feat(map): add min/max highlighting toggle and live safeguards

- Add "Highlight Min/Max" option to ReadoutPanel showing peak rings.
- Reset to review mode and blank wafer map when switching away from map tab.
- Disable hover highlights and sensor dialog triggers during live stream.
- Lower trendPane height and add top margin headroom for tick labels.
- Add test coverage for blanking states, toggle overrides, and interactions.

src/pygui/ISC/HomePage.qml

@@ -23,6 +23,9 @@ Rectangle {
         if (selectedTabIndex === 2) {
             file_browser.refreshFiles();
             streamController.unloadFile()
+        } else if (streamController.mode === "live") {
+            // Leaving the map tab mid-stream: stop and blank the live map.
+            streamController.setMode("review")
         }
     }
 

src/pygui/ISC/Tabs/WaferMapTab.qml

@@ -144,7 +144,7 @@ Item {
             ColumnLayout {
                 Layout.fillWidth: true
                 Layout.fillHeight: true
-                spacing: 8
+                spacing: 16
 
                 WaferMapView {
                     id: waferView
@@ -154,14 +154,15 @@ Item {
                     Layout.minimumHeight: 280
                     blend: readoutPanel.heatmapBlend
                     showLabels: readoutPanel.showLabels
+                    showExtremes: readoutPanel.showExtremes
                     showThickness: readoutPanel.showThickness
                 }
                 Rectangle {
                     id: trendPane
                     Layout.fillWidth: true
-                    Layout.fillHeight: true
+                    Layout.fillHeight: false
                     Layout.preferredHeight: 220
-                    Layout.minimumHeight: 160
+                    Layout.minimumHeight: 120
                     visible: trendChart.hasData && streamController.mode === "live"
                     color: Theme.cardBackground
                     border.color: Theme.cardBorder
@@ -183,9 +184,11 @@ Item {
 
                 Item {
                     Layout.fillWidth: true
+                    visible: transportBar.hasContent
                     implicitHeight: trendPane.visible ? 52 : 16
                 }
                 TransportBar {
+                    id: transportBar
                     Layout.fillWidth: true
                 }
             }

src/pygui/ISC/Tabs/components/ReadoutPanel.qml

@@ -12,6 +12,7 @@ ColumnLayout {
     spacing: 6
     property var s: streamController.stats
     property alias showLabels: labelsToggle.checked
+    property alias showExtremes: extremesToggle.checked
     property alias heatmapBlend: heatmapSlider.value
     property alias showThickness: thicknessToggle.checked
 
@@ -353,6 +354,13 @@ ColumnLayout {
                 font.pixelSize: Theme.fontSm
             }
 
+            PanelCheckBox {
+                id: extremesToggle
+                text: "Highlight Min/Max"
+                checked: true
+                font.pixelSize: Theme.fontSm
+            }
+
             PanelCheckBox {
                 id: clusterAverageToggle
                 text: "Average Clusters"

src/pygui/ISC/Tabs/components/WaferMapView.qml

@@ -7,6 +7,7 @@ Item {
     id: root
     property real blend: 0.0
     property bool showLabels: true
+    property alias showExtremes: map.showExtremes
     property alias showThickness: map.showThickness
 
     WaferMapItem {
@@ -39,7 +40,9 @@ Item {
         HoverHandler {
             id: hoverHandler
             onPointChanged: {
-                map.hoveredIndex = map.which_marker(hoverHandler.point.position.x, hoverHandler.point.position.y);
+                map.hoveredIndex = streamController.mode === "live"
+                    ? -1
+                    : map.which_marker(hoverHandler.point.position.x, hoverHandler.point.position.y);
             }
             onHoveredChanged: if (!hoverHandler.hovered) map.hoveredIndex = -1
             cursorShape: map.hoveredIndex >= 0 ? Qt.PointingHandCursor : Qt.ArrowCursor
@@ -47,6 +50,8 @@ Item {
 
         TapHandler {
             onTapped: ev => {
+                if (streamController.mode === "live")
+                    return;
                 var idx = map.which_marker(ev.position.x, ev.position.y);
                 if (idx >= 0)
                     replaceDialog.openFor(idx);

src/pygui/backend/controllers/session_controller.py

@@ -225,6 +225,12 @@ class SessionController(QObject):
             return
         if mode != "live":
             self.stopStream()
+            if self._mode == "live":
+                # Leaving a live session: blank the wafer map instead of
+                # freezing the last streamed frame on screen.
+                self._last = None
+                self._last_raw_frame = None
+                self.frameUpdated.emit()
         self._play_timer.stop()
         self._mode = mode
         self.modeChanged.emit()

src/pygui/backend/visualization/trend_chart_item.py

@@ -58,6 +58,9 @@ class TrendChartItem(QQuickPaintedItem):
         # `_padding` alone — that mismatch is what clipped y-axis text before.
         self._margin_left: int = 48
         self._margin_bottom: int = 30
+        # Top tick label is drawn centered on the plot's top edge (y_px - 7),
+        # so the plot needs headroom or the label kisses the card border.
+        self._margin_top: int = 10
         self._line_color = QColor("#5B9DF5")
         self._grid_color = QColor("#2A3441")
         self._text_color = QColor("#CBD5E1")
@@ -178,10 +181,11 @@ class TrendChartItem(QQuickPaintedItem):
             return
 
         left = self._padding + self._margin_left
+        top = self._padding + self._margin_top
         bottom_inset = self._padding + self._margin_bottom
-        plot_rect = QRectF(left, self._padding,
+        plot_rect = QRectF(left, top,
                            max(1, w - left - self._padding),
-                           max(1, h - self._padding - bottom_inset))
+                           max(1, h - top - bottom_inset))
 
         self._draw_grid(painter, plot_rect)
 

src/pygui/backend/visualization/wafer_map_item.py

@@ -62,6 +62,7 @@ class WaferMapItem(QQuickPaintedItem):
     marginChanged   = Signal()
     blendChanged    = Signal()
     showLabelsChanged = Signal()
+    showExtremesChanged = Signal()
     colorsChanged   = Signal()
     shapeChanged    = Signal()
     sizeChanged     = Signal()
@@ -80,6 +81,7 @@ class WaferMapItem(QQuickPaintedItem):
         self._margin:   float = 1.0
         self._blend:    float = 0.0
         self._show_labels: bool = True
+        self._show_extremes: bool = True
         self._shape: str = "round"
         self._size: float = 300.0
         self._thickness_data: list[float] = []
@@ -199,6 +201,16 @@ class WaferMapItem(QQuickPaintedItem):
         self.showLabelsChanged.emit()
         self.update()
 
+    @Property(bool, notify=showExtremesChanged)
+    def showExtremes(self) -> bool:
+        return self._show_extremes
+
+    @showExtremes.setter  # type: ignore[no-redef]
+    def showExtremes(self, val: bool) -> None:
+        self._show_extremes = bool(val)
+        self.showExtremesChanged.emit()
+        self.update()
+
     @Property(str, notify=shapeChanged)
     def shape(self) -> str:
         return self._shape
@@ -340,7 +352,6 @@ class WaferMapItem(QQuickPaintedItem):
             img.fill(0)  # transparent background
             painter = QPainter(img)
             self.paint(painter)
-            self._paint_extremes(painter)
             if lines:
                 painter.fillRect(QRectF(0, h, w, footer_h), QColor("#101014"))
                 painter.setPen(QColor("#CBD5E1"))
@@ -357,12 +368,8 @@ class WaferMapItem(QQuickPaintedItem):
     # ── internal ─────────────────────────────────────────────────────────
 
     def _paint_extremes(self, painter: QPainter) -> None:
-        """Ring the hottest (high color) and coldest (low color) markers.
+        """Ring the hottest (high color) and coldest (low color) markers."""
-
+        if not self._show_extremes or not self._values or not self._markers:
-        Export-only overlay — paint() itself stays untouched so the live
-        view is unchanged.
-        """
-        if not self._values or not self._markers:
             return
         s = compute_stats(self._values)
         ring_r = self._marker_r + 5
@@ -606,6 +613,7 @@ class WaferMapItem(QQuickPaintedItem):
             painter.setOpacity(1.0)
 
         self._paint_markers(painter)
+        self._paint_extremes(painter)
 
     def _paint_template(self, painter: QPainter, cx: int, cy: int, r_px: int) -> None:
         ds = self._draw_size()

tests/test_session_controller.py

@@ -53,6 +53,29 @@ def test_pause_stop_timer(controller):
     controller.stop()
     assert controller.frameIndex == 0
 
+def test_leaving_live_mode_blanks_wafer_map(controller):
+    """Stopping a live session (tab switch → setMode) must not leave stale
+    sensor values on the wafer map — it should read as blank."""
+    frame_signal = MagicMock()
+    controller.frameUpdated.connect(frame_signal)
+
+    controller.setMode("live")
+    controller._on_live_frame(Frame(seq=1, time=0.0, values=[100.0] * 22))
+    assert controller.sensorValues, "sanity: live frame should populate the map"
+
+    controller.setMode("review")
+    assert controller.sensorValues == []
+    assert controller.stats == {}
+    assert frame_signal.called, "QML needs frameUpdated to repaint blank"
+
+
+def test_leaving_live_mode_stops_stream(controller):
+    controller.setMode("live")
+    controller.setMode("review")
+    assert controller._reader is None
+    assert not controller._repaint_timer.isActive()
+
+
 def test_compare_files_integration(controller):
     # Mock the comparisonResult signal
     mock_slot = MagicMock()

tests/test_wafer_map_item.py

@@ -161,6 +161,36 @@ def test_export_image_highlights_hottest_and_coldest(tmp_path):
     assert "#5b9df5" in found  # coldest ring (sensorLow)
 
 
+def test_show_extremes_toggle_gates_peak_rings(tmp_path):
+    """showExtremes (Display setting) hides the hot/cold rings when off.
+    Same pixel probe as the highlight test: with rings off, no high/low
+    colored pixels should appear anywhere."""
+    from PySide6.QtGui import QImage
+
+    from pygui.backend.visualization.wafer_map_item import WaferMapItem
+
+    item = WaferMapItem()
+    assert item.showExtremes is True  # rings on by default
+
+    item.setWidth(200)
+    item.setHeight(200)
+    item.sensors = [
+        {"label": "1", "x": -50.0, "y": 0.0},
+        {"label": "2", "x": 0.0, "y": 0.0},
+        {"label": "3", "x": 50.0, "y": 0.0},
+    ]
+    item.values = [10.0, 20.0, 30.0]
+    item.showExtremes = False
+    out = tmp_path / "wafer.png"
+    assert item.export_image(str(out)) is True
+
+    img = QImage(str(out))
+    found = {img.pixelColor(x, y).name()
+             for y in range(img.height()) for x in range(img.width())}
+    assert "#ef4444" not in found
+    assert "#5b9df5" not in found
+
+
 def test_readout_text_full_stats():
     """Export footer readout carries every READOUT stat with sensor indices.