fix(gui): keep the smart panel resolution tied to DAQStatus

The visible-resolution field is fed from DAQStatusModel.last_best_res, but
the update was guarded by a bare `is not None`. main now clears
last_best_res on mount (daq.py), so on a fresh sample the DAQ reports "no
resolution" and the panel silently kept the previous crystal's number --
and then sized detector distance, exposure and the dose budget from it.

Track the DAQ value explicitly instead:

- Push on a change of the DAQ value rather than on every 2 Hz tick, so a new
  raster result always lands while a repeat leaves a manual override alone.
- Handle None: reset the field to its default instead of leaving a stale
  value, and mark the row "(no raster)" in the alert colour. There was
  previously nothing to distinguish a measured resolution from a default or
  a typed one, which is what made this hard to spot at the beamline; it also
  shows when the status endpoint's pgroup gate has stripped the value.
- Use set_committed_value, which compares against what the field actually
  shows, rather than update_value, which compares against saved_value.
  on_editing_finished self-assigns saved_value (number_line_edit.py:102), so
  it only ever reflects programmatic writes.
- Name the entry limits so the clamp on the DAQ value cannot drift from the
  widget's own validator range.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018JVrLMLGNUXhfJjWxUcTBj

src/aare/gui/panels/smart_rotation_panel.py

@@ -55,6 +55,15 @@ DEFAULT_MIN_EXP_TIME_S = 0.0005
 # there. Stated explicitly so it does not silently drop to 1.2 ms if
 # EXP_TIME_STEP_S is ever made finer.
 STRATEGY_MIN_EXP_TIME_S = {MXBeamline.X06DA: 0.002}
+# Entry limits for the visible-resolution field. Named because the clamp on
+# the DAQ value has to use the same numbers as the widget's validator.
+VISIBLE_RES_MIN_A = 0.8
+VISIBLE_RES_MAX_A = 10.0
+VISIBLE_RES_DEFAULT_A = 2.0
+# Two DAQ resolutions closer than this are the same raster result reported
+# again, not a new one.
+DAQ_RES_EPS_A = 0.001
+VISIBLE_RES_LABEL = "Visible resolution"
 DTZ_STEP_MM = 10.0
 EXP_TIME_STEP_S = 0.001
 TRANSMISSION_SIG_DIGITS = 2
@@ -98,6 +107,10 @@ class SimpleRotationSettingsPanel(QWidget):
         super().__init__(parent)
 
         self._beamline = mx_beamline()
+        self._daq_best_res = None
+        # Distinguishes "no DAQ resolution yet" from "DAQ reports none", so the
+        # first status tick always paints the label.
+        self._daq_res_applied = False
         self.n_images = 1
         self.transmission = 1.0
         self.delivered_dose_MGy = 0.0
@@ -126,10 +139,17 @@ class SimpleRotationSettingsPanel(QWidget):
         m = self._layout.contentsMargins()
         self._layout.setContentsMargins(m.left(), 0, m.right(), 3)
 
-        # Visible resolution (entry)
-        self._layout.addWidget(QLabel("Visible resolution", parent=self), 0, 0)
+        # Visible resolution (entry). The label carries the provenance of the
+        # value: silence means it came from the DAQ, otherwise it says so.
+        self.visible_res_label = QLabel(VISIBLE_RES_LABEL, parent=self)
+        self._layout.addWidget(self.visible_res_label, 0, 0)
         self.visible_res_enter = NumberLineEdit(
-            0.8, 10.0, decimals=2, default=2.0, parent=self, track_pending=True
+            VISIBLE_RES_MIN_A,
+            VISIBLE_RES_MAX_A,
+            decimals=2,
+            default=VISIBLE_RES_DEFAULT_A,
+            parent=self,
+            track_pending=True,
         )
         self._layout.addWidget(self.visible_res_enter, 0, 1, 1, 3)
         self._layout.addWidget(QLabel("Å", parent=self), 0, 4)
@@ -300,18 +320,10 @@ class SimpleRotationSettingsPanel(QWidget):
     @Slot(DAQStatusModel)
     def update_daq_status(self, s: DAQStatusModel):
         self._d = s
-        # TODO only update best_res after raster finished otherwise ask to update. or have toggle to overwrite with user value
         # TODO only take best res from flat face scan
         # TODO identify flat face!
-        best_res = s.last_best_res
         self._omega = s.geom.omega_deg
-
-        if best_res is not None:
-            # clamp to control limits and update field; this will also trigger recalculation
-            lo, hi = 0.8, 10.0
-            v = max(lo, min(hi, float(best_res)))
-            self.visible_res_enter.update_value(v)
-            self.set_visible_resolution(v)
+        self._apply_daq_resolution(s.last_best_res)
 
         self._wilson_b = s.last_best_b_factor
 
@@ -337,6 +349,51 @@ class SimpleRotationSettingsPanel(QWidget):
         self.wavelength_label.setText(f"<b>{s.diffraction.wavelength_angstrom:.3f}</b>")
         self.update_calculated_labels()
 
+    def _apply_daq_resolution(self, best_res: float | None) -> None:
+        """Track ``DAQStatusModel.last_best_res`` in the resolution field.
+
+        Written on every *change* of the DAQ value rather than on every 2 Hz
+        tick, so a fresh raster result always lands while a repeat of the same
+        value leaves a manual override alone.
+
+        Two things this deliberately does not use:
+
+        * ``update_value`` compares against ``saved_value``, which
+          ``on_editing_finished`` never updates (it self-assigns), so it only
+          ever sees programmatic writes. Once the operator has typed over a
+          pushed value, the same DAQ value could never re-assert itself.
+          ``set_committed_value`` compares against what the field actually
+          shows, which is the question being asked here.
+        * A bare ``is not None`` guard. The DAQ clears ``last_best_res`` on
+          mount, and skipping the update then leaves the previous crystal's
+          resolution in the field with nothing to say it is stale.
+        """
+        if not self._daq_res_applied:
+            unchanged = False
+        elif best_res is None or self._daq_best_res is None:
+            unchanged = best_res is None and self._daq_best_res is None
+        else:
+            unchanged = abs(best_res - self._daq_best_res) <= DAQ_RES_EPS_A
+        if unchanged:
+            return
+
+        self._daq_res_applied = True
+        self._daq_best_res = best_res
+        if best_res is None:
+            # No raster result for this sample: either none has run yet, or the
+            # pgroup gate in the status endpoint stripped it. Either way the
+            # field is showing a default, and the strategy below is built on a
+            # number nothing measured -- say so instead of looking authoritative.
+            value = self.visible_res_enter.get_default()
+            self.visible_res_label.setText(
+                f"""{VISIBLE_RES_LABEL} <span style="color: {STATUS_ALERT} ; ">(no raster)</span>"""
+            )
+        else:
+            value = max(VISIBLE_RES_MIN_A, min(VISIBLE_RES_MAX_A, float(best_res)))
+            self.visible_res_label.setText(VISIBLE_RES_LABEL)
+        self.visible_res_enter.set_committed_value(value)
+        self.update_calculated_labels()
+
     @Slot(float)
     def set_visible_resolution(self, v: float):
         self.update_calculated_labels()