feat(crosshair): keep the pin across data/scan resets

bec_widgets/utils/crosshair.py

@@ -865,18 +865,23 @@ class Crosshair(QObject):
 
     @SafeSlot()
     def reset(self):
-        """Resets the crosshair to its initial state."""
+        """Reset the transient crosshair markers (e.g. on new data / a new scan).
+
+        The pinned marker is intentionally *not* cleared here: it is a persistent
+        user annotation that survives data and scan changes. Use :meth:`clear_pin`
+        for an explicit removal and :meth:`cleanup` for full teardown.
+        """
         if self.marker_2d_row is not None:
             self.plot_item.removeItem(self.marker_2d_row)
             self.marker_2d_row = None
         if self.marker_2d_col is not None:
             self.plot_item.removeItem(self.marker_2d_col)
             self.marker_2d_col = None
-        self.clear_pin()
         self.clear_markers()
 
     def cleanup(self):
         self.reset()
+        self.clear_pin()
         self.plot_item.removeItem(self.v_line)
         self.plot_item.removeItem(self.h_line)
         self.plot_item.removeItem(self.coord_label)

tests/unit_tests/test_crosshair.py

@@ -573,10 +573,17 @@ def test_set_pin_2d_emits_pixel_coordinates(image_widget_with_crosshair):
     assert (px, py) == (40, 60)
 
 
-def test_reset_clears_pin(image_widget_with_crosshair):
+def test_reset_preserves_pin_cleanup_removes_it(image_widget_with_crosshair):
     crosshair, _ = image_widget_with_crosshair
     crosshair.set_pin(40, 60)
     assert crosshair.pinned_point is not None
+
+    # A data/scan reset keeps the pin (a persistent annotation).
     crosshair.reset()
+    assert crosshair.pinned_point is not None
+    assert crosshair.pinned_pos is not None
+
+    # Full teardown removes it.
+    crosshair.cleanup()
     assert crosshair.pinned_point is None
     assert crosshair.pinned_pos is None

tests/unit_tests/test_image_view_next_gen.py

@@ -1070,6 +1070,31 @@ def test_pinned_roi_profiles_keep_style_on_theme_change(qtbot, mocked_client):
     assert bec_image_view.x_roi_curve.opts["pen"].color().name() == "#000000"
 
 
+def test_pin_survives_scan_reset(qtbot, mocked_client):
+    """A scan transition (crosshair.reset()) must not wipe the pin or its frozen profiles."""
+    import numpy as np
+
+    bec_image_view = create_widget(qtbot, Image, client=mocked_client)
+    bec_image_view.on_image_update_2d({"data": np.arange(25).reshape(5, 5)}, {})
+    switch = bec_image_view.toolbar.components.get_action("image_switch_crosshair")
+    switch.actions["crosshair_roi"].action.trigger()
+    qtbot.wait(50)
+
+    bec_image_view.crosshair.set_pin(2.0, 3.0)
+    assert bec_image_view.x_roi_pinned is not None
+    pin_point = bec_image_view.crosshair.pinned_point
+    assert pin_point is not None
+
+    # Image._handle_scan_change calls crosshair.reset() on each new scan id.
+    bec_image_view.crosshair.reset()
+
+    # The pin marker and the frozen reference profiles must still be there.
+    assert bec_image_view.crosshair.pinned_point is pin_point
+    assert bec_image_view.crosshair.pinned_pos is not None
+    assert bec_image_view.x_roi_pinned is not None
+    assert bec_image_view.y_roi_pinned is not None
+
+
 def test_detached_pin_can_be_removed_with_right_click(qtbot, mocked_client, monkeypatch):
     """A pin left on the plot after disabling crosshair remains removable."""
     from qtpy.QtWidgets import QMenu
@@ -1100,6 +1125,8 @@ def test_detached_pin_can_be_removed_with_right_click(qtbot, mocked_client, monk
     assert cleared == [True]
 
 
+
+
 ##############################################
 # Device selection toolbar sync
 ##############################################