fix(pseudo-motor): Add subscription callbacks to readback signal, and SUB_READBACK event from positioners

ophyd_devices/interfaces/base_classes/psi_pseudo_motor_base.py

@@ -98,8 +98,23 @@ class PSIPseudoMotorBase(ABC, PSIDeviceBase, PositionerBase):
             move_signature = inspect.signature(positioner.move)
             if "wait" in move_signature.parameters:
                 self._positioner_move_kwargs[name] = {"wait": False}
+
+        # Subscribe callback to updates of the readback signals
+        self.readback.subscribe(self._run_readback_signal_subs, event_type=self.readback.SUB_VALUE)
+        # Subscribe to "readback" event on each positioner
+        for positioner in self.positioner_objects.values():
+            positioner.subscribe(self._run_readback_event_subs, event_type=positioner.SUB_READBACK)
         return super().wait_for_connection(*args, **kwargs)
 
+    def _run_readback_signal_subs(self, value: float, old_value: float, **kwargs):
+        """Run subscriptions on the readback signal when it updates."""
+        self._run_subs(sub_type=self.SUB_READBACK, old_value=old_value, value=value)
+
+    def _run_readback_event_subs(self, value: float, old_value: float, **kwargs):
+        """Run subscriptions on the readback event when it updates."""
+        new_val = self.readback.get()
+        self._run_subs(sub_type=self.SUB_READBACK, value=new_val)
+
     def _check_method_signatures(self) -> None:
         """Ensure calculation method parameters match configured positioner keys."""
         input_names = set(self.positioner_objects.keys())