.drawer_geometry())
+            self.drawer.raise_()
+        if self.toasts.isVisible():
+            root = self.toasts.rootObject()
+            height = int(root.property("implicitHeight")) if root is not None else 0
+            rect = self.toast_geometry(max(0, height - 16))
+            self.toasts.setGeometry(rect.adjusted(-8, -8, 8, 8) & self.window.rect())
+            self.toasts.raise_()
+
+    def _apply_theme(self) -> None:
+        if self.bell is not None:
+            self.bell.setClearColor(self.status_bar.palette().window().color())
+        self.drawer.setClearColor(self.window.palette().window().color())
+
+    def _destroy_views(self) -> None:
+        for view in (self.toasts, self.drawer, self.bell):
+            if view is None:
+                continue
+            release_quick_widget(view)
+            view.hide()
+            view.deleteLater()

bec_widgets/widgets/containers/main_window/addons/notification_center/notification_qwidget.py

@@ -0,0 +1,740 @@
+"""Notification toasts, history drawer and bell built with QWidgets.
+
+Same UX as :mod:`notification_qml`; the state comes from
+:class:`~.notification_ux_common.NotificationHostBase`.
+"""
+
+from __future__ import annotations
+
+from bec_qthemes import material_icon
+from qtpy.QtCore import QAbstractListModel, QModelIndex, QRectF, QSize, Qt
+from qtpy.QtGui import QColor, QFont, QFontDatabase, QPainter, QPainterPath, QPen
+from qtpy.QtWidgets import (
+    QFrame,
+    QGraphicsDropShadowEffect,
+    QHBoxLayout,
+    QLabel,
+    QLineEdit,
+    QListView,
+    QPlainTextEdit,
+    QPushButton,
+    QScrollArea,
+    QStackedWidget,
+    QStyle,
+    QStyledItemDelegate,
+    QToolButton,
+    QVBoxLayout,
+    QWidget,
+)
+
+from bec_widgets.utils.quick.host import ThemeTokens
+from bec_widgets.utils.ux_kit import IconButton, TextButton, field_qss, rgba
+from bec_widgets.widgets.containers.main_window.addons.notification_center.notification_ux_common import (
+    NotificationHostBase,
+)
+
+
+def _icon_badge(painter: QPainter, rect: QRectF, icon: str, color: QColor, tint: QColor):
+    """Paint a round tinted badge with a Material icon, as used by toasts and rows."""
+    painter.setPen(Qt.PenStyle.NoPen)
+    painter.setBrush(tint)
+    painter.drawEllipse(rect)
+    size = int(rect.width() * 0.6)
+    pixmap = material_icon(icon, size=(size * 2, size * 2), color=color, filled=True)
+    target = QRectF(rect.center().x() - size / 2, rect.center().y() - size / 2, size, size).toRect()
+    painter.drawPixmap(target, pixmap)
+
+
+class _Badge(QWidget):
+    """Round severity icon painted on a tinted circle."""
+
+    def __init__(self, parent: QWidget | None = None, size: int = 32):
+        super().__init__(parent)
+        self.setFixedSize(size, size)
+        self._icon = "info"
+        self._color = QColor("#888")
+        self._tint = QColor("#333")
+
+    def set_icon(self, icon: str, color: str, tint: str) -> None:
+        """Set icon name and colours."""
+        self._icon, self._color, self._tint = icon, QColor(color), QColor(tint)
+        self.update()
+
+    def paintEvent(self, _event):  # pylint: disable=invalid-name
+        painter = QPainter(self)
+        painter.setRenderHint(QPainter.RenderHint.Antialiasing)
+        _icon_badge(painter, QRectF(self.rect()), self._icon, self._color, self._tint)
+        painter.end()
+
+
+class ToastCard(QFrame):
+    """One toast: badge, title, message, meta line and actions."""
+
+    def __init__(self, host: NotificationHostBase, parent: QWidget | None = None):
+        super().__init__(parent)
+        self.host = host
+        self.entry_id = ""
+        self._row: dict = {}
+        self.setObjectName("toastCard")
+        self.setAttribute(Qt.WidgetAttribute.WA_StyledBackground, False)
+
+        self.badge = _Badge(self, 32)
+        self.title = QLabel(self)
+        self.title.setTextFormat(Qt.TextFormat.PlainText)
+        self.count = QLabel(self)
+        self.close_btn = IconButton("close", "Dismiss", self, size=16)
+        self.close_btn.setFixedSize(24, 24)
+        self.close_btn.clicked.connect(lambda: self.host.dismiss_toast(self.entry_id))
+        self.body = QLabel(self)
+        self.body.setWordWrap(True)
+        self.body.setTextFormat(Qt.TextFormat.PlainText)
+        self.meta = QLabel(self)
+        self.details_btn = TextButton("Details", "ghost", "open_in_new", self)
+        self.details_btn.setMinimumHeight(28)
+        self.details_btn.clicked.connect(lambda: self.host.open_details(self.entry_id))
+        self.copy_btn = IconButton("content_copy", "Copy report", self, size=16)
+        self.copy_btn.setFixedSize(28, 28)
+        self.copy_btn.clicked.connect(lambda: self.host.copy_details(self.entry_id))
+        self.ack_btn = TextButton("Acknowledge", "danger", "done", self)
+        self.ack_btn.setMinimumHeight(28)
+        self.ack_btn.clicked.connect(lambda: self.host.acknowledge(self.entry_id))
+
+        head = QHBoxLayout()
+        head.setSpacing(6)
+        head.addWidget(self.title, 1)
+        head.addWidget(self.count)
+        head.addWidget(self.close_btn)
+        text = QVBoxLayout()
+        text.setSpacing(3)
+        text.addLayout(head)
+        text.addWidget(self.body)
+        text.addWidget(self.meta)
+        self.actions = QHBoxLayout()
+        self.actions.setSpacing(6)
+        self.actions.addStretch(1)
+        self.actions.addWidget(self.copy_btn)
+        self.actions.addWidget(self.details_btn)
+        self.actions.addWidget(self.ack_btn)
+        text.addLayout(self.actions)
+        row = QHBoxLayout(self)
+        row.setContentsMargins(14, 12, 10, 10)
+        row.setSpacing(12)
+        row.addWidget(self.badge, 0, Qt.AlignmentFlag.AlignTop)
+        row.addLayout(text, 1)
+
+        shadow = QGraphicsDropShadowEffect(self)
+        shadow.setBlurRadius(24)
+        shadow.setOffset(0, 4)
+        shadow.setColor(QColor(0, 0, 0, 90))
+        self.setGraphicsEffect(shadow)
+
+    def set_row(self, row: dict, tokens: ThemeTokens) -> None:
+        """Show the entry described by ``row``."""
+        self._row = row
+        self.entry_id = row["id"]
+        self.badge.set_icon(row["icon"], row["color"], row["tint"])
+        self.title.setText(row["title"])
+        self.title.setToolTip(row["title"])
+        self.count.setText(f"×{row['count']}")
+        self.count.setVisible(row["count"] > 1)
+        body = row["body"] or ""
+        self.body.setText(body if len(body) <= 220 else body[:217] + "…")
+        self.body.setToolTip(body if len(body) > 220 else "")
+        self.body.setVisible(bool(body))
+        self.meta.setText(row["meta"])
+        self.close_btn.setVisible(not row["needsAck"])
+        self.ack_btn.setVisible(row["needsAck"])
+        self.details_btn.setVisible(row["hasDetails"] or row["needsAck"])
+        self.copy_btn.setVisible(row["severity"] in ("error", "critical"))
+        self._style(tokens)
+        self.update()
+
+    def _style(self, tokens: ThemeTokens) -> None:
+        self.title.setStyleSheet(
+            f"color: {tokens.fg.name()}; font-size: 13px; font-weight: 600; background: none;"
+        )
+        self.body.setStyleSheet(
+            f"color: {tokens.fg_muted.name()}; font-size: 12px; background: none;"
+        )
+        self.meta.setStyleSheet(
+            f"color: {tokens.fg_subtle.name()}; font-size: 11px; background: none;"
+        )
+        self.count.setStyleSheet(
+            f"color: {self._row.get('color', tokens.fg.name())}; font-size: 11px;"
+            f" font-weight: 700; background: {self._row.get('tint', 'transparent')};"
+            " border-radius: 8px; padding: 0px 6px;"
+        )
+        self.count.setFixedHeight(16)
+        for button in (self.close_btn, self.details_btn, self.copy_btn, self.ack_btn):
+            button.refresh_theme(tokens)
+
+    def paintEvent(self, _event):  # pylint: disable=invalid-name
+        tokens = ThemeTokens()
+        painter = QPainter(self)
+        painter.setRenderHint(QPainter.RenderHint.Antialiasing)
+        rect = QRectF(self.rect()).adjusted(0.5, 0.5, -0.5, -0.5)
+        path = QPainterPath()
+        path.addRoundedRect(rect, 10, 10)
+        painter.fillPath(path, tokens.card)
+        accent = QColor(self._row.get("color", tokens.border.name()))
+        critical = self._row.get("needsAck", False)
+        painter.setPen(QPen(accent if critical else tokens.border, 1.5 if critical else 1))
+        painter.drawPath(path)
+        # severity stripe along the straight part of the left edge
+        painter.setPen(Qt.PenStyle.NoPen)
+        painter.setBrush(accent)
+        painter.drawRoundedRect(QRectF(rect.left(), rect.top() + 10, 4, rect.height() - 20), 2, 2)
+        painter.end()
+
+
+class ToastStack(QWidget):
+    """Bottom-right column of toasts with an overflow link; hovering pauses the countdowns."""
+
+    def __init__(self, host: NotificationHostBase, parent: QWidget):
+        super().__init__(parent)
+        self.host = host
+        self.setAttribute(Qt.WidgetAttribute.WA_TranslucentBackground, True)
+        self._cards: dict[str, ToastCard] = {}
+        self._layout = QVBoxLayout(self)
+        self._layout.setContentsMargins(8, 8, 8, 8)  # room for the shadow
+        self._layout.setSpacing(10)
+        self.more_btn = TextButton("", "neutral", "expand_less", self)
+        self.more_btn.clicked.connect(lambda: self.host.set_drawer_open(True))
+        self._layout.addWidget(self.more_btn, 0, Qt.AlignmentFlag.AlignRight)
+
+    def set_state(self, state: dict, tokens: ThemeTokens) -> None:
+        """Show the toasts of ``state``; cards are reused by entry id."""
+        rows = state["toasts"]
+        wanted = [row["id"] for row in rows]
+        for entry_id in list(self._cards):
+            if entry_id not in wanted:
+                card = self._cards.pop(entry_id)
+                self._layout.removeWidget(card)
+                card.deleteLater()
+        # newest at the bottom, nearest to the status bar
+        for position, row in enumerate(rows, start=1):
+            card = self._cards.get(row["id"])
+            if card is None:
+                card = ToastCard(self.host, self)
+                self._cards[row["id"]] = card
+            card.set_row(row, tokens)
+            if self._layout.indexOf(card) != position:
+                self._layout.removeWidget(card)
+                self._layout.insertWidget(position, card)
+        overflow = state["overflow"]
+        self.more_btn.setText(f"{overflow} more in notifications")
+        self.more_btn.setVisible(overflow > 0)
+        self.more_btn.refresh_theme(tokens)
+        # solid like a card: the link floats over plots
+        self.more_btn.setStyleSheet(
+            self.more_btn.styleSheet()
+            + f"QPushButton {{ background: {tokens.card.name()}; }}"
+            + f"QPushButton:hover {{ background: {tokens.hover.name()}; }}"
+        )
+        self.setVisible(bool(rows))
+
+    @property
+    def cards(self) -> list[ToastCard]:
+        """Cards on screen, oldest first."""
+        return [
+            self._layout.itemAt(i).widget()
+            for i in range(self._layout.count())
+            if isinstance(self._layout.itemAt(i).widget(), ToastCard)
+        ]
+
+    def enterEvent(self, event):  # pylint: disable=invalid-name
+        self.host.set_toasts_hovered(True)
+        super().enterEvent(event)
+
+    def leaveEvent(self, event):  # pylint: disable=invalid-name
+        self.host.set_toasts_hovered(False)
+        super().leaveEvent(event)
+
+
+class _RowsModel(QAbstractListModel):
+    """Rows of the history list; each row is the dictionary from ``entry_row``."""
+
+    def __init__(self, parent=None):
+        super().__init__(parent)
+        self.rows: list[dict] = []
+
+    def set_rows(self, rows: list[dict]) -> None:
+        """Replace the rows."""
+        self.beginResetModel()
+        self.rows = rows
+        self.endResetModel()
+
+    def rowCount(self, parent: QModelIndex = QModelIndex()) -> int:  # pylint: disable=invalid-name
+        return 0 if parent.isValid() else len(self.rows)
+
+    def data(self, index: QModelIndex, role: int = Qt.ItemDataRole.DisplayRole):
+        if not index.isValid():
+            return None
+        row = self.rows[index.row()]
+        if role == Qt.ItemDataRole.UserRole:
+            return row
+        if role == Qt.ItemDataRole.DisplayRole:
+            return row["title"]
+        if role == Qt.ItemDataRole.ToolTipRole:
+            return row["timeAbs"]
+        return None
+
+
+class _RowDelegate(QStyledItemDelegate):
+    """Paints a history row: stripe, badge, title, time, message and meta line."""
+
+    HEIGHT = 78
+
+    def sizeHint(self, _option, _index):  # pylint: disable=invalid-name
+        return QSize(200, self.HEIGHT)
+
+    def paint(self, painter: QPainter, option, index):
+        row = index.data(Qt.ItemDataRole.UserRole)
+        if row is None:
+            return
+        tokens = ThemeTokens()
+        painter.save()
+        painter.setRenderHint(QPainter.RenderHint.Antialiasing)
+        rect = QRectF(option.rect).adjusted(8, 3, -8, -3)
+        hovered = bool(option.state & QStyle.StateFlag.State_MouseOver)
+        background = QColor(row["tint"]) if row["needsAck"] else tokens.card
+        if hovered:
+            background = tokens.hover if not row["needsAck"] else QColor(row["tint"]).lighter(110)
+        path = QPainterPath()
+        path.addRoundedRect(rect, 8, 8)
+        painter.fillPath(path, background)
+        painter.setPen(QPen(QColor(row["color"]) if row["needsAck"] else tokens.border, 1))
+        painter.drawPath(path)
+        _icon_badge(
+            painter,
+            QRectF(rect.left() + 10, rect.top() + 10, 28, 28),
+            row["icon"],
+            QColor(row["color"]),
+            QColor(row["tint"]) if not row["needsAck"] else tokens.card,
+        )
+        left = rect.left() + 48
+        right = rect.right() - 10
+        font = QFont(option.font)
+        font.setPixelSize(11)
+        painter.setFont(font)
+        time_w = painter.fontMetrics().horizontalAdvance(row["time"])
+        painter.setPen(tokens.fg_subtle)
+        painter.drawText(
+            QRectF(right - time_w, rect.top() + 8, time_w, 18),
+            Qt.AlignmentFlag.AlignVCenter,
+            row["time"],
+        )
+        title_right = right - time_w - 8
+        if row["unread"]:
+            painter.setPen(Qt.PenStyle.NoPen)
+            painter.setBrush(tokens.primary)
+            painter.drawEllipse(QRectF(title_right - 7, rect.top() + 14, 7, 7))
+            title_right -= 14
+        if row["count"] > 1:
+            badge = f"×{row['count']}"
+            badge_w = painter.fontMetrics().horizontalAdvance(badge) + 12
+            badge_rect = QRectF(title_right - badge_w, rect.top() + 9, badge_w, 16)
+            painter.setPen(Qt.PenStyle.NoPen)
+            painter.setBrush(QColor(row["tint"]))
+            painter.drawRoundedRect(badge_rect, 8, 8)
+            painter.setPen(QColor(row["color"]))
+            painter.drawText(badge_rect, Qt.AlignmentFlag.AlignCenter, badge)
+            title_right -= badge_w + 6
+        font.setPixelSize(13)
+        font.setWeight(QFont.Weight.DemiBold)
+        painter.setFont(font)
+        painter.setPen(tokens.fg)
+        title = painter.fontMetrics().elidedText(
+            row["title"], Qt.TextElideMode.ElideRight, int(title_right - left)
+        )
+        painter.drawText(
+            QRectF(left, rect.top() + 8, title_right - left, 18),
+            Qt.AlignmentFlag.AlignVCenter,
+            title,
+        )
+        font.setPixelSize(12)
+        font.setWeight(QFont.Weight.Normal)
+        painter.setFont(font)
+        painter.setPen(tokens.fg_muted)
+        body = painter.fontMetrics().elidedText(
+            row["body"].replace("\n", " "), Qt.TextElideMode.ElideRight, int(right - left)
+        )
+        painter.drawText(
+            QRectF(left, rect.top() + 28, right - left, 18), Qt.AlignmentFlag.AlignVCenter, body
+        )
+        font.setPixelSize(11)
+        painter.setFont(font)
+        meta_color = QColor(row["color"]) if row["needsAck"] else tokens.fg_subtle
+        painter.setPen(meta_color)
+        meta = ("Needs acknowledgement · " if row["needsAck"] else "") + " · ".join(
+            part for part in (row["severityLabel"], row["source"], row["scan"]) if part
+        )
+        meta = painter.fontMetrics().elidedText(
+            meta, Qt.TextElideMode.ElideRight, int(right - left)
+        )
+        painter.drawText(
+            QRectF(left, rect.top() + 48, right - left, 16), Qt.AlignmentFlag.AlignVCenter, meta
+        )
+        painter.restore()
+
+
+class _DetailsPage(QWidget):
+    """Full view of one entry: message, metadata, details text and actions."""
+
+    def __init__(self, host: NotificationHostBase, parent: QWidget | None = None):
+        super().__init__(parent)
+        self.host = host
+        self.entry_id = ""
+        self.back_btn = TextButton("All notifications", "ghost", "arrow_back", self)
+        self.back_btn.clicked.connect(lambda: self.host.select(None))
+        self.badge = _Badge(self, 36)
+        self.title = QLabel(self)
+        self.title.setWordWrap(True)
+        self.title.setTextInteractionFlags(Qt.TextInteractionFlag.TextSelectableByMouse)
+        self.pill = QLabel(self)
+        self.pill.setFixedHeight(18)
+        self.body = QLabel(self)
+        self.body.setWordWrap(True)
+        self.body.setTextInteractionFlags(Qt.TextInteractionFlag.TextSelectableByMouse)
+        self.facts = QLabel(self)
+        self.facts.setTextFormat(Qt.TextFormat.RichText)
+        self.details_label = QLabel("Details", self)
+        self.details = QPlainTextEdit(self)
+        self.details.setReadOnly(True)
+        self.details.setLineWrapMode(QPlainTextEdit.LineWrapMode.NoWrap)
+        mono = QFontDatabase.systemFont(QFontDatabase.SystemFont.FixedFont)
+        mono.setPixelSize(11)
+        self.details.setFont(mono)
+        self.copy_btn = TextButton("Copy report", "neutral", "content_copy", self)
+        self.copy_btn.clicked.connect(self._copy)
+        self.ack_btn = TextButton("Acknowledge", "danger", "done", self)
+        self.ack_btn.clicked.connect(lambda: self.host.acknowledge(self.entry_id))
+        self.remove_btn = TextButton("Remove", "ghost", "delete", self)
+        self.remove_btn.clicked.connect(lambda: self.host.remove(self.entry_id))
+
+        head = QHBoxLayout()
+        head.setSpacing(12)
+        head.addWidget(self.badge, 0, Qt.AlignmentFlag.AlignTop)
+        title_col = QVBoxLayout()
+        title_col.setSpacing(4)
+        title_col.addWidget(self.pill, 0, Qt.AlignmentFlag.AlignLeft)
+        title_col.addWidget(self.title)
+        head.addLayout(title_col, 1)
+        actions = QHBoxLayout()
+        actions.setSpacing(6)
+        actions.addWidget(self.copy_btn)
+        actions.addWidget(self.ack_btn)
+        actions.addStretch(1)
+        actions.addWidget(self.remove_btn)
+        layout = QVBoxLayout(self)
+        layout.setContentsMargins(12, 4, 12, 12)
+        layout.setSpacing(10)
+        layout.addWidget(self.back_btn, 0, Qt.AlignmentFlag.AlignLeft)
+        layout.addLayout(head)
+        layout.addWidget(self.body)
+        layout.addWidget(self.facts)
+        layout.addWidget(self.details_label)
+        layout.addWidget(self.details, 1)
+        layout.addStretch(0)
+        layout.addLayout(actions)
+
+    def _copy(self) -> None:
+        if self.host.copy_details(self.entry_id):
+            self.copy_btn.setText("Copied")
+
+    def set_row(self, row: dict, tokens: ThemeTokens) -> None:
+        """Show ``row``."""
+        if row["id"] != self.entry_id:
+            self.copy_btn.setText("Copy report")
+        self.entry_id = row["id"]
+        self.badge.set_icon(row["icon"], row["color"], row["tint"])
+        self.title.setText(row["title"])
+        label = row["severityLabel"] + (" · needs acknowledgement" if row["needsAck"] else "")
+        self.pill.setText(label)
+        self.body.setText(row["body"] or "No message.")
+        facts = [("When", row["timeAbs"])]
+        if row["count"] > 1:
+            facts.append(("Repeated", f"{row['count']} times since {row['firstAbs']}"))
+        if row["source"]:
+            facts.append(("Source", row["source"]))
+        if row["scan"]:
+            facts.append(("Scan", row["scan"]))
+        self.facts.setText(
+            "<table cellspacing='0' cellpadding='2'>"
+            + "".join(
+                f"<tr><td style='color:{tokens.fg_subtle.name()}; padding-right:12px'>{k}</td>"
+                f"<td style='color:{tokens.fg.name()}'>{v}</td></tr>"
+                for k, v in facts
+            )
+            + "</table>"
+        )
+        if self.details.toPlainText() != row["details"]:
+            self.details.setPlainText(row["details"])
+        self.details.setVisible(row["hasDetails"])
+        self.details_label.setVisible(row["hasDetails"])
+        self.ack_btn.setVisible(row["needsAck"])
+        self.title.setStyleSheet(
+            f"color: {tokens.fg.name()}; font-size: 15px; font-weight: 600; background: none;"
+        )
+        self.pill.setStyleSheet(
+            f"color: {row['color']}; background: {row['tint']}; border-radius: 9px;"
+            " padding: 1px 8px; font-size: 11px; font-weight: 600;"
+        )
+        self.body.setStyleSheet(f"color: {tokens.fg.name()}; font-size: 13px; background: none;")
+        self.facts.setStyleSheet("font-size: 12px; background: none;")
+        self.details_label.setStyleSheet(
+            f"color: {tokens.fg_subtle.name()}; font-size: 11px; font-weight: 600;"
+            " text-transform: uppercase; background: none;"
+        )
+        self.details.setStyleSheet(
+            f"QPlainTextEdit {{ background: {tokens.field.name()}; color: {tokens.fg.name()};"
+            f" border: 1px solid {tokens.border.name()}; border-radius: 8px; padding: 6px; }}"
+        )
+        for button in (self.back_btn, self.copy_btn, self.ack_btn, self.remove_btn):
+            button.refresh_theme(tokens)
+
+
+class HistoryDrawer(QFrame):
+    """Right-edge panel with filters, search, the notification history and details."""
+
+    def __init__(self, host: NotificationHostBase, parent: QWidget):
+        super().__init__(parent)
+        self.host = host
+        self.setObjectName("notificationDrawer")
+        self.title = QLabel("Notifications", self)
+        self.subtitle = QLabel(self)
+        self.read_btn = IconButton("done_all", "Mark all as read", self)
+        self.read_btn.clicked.connect(self.host.mark_all_read)
+        self.clear_btn = IconButton("clear_all", "Clear history", self)
+        self.clear_btn.clicked.connect(self.host.clear_history)
+        self.close_btn = IconButton("close", "Close", self)
+        self.close_btn.clicked.connect(lambda: self.host.set_drawer_open(False))
+        self.chips: dict[str, QPushButton] = {}
+        chips_row = QHBoxLayout()
+        chips_row.setSpacing(6)
+        for key in ("all", "errors", "warnings", "info"):
+            chip = QPushButton(self)
+            chip.setCheckable(True)
+            chip.setFixedHeight(26)
+            chip.setCursor(Qt.CursorShape.PointingHandCursor)
+            chip.clicked.connect(lambda _=False, k=key: self.host.set_filter(k))
+            self.chips[key] = chip
+            chips_row.addWidget(chip)
+        chips_row.addStretch(1)
+        self.search = QLineEdit(self)
+        self.search.setPlaceholderText("Search notifications")
+        self.search.setClearButtonEnabled(True)
+        self.search.textChanged.connect(self.host.set_search)
+
+        self.model = _RowsModel(self)
+        self.list = QListView(self)
+        self.list.setModel(self.model)
+        self.list.setItemDelegate(_RowDelegate(self.list))
+        self.list.setMouseTracking(True)
+        self.list.setUniformItemSizes(True)
+        self.list.setVerticalScrollMode(QListView.ScrollMode.ScrollPerPixel)
+        self.list.setFrameShape(QFrame.Shape.NoFrame)
+        self.list.clicked.connect(
+            lambda index: self.host.select(index.data(Qt.ItemDataRole.UserRole)["id"])
+        )
+        self.empty = QLabel(self)
+        self.empty.setAlignment(Qt.AlignmentFlag.AlignCenter)
+        self.empty.setWordWrap(True)
+        self.details = _DetailsPage(host, self)
+        details_scroll = QScrollArea(self)
+        details_scroll.setWidgetResizable(True)
+        details_scroll.setFrameShape(QFrame.Shape.NoFrame)
+        details_scroll.setWidget(self.details)
+        self.pages = QStackedWidget(self)
+        self.pages.addWidget(self.list)
+        self.pages.addWidget(self.empty)
+        self.pages.addWidget(details_scroll)
+
+        header = QHBoxLayout()
+        header.setSpacing(4)
+        title_col = QVBoxLayout()
+        title_col.setSpacing(0)
+        title_col.addWidget(self.title)
+        title_col.addWidget(self.subtitle)
+        header.addLayout(title_col, 1)
+        header.addWidget(self.read_btn)
+        header.addWidget(self.clear_btn)
+        header.addWidget(self.close_btn)
+        self.list_tools = QWidget(self)
+        tools = QVBoxLayout(self.list_tools)
+        tools.setContentsMargins(0, 0, 0, 0)
+        tools.setSpacing(8)
+        tools.addLayout(chips_row)
+        tools.addWidget(self.search)
+        top = QVBoxLayout()
+        top.setContentsMargins(16, 14, 12, 8)
+        top.setSpacing(10)
+        top.addLayout(header)
+        top.addWidget(self.list_tools)
+        layout = QVBoxLayout(self)
+        layout.setContentsMargins(0, 0, 0, 0)
+        layout.setSpacing(0)
+        layout.addLayout(top)
+        layout.addWidget(self.pages, 1)
+
+        shadow = QGraphicsDropShadowEffect(self)
+        shadow.setBlurRadius(28)
+        shadow.setOffset(-4, 0)
+        shadow.setColor(QColor(0, 0, 0, 80))
+        self.setGraphicsEffect(shadow)
+
+    def set_state(self, state: dict, tokens: ThemeTokens) -> None:
+        """Render the drawer part of ``state``."""
+        self.setVisible(state["drawerOpen"])
+        if not state["drawerOpen"]:
+            return
+        self._style(tokens)
+        unread = state["openCriticals"]
+        self.subtitle.setText(
+            f"{state['total']} in history" + (f" · {unread} critical open" if unread else "")
+        )
+        for item in state["filters"]:
+            chip = self.chips[item["key"]]
+            chip.setText(f"{item['label']}  {item['count']}")
+            chip.setChecked(item["active"])
+        if self.search.text() != state["search"]:
+            self.search.blockSignals(True)
+            self.search.setText(state["search"])
+            self.search.blockSignals(False)
+        self.model.set_rows(state["rows"])
+        selected = state["selected"]
+        self.list_tools.setVisible(selected is None)
+        if selected is not None:
+            self.details.set_row(selected, tokens)
+            self.pages.setCurrentIndex(2)
+        elif state["rows"]:
+            self.pages.setCurrentIndex(0)
+        else:
+            if state["total"]:
+                self.empty.setText("Nothing matches this filter.")
+            else:
+                self.empty.setText("You're all caught up.\nNew messages and errors appear here.")
+            self.pages.setCurrentIndex(1)
+
+    def _style(self, tokens: ThemeTokens) -> None:
+        chip_qss = (
+            f"QPushButton {{ background: transparent; color: {tokens.fg_muted.name()};"
+            f" border: 1px solid {tokens.border.name()}; border-radius: 13px;"
+            f" padding: 3px 10px; font-size: 12px; }}"
+            f"QPushButton:hover {{ background: {tokens.hover.name()}; }}"
+            f"QPushButton:checked {{ background: {rgba(tokens.primary, 0.18)};"
+            f" color: {tokens.fg.name()}; border-color: {tokens.primary.name()};"
+            f" font-weight: 600; }}"
+        )
+        self.setStyleSheet(
+            f"QFrame#notificationDrawer {{ background: {tokens.bg.name()};"
+            f" border-left: 1px solid {tokens.border.name()}; }}"
+            f"QListView, QScrollArea, QStackedWidget, QScrollArea > QWidget > QWidget"
+            f" {{ background: {tokens.bg.name()}; border: none; }}" + field_qss(tokens)
+        )
+        for chip in self.chips.values():
+            chip.setStyleSheet(chip_qss)
+        self.title.setStyleSheet(
+            f"color: {tokens.fg.name()}; font-size: 15px; font-weight: 600; background: none;"
+        )
+        self.subtitle.setStyleSheet(
+            f"color: {tokens.fg_subtle.name()}; font-size: 11px; background: none;"
+        )
+        self.empty.setStyleSheet(
+            f"color: {tokens.fg_subtle.name()}; font-size: 13px; background: none;"
+        )
+        for button in (self.read_btn, self.clear_btn, self.close_btn):
+            button.refresh_theme(tokens)
+
+
+class BellButton(QToolButton):
+    """Status-bar bell with a badge counting unread notifications."""
+
+    def __init__(self, host: NotificationHostBase, parent: QWidget | None = None):
+        super().__init__(parent)
+        self.host = host
+        self._state: dict = {}
+        self.setAutoRaise(True)
+        self.setCheckable(True)
+        self.setFixedSize(36, 24)
+        self.setIconSize(QSize(18, 18))
+        self.setCursor(Qt.CursorShape.PointingHandCursor)
+        self.setAccessibleName("Notifications")
+        self.clicked.connect(self.host.toggle_drawer)
+
+    def set_state(self, state: dict, tokens: ThemeTokens) -> None:
+        """Update icon, badge and tooltip."""
+        self._state = state
+        self.setChecked(state["drawerOpen"])
+        color = state["bellColor"] if state["unread"] or state["openCriticals"] else tokens.fg_muted
+        self.setIcon(
+            material_icon(state["bellIcon"], size=(36, 36), color=color, convert_to_pixmap=False)
+        )
+        self.setToolTip(state["bellTip"])
+        self.setStyleSheet(
+            f"QToolButton {{ border: none; border-radius: 6px; background: transparent; }}"
+            f"QToolButton:hover, QToolButton:checked {{ background: {tokens.hover.name()}; }}"
+        )
+        self.update()
+
+    def paintEvent(self, event):  # pylint: disable=invalid-name
+        super().paintEvent(event)
+        unread = self._state.get("unread", 0)
+        if not unread:
+            return
+        text = "99+" if unread > 99 else str(unread)
+        painter = QPainter(self)
+        painter.setRenderHint(QPainter.RenderHint.Antialiasing)
+        font = self.font()
+        font.setPixelSize(9)
+        font.setWeight(QFont.Weight.Bold)
+        painter.setFont(font)
+        width = max(14, painter.fontMetrics().horizontalAdvance(text) + 8)
+        rect = QRectF(self.width() - width - 1, 1, width, 14)
+        painter.setPen(Qt.PenStyle.NoPen)
+        painter.setBrush(QColor(self._state["bellColor"]))
+        painter.drawRoundedRect(rect, 7, 7)
+        painter.setPen(QColor("white"))
+        painter.drawText(rect, Qt.AlignmentFlag.AlignCenter, text)
+        painter.end()
+
+
+class NotificationHostQWidget(NotificationHostBase):
+    """Notification UI drawn with QWidgets. See :class:`NotificationHostBase`."""
+
+    def _create_views(self) -> None:
+        self.toasts = ToastStack(self, self.window)
+        self.drawer = HistoryDrawer(self, self.window)
+        self.drawer.hide()
+        self.toasts.hide()
+        self.bell = BellButton(self)
+        if self.status_bar is not None:
+            self.status_bar.addPermanentWidget(self.bell)
+
+    def _sync_views(self, state: dict) -> None:
+        tokens = ThemeTokens()
+        self.toasts.set_state(state, tokens)
+        self.drawer.set_state(state, tokens)
+        self.bell.set_state(state, tokens)
+
+    def _place_views(self) -> None:
+        if self.drawer.isVisible():
+            self.drawer.setGeometry(self.drawer_geometry())
+            self.drawer.raise_()
+        if self.toasts.isVisible():
+            # the stack has an 8 px margin for the shadow, so the cards line up with MARGIN
+            width = self.toast_geometry(0).width() + 16
+            layout = self.toasts.layout()
+            height = (
+                layout.totalHeightForWidth(width)
+                if layout.hasHeightForWidth()
+                else layout.totalSizeHint().height()
+            )
+            rect = self.toast_geometry(height - 16)
+            self.toasts.setGeometry(rect.adjusted(-8, -8, 8, 8) & self.window.rect())
+            self.toasts.raise_()
+
+    def _destroy_views(self) -> None:
+        for widget in (self.toasts, self.drawer, self.bell):
+            widget.hide()
+            widget.deleteLater()

bec_widgets/widgets/containers/main_window/addons/notification_center/notification_ux_common.py

@@ -0,0 +1,962 @@
+"""Toolkit-independent core of the reworked notification and error UX.
+
+The QML and QWidget versions of the notification UI share everything that is not drawing:
+
+- :class:`NotificationHub` is the application-wide history of notifications. BEC alarms,
+  errors caught by ``SafeSlot(popup_error=True)``, uncaught exceptions and calls to
+  :meth:`NotificationHub.notify` all end up here. Repeated messages are folded into one entry
+  with a counter instead of flooding the screen.
+- :class:`ToastQueue` decides which entries are shown as short toasts: at most a few at a time,
+  auto-dismissed after a severity dependent time (paused while hovered) except for critical
+  errors, which stay until they are acknowledged.
+- :class:`NotificationHostBase` attaches the UI to a window: a toast stack in the bottom right
+  corner, a history drawer on the right edge and a bell button with an unread badge for the
+  status bar. Subclasses only create and place their views and render :meth:`view_state`.
+"""
+
+from __future__ import annotations
+
+import time
+from dataclasses import dataclass, field
+from datetime import datetime
+from enum import Enum
+from typing import Any
+from uuid import uuid4
+
+import shiboken6
+from bec_lib.endpoints import MessageEndpoints
+from bec_lib.logger import bec_logger
+from bec_lib.messages import ErrorInfo
+from qtpy.QtCore import QEvent, QObject, QRect, Qt, QThread, QTimer, Signal
+from qtpy.QtGui import QColor
+from qtpy.QtWidgets import QApplication, QMainWindow, QStatusBar, QWidget
+
+from bec_widgets.utils.quick.host import ThemeTokens, _blend
+
+logger = bec_logger.logger
+
+
+class Severity(str, Enum):
+    """Severity of a notification, from least to most serious."""
+
+    INFO = "info"
+    SUCCESS = "success"
+    WARNING = "warning"
+    ERROR = "error"
+    CRITICAL = "critical"
+
+
+# label, Material icon, toast lifetime in ms (0 = until acknowledged) and rank for sorting
+SEVERITY_META: dict[Severity, dict[str, Any]] = {
+    Severity.INFO: {"label": "Info", "icon": "info", "lifetime": 4000, "rank": 0},
+    Severity.SUCCESS: {"label": "Done", "icon": "check_circle", "lifetime": 4000, "rank": 1},
+    Severity.WARNING: {"label": "Warning", "icon": "warning", "lifetime": 8000, "rank": 2},
+    Severity.ERROR: {"label": "Error", "icon": "error", "lifetime": 12000, "rank": 3},
+    Severity.CRITICAL: {"label": "Critical", "icon": "dangerous", "lifetime": 0, "rank": 4},
+}
+
+# legacy banner kinds and BEC alarm levels mapped onto the new severities
+_LEGACY_KINDS = {
+    "info": Severity.INFO,
+    "warning": Severity.WARNING,
+    "minor": Severity.ERROR,
+    "major": Severity.CRITICAL,
+}
+_ALARM_LEVELS = {0: Severity.WARNING, 1: Severity.ERROR, 2: Severity.CRITICAL}
+
+# history filters: key -> (label, severities)
+FILTERS: dict[str, tuple[str, tuple[Severity, ...]]] = {
+    "all": ("All", tuple(Severity)),
+    "errors": ("Errors", (Severity.ERROR, Severity.CRITICAL)),
+    "warnings": ("Warnings", (Severity.WARNING,)),
+    "info": ("Info", (Severity.INFO, Severity.SUCCESS)),
+}
+
+
+def to_severity(value: Any) -> Severity:
+    """Normalise a severity given as :class:`Severity`, legacy banner kind or alarm level.
+
+    Args:
+        value: ``Severity``, its value, a legacy kind (``info``/``warning``/``minor``/``major``)
+            or an integer BEC alarm level (0, 1, 2).
+
+    Returns:
+        Severity: The matching severity; unknown values become ``WARNING``.
+    """
+    if isinstance(value, Severity):
+        return value
+    raw = getattr(value, "value", value)
+    if isinstance(raw, str):
+        raw = raw.lower()
+        if raw in _LEGACY_KINDS:
+            return _LEGACY_KINDS[raw]
+        try:
+            return Severity(raw)
+        except ValueError:
+            return Severity.WARNING
+    if isinstance(raw, int) and not isinstance(raw, bool):
+        return _ALARM_LEVELS.get(raw, Severity.WARNING)
+    return Severity.WARNING
+
+
+def severity_color(tokens: ThemeTokens, severity: Severity) -> QColor:
+    """Theme colour used for a severity: icon, accent stripe and badge."""
+    if severity == Severity.INFO:
+        return QColor(tokens.accent)
+    if severity == Severity.SUCCESS:
+        return QColor(tokens.success)
+    if severity == Severity.WARNING:
+        return QColor(tokens.warning)
+    if severity == Severity.ERROR:
+        # orange: between warning and critical so the two error levels read differently
+        return _blend(tokens.warning, tokens.danger, 0.55)
+    return QColor(tokens.danger)
+
+
+def split_traceback(text: str) -> tuple[str, str]:
+    """Return ``(exception type, message)`` from the last line of a formatted traceback."""
+    lines = [line.strip() for line in (text or "").strip().splitlines() if line.strip()]
+    if not lines:
+        return "Error", ""
+    last = lines[-1]
+    head, sep, tail = last.partition(":")
+    if sep and head and " " not in head.strip():
+        return head.strip().rsplit(".", 1)[-1], tail.strip()
+    return "Error", last
+
+
+def relative_time(timestamp: float, now: float | None = None) -> str:
+    """Short human readable age of ``timestamp`` such as ``2 min ago`` or ``13:04``."""
+    now = time.time() if now is None else now
+    seconds = max(0, int(now - timestamp))
+    if seconds < 30:
+        return "just now"
+    if seconds < 3600:
+        return f"{max(1, seconds // 60)} min ago"
+    stamp = datetime.fromtimestamp(timestamp)
+    if stamp.date() == datetime.fromtimestamp(now).date():
+        return stamp.strftime("%H:%M")
+    return stamp.strftime("%b %d, %H:%M")
+
+
+def absolute_time(timestamp: float) -> str:
+    """Full local timestamp."""
+    return datetime.fromtimestamp(timestamp).strftime("%Y-%m-%d %H:%M:%S")
+
+
+@dataclass
+class NotificationEntry:
+    """One notification in the history."""
+
+    id: str
+    severity: Severity
+    title: str
+    body: str = ""
+    details: str = ""
+    source: str = ""
+    scan_number: int | None = None
+    created: float = field(default_factory=time.time)
+    updated: float = field(default_factory=time.time)
+    count: int = 1
+    read: bool = False
+    acknowledged: bool = False
+
+    @property
+    def needs_ack(self) -> bool:
+        """A critical entry stays pinned and on screen until somebody acknowledges it."""
+        return self.severity == Severity.CRITICAL and not self.acknowledged
+
+    def copy_text(self) -> str:
+        """Plain-text report used by the Copy action, ready to paste into a logbook or issue."""
+        lines = [f"[{SEVERITY_META[self.severity]['label']}] {self.title}"]
+        lines.append(f"Time: {absolute_time(self.updated)}")
+        if self.count > 1:
+            lines.append(f"Occurrences: {self.count} (first at {absolute_time(self.created)})")
+        if self.source:
+            lines.append(f"Source: {self.source}")
+        if self.scan_number is not None:
+            lines.append(f"Scan: #{self.scan_number}")
+        if self.body:
+            lines.extend(["", self.body])
+        if self.details:
+            lines.extend(["", self.details])
+        return "\n".join(lines)
+
+
+class NotificationHub(QObject):
+    """Application-wide notification history shared by every window and both UI versions.
+
+    Signals:
+        posted(str): A notification was added, or a repeated one was folded into an entry.
+        changed(): Anything in the history changed.
+        scan_started(): A new scan opened; hosts hide the non-critical toasts.
+    """
+
+    MAX_ENTRIES = 500
+    DEDUP_WINDOW_S = 120.0
+
+    posted = Signal(str)
+    changed = Signal()
+    scan_started = Signal()
+    _post_requested = Signal(dict)
+
+    _instance: NotificationHub | None = None
+
+    def __init__(self, parent: QObject | None = None):
+        super().__init__(parent)
+        self._entries: list[NotificationEntry] = []
+        self._hosts = 0
+        self._dispatcher = None
+        self._post_requested.connect(self._post, Qt.ConnectionType.QueuedConnection)
+
+    @classmethod
+    def instance(cls) -> NotificationHub:
+        """Return the hub of this application, creating it on first use."""
+        inst = cls._instance
+        if inst is None or not shiboken6.isValid(inst):
+            inst = cls(QApplication.instance())
+            cls._instance = inst
+        return inst
+
+    @classmethod
+    def reset_instance(cls) -> None:
+        """Drop the hub, e.g. between tests. Its BEC subscriptions are disconnected."""
+        inst = cls._instance
+        cls._instance = None
+        if inst is not None and shiboken6.isValid(inst):
+            inst.disconnect_bec()
+            shiboken6.delete(inst)
+
+    # ------------------------------------------------------------------ public API
+    def notify(
+        self,
+        title: str,
+        body: str = "",
+        severity: Severity | str | int = Severity.INFO,
+        *,
+        details: str = "",
+        source: str = "",
+        scan_number: int | None = None,
+        entry_id: str | None = None,
+    ) -> str:
+        """Post a notification. Safe to call from any thread.
+
+        Args:
+            title(str): Short headline, e.g. ``Motor samx not reachable``.
+            body(str): One or two sentences for the toast and the history row.
+            severity(Severity | str | int): Severity, legacy kind or alarm level.
+            details(str): Optional long text such as a traceback, shown in the details view.
+            source(str): Where it came from, e.g. ``Scan server`` or a widget name.
+            scan_number(int | None): Scan the notification refers to.
+            entry_id(str | None): Stable id; a second post with the same id is ignored.
+
+        Returns:
+            str: The id of the (possibly folded) entry.
+        """
+        payload = {
+            "title": str(title or "Notification"),
+            "body": str(body or ""),
+            "severity": to_severity(severity),
+            "details": str(details or ""),
+            "source": str(source or ""),
+            "scan_number": scan_number,
+            "entry_id": entry_id or uuid4().hex,
+        }
+        if QThread.currentThread() is not self.thread():
+            self._post_requested.emit(payload)
+            return payload["entry_id"]
+        return self._post(payload)
+
+    def report_exception(self, title: str, traceback_text: str, source: str = "") -> str:
+        """Post an error from a formatted traceback; used instead of a modal error dialog."""
+        exc_type, message = split_traceback(traceback_text)
+        return self.notify(
+            exc_type,
+            message or "An unexpected error occurred.",
+            Severity.ERROR,
+            details=traceback_text.strip(),
+            source=source or title,
+        )
+
+    def post_alarm(self, msg: dict, meta: dict | None = None) -> str | None:
+        """Translate a BEC alarm message into a notification.
+
+        Args:
+            msg(dict): Alarm content with ``severity``, ``alarm_type``, ``msg`` and ``info``.
+            meta(dict | None): Message metadata, may hold ``scan_id`` and ``scan_number``.
+
+        Returns:
+            str | None: Id of the entry, or None if the alarm was already posted.
+        """
+        msg = msg or {}
+        meta = meta or {}
+        info = msg.get("info")
+        alarm_id = info.get("id") if isinstance(info, dict) else getattr(info, "id", None)
+        if isinstance(info, dict):
+            try:
+                info = ErrorInfo(**info)
+            except Exception:  # pylint: disable=broad-except
+                # incomplete payload: keep what is there
+                info = type("PartialInfo", (), dict(info))()
+        if alarm_id and self.get(alarm_id) is not None:
+            return None
+        trace = getattr(info, "error_message", None) or msg.get("msg") or ""
+        compact = getattr(info, "compact_error_message", None)
+        exc_type, last_line = split_traceback(trace)
+        title = msg.get("alarm_type") or getattr(info, "exception_type", None) or exc_type
+        body = compact or last_line or str(msg.get("msg") or "")
+        details = trace if trace.strip() and trace.strip() != body.strip() else ""
+        if meta.get("scan_id") and details:
+            details = f"Scan id: {meta['scan_id']}\n\n{details}"
+        device = getattr(info, "device", None)
+        source = f"Device {device}" if device else "BEC server"
+        return self.notify(
+            title,
+            body,
+            msg.get("severity", 0),
+            details=details,
+            source=source,
+            scan_number=meta.get("scan_number"),
+            entry_id=alarm_id,
+        )
+
+    @property
+    def entries(self) -> list[NotificationEntry]:
+        """History, newest first."""
+        return list(self._entries)
+
+    def get(self, entry_id: str) -> NotificationEntry | None:
+        """Return the entry with ``entry_id`` or None."""
+        for entry in self._entries:
+            if entry.id == entry_id:
+                return entry
+        return None
+
+    def acknowledge(self, entry_id: str) -> None:
+        """Acknowledge a (critical) entry; it is unpinned and its toast closes."""
+        entry = self.get(entry_id)
+        if entry is None or entry.acknowledged:
+            return
+        entry.acknowledged = True
+        entry.read = True
+        self.changed.emit()
+
+    def remove(self, entry_id: str) -> None:
+        """Remove one entry from the history."""
+        entry = self.get(entry_id)
+        if entry is not None:
+            self._entries.remove(entry)
+            self.changed.emit()
+
+    def clear(self) -> None:
+        """Clear the history but keep critical errors nobody has acknowledged yet."""
+        kept = [entry for entry in self._entries if entry.needs_ack]
+        if len(kept) != len(self._entries):
+            self._entries = kept
+            self.changed.emit()
+
+    def mark_read(self, entry_ids: list[str] | None = None) -> None:
+        """Mark the given entries, or all of them, as read."""
+        touched = False
+        for entry in self._entries:
+            if not entry.read and (entry_ids is None or entry.id in entry_ids):
+                entry.read = True
+                touched = True
+        if touched:
+            self.changed.emit()
+
+    def unread_count(self) -> int:
+        """Number of unread entries."""
+        return sum(1 for entry in self._entries if not entry.read)
+
+    def top_unread_severity(self) -> Severity | None:
+        """Most serious severity among unread or unacknowledged entries."""
+        open_entries = [e for e in self._entries if not e.read or e.needs_ack]
+        if not open_entries:
+            return None
+        return max(open_entries, key=lambda e: SEVERITY_META[e.severity]["rank"]).severity
+
+    # ------------------------------------------------------------------ hosts and BEC feed
+    def register_host(self) -> None:
+        """Called by a host when it attaches; errors are then routed here, not to dialogs."""
+        self._hosts += 1
+
+    def unregister_host(self) -> None:
+        """Called by a host when it detaches."""
+        self._hosts = max(0, self._hosts - 1)
+
+    @property
+    def has_hosts(self) -> bool:
+        """Whether any window currently shows notifications."""
+        return self._hosts > 0
+
+    def connect_bec(self, dispatcher) -> None:
+        """Subscribe to BEC alarms and scan status once per application."""
+        if self._dispatcher is not None or dispatcher is None:
+            return
+        self._dispatcher = dispatcher
+        dispatcher.connect_slot(self._on_alarm, MessageEndpoints.alarm())
+        dispatcher.connect_slot(self._on_scan_status, MessageEndpoints.scan_status())
+
+    def disconnect_bec(self) -> None:
+        """Undo :meth:`connect_bec`."""
+        dispatcher, self._dispatcher = self._dispatcher, None
+        if dispatcher is None:
+            return
+        try:
+            dispatcher.disconnect_slot(self._on_alarm, MessageEndpoints.alarm())
+            dispatcher.disconnect_slot(self._on_scan_status, MessageEndpoints.scan_status())
+        except Exception as exc:  # pylint: disable=broad-except
+            logger.warning(f"NotificationHub could not disconnect from BEC: {exc}")
+
+    def _on_alarm(self, msg: dict, meta: dict) -> None:
+        try:
+            self.post_alarm(msg, meta)
+        except Exception as exc:  # pylint: disable=broad-except
+            logger.error(f"Could not turn alarm into a notification: {exc}")
+
+    def _on_scan_status(self, msg: dict, _meta: dict) -> None:
+        if (msg or {}).get("status") == "open":
+            self.scan_started.emit()
+
+    # ------------------------------------------------------------------ internals
+    def _post(self, payload: dict) -> str:
+        entry_id = payload["entry_id"]
+        if self.get(entry_id) is not None:
+            return entry_id
+        now = time.time()
+        for entry in self._entries:
+            if now - entry.updated > self.DEDUP_WINDOW_S:
+                break
+            if (
+                entry.severity == payload["severity"]
+                and entry.title == payload["title"]
+                and entry.body == payload["body"]
+                and entry.source == payload["source"]
+            ):
+                entry.count += 1
+                entry.updated = now
+                entry.read = False
+                entry.acknowledged = False
+                entry.details = payload["details"] or entry.details
+                self._entries.remove(entry)
+                self._entries.insert(0, entry)
+                self.changed.emit()
+                self.posted.emit(entry.id)
+                return entry.id
+        entry = NotificationEntry(
+            id=entry_id,
+            severity=payload["severity"],
+            title=payload["title"],
+            body=payload["body"],
+            details=payload["details"],
+            source=payload["source"],
+            scan_number=payload["scan_number"],
+            created=now,
+            updated=now,
+        )
+        self._entries.insert(0, entry)
+        self._trim()
+        self.changed.emit()
+        self.posted.emit(entry.id)
+        return entry.id
+
+    def _trim(self) -> None:
+        excess = len(self._entries) - self.MAX_ENTRIES
+        if excess <= 0:
+            return
+        for entry in reversed(list(self._entries)):
+            if excess <= 0:
+                break
+            if not entry.needs_ack:
+                self._entries.remove(entry)
+                excess -= 1
+
+
+class ToastQueue(QObject):
+    """Decides which notifications are on screen as toasts and for how long.
+
+    At most :attr:`MAX_VISIBLE` toasts are shown; newer ones replace the oldest non-critical
+    toast and the rest are counted as overflow ("+3 more"), which stays reachable in the
+    history. Hovering the stack pauses every countdown.
+
+    Signals:
+        changed(): The visible toasts or the overflow count changed.
+    """
+
+    MAX_VISIBLE = 3
+
+    changed = Signal()
+
+    def __init__(self, hub: NotificationHub, parent: QObject | None = None):
+        super().__init__(parent)
+        self._hub = hub
+        self._visible: list[str] = []  # oldest first
+        self._timers: dict[str, QTimer] = {}
+        self._remaining: dict[str, int] = {}
+        self._started: dict[str, float] = {}
+        self._paused = False
+        self._suspended = False
+        self.overflow = 0
+        hub.posted.connect(self._on_posted)
+        hub.changed.connect(self._on_hub_changed)
+        hub.scan_started.connect(self.dismiss_transient)
+
+    @property
+    def visible_ids(self) -> list[str]:
+        """Ids of the toasts on screen, oldest first."""
+        return list(self._visible)
+
+    def set_suspended(self, suspended: bool) -> None:
+        """Hide all toasts while the history drawer is open; they stay in the history."""
+        self._suspended = suspended
+        if suspended:
+            self.dismiss_all(keep_critical=False)
+
+    def set_paused(self, paused: bool) -> None:
+        """Pause or resume all countdowns, e.g. while the pointer is over the stack."""
+        if paused == self._paused:
+            return
+        self._paused = paused
+        now = time.monotonic()
+        for entry_id, timer in self._timers.items():
+            if paused:
+                elapsed = int((now - self._started[entry_id]) * 1000)
+                self._remaining[entry_id] = max(500, self._remaining[entry_id] - elapsed)
+                timer.stop()
+            else:
+                self._started[entry_id] = now
+                timer.start(self._remaining[entry_id])
+
+    def dismiss(self, entry_id: str) -> None:
+        """Close one toast; the entry stays in the history."""
+        if entry_id not in self._visible:
+            return
+        self._visible.remove(entry_id)
+        self._stop_timer(entry_id)
+        self.changed.emit()
+
+    def dismiss_transient(self) -> None:
+        """Close all toasts except unacknowledged critical errors (used when a scan starts)."""
+        self.dismiss_all(keep_critical=True)
+
+    def dismiss_all(self, keep_critical: bool = True) -> None:
+        """Close all toasts, optionally keeping the critical ones."""
+        keep = []
+        for entry_id in self._visible:
+            entry = self._hub.get(entry_id)
+            if keep_critical and entry is not None and entry.needs_ack:
+                keep.append(entry_id)
+            else:
+                self._stop_timer(entry_id)
+        changed = keep != self._visible or self.overflow
+        self._visible = keep
+        self.overflow = 0
+        if changed:
+            self.changed.emit()
+
+    def cleanup(self) -> None:
+        """Stop all timers and disconnect from the hub."""
+        for entry_id in list(self._timers):
+            self._stop_timer(entry_id)
+        for signal, slot in (
+            (self._hub.posted, self._on_posted),
+            (self._hub.changed, self._on_hub_changed),
+            (self._hub.scan_started, self.dismiss_transient),
+        ):
+            try:
+                signal.disconnect(slot)
+            except (RuntimeError, TypeError):
+                pass
+
+    # ------------------------------------------------------------------ internals
+    def _on_posted(self, entry_id: str) -> None:
+        if self._suspended:
+            return
+        entry = self._hub.get(entry_id)
+        if entry is None:
+            return
+        if entry_id in self._visible:
+            # a repeat: move it to the newest position and restart its countdown
+            self._visible.remove(entry_id)
+            self._visible.append(entry_id)
+            self._start_timer(entry)
+            self.changed.emit()
+            return
+        if len(self._visible) >= self.MAX_VISIBLE:
+            victim = next(
+                (i for i in self._visible if not getattr(self._hub.get(i), "needs_ack", False)),
+                None,
+            )
+            if victim is None and not entry.needs_ack:
+                self.overflow += 1
+                self.changed.emit()
+                return
+            victim = victim or self._visible[0]
+            self._visible.remove(victim)
+            self._stop_timer(victim)
+            self.overflow += 1
+        self._visible.append(entry_id)
+        self._start_timer(entry)
+        self.changed.emit()
+
+    def _on_hub_changed(self) -> None:
+        gone = [
+            i
+            for i in self._visible
+            if (entry := self._hub.get(i)) is None
+            or (entry.severity == Severity.CRITICAL and entry.acknowledged)
+        ]
+        for entry_id in gone:
+            self._visible.remove(entry_id)
+            self._stop_timer(entry_id)
+        if gone:
+            self.changed.emit()
+
+    def _start_timer(self, entry: NotificationEntry) -> None:
+        self._stop_timer(entry.id)
+        lifetime = SEVERITY_META[entry.severity]["lifetime"]
+        if lifetime <= 0:
+            return
+        timer = QTimer(self)
+        timer.setSingleShot(True)
+        timer.timeout.connect(lambda entry_id=entry.id: self.dismiss(entry_id))
+        self._timers[entry.id] = timer
+        self._remaining[entry.id] = lifetime
+        self._started[entry.id] = time.monotonic()
+        if not self._paused:
+            timer.start(lifetime)
+
+    def _stop_timer(self, entry_id: str) -> None:
+        timer = self._timers.pop(entry_id, None)
+        self._remaining.pop(entry_id, None)
+        self._started.pop(entry_id, None)
+        if timer is not None:
+            timer.stop()
+            timer.deleteLater()
+
+
+def entry_row(entry: NotificationEntry, tokens: ThemeTokens, now: float | None = None) -> dict:
+    """Flat dictionary describing one entry, consumed by both views."""
+    meta = SEVERITY_META[entry.severity]
+    color = severity_color(tokens, entry.severity)
+    subtitle = [part for part in (entry.source, relative_time(entry.updated, now)) if part]
+    if entry.scan_number is not None:
+        subtitle.insert(1 if entry.source else 0, f"Scan #{entry.scan_number}")
+    return {
+        "id": entry.id,
+        "entryId": entry.id,
+        "severity": entry.severity.value,
+        "severityLabel": meta["label"],
+        "icon": meta["icon"],
+        "color": color.name(),
+        "tint": tokens.soft(color, 0.14).name(),
+        "title": entry.title,
+        "body": entry.body,
+        "details": entry.details,
+        "hasDetails": bool(entry.details),
+        "source": entry.source,
+        "meta": " · ".join(subtitle),
+        "time": relative_time(entry.updated, now),
+        "timeAbs": absolute_time(entry.updated),
+        "firstAbs": absolute_time(entry.created),
+        "scan": "" if entry.scan_number is None else f"#{entry.scan_number}",
+        "count": entry.count,
+        "unread": not entry.read,
+        "needsAck": entry.needs_ack,
+        "critical": entry.severity == Severity.CRITICAL,
+    }
+
+
+class NotificationHostBase(QObject):
+    """Attach the notification UI (toasts, history drawer, bell) to a window.
+
+    Subclasses implement :meth:`_create_views`, :meth:`_sync_views` and :meth:`_place_views`.
+
+    Args:
+        window(QWidget): Window to overlay, usually a ``QMainWindow``.
+        status_bar(QStatusBar | None): Where to put the bell; defaults to the window's status
+            bar if it is a ``QMainWindow``. Pass ``None`` on a plain widget to skip the bell.
+        dispatcher: ``BECDispatcher`` used to receive BEC alarms; optional.
+    """
+
+    TOAST_WIDTH = 380
+    DRAWER_WIDTH = 400
+    MARGIN = 16
+
+    def __init__(self, window: QWidget, status_bar: QStatusBar | None = None, dispatcher=None):
+        super().__init__(window)
+        self.window = window
+        self.hub = NotificationHub.instance()
+        self.hub.register_host()
+        self.hub.connect_bec(dispatcher)
+        self.queue = ToastQueue(self.hub, self)
+        self.drawer_open = False
+        self.filter_key = "all"
+        self.search = ""
+        self.selected_id: str | None = None
+        self._sync_pending = False
+        if status_bar is None and isinstance(window, QMainWindow):
+            status_bar = window.statusBar()
+        self.status_bar = status_bar
+        self._create_views()
+        self.hub.changed.connect(self.sync)
+        self.queue.changed.connect(self.sync)
+        self._tick = QTimer(self)
+        self._tick.setInterval(30_000)
+        self._tick.timeout.connect(self.sync)
+        self._tick.start()
+        app = QApplication.instance()
+        theme = getattr(app, "theme", None)
+        if theme is not None:
+            theme.theme_changed.connect(self._on_theme_changed)
+        window.installEventFilter(self)
+        self._cleaned = False
+        self.sync_now()
+
+    # ------------------------------------------------------------------ actions
+    def toggle_drawer(self) -> None:
+        """Open or close the history drawer."""
+        self.set_drawer_open(not self.drawer_open)
+
+    def set_drawer_open(self, open_: bool) -> None:
+        """Open or close the history drawer. Opening marks everything as read."""
+        self.drawer_open = bool(open_)
+        self.queue.set_suspended(self.drawer_open)
+        if self.drawer_open:
+            self.hub.mark_read()
+        else:
+            self.selected_id = None
+        self.sync()
+
+    def open_details(self, entry_id: str) -> None:
+        """Open the drawer on the details of one entry (the toast's Details action)."""
+        self.selected_id = entry_id
+        self.set_drawer_open(True)
+
+    def select(self, entry_id: str | None) -> None:
+        """Show the details of ``entry_id``; None goes back to the list."""
+        self.selected_id = entry_id or None
+        self.sync()
+
+    def set_filter(self, key: str) -> None:
+        """Filter the history by one of :data:`FILTERS`."""
+        self.filter_key = key if key in FILTERS else "all"
+        self.sync()
+
+    def set_search(self, text: str) -> None:
+        """Filter the history by text in title, message, source or details."""
+        self.search = text or ""
+        self.sync()
+
+    def acknowledge(self, entry_id: str) -> None:
+        """Acknowledge a critical error."""
+        self.hub.acknowledge(entry_id)
+
+    def remove(self, entry_id: str) -> None:
+        """Remove an entry from the history."""
+        if self.selected_id == entry_id:
+            self.selected_id = None
+        self.queue.dismiss(entry_id)
+        self.hub.remove(entry_id)
+
+    def dismiss_toast(self, entry_id: str) -> None:
+        """Close a toast without touching the history."""
+        entry = self.hub.get(entry_id)
+        if entry is not None and entry.needs_ack:
+            self.hub.acknowledge(entry_id)
+        self.queue.dismiss(entry_id)
+        if entry is not None:
+            self.hub.mark_read([entry_id])
+
+    def copy_details(self, entry_id: str) -> bool:
+        """Copy a plain-text report of the entry to the clipboard."""
+        entry = self.hub.get(entry_id)
+        if entry is None:
+            return False
+        QApplication.clipboard().setText(entry.copy_text())
+        return True
+
+    def mark_all_read(self) -> None:
+        """Mark the whole history as read."""
+        self.hub.mark_read()
+
+    def clear_history(self) -> None:
+        """Clear the history; unacknowledged critical errors stay."""
+        self.selected_id = None
+        self.hub.clear()
+
+    def set_toasts_hovered(self, hovered: bool) -> None:
+        """Pause the toast countdowns while the pointer is over them."""
+        self.queue.set_paused(hovered)
+
+    # ------------------------------------------------------------------ state
+    def filtered_entries(self) -> list[NotificationEntry]:
+        """History entries matching the filter and search, critical ones pinned on top."""
+        severities = FILTERS[self.filter_key][1]
+        needle = self.search.strip().lower()
+        rows = []
+        for entry in self.hub.entries:
+            if entry.severity not in severities:
+                continue
+            if needle and not any(
+                needle in text.lower()
+                for text in (entry.title, entry.body, entry.source, entry.details)
+            ):
+                continue
+            rows.append(entry)
+        rows.sort(key=lambda e: not e.needs_ack)  # stable: keeps newest first otherwise
+        return rows
+
+    def view_state(self) -> dict:
+        """Everything the views need to render, as plain Python data."""
+        tokens = ThemeTokens()
+        now = time.time()
+        entries = self.hub.entries
+        counts = {
+            key: sum(1 for e in entries if e.severity in severities)
+            for key, (_label, severities) in FILTERS.items()
+        }
+        toasts = []
+        if not self.drawer_open:
+            for entry_id in self.queue.visible_ids:
+                entry = self.hub.get(entry_id)
+                if entry is not None:
+                    toasts.append(entry_row(entry, tokens, now))
+        selected = self.hub.get(self.selected_id) if self.selected_id else None
+        top = self.hub.top_unread_severity()
+        unread = self.hub.unread_count()
+        open_criticals = sum(1 for e in entries if e.needs_ack)
+        if open_criticals:
+            bell_tip = f"{open_criticals} critical error(s) need attention"
+        elif unread:
+            bell_tip = f"{unread} unread notification(s)"
+        else:
+            bell_tip = "Notifications"
+        return {
+            "drawerOpen": self.drawer_open,
+            "toasts": toasts,
+            "overflow": self.queue.overflow if toasts else 0,
+            # the list is only built while the drawer is visible
+            "rows": (
+                [entry_row(e, tokens, now) for e in self.filtered_entries()]
+                if self.drawer_open
+                else []
+            ),
+            "filters": [
+                {"key": key, "label": label, "count": counts[key], "active": key == self.filter_key}
+                for key, (label, _sev) in FILTERS.items()
+            ],
+            "filterKey": self.filter_key,
+            "search": self.search,
+            "total": len(entries),
+            "selected": entry_row(selected, tokens, now) if selected is not None else None,
+            "unread": unread,
+            "openCriticals": open_criticals,
+            "bellColor": (
+                severity_color(tokens, top).name() if top is not None else tokens.fg_muted.name()
+            ),
+            "bellIcon": "notifications_active" if unread or open_criticals else "notifications",
+            "bellTip": bell_tip,
+        }
+
+    def sync(self, *_args) -> None:
+        """Schedule a view update; bursts of changes are folded into one update."""
+        if self._cleaned or self._sync_pending:
+            return
+        self._sync_pending = True
+        QTimer.singleShot(0, self.sync_now)
+
+    def sync_now(self) -> None:
+        """Push the current state into the views and re-place them right away."""
+        self._sync_pending = False
+        if self._cleaned:
+            return
+        state = self.view_state()
+        self._sync_views(state)
+        self._place_views()
+
+    def content_rect(self) -> QRect:
+        """Area of the window the overlays may cover: below menu and tool bars, above status."""
+        rect = self.window.rect()
+        top = 0
+        bottom = rect.bottom()
+        if isinstance(self.window, QMainWindow):
+            menu = self.window.menuWidget()
+            if menu is not None and menu.isVisible():
+                top = menu.geometry().bottom() + 1
+            central = self.window.centralWidget()
+            if central is not None:
+                top = max(top, central.geometry().top())
+            status = self.window.statusBar() if self.window.statusBar() else None
+            if status is not None and status.isVisible():
+                bottom = status.geometry().top() - 1
+        return QRect(rect.left(), top, rect.width(), max(0, bottom - top + 1))
+
+    def toast_geometry(self, content_height: int) -> QRect:
+        """Bottom-right rectangle for a toast stack of ``content_height`` pixels."""
+        area = self.content_rect()
+        width = min(self.TOAST_WIDTH, max(200, area.width() - 2 * self.MARGIN))
+        height = min(content_height, max(0, area.height() - 2 * self.MARGIN))
+        return QRect(
+            area.right() - self.MARGIN - width + 1,
+            area.bottom() - self.MARGIN - height + 1,
+            width,
+            height,
+        )
+
+    def drawer_geometry(self) -> QRect:
+        """Right-edge rectangle of the history drawer."""
+        area = self.content_rect()
+        width = min(self.DRAWER_WIDTH, area.width())
+        return QRect(area.right() - width + 1, area.top(), width, area.height())
+
+    # ------------------------------------------------------------------ plumbing
+    def eventFilter(self, watched, event):  # pylint: disable=invalid-name
+        if watched is self.window and event.type() in (QEvent.Type.Resize, QEvent.Type.Show):
+            self._place_views()
+        return False
+
+    def _on_theme_changed(self, *_args) -> None:
+        self._apply_theme()
+        self.sync()
+
+    def cleanup(self) -> None:
+        """Detach from the window and the hub."""
+        if self._cleaned:
+            return
+        self._cleaned = True
+        self._tick.stop()
+        self.queue.cleanup()
+        for signal, slot in ((self.hub.changed, self.sync), (self.queue.changed, self.sync)):
+            try:
+                signal.disconnect(slot)
+            except (RuntimeError, TypeError):
+                pass
+        app = QApplication.instance()
+        theme = getattr(app, "theme", None)
+        if theme is not None:
+            try:
+                theme.theme_changed.disconnect(self._on_theme_changed)
+            except (RuntimeError, TypeError):
+                pass
+        if shiboken6.isValid(self.window):
+            self.window.removeEventFilter(self)
+        self.hub.unregister_host()
+        self._destroy_views()
+
+    # ------------------------------------------------------------------ for subclasses
+    def _create_views(self) -> None:
+        raise NotImplementedError
+
+    def _sync_views(self, state: dict) -> None:
+        raise NotImplementedError
+
+    def _place_views(self) -> None:
+        raise NotImplementedError
+
+    def _apply_theme(self) -> None:
+        """Re-style the views after a theme change; QML follows the theme by itself."""
+
+    def _destroy_views(self) -> None:
+        """Release the views."""

bec_widgets/widgets/containers/main_window/addons/notification_center/qml/NotificationBell.qml

@@ -0,0 +1,54 @@
+import QtQuick
+import QtQuick.Controls.Basic
+import BecUi
+
+// Status-bar bell. The badge counts unread notifications and takes the colour of the most
+// serious one; a critical error that is not acknowledged keeps the bell coloured.
+AbstractButton {
+    id: root
+    required property var backend
+    readonly property var st: backend.state
+    readonly property int unread: st.unread || 0
+    readonly property bool alert: unread > 0 || (st.openCriticals || 0) > 0
+
+    implicitWidth: 36
+    implicitHeight: 24
+    hoverEnabled: true
+    checked: st.drawerOpen || false
+    Accessible.name: "Notifications"
+    onClicked: backend.toggleDrawer()
+
+    background: Rectangle {
+        radius: 6
+        color: root.down ? theme.pressed : (root.hovered || root.checked ? theme.hover : "transparent")
+    }
+    contentItem: Item {
+        Icon {
+            anchors.centerIn: parent
+            name: root.st.bellIcon || "notifications"
+            color: root.alert ? (root.st.bellColor || theme.fgMuted) : theme.fgMuted
+            size: 18
+        }
+    }
+    Rectangle {
+        visible: root.unread > 0
+        anchors.right: parent.right
+        anchors.top: parent.top
+        anchors.margins: 1
+        height: 14
+        width: Math.max(14, badgeText.implicitWidth + 8)
+        radius: 7
+        color: root.st.bellColor || theme.primary
+        Text {
+            id: badgeText
+            anchors.centerIn: parent
+            text: root.unread > 99 ? "99+" : root.unread
+            color: "white"
+            font.pixelSize: 9
+            font.weight: Font.Bold
+        }
+    }
+    ToolTip.visible: hovered
+    ToolTip.delay: 400
+    ToolTip.text: st.bellTip || "Notifications"
+}

bec_widgets/widgets/containers/main_window/addons/notification_center/qml/NotificationDrawer.qml

@@ -0,0 +1,414 @@
+import QtQuick
+import QtQuick.Controls.Basic
+import QtQuick.Layouts
+import BecUi
+
+// Right-edge history drawer: filter chips, search, the list of notifications and the
+// details of one entry with its full text, metadata and actions.
+Rectangle {
+    id: root
+    required property var backend
+    readonly property var st: backend.state
+    readonly property var sel: st.selected || ({})
+    readonly property bool hasSelection: sel.entryId !== undefined
+
+    color: theme.bg
+
+    // shadow towards the content and a hairline border
+    Rectangle {
+        anchors.right: parent.left
+        width: 8; height: parent.height
+        gradient: Gradient {
+            orientation: Gradient.Horizontal
+            GradientStop { position: 0.0; color: "transparent" }
+            GradientStop { position: 1.0; color: Qt.rgba(0, 0, 0, theme.dark ? 0.3 : 0.08) }
+        }
+    }
+    Rectangle { anchors.left: parent.left; width: 1; height: parent.height; color: theme.border }
+
+    ColumnLayout {
+        anchors.fill: parent
+        anchors.leftMargin: 1
+        spacing: 0
+
+        // ---------------------------------------------------------------- header
+        ColumnLayout {
+            Layout.fillWidth: true
+            Layout.leftMargin: 16
+            Layout.rightMargin: 12
+            Layout.topMargin: 14
+            Layout.bottomMargin: 8
+            spacing: 10
+
+            RowLayout {
+                Layout.fillWidth: true
+                spacing: 4
+                ColumnLayout {
+                    Layout.fillWidth: true
+                    spacing: 0
+                    Text {
+                        Layout.fillWidth: true
+                        text: "Notifications"
+                        color: theme.fg
+                        font.pixelSize: 15
+                        font.weight: Font.DemiBold
+                    }
+                    Text {
+                        Layout.fillWidth: true
+                        text: (root.st.total || 0) + " in history"
+                            + ((root.st.openCriticals || 0) > 0 ? " · " + root.st.openCriticals + " critical open" : "")
+                        color: theme.fgSubtle
+                        font.pixelSize: 11
+                    }
+                }
+                IconButton { iconName: "done_all"; tip: "Mark all as read"; onClicked: root.backend.markAllRead() }
+                IconButton { iconName: "clear_all"; tip: "Clear history"; onClicked: root.backend.clearHistory() }
+                IconButton { iconName: "close"; tip: "Close"; onClicked: root.backend.setDrawerOpen(false) }
+            }
+
+            Flow {
+                Layout.fillWidth: true
+                visible: !root.hasSelection
+                spacing: 6
+                Repeater {
+                    model: root.st.filters || []
+                    delegate: AbstractButton {
+                        id: chip
+                        required property var modelData
+                        implicitHeight: 26
+                        implicitWidth: chipLabel.implicitWidth + 22
+                        hoverEnabled: true
+                        onClicked: root.backend.setFilter(modelData.key)
+                        background: Rectangle {
+                            radius: 13
+                            color: chip.modelData.active ? Qt.rgba(theme.primary.r, theme.primary.g, theme.primary.b, 0.18)
+                                 : chip.hovered ? theme.hover : "transparent"
+                            border.color: chip.modelData.active ? theme.primary : theme.border
+                        }
+                        contentItem: Text {
+                            id: chipLabel
+                            text: chip.modelData.label + "  " + chip.modelData.count
+                            color: chip.modelData.active ? theme.fg : theme.fgMuted
+                            font.pixelSize: 12
+                            font.weight: chip.modelData.active ? Font.DemiBold : Font.Normal
+                            horizontalAlignment: Text.AlignHCenter
+                            verticalAlignment: Text.AlignVCenter
+                        }
+                    }
+                }
+            }
+
+            InputField {
+                id: search
+                Layout.fillWidth: true
+                visible: !root.hasSelection
+                placeholderText: "Search notifications"
+                text: root.st.search || ""
+                onTextEdited: root.backend.setSearch(text)
+            }
+        }
+
+        // ---------------------------------------------------------------- list
+        ListView {
+            id: list
+            Layout.fillWidth: true
+            Layout.fillHeight: true
+            visible: !root.hasSelection && count > 0
+            clip: true
+            model: root.backend.rows
+            spacing: 0
+            boundsBehavior: Flickable.StopAtBounds
+            ScrollBar.vertical: ScrollBar { policy: ScrollBar.AsNeeded }
+
+            delegate: Item {
+                id: row
+                required property string entryId
+                required property string icon
+                required property color color
+                required property color tint
+                required property string title
+                required property string body
+                required property string time
+                required property string timeAbs
+                required property string severityLabel
+                required property string source
+                required property string scan
+                required property int count
+                required property bool unread
+                required property bool needsAck
+
+                width: ListView.view.width
+                height: 78
+
+                Rectangle {
+                    anchors.fill: parent
+                    anchors.leftMargin: 8
+                    anchors.rightMargin: 8
+                    anchors.topMargin: 3
+                    anchors.bottomMargin: 3
+                    radius: 8
+                    color: row.needsAck ? (rowMouse.containsMouse ? Qt.lighter(row.tint, 1.1) : row.tint)
+                         : (rowMouse.containsMouse ? theme.hover : theme.card)
+                    border.color: row.needsAck ? row.color : theme.border
+
+                    Rectangle {
+                        x: 10; y: 10
+                        width: 28; height: 28; radius: 14
+                        color: row.needsAck ? theme.card : row.tint
+                        Icon { anchors.centerIn: parent; name: row.icon; color: row.color; filled: true; size: 17 }
+                    }
+
+                    ColumnLayout {
+                        anchors.fill: parent
+                        anchors.leftMargin: 48
+                        anchors.rightMargin: 10
+                        anchors.topMargin: 6
+                        anchors.bottomMargin: 6
+                        spacing: 2
+
+                        RowLayout {
+                            Layout.fillWidth: true
+                            spacing: 6
+                            Text {
+                                Layout.fillWidth: true
+                                text: row.title
+                                textFormat: Text.PlainText
+                                color: theme.fg
+                                font.pixelSize: 13
+                                font.weight: Font.DemiBold
+                                elide: Text.ElideRight
+                            }
+                            Rectangle {
+                                visible: row.count > 1
+                                implicitWidth: rowCount.implicitWidth + 12
+                                implicitHeight: 16
+                                radius: 8
+                                color: row.tint
+                                Text {
+                                    id: rowCount
+                                    anchors.centerIn: parent
+                                    text: "×" + row.count
+                                    color: row.color
+                                    font.pixelSize: 11
+                                }
+                            }
+                            Rectangle {
+                                visible: row.unread
+                                width: 7; height: 7; radius: 3.5
+                                color: theme.primary
+                            }
+                            Text {
+                                text: row.time
+                                color: theme.fgSubtle
+                                font.pixelSize: 11
+                            }
+                        }
+                        Text {
+                            Layout.fillWidth: true
+                            text: row.body.replace(/\n/g, " ")
+                            textFormat: Text.PlainText
+                            color: theme.fgMuted
+                            font.pixelSize: 12
+                            elide: Text.ElideRight
+                        }
+                        Text {
+                            Layout.fillWidth: true
+                            text: (row.needsAck ? "Needs acknowledgement · " : "")
+                                + [row.severityLabel, row.source, row.scan].filter(function (p) { return p !== "" }).join(" · ")
+                            color: row.needsAck ? row.color : theme.fgSubtle
+                            font.pixelSize: 11
+                            elide: Text.ElideRight
+                        }
+                    }
+                    MouseArea {
+                        id: rowMouse
+                        anchors.fill: parent
+                        hoverEnabled: true
+                        cursorShape: Qt.PointingHandCursor
+                        onClicked: root.backend.select(row.entryId)
+                        ToolTip.visible: containsMouse
+                        ToolTip.delay: 800
+                        ToolTip.text: row.timeAbs
+                    }
+                }
+            }
+        }
+
+        // ---------------------------------------------------------------- empty state
+        Item {
+            Layout.fillWidth: true
+            Layout.fillHeight: true
+            visible: !root.hasSelection && list.count === 0
+            Column {
+                anchors.centerIn: parent
+                spacing: 8
+                Icon {
+                    anchors.horizontalCenter: parent.horizontalCenter
+                    name: (root.st.total || 0) > 0 ? "filter_alt_off" : "inbox"
+                    color: theme.fgSubtle
+                    size: 32
+                }
+                Text {
+                    anchors.horizontalCenter: parent.horizontalCenter
+                    horizontalAlignment: Text.AlignHCenter
+                    text: (root.st.total || 0) > 0 ? "Nothing matches this filter."
+                        : "You're all caught up.\nNew messages and errors appear here."
+                    color: theme.fgSubtle
+                    font.pixelSize: 13
+                }
+            }
+        }
+
+        // ---------------------------------------------------------------- details
+        Flickable {
+            id: detailsView
+            Layout.fillWidth: true
+            Layout.fillHeight: true
+            visible: root.hasSelection
+            clip: true
+            contentHeight: details.implicitHeight + 16
+            boundsBehavior: Flickable.StopAtBounds
+            ScrollBar.vertical: ScrollBar { policy: ScrollBar.AsNeeded }
+
+            ColumnLayout {
+                id: details
+                width: detailsView.width - 24
+                x: 12
+                spacing: 10
+
+                TextButton {
+                    text: "All notifications"
+                    iconName: "arrow_back"
+                    variant: "ghost"
+                    onClicked: root.backend.select("")
+                }
+                RowLayout {
+                    Layout.fillWidth: true
+                    spacing: 12
+                    Rectangle {
+                        Layout.alignment: Qt.AlignTop
+                        width: 36; height: 36; radius: 18
+                        color: root.sel.tint || theme.hover
+                        Icon { anchors.centerIn: parent; name: root.sel.icon || ""; color: root.sel.color || theme.fg; filled: true; size: 21 }
+                    }
+                    ColumnLayout {
+                        Layout.fillWidth: true
+                        spacing: 4
+                        Rectangle {
+                            implicitHeight: 18
+                            implicitWidth: pillText.implicitWidth + 16
+                            radius: 9
+                            color: root.sel.tint || "transparent"
+                            Text {
+                                id: pillText
+                                anchors.centerIn: parent
+                                text: (root.sel.severityLabel || "") + (root.sel.needsAck ? " · needs acknowledgement" : "")
+                                color: root.sel.color || theme.fg
+                                font.pixelSize: 11
+                                font.weight: Font.DemiBold
+                            }
+                        }
+                        TextEdit {
+                            Layout.fillWidth: true
+                            text: root.sel.title || ""
+                            textFormat: TextEdit.PlainText
+                            readOnly: true
+                            selectByMouse: true
+                            wrapMode: TextEdit.Wrap
+                            color: theme.fg
+                            selectionColor: theme.primary
+                            font.pixelSize: 15
+                            font.weight: Font.DemiBold
+                        }
+                    }
+                }
+                TextEdit {
+                    Layout.fillWidth: true
+                    text: root.sel.body || "No message."
+                    textFormat: TextEdit.PlainText
+                    readOnly: true
+                    selectByMouse: true
+                    wrapMode: TextEdit.Wrap
+                    color: theme.fg
+                    selectionColor: theme.primary
+                    font.pixelSize: 13
+                }
+                GridLayout {
+                    columns: 2
+                    columnSpacing: 12
+                    rowSpacing: 4
+                    Text { text: "When"; color: theme.fgSubtle; font.pixelSize: 12 }
+                    Text { text: root.sel.timeAbs || ""; color: theme.fg; font.pixelSize: 12 }
+                    Text { visible: (root.sel.count || 0) > 1; text: "Repeated"; color: theme.fgSubtle; font.pixelSize: 12 }
+                    Text { visible: (root.sel.count || 0) > 1; text: (root.sel.count || 0) + " times since " + (root.sel.firstAbs || ""); color: theme.fg; font.pixelSize: 12 }
+                    Text { visible: (root.sel.source || "") !== ""; text: "Source"; color: theme.fgSubtle; font.pixelSize: 12 }
+                    Text { visible: (root.sel.source || "") !== ""; text: root.sel.source || ""; color: theme.fg; font.pixelSize: 12 }
+                    Text { visible: (root.sel.scan || "") !== ""; text: "Scan"; color: theme.fgSubtle; font.pixelSize: 12 }
+                    Text { visible: (root.sel.scan || "") !== ""; text: root.sel.scan || ""; color: theme.fg; font.pixelSize: 12 }
+                }
+                Text {
+                    visible: root.sel.hasDetails || false
+                    text: "DETAILS"
+                    color: theme.fgSubtle
+                    font.pixelSize: 11
+                    font.weight: Font.DemiBold
+                }
+                Rectangle {
+                    Layout.fillWidth: true
+                    Layout.preferredHeight: Math.min(320, traceText.contentHeight + 16)
+                    visible: root.sel.hasDetails || false
+                    radius: 8
+                    color: theme.field
+                    border.color: theme.border
+                    Flickable {
+                        id: traceFlick
+                        anchors.fill: parent
+                        anchors.margins: 8
+                        clip: true
+                        contentWidth: traceText.contentWidth
+                        contentHeight: traceText.contentHeight
+                        boundsBehavior: Flickable.StopAtBounds
+                        ScrollBar.vertical: ScrollBar { policy: ScrollBar.AsNeeded }
+                        ScrollBar.horizontal: ScrollBar { policy: ScrollBar.AsNeeded }
+                        TextEdit {
+                            id: traceText
+                            text: root.sel.details || ""
+                            textFormat: TextEdit.PlainText
+                            readOnly: true
+                            selectByMouse: true
+                            color: theme.fg
+                            selectionColor: theme.primary
+                            font.family: "monospace"
+                            font.pixelSize: 11
+                        }
+                    }
+                }
+                RowLayout {
+                    Layout.fillWidth: true
+                    spacing: 6
+                    TextButton {
+                        id: copyReport
+                        property string copiedId: ""
+                        text: copiedId !== "" && copiedId === root.sel.entryId ? "Copied" : "Copy report"
+                        iconName: "content_copy"
+                        onClicked: if (root.backend.copyDetails(root.sel.entryId)) copiedId = root.sel.entryId
+                    }
+                    TextButton {
+                        visible: root.sel.needsAck || false
+                        text: "Acknowledge"
+                        iconName: "done"
+                        variant: "danger"
+                        onClicked: root.backend.acknowledge(root.sel.entryId)
+                    }
+                    Item { Layout.fillWidth: true }
+                    TextButton {
+                        text: "Remove"
+                        iconName: "delete"
+                        variant: "ghost"
+                        onClicked: root.backend.remove(root.sel.entryId)
+                    }
+                }
+            }
+        }
+    }
+}

bec_widgets/widgets/containers/main_window/addons/notification_center/qml/NotificationToasts.qml

@@ -0,0 +1,203 @@
+import QtQuick
+import QtQuick.Layouts
+import BecUi
+
+// Bottom-right toast stack. Newest toast at the bottom, nearest to the status bar.
+// Hovering the stack pauses every countdown. Critical errors stay until acknowledged.
+Item {
+    id: root
+    required property var backend
+    readonly property var st: backend.state
+
+    implicitWidth: 396
+    implicitHeight: stack.implicitHeight + 16
+
+    HoverHandler {
+        onHoveredChanged: root.backend.setHovered(hovered)
+    }
+
+    Column {
+        id: stack
+        anchors.left: parent.left
+        anchors.right: parent.right
+        anchors.bottom: parent.bottom
+        anchors.margins: 8
+        spacing: 10
+
+        move: Transition { NumberAnimation { properties: "y"; duration: 140; easing.type: Easing.OutCubic } }
+        add: Transition {
+            NumberAnimation { property: "opacity"; from: 0; to: 1; duration: 160 }
+            NumberAnimation { property: "x"; from: 40; to: 0; duration: 180; easing.type: Easing.OutCubic }
+        }
+
+        Item {
+            width: stack.width
+            height: moreButton.visible ? moreButton.implicitHeight : 0
+            visible: (root.st.overflow || 0) > 0
+            TextButton {
+                id: moreButton
+                anchors.right: parent.right
+                visible: parent.visible
+                text: (root.st.overflow || 0) + " more in notifications"
+                iconName: "expand_less"
+                background: Rectangle {
+                    radius: 6
+                    color: moreButton.hovered ? theme.hover : theme.card
+                    border.color: theme.border
+                }
+                onClicked: root.backend.setDrawerOpen(true)
+            }
+        }
+
+        Repeater {
+            model: root.backend.toasts
+            delegate: Item {
+                id: toast
+                required property string entryId
+                required property string icon
+                required property color color
+                required property color tint
+                required property string title
+                required property string body
+                required property string meta
+                required property string severity
+                required property int count
+                required property bool needsAck
+                required property bool hasDetails
+
+                width: stack.width
+                height: card.height
+
+                // soft shadow
+                Rectangle {
+                    x: 0; y: 3
+                    width: card.width; height: card.height
+                    radius: 11
+                    color: Qt.rgba(0, 0, 0, theme.dark ? 0.35 : 0.07)
+                }
+
+                Rectangle {
+                    id: card
+                    width: parent.width
+                    height: content.implicitHeight + 22
+                    radius: 10
+                    color: theme.card
+                    border.width: toast.needsAck ? 1.5 : 1
+                    border.color: toast.needsAck ? toast.color : theme.border
+
+                    Rectangle {
+                        x: 0; y: card.radius
+                        width: 4; height: parent.height - 2 * card.radius
+                        radius: 2
+                        color: toast.color
+                    }
+
+                    RowLayout {
+                        id: content
+                        anchors.left: parent.left
+                        anchors.right: parent.right
+                        anchors.top: parent.top
+                        anchors.leftMargin: 14
+                        anchors.rightMargin: 10
+                        anchors.topMargin: 12
+                        spacing: 12
+
+                        Rectangle {
+                            Layout.alignment: Qt.AlignTop
+                            width: 32; height: 32; radius: 16
+                            color: toast.tint
+                            Icon { anchors.centerIn: parent; name: toast.icon; color: toast.color; filled: true; size: 19 }
+                        }
+
+                        ColumnLayout {
+                            Layout.fillWidth: true
+                            spacing: 3
+
+                            RowLayout {
+                                Layout.fillWidth: true
+                                spacing: 6
+                                Text {
+                                    Layout.fillWidth: true
+                                    text: toast.title
+                                    textFormat: Text.PlainText
+                                    color: theme.fg
+                                    font.pixelSize: 13
+                                    font.weight: Font.DemiBold
+                                    elide: Text.ElideRight
+                                }
+                                Rectangle {
+                                    visible: toast.count > 1
+                                    implicitWidth: countLabel.implicitWidth + 12
+                                    implicitHeight: 16
+                                    radius: 8
+                                    color: toast.tint
+                                    Text {
+                                        id: countLabel
+                                        anchors.centerIn: parent
+                                        text: "×" + toast.count
+                                        color: toast.color
+                                        font.pixelSize: 11
+                                        font.weight: Font.Bold
+                                    }
+                                }
+                                IconButton {
+                                    visible: !toast.needsAck
+                                    implicitWidth: 24; implicitHeight: 24
+                                    iconName: "close"; iconSize: 16
+                                    tip: "Dismiss"
+                                    onClicked: root.backend.dismissToast(toast.entryId)
+                                }
+                            }
+                            Text {
+                                Layout.fillWidth: true
+                                visible: toast.body !== ""
+                                text: toast.body
+                                textFormat: Text.PlainText
+                                color: theme.fgMuted
+                                font.pixelSize: 12
+                                wrapMode: Text.Wrap
+                                maximumLineCount: 4
+                                elide: Text.ElideRight
+                            }
+                            Text {
+                                Layout.fillWidth: true
+                                text: toast.meta
+                                color: theme.fgSubtle
+                                font.pixelSize: 11
+                                elide: Text.ElideRight
+                            }
+                            RowLayout {
+                                Layout.fillWidth: true
+                                spacing: 6
+                                visible: copyButton.visible || detailsButton.visible || ackButton.visible
+                                Item { Layout.fillWidth: true }
+                                IconButton {
+                                    id: copyButton
+                                    visible: toast.severity === "error" || toast.severity === "critical"
+                                    implicitWidth: 28; implicitHeight: 28
+                                    iconName: "content_copy"; iconSize: 16
+                                    tip: "Copy report"
+                                    onClicked: root.backend.copyDetails(toast.entryId)
+                                }
+                                TextButton {
+                                    id: detailsButton
+                                    visible: toast.hasDetails || toast.needsAck
+                                    implicitHeight: 28
+                                    text: "Details"; iconName: "open_in_new"; variant: "ghost"
+                                    onClicked: root.backend.openDetails(toast.entryId)
+                                }
+                                TextButton {
+                                    id: ackButton
+                                    visible: toast.needsAck
+                                    implicitHeight: 28
+                                    text: "Acknowledge"; iconName: "done"; variant: "danger"
+                                    onClicked: root.backend.acknowledge(toast.entryId)
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+}

bec_widgets/widgets/containers/main_window/main_window.py

@@ -64,9 +64,16 @@ class BECMainWindow(BECWidget, QMainWindow):
         self.setWindowTitle(window_title)
         self.setAttribute(Qt.WidgetAttribute.WA_DeleteOnClose, True)
 
-        # Notification Centre overlay
-        self.notification_centre = NotificationCentre(parent=self)  # Notification layer
-        self.notification_broker = BECNotificationBroker(parent=self)
+        # Notification Centre overlay. BEC_NOTIFICATION_UI=qml|qwidget opts into the reworked
+        # toasts and history drawer, which also replace the modal error dialogs.
+        self._notification_ui = os.environ.get("BEC_NOTIFICATION_UI", "legacy").lower()
+        self.notifications = None
+        if self._notification_ui in ("qml", "qwidget"):
+            self.notification_centre = None
+            self.notification_broker = None
+        else:
+            self.notification_centre = NotificationCentre(parent=self)  # Notification layer
+            self.notification_broker = BECNotificationBroker(parent=self)
         self._nc_margin = 16
         self._position_notification_centre()
         self._widget_hierarchy_dialog: WidgetHierarchyDialog | None = None
@@ -95,7 +102,10 @@ class BECMainWindow(BECWidget, QMainWindow):
                 during __init__ when we first install ``self._full_content``).
         """
         super().setCentralWidget(widget)
-        self.notification_centre.raise_()
+        if self.notification_centre is not None:
+            self.notification_centre.raise_()
+        if self.notifications is not None:
+            self.notifications.sync()
         self.statusBar().raise_()
 
     def resizeEvent(self, event):
@@ -104,7 +114,7 @@ class BECMainWindow(BECWidget, QMainWindow):
 
     def _position_notification_centre(self):
         """Keep the notification panel at a fixed margin top-right."""
-        if not hasattr(self, "notification_centre"):
+        if getattr(self, "notification_centre", None) is None:
             return
         margin = getattr(self, "_nc_margin", 16)  # px
         nc = self.notification_centre
@@ -158,6 +168,9 @@ class BECMainWindow(BECWidget, QMainWindow):
         """
         Add the notification indicator to the status bar and hook the signals.
         """
+        if self.notification_centre is None:
+            self._add_reworked_notifications()
+            return
         # Add the notification indicator to the status bar
         self.notification_indicator = NotificationIndicator(self)
         self.status_bar.addPermanentWidget(self.notification_indicator)
@@ -168,6 +181,20 @@ class BECMainWindow(BECWidget, QMainWindow):
         self.notification_indicator.show_all_requested.connect(self.notification_centre.show_all)
         self.notification_indicator.hide_all_requested.connect(self.notification_centre.hide_all)
 
+    def _add_reworked_notifications(self):
+        """Attach the reworked toasts, history drawer and bell (QML or QWidget version)."""
+        if self._notification_ui == "qml":
+            from bec_widgets.widgets.containers.main_window.addons.notification_center.notification_qml import (
+                NotificationHostQML as Host,
+            )
+        else:
+            from bec_widgets.widgets.containers.main_window.addons.notification_center.notification_qwidget import (
+                NotificationHostQWidget as Host,
+            )
+        self.notifications = Host(self, status_bar=self.status_bar, dispatcher=self.bec_dispatcher)
+        # the guided tour points at the bell
+        self.notification_indicator = self.notifications.bell
+
     ################################################################################
     # Client message status bar widget helpers
 
@@ -539,6 +566,9 @@ class BECMainWindow(BECWidget, QMainWindow):
         self._scan_progress_bar_full.deleteLater()
         self._scan_progress_hover.close()
         self._scan_progress_hover.deleteLater()
+        if self.notifications is not None:
+            self.notifications.cleanup()
+            self.notifications = None
         super().cleanup()
 
 

tests/unit_tests/test_notification_ports.py

@@ -0,0 +1,551 @@
+# pylint: disable=missing-function-docstring,redefined-outer-name,protected-access
+import threading
+import time
+import traceback
+from unittest import mock
+
+import pytest
+from qtpy.QtWidgets import QApplication, QLabel, QMainWindow, QMessageBox, QWidget
+
+from bec_widgets.utils.error_popups import ErrorPopupUtility, SafeSlot, WarningPopupUtility
+from bec_widgets.widgets.containers.main_window.addons.notification_center import (
+    notification_ux_common as common,
+)
+from bec_widgets.widgets.containers.main_window.addons.notification_center.notification_qml import (
+    NotificationHostQML,
+)
+from bec_widgets.widgets.containers.main_window.addons.notification_center.notification_qwidget import (
+    NotificationHostQWidget,
+)
+from bec_widgets.widgets.containers.main_window.addons.notification_center.notification_ux_common import (
+    NotificationHub,
+    Severity,
+    ToastQueue,
+)
+
+TRACE = """Traceback (most recent call last):
+  File "x.py", line 1, in move
+    raise ValueError("Target 12.5 is outside the limits.")
+ValueError: Target 12.5 is outside the limits."""
+
+
+@pytest.fixture
+def hub():
+    yield NotificationHub.instance()
+    NotificationHub.reset_instance()
+
+
+@pytest.fixture
+def window(qtbot):
+    win = QMainWindow()
+    win.setCentralWidget(QLabel("content"))
+    win.statusBar().addWidget(QLabel("status"))
+    win.resize(1000, 700)
+    qtbot.addWidget(win)
+    win.show()
+    qtbot.waitExposed(win)
+    yield win
+
+
+@pytest.fixture(params=["qwidget", "qml"])
+def host(request, window, hub, qtbot):
+    cls = NotificationHostQWidget if request.param == "qwidget" else NotificationHostQML
+    attached = cls(window)
+    yield attached
+    attached.cleanup()
+
+
+def flush(qtbot, host):
+    """Run the coalesced view update."""
+    host.sync_now()
+    qtbot.wait(10)
+
+
+def toast_count(host) -> int:
+    if isinstance(host, NotificationHostQML):
+        return host.backend.toasts.rowCount()
+    return len(host.toasts.cards)
+
+
+def row_count(host) -> int:
+    if isinstance(host, NotificationHostQML):
+        return host.backend.rows.rowCount()
+    return host.drawer.model.rowCount()
+
+
+# ---------------------------------------------------------------------------- pure helpers
+
+
+@pytest.mark.parametrize(
+    "value, expected",
+    [
+        ("info", Severity.INFO),
+        ("minor", Severity.ERROR),
+        ("major", Severity.CRITICAL),
+        (0, Severity.WARNING),
+        (1, Severity.ERROR),
+        (2, Severity.CRITICAL),
+        (Severity.SUCCESS, Severity.SUCCESS),
+        ("nonsense", Severity.WARNING),
+        (None, Severity.WARNING),
+    ],
+)
+def test_to_severity(value, expected):
+    assert common.to_severity(value) == expected
+
+
+def test_split_traceback():
+    assert common.split_traceback(TRACE) == ("ValueError", "Target 12.5 is outside the limits.")
+    assert common.split_traceback("") == ("Error", "")
+    assert common.split_traceback("something odd happened") == ("Error", "something odd happened")
+    assert common.split_traceback("ophyd.utils.errors.WaitTimeoutError: late")[0] == (
+        "WaitTimeoutError"
+    )
+
+
+def test_relative_time():
+    now = time.time()
+    assert common.relative_time(now - 5, now) == "just now"
+    assert common.relative_time(now - 300, now) == "5 min ago"
+
+
+# ---------------------------------------------------------------------------- hub
+
+
+def test_hub_is_singleton(hub):
+    assert NotificationHub.instance() is hub
+
+
+def test_notify_adds_entry_newest_first(hub):
+    first = hub.notify("A", "one")
+    second = hub.notify("B", "two", "warning", source="x")
+    assert [e.id for e in hub.entries] == [second, first]
+    assert hub.get(second).severity == Severity.WARNING
+    assert hub.unread_count() == 2
+
+
+def test_repeated_notifications_fold_into_one_entry(hub):
+    first = hub.notify("Readback failed", "timeout", "error", source="samx")
+    hub.notify("Other", "x")
+    again = hub.notify("Readback failed", "timeout", "error", source="samx")
+    assert again == first
+    assert len(hub.entries) == 2
+    assert hub.entries[0].id == first  # moved to the top
+    assert hub.get(first).count == 2
+    # a different source is a different problem
+    hub.notify("Readback failed", "timeout", "error", source="samy")
+    assert len(hub.entries) == 3
+
+
+def test_same_entry_id_is_posted_once(hub):
+    hub.notify("A", entry_id="fixed")
+    hub.notify("A changed", entry_id="fixed")
+    assert len(hub.entries) == 1
+
+
+def test_history_is_trimmed_but_keeps_open_critical(hub, monkeypatch):
+    monkeypatch.setattr(NotificationHub, "MAX_ENTRIES", 5)
+    critical = hub.notify("Beam lost", severity="critical")
+    for i in range(10):
+        hub.notify(f"info {i}")
+    assert len(hub.entries) == 5
+    assert hub.get(critical) is not None
+
+
+def test_clear_keeps_unacknowledged_critical(hub):
+    critical = hub.notify("Beam lost", severity="critical")
+    hub.notify("hello")
+    hub.clear()
+    assert [e.id for e in hub.entries] == [critical]
+    hub.acknowledge(critical)
+    hub.clear()
+    assert hub.entries == []
+
+
+def test_acknowledge_and_top_severity(hub):
+    hub.notify("w", severity="warning")
+    critical = hub.notify("c", severity="critical")
+    assert hub.top_unread_severity() == Severity.CRITICAL
+    hub.mark_read()
+    # still open: a critical error needs an acknowledgement, reading it is not enough
+    assert hub.top_unread_severity() == Severity.CRITICAL
+    hub.acknowledge(critical)
+    assert hub.top_unread_severity() is None
+
+
+def test_post_alarm_parses_error_info(hub):
+    entry_id = hub.post_alarm(
+        {
+            "severity": 2,
+            "alarm_type": "DeviceTimeoutError",
+            "info": {
+                "id": "abc",
+                "error_message": TRACE,
+                "compact_error_message": "Device eiger did not respond.",
+                "exception_type": "DeviceTimeoutError",
+                "device": "eiger",
+            },
+        },
+        {"scan_number": 12, "scan_id": "sid"},
+    )
+    entry = hub.get(entry_id)
+    assert entry_id == "abc"
+    assert entry.severity == Severity.CRITICAL
+    assert entry.title == "DeviceTimeoutError"
+    assert entry.body == "Device eiger did not respond."
+    assert entry.source == "Device eiger"
+    assert entry.scan_number == 12
+    assert "sid" in entry.details and "Traceback" in entry.details
+    # the same alarm arriving again is ignored
+    assert hub.post_alarm({"severity": 2, "info": {"id": "abc", "error_message": "x"}}) is None
+
+
+def test_post_alarm_without_info(hub):
+    entry_id = hub.post_alarm({"severity": 0, "alarm_type": "Warning", "msg": "low beam"})
+    entry = hub.get(entry_id)
+    assert entry.severity == Severity.WARNING
+    assert entry.body == "low beam"
+    assert entry.details == ""
+
+
+def test_report_exception(hub):
+    entry = hub.get(hub.report_exception("Method error", TRACE, source="Box.move"))
+    assert entry.title == "ValueError"
+    assert entry.body == "Target 12.5 is outside the limits."
+    assert entry.source == "Box.move"
+    assert entry.severity == Severity.ERROR
+    assert "Traceback" in entry.details
+    report = entry.copy_text()
+    assert "[Error] ValueError" in report and "Source: Box.move" in report and TRACE in report
+
+
+def test_notify_from_worker_thread_is_queued(hub, qtbot):
+    thread = threading.Thread(target=lambda: hub.notify("from thread"))
+    thread.start()
+    thread.join()
+    qtbot.waitUntil(lambda: len(hub.entries) == 1, timeout=1000)
+    assert hub.entries[0].title == "from thread"
+
+
+def test_bec_alarm_subscription(hub, bec_dispatcher):
+    with mock.patch.object(bec_dispatcher, "connect_slot") as connect:
+        hub.connect_bec(bec_dispatcher)
+        hub.connect_bec(bec_dispatcher)  # only once
+    assert connect.call_count == 2
+    with mock.patch.object(bec_dispatcher, "disconnect_slot") as disconnect:
+        hub.disconnect_bec()
+    assert disconnect.call_count == 2
+
+
+def test_scan_start_signal(hub, qtbot):
+    with qtbot.waitSignal(hub.scan_started, timeout=500):
+        hub._on_scan_status({"status": "open"}, {})
+    with qtbot.assertNotEmitted(hub.scan_started):
+        hub._on_scan_status({"status": "closed"}, {})
+
+
+# ---------------------------------------------------------------------------- toast queue
+
+
+@pytest.fixture
+def queue(hub):
+    toast_queue = ToastQueue(hub)
+    yield toast_queue
+    toast_queue.cleanup()
+    toast_queue.deleteLater()
+
+
+def test_queue_limits_visible_toasts(hub, queue):
+    ids = [hub.notify(f"n{i}", severity="error") for i in range(5)]
+    assert queue.visible_ids == ids[-3:]
+    assert queue.overflow == 2
+
+
+def test_queue_critical_evicts_oldest_transient(hub, queue):
+    critical = [hub.notify(f"c{i}", severity="critical") for i in range(2)]
+    info = hub.notify("info")
+    new_critical = hub.notify("c-new", severity="critical")
+    assert info not in queue.visible_ids
+    assert queue.visible_ids == critical + [new_critical]
+    # all slots held by critical errors: a transient toast only counts as overflow
+    hub.notify("more info")
+    assert queue.visible_ids == critical + [new_critical]
+
+
+def test_queue_auto_dismiss_and_pause(hub, queue, qtbot, monkeypatch):
+    monkeypatch.setitem(common.SEVERITY_META[Severity.INFO], "lifetime", 80)
+    entry_id = hub.notify("short")
+    queue.set_paused(True)
+    qtbot.wait(150)
+    assert entry_id in queue.visible_ids
+    queue.set_paused(False)
+    qtbot.waitUntil(lambda: entry_id not in queue.visible_ids, timeout=2000)
+    # the entry stays in the history
+    assert hub.get(entry_id) is not None
+
+
+def test_queue_critical_stays_until_acknowledged(hub, queue):
+    critical = hub.notify("c", severity="critical")
+    assert critical not in queue._timers
+    hub.acknowledge(critical)
+    assert critical not in queue.visible_ids
+
+
+def test_queue_scan_start_keeps_critical(hub, queue):
+    hub.notify("info")
+    critical = hub.notify("c", severity="critical")
+    hub.scan_started.emit()
+    assert queue.visible_ids == [critical]
+
+
+def test_queue_repeat_moves_toast_to_newest(hub, queue):
+    first = hub.notify("a", "x", "error")
+    hub.notify("b", "y", "error")
+    hub.notify("a", "x", "error")
+    assert queue.visible_ids[-1] == first
+    assert len(queue.visible_ids) == 2
+
+
+def test_queue_suspended_shows_nothing(hub, queue):
+    hub.notify("a")
+    queue.set_suspended(True)
+    assert queue.visible_ids == []
+    hub.notify("b")
+    assert queue.visible_ids == []
+
+
+# ---------------------------------------------------------------------------- hosts (both views)
+
+
+def test_host_shows_toasts_and_bell(host, hub, qtbot):
+    hub.notify("Hello", "world")
+    hub.notify("Broken", "it failed", "critical")
+    flush(qtbot, host)
+    assert toast_count(host) == 2
+    assert host.toasts.isVisible()
+    state = host.view_state()
+    assert state["unread"] == 2
+    assert state["openCriticals"] == 1
+    assert "critical" in state["bellTip"]
+    assert host.toasts.geometry().right() <= host.window.width()
+    assert host.toasts.geometry().bottom() < host.window.statusBar().geometry().top()
+
+
+def test_host_drawer_lists_filters_and_details(host, hub, qtbot):
+    hub.notify("Info one", "a")
+    error = hub.report_exception("Method error", TRACE, source="Box.move")
+    hub.notify("Warn", "low beam", "warning")
+    host.set_drawer_open(True)
+    flush(qtbot, host)
+    assert host.drawer.isVisible()
+    assert toast_count(host) == 0  # toasts give way to the drawer
+    assert hub.unread_count() == 0  # opening the drawer reads everything
+    assert row_count(host) == 3
+    host.set_filter("errors")
+    flush(qtbot, host)
+    assert row_count(host) == 1
+    host.set_filter("all")
+    host.set_search("low beam")
+    flush(qtbot, host)
+    assert row_count(host) == 1
+    host.set_search("")
+    host.select(error)
+    flush(qtbot, host)
+    assert host.view_state()["selected"]["entryId"] == error
+    assert host.copy_details(error)
+    assert "ValueError" in QApplication.clipboard().text()
+    host.remove(error)
+    flush(qtbot, host)
+    assert hub.get(error) is None
+    assert host.view_state()["selected"] is None
+    host.set_drawer_open(False)
+    flush(qtbot, host)
+    assert not host.drawer.isVisible()
+
+
+def test_host_critical_pinned_on_top(host, hub, qtbot):
+    critical = hub.notify("Beam lost", severity="critical")
+    hub.notify("newer info")
+    host.set_drawer_open(True)
+    flush(qtbot, host)
+    assert host.view_state()["rows"][0]["entryId"] == critical
+    host.acknowledge(critical)
+    flush(qtbot, host)
+    assert host.view_state()["rows"][0]["entryId"] != critical
+
+
+def test_host_open_details_from_toast(host, hub, qtbot):
+    entry_id = hub.notify("Broken", "x", "error", details="trace")
+    flush(qtbot, host)
+    host.open_details(entry_id)
+    flush(qtbot, host)
+    assert host.drawer_open
+    assert host.view_state()["selected"]["details"] == "trace"
+
+
+def test_host_dismiss_critical_toast_acknowledges(host, hub, qtbot):
+    critical = hub.notify("Beam lost", severity="critical")
+    flush(qtbot, host)
+    host.dismiss_toast(critical)
+    flush(qtbot, host)
+    assert hub.get(critical).acknowledged
+    assert toast_count(host) == 0
+
+
+def test_host_follows_theme(host, hub, qtbot):
+    from bec_widgets.utils.colors import apply_theme
+
+    hub.notify("x", severity="warning")
+    flush(qtbot, host)
+    apply_theme("dark")
+    flush(qtbot, host)
+    apply_theme("light")
+    flush(qtbot, host)
+    assert toast_count(host) == 1
+
+
+def test_host_cleanup_unregisters(window, hub):
+    attached = NotificationHostQWidget(window)
+    assert hub.has_hosts
+    attached.cleanup()
+    attached.cleanup()  # idempotent
+    assert not hub.has_hosts
+
+
+def test_qml_views_load_without_errors(window, hub):
+    attached = NotificationHostQML(window)
+    try:
+        for view in (attached.toasts, attached.drawer, attached.bell):
+            assert view.errors() == []
+            assert view.rootObject() is not None
+    finally:
+        attached.cleanup()
+
+
+def test_qwidget_toast_buttons(window, hub, qtbot):
+    attached = NotificationHostQWidget(window)
+    try:
+        hub.notify("Broken", "x", "critical", details="trace")
+        flush(qtbot, attached)
+        card = attached.toasts.cards[0]
+        assert card.ack_btn.isVisibleTo(card)
+        assert not card.close_btn.isVisibleTo(card)
+        card.details_btn.click()
+        flush(qtbot, attached)
+        assert attached.drawer_open
+        attached.drawer.details.ack_btn.click()
+        flush(qtbot, attached)
+        assert hub.entries[0].acknowledged
+    finally:
+        attached.cleanup()
+
+
+# ---------------------------------------------------------------------------- error routing
+
+
+class _Failing(QWidget):
+    @SafeSlot(popup_error=True)
+    def fail(self):
+        raise ValueError("Target 12.5 is outside the limits.")
+
+
+def test_safeslot_error_becomes_notification_when_host_attached(window, hub, qtbot):
+    attached = NotificationHostQWidget(window)
+    widget = _Failing()
+    qtbot.addWidget(widget)
+    try:
+        with (
+            mock.patch.object(QMessageBox, "exec_") as exec_,
+            qtbot.assertNotEmitted(ErrorPopupUtility().error_occurred),
+        ):
+            widget.fail()
+        exec_.assert_not_called()
+        entry = hub.entries[0]
+        assert entry.title == "ValueError"
+        assert entry.source == "_Failing.fail"
+        assert "Traceback" in entry.details
+    finally:
+        attached.cleanup()
+
+
+def test_safeslot_error_uses_dialog_without_host(hub, qtbot):
+    widget = _Failing()
+    qtbot.addWidget(widget)
+    with qtbot.waitSignal(ErrorPopupUtility().error_occurred, timeout=1000):
+        widget.fail()
+    assert hub.entries == []
+
+
+def test_warning_popup_becomes_notification(window, hub):
+    attached = NotificationHostQWidget(window)
+    try:
+        with mock.patch.object(QMessageBox, "exec_") as exec_:
+            WarningPopupUtility().show_warning("Export", "No data to export.", "details", window)
+        exec_.assert_not_called()
+        entry = hub.entries[0]
+        assert (entry.title, entry.body, entry.severity) == (
+            "Export",
+            "No data to export.",
+            Severity.WARNING,
+        )
+        assert entry.details == "details"
+    finally:
+        attached.cleanup()
+
+
+def test_application_error_routed(window, hub):
+    attached = NotificationHostQWidget(window)
+    try:
+        util = ErrorPopupUtility()
+        util.enable_global_error_popups(True)
+        try:
+            raise RuntimeError("boom")
+        except RuntimeError as exc:
+            util.custom_exception_hook(type(exc), exc, exc.__traceback__)
+        assert hub.entries[0].title == "RuntimeError"
+        assert hub.entries[0].source == "Application Error"
+    finally:
+        util.enable_global_error_popups(False)
+        attached.cleanup()
+
+
+# ---------------------------------------------------------------------------- main window opt-in
+
+
+@pytest.mark.parametrize("variant", ["qwidget", "qml"])
+def test_main_window_opt_in(qtbot, monkeypatch, variant, mocked_client):
+    from bec_widgets.widgets.containers.main_window.main_window import BECMainWindow
+
+    monkeypatch.setenv("BEC_NOTIFICATION_UI", variant)
+    win = BECMainWindow(client=mocked_client)
+    qtbot.addWidget(win)
+    try:
+        assert win.notification_centre is None
+        assert win.notifications is not None
+        assert win.notification_indicator is win.notifications.bell
+        win.notifications.hub.notify("hello")
+        win.notifications.sync_now()
+        assert win.notifications.view_state()["unread"] == 1
+    finally:
+        win.close()
+
+
+def test_main_window_default_is_legacy(qtbot, mocked_client, monkeypatch):
+    from bec_widgets.widgets.containers.main_window.main_window import BECMainWindow
+
+    monkeypatch.delenv("BEC_NOTIFICATION_UI", raising=False)
+    win = BECMainWindow(client=mocked_client)
+    qtbot.addWidget(win)
+    try:
+        assert win.notification_centre is not None
+        assert win.notifications is None
+    finally:
+        win.close()
+
+
+def test_traceback_helper_matches_python():
+    try:
+        raise KeyError("missing")
+    except KeyError:
+        text = traceback.format_exc()
+    assert common.split_traceback(text) == ("KeyError", "'missing'")