when a machine becomes invalidated (e.g. due to lever or worst case an explosion)
it would be nice to have current progress stored in the controller
and when the machine is valid again (lever back in correct position)
it should continue processing
only when the controller is broken/destroyed it cannot contiue (and might give back input items).

The existing "stop and retry" mechanic when invalidation happens, power out, etc, is intentional.