Add calibration_required property to Camera and CSM things.

src/openflexure_microscope_server/things/camera/__init__.py

@@ -198,6 +198,15 @@ class BaseCamera(lt.Thing):
         """Close hardware connection when the Thing context manager is closed."""
         raise NotImplementedError("CameraThings must define their own __exit__ method")
 
+    @lt.thing_property
+    def calibration_required(self) -> bool:
+        """Whether the camera needs calibrating.
+
+        This always returns False in BaseCamera. It should be reimplemented by child
+        classes if calibration is required.
+        """
+        return False
+
     @lt.thing_action
     def start_streaming(
         self, main_resolution: tuple[int, int], buffer_count: int

src/openflexure_microscope_server/things/camera/picamera.py

@@ -213,6 +213,11 @@ class StreamingPiCamera2(BaseCamera):
         finally:
             self._setting_save_in_progress = False
 
+    @lt.thing_property
+    def calibration_required(self) -> bool:
+        """Whether the camera needs calibrating."""
+        return not self.lens_shading_is_static
+
     ## Persistent controls! These are settings
 
     _analogue_gain: float = 1.0

src/openflexure_microscope_server/things/camera_stage_mapping.py

@@ -242,6 +242,11 @@ class CameraStageMapper(lt.Thing):
             return None
         return self.last_calibration["image_resolution"]
 
+    @lt.thing_property
+    def calibration_required(self) -> bool:
+        """Whether the camera stage mapper needs calibrating."""
+        return self.image_to_stage_displacement_matrix is None
+
     def assert_calibrated(self) -> None:
         """Raise an exception if the image_to_stage_displacement matrix is not set."""
         if self.image_to_stage_displacement_matrix is None: