GenerativeUiInterfaceGetSurfaceMessage

Read back what the device is showing: the surface's components and data model, the last applied sequence, whether the surface is visible, and the screen. Use it to see the result of your updates or before editing a UI you did not just create. This is a synchronous call: the reply (get-surface-response) comes from the device. If the device is not connected Port OS wakes it first, and if it does not answer within the reply window the call fails with a timeout. `surfaceId` is optional; without it the surface the device shows is returned. When the device holds no surface, `surfaceId` in the reply is null and `components` is empty. `visible` is false when the viewer left the surface with the remote; it stays held until closed or replaced.