Complete UI for arbitrary dectector settings. Required better method for invoking actions.

Error handling was fixed in the process of getting the above correct.

src/openflexure_microscope_server/background_detect.py

@@ -8,7 +8,7 @@ current camera field of view contains sample.
 from typing import Optional, Any
 import cv2
 import numpy as np
-from pydantic import BaseModel
+from pydantic import BaseModel, Field, ConfigDict
 from pydantic.errors import PydanticUserError
 from scipy.stats import norm
 from labthings_fastapi.thing_description import type_to_dataschema
@@ -153,13 +153,18 @@ class ChannelDistributions(BaseModel):
 class ColourChannelDetectSettings(BaseModel):
     """A BaseModel for storing the settings for colour channel detectors."""
 
+    model_config = ConfigDict(extra="forbid")
+
     channel_tolerance: float = 7.0
     """Channel Tolerance
 
     The number of standard deviations a pixel value must be from the background mean
     to be considered sample.
     """
-    min_sample_coverage: float = 25.0
+
+    # Use Field to set Title reported to UI. By default Pydantic will convert the name
+    # from snake_case to Title Case.
+    min_sample_coverage: float = Field(25, title="Sample Coverage Required (%)")
     """Sample Coverage Required (%)
 
     The minimum percentage of the image that needs to be identified as sample for the

src/openflexure_microscope_server/things/camera/__init__.py

@@ -516,6 +516,20 @@ class BaseCamera(lt.Thing):
         """The status of the active detector for the UI."""
         return self.active_detector.status
 
+    @lt.thing_action
+    def update_detector_settings(self, data) -> None:
+        """Update the settings of the current detector.
+
+        This is an action not a setting/property as the data model depends on the
+        selected detector. As such, it cannot be specified with the necessary precision
+        to be included in a ThingDescription as a setting/property, while retaining
+        enough useful information to communicate to the UI how it is set and read.
+
+        The information on how to read the settings is exposed in
+        ``background_detector_status``.
+        """
+        self.active_detector.settings = data
+
     @lt.thing_setting
     def background_detector_data(self) -> dict:
         """The data for each background detector, used to save to disk."""