Flash LED endpoint in simulator for parity

src/openflexure_microscope_server/things/camera/simulation.py

@@ -342,7 +342,11 @@ class SimulatedCamera(BaseCamera):
     def generate_frame(self) -> Image.Image:
         """Generate a frame with blobs based on the stage coordinates."""
         pos = self._stage.instantaneous_position
-        return self.generate_image((pos["y"], pos["x"], pos["z"]))
+        frame = self.generate_image((pos["y"], pos["x"], pos["z"]))
+        # Simulate LED turning off by setting all channels to 0
+        if not self._stage.led_on:
+            frame = np.full((self.shape[0], self.shape[1], 3), 0, dtype=np.uint8)
+        return frame
 
     def __enter__(self) -> Self:
         """Start the capture thread when the Thing context manager is opened."""

src/openflexure_microscope_server/things/stage/dummy.py

@@ -4,7 +4,7 @@ from __future__ import annotations
 
 import time
 from types import TracebackType
-from typing import Any, Optional, Self
+from typing import Any, Literal, Optional, Self
 
 import labthings_fastapi as lt
 
@@ -18,6 +18,8 @@ class DummyStage(BaseStage):
     hardware attached.
     """
 
+    led_on: bool = lt.property(default=True)
+
     def __init__(
         self,
         thing_server_interface: lt.ThingServerInterface,
@@ -115,3 +117,18 @@ class DummyStage(BaseStage):
         """
         self._hardware_position = dict.fromkeys(self.axis_names, 0)
         self.instantaneous_position = self._hardware_position
+
+    # led_channel is unused in the simulation, but must exist to match the real API
+    @lt.action
+    def flash_led(
+        self,
+        number_of_flashes: int = 10,
+        dt: float = 0.5,
+        led_channel: Literal["cc"] = "cc",  # noqa: ARG002
+    ) -> None:
+        """Flash the LED to identify the board (simulated)."""
+        for _ in range(number_of_flashes):
+            self.led_on = False
+            time.sleep(dt)
+            self.led_on = True
+            time.sleep(dt)