feat: auto-centering row with apply-after-mount, grid button raster-only

Auto Centering moves out of the experiment tabs to its own row between
Manual sample and Exp. Config., with an apply-after-mount checkbox that
re-runs it on every detected sample mount (guarded against firing on GUI
startup). Draw a Grid now only shows on the Raster scan tab.

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

tests/unit/gui/test_data_collection_settings.py

@@ -12,6 +12,7 @@ from aarecommon.math.coordinate import Coordinate, SmargonCoordinate
 from aarecommon.math.diffraction_geometry import DiffractionGeometry
 from aarecommon.models.models import SampleGeometryModel
 
+from aare.gui.panels.data_collection_settings import DataCollectionSettings
 from aare.gui.panels.raster_data_collection import RasterDataCollectionPanel
 from aare.gui.panels.rotation_data_collection import RotationDataCollectionPanel
 from aare.gui.scan_logic.raster_grid_manager import RasterGridManager
@@ -171,8 +172,8 @@ def test_user_override_persists_across_samples(panel, diffraction):
 
 
 @pytest.fixture
-def raster_panel(qapp, diffraction):
-    geom = SampleGeometryModel(
+def geom():
+    return SampleGeometryModel(
         beam_location_pxl=Coordinate(x=500, y=500),
         pixel_in_mm=0.001,
         aerotech=Coordinate(x=0, y=0, z=0),
@@ -181,6 +182,10 @@ def raster_panel(qapp, diffraction):
         omega_deg=0.0,
         beam_size_mm=Coordinate(x=0.01, y=0.01),
     )
+
+
+@pytest.fixture
+def raster_panel(qapp, diffraction, geom):
     mgr = RasterGridManager(geom)
     return RasterDataCollectionPanel(raster_mgr=mgr, diffraction=diffraction)
 
@@ -212,3 +217,53 @@ def test_grid_size_field_shares_panel_toggle(raster_panel):
     _edit(raster_panel.high_res_enter, "2.50")
     assert raster_panel._source == DbOverrideLineEdit.SOURCE_MINE
     assert raster_panel.width_enter.source() == DbOverrideLineEdit.SOURCE_MINE
+
+
+# ---------------------------------------------------------------------------
+# DataCollectionSettings: per-tab grid button + auto-center after mount
+# ---------------------------------------------------------------------------
+
+
+@pytest.fixture
+def settings_panel(qapp, diffraction, geom):
+    return DataCollectionSettings(geom, RasterGridManager(geom), diffraction)
+
+
+def test_grid_button_only_on_raster_tab(settings_panel):
+    assert not settings_panel.bounding_box.isHidden()  # Raster is the default tab
+    for idx in (1, 2, 3):
+        settings_panel._tab_bar.setCurrentIndex(idx)
+        assert settings_panel.bounding_box.isHidden()
+    settings_panel._tab_bar.setCurrentIndex(0)
+    assert not settings_panel.bounding_box.isHidden()
+
+
+def test_auto_center_fires_on_mount_only_when_armed(settings_panel):
+    clicks = []
+    settings_panel.find_tip.clicked.connect(lambda: clicks.append(1))
+    settings_panel.auto_center_after_mount.setChecked(True)
+
+    # First status with a sample already mounted = GUI (re)start: hardware
+    # must not move, only the id is recorded.
+    settings_panel._track_sample(1)
+    assert not clicks
+
+    # Real mount after an unmount fires the centering.
+    settings_panel._track_sample(None)
+    settings_panel._track_sample(2)
+    assert len(clicks) == 1
+
+    # Direct sample exchange (no unmount tick in between) also fires.
+    settings_panel._track_sample(3)
+    assert len(clicks) == 2
+
+    # Remounting the SAME sample counts as a fresh mount.
+    settings_panel._track_sample(None)
+    settings_panel._track_sample(3)
+    assert len(clicks) == 3
+
+    # Disarmed: mounts no longer trigger.
+    settings_panel.auto_center_after_mount.setChecked(False)
+    settings_panel._track_sample(None)
+    settings_panel._track_sample(4)
+    assert len(clicks) == 3