fix(LamNI): push smear composite via new IDSCamera RPC method

dev.cam_xeye.image.put(composite) failed on real hardware --
PreviewSignal is a BECMessageSignal subclass, and BEC hardcodes
rpc_access=False for that signal_info, so the client-side device proxy
never exposes `image` as an attribute at all (confirmed: this is a
structural BEC constraint, not specific to this device -- no existing
RPC surface, device or widget, offers a raw-array setter either).

Add IDSCamera.push_preview_image(data), a small device-server-side
method (alongside the existing get_last_image()) that does
self.image.put(data) from within the device-server process, where
PreviewSignal is a normal ophyd attribute. _push_smear_composite now
calls dev.cam_xeye.push_preview_image(composite) instead of writing to
the signal directly.

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

csaxs_bec/bec_ipython_client/plugins/LamNI/x_ray_eye_align.py

@@ -674,9 +674,15 @@ class XrayEyeAlign:
         between this push and the next raw frame the live thread would
         otherwise publish to the same PreviewSignal/device_preview
         channel the GUI is subscribed to.
+
+        dev.cam_xeye.image is a PreviewSignal, which is not remotely
+        writable from client code (BEC excludes BECMessageSignal
+        subclasses from the client-side device RPC proxy) -- push via the
+        push_preview_image() device method instead, which runs
+        device-server side where self.image is a normal ophyd attribute.
         """
         dev.cam_xeye.live_mode_enabled.put(False)
-        dev.cam_xeye.image.put(composite)
+        dev.cam_xeye.push_preview_image(composite)
         time.sleep(hold_display_s)
         dev.cam_xeye.live_mode_enabled.put(True)
 

csaxs_bec/devices/ids_cameras/ids_camera.py

@@ -51,7 +51,14 @@ class IDSCamera(PSIDeviceBase):
         kind=Kind.config,
     )
 
-    USER_ACCESS = ["start_live_mode", "stop_live_mode", "mask", "set_rect_roi", "get_last_image"]
+    USER_ACCESS = [
+        "start_live_mode",
+        "stop_live_mode",
+        "mask",
+        "set_rect_roi",
+        "get_last_image",
+        "push_preview_image",
+    ]
 
     def __init__(
         self,
@@ -195,6 +202,20 @@ class IDSCamera(PSIDeviceBase):
         if image:
             return image.data
 
+    def push_preview_image(self, data: np.ndarray) -> None:
+        """Push an arbitrary array to this camera's own preview signal.
+
+        self.image is a PreviewSignal, which is deliberately excluded from
+        the client-side device RPC/signal proxy (rpc_access defaults to
+        False for BECMessageSignal subclasses, with no override) -- so
+        client code cannot do dev.cam_xeye.image.put(...) directly. This
+        method runs device-server side, where self.image is a normal ophyd
+        attribute, and is the supported way for a client to publish a
+        custom (e.g. composite/processed) image through the same
+        device_preview channel the GUI already subscribes to.
+        """
+        self.image.put(data)
+
     ############## User Interface Methods ##############
 
     def on_connected(self):

tests/tests_bec_ipython_client/test_x_ray_eye_align.py

@@ -395,7 +395,7 @@ def test_push_smear_composite_duty_cycles_live_mode(bec_client_mock):
         False,
         True,
     ]
-    dev_mock.cam_xeye.image.put.assert_called_once_with(composite)
+    dev_mock.cam_xeye.push_preview_image.assert_called_once_with(composite)
 
 
 def test_smear_sweep_max_projection(bec_client_mock):