fix: send light slider changes from every input path, guard readback

Sliders only emitted on sliderReleased, so right-click+wheel, arrow keys
and groove clicks changed the value locally without a PUT and the 500 ms
status poll snapped it back. setTracking(False) + valueChanged now sends
one PUT per deliberate change; readback setValue is wrapped in
blockSignals to avoid echoing PUTs, and a 1.5 s grace window stops
in-flight stale status responses from bouncing the slider.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/aare/gui/panels/illumination_panel.py

@@ -1,9 +1,15 @@
+import time
+
 from aarecommon.models.models import DAQStatusModel
 from PySide6.QtCore import Qt, Signal, Slot
 from PySide6.QtWidgets import QGridLayout, QLabel, QSlider, QWidget
 
 from aare.gui.widgets.title_label import TitleLabel
 
+# Skip readback updates this long after a user change: a status response already
+# in flight when the PUT was queued would otherwise snap the slider back.
+READBACK_GRACE_S = 1.5
+
 
 class IlluminationPanel(QWidget):
     front_light = Signal(int)
@@ -21,11 +27,18 @@ class IlluminationPanel(QWidget):
         front_label.setAlignment(Qt.AlignmentFlag.AlignCenter)
         grid_layout.addWidget(front_label, 1, 0, 1, 2)
         self.is_sliding = False
+        self._last_user_change = 0.0
 
         self.front_light_slider = QSlider(orientation=Qt.Orientation.Horizontal, parent=self)
         self.front_light_slider.setRange(0, 100)
+        # tracking off: valueChanged fires once per deliberate change (wheel notch,
+        # key step, groove page-step, drag release). sliderReleased alone missed
+        # every path except a handle drag, so wheel adjustments were never sent
+        # and the 500 ms status poll reverted them.
+        self.front_light_slider.setTracking(False)
         self.front_light_slider.sliderPressed.connect(self.on_slider_pressed)
-        self.front_light_slider.sliderReleased.connect(self.on_front_slider_released)
+        self.front_light_slider.sliderReleased.connect(self.on_slider_released)
+        self.front_light_slider.valueChanged.connect(self.on_front_value_changed)
         grid_layout.addWidget(self.front_light_slider, 2, 0, 1, 2)
 
         back_label = QLabel("Back light", parent=self)
@@ -34,8 +47,10 @@ class IlluminationPanel(QWidget):
 
         self.back_light_slider = QSlider(orientation=Qt.Orientation.Horizontal, parent=self)
         self.back_light_slider.setRange(0, 100)
+        self.back_light_slider.setTracking(False)
         self.back_light_slider.sliderPressed.connect(self.on_slider_pressed)
-        self.back_light_slider.sliderReleased.connect(self.on_back_slider_released)
+        self.back_light_slider.sliderReleased.connect(self.on_slider_released)
+        self.back_light_slider.valueChanged.connect(self.on_back_value_changed)
         grid_layout.addWidget(self.back_light_slider, 4, 0, 1, 2)
 
     @Slot()
@@ -43,17 +58,76 @@ class IlluminationPanel(QWidget):
         self.is_sliding = True
 
     @Slot()
-    def on_front_slider_released(self):
+    def on_slider_released(self):
         self.is_sliding = False
-        self.front_light.emit(self.front_light_slider.value())
 
-    @Slot()
-    def on_back_slider_released(self):
-        self.is_sliding = False
-        self.back_light.emit(self.back_light_slider.value())
+    @Slot(int)
+    def on_front_value_changed(self, v: int):
+        self._last_user_change = time.monotonic()
+        self.front_light.emit(v)
+
+    @Slot(int)
+    def on_back_value_changed(self, v: int):
+        self._last_user_change = time.monotonic()
+        self.back_light.emit(v)
 
     @Slot(DAQStatusModel)
     def update_daq_status(self, s: DAQStatusModel):
-        if not self.is_sliding:  # Update only if not sliding
-            self.front_light_slider.setValue(round(s.bl.front_light))
-            self.back_light_slider.setValue(round(s.bl.back_light))
+        if self.is_sliding or time.monotonic() - self._last_user_change < READBACK_GRACE_S:
+            return
+        # blockSignals: readback must not loop back into valueChanged and echo
+        # a PUT to the server every poll.
+        for slider, val in (
+            (self.front_light_slider, s.bl.front_light),
+            (self.back_light_slider, s.bl.back_light),
+        ):
+            slider.blockSignals(True)
+            slider.setValue(round(val))
+            slider.blockSignals(False)
+
+
+if __name__ == "__main__":
+    # ponytail: smallest check that fails if the send/readback wiring breaks
+    import os
+    from types import SimpleNamespace
+
+    os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
+    from PySide6.QtCore import QPoint, QPointF
+    from PySide6.QtGui import QWheelEvent
+    from PySide6.QtWidgets import QApplication
+
+    app = QApplication([])
+    panel = IlluminationPanel()
+    sent = []
+    panel.front_light.connect(sent.append)
+
+    # wheel notch must emit (was silently discarded before)
+    panel.front_light_slider.setFocus()
+    QApplication.sendEvent(
+        panel.front_light_slider,
+        QWheelEvent(
+            QPointF(5, 5),
+            QPointF(5, 5),
+            QPoint(0, 0),
+            QPoint(0, 120),
+            Qt.MouseButton.RightButton,
+            Qt.KeyboardModifier.NoModifier,
+            Qt.ScrollPhase.NoScrollPhase,
+            False,
+        ),
+    )
+    assert sent, "wheel adjustment must emit front_light"
+
+    # readback right after a user change must not clobber the slider
+    held = panel.front_light_slider.value()
+    status = SimpleNamespace(bl=SimpleNamespace(front_light=90.0, back_light=10.0))
+    panel.update_daq_status(status)
+    assert panel.front_light_slider.value() == held, "grace window must hold user value"
+
+    # after the grace window, readback applies without emitting a PUT
+    panel._last_user_change = time.monotonic() - READBACK_GRACE_S - 1
+    n_sent = len(sent)
+    panel.update_daq_status(status)
+    assert panel.front_light_slider.value() == 90, "readback must apply after grace"
+    assert len(sent) == n_sent, "readback must not echo a PUT"
+    print("gude")