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.

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.