We have the chicken guard ones that can work on a sensor as well as a timer, with the metal doors & sliders to go with them.
But... (big but!)... in our case, these automatic doors are used to block off the small chicken run that’s attached to the coop, the food is in that little run and by closing it off the rats can’t get to the food at night.
These small run + coops are themselves inside a very spacious fox proof enclosure, which the birds have access to from dawn until dusk.
So because the large external run is fox proof. when the automatic closers on the little runs fail, the chickens are still safe. And automatic closers c.a.n and w.i.l.l fail at some point, even if it is just because of frost or a stick being accidentally stuck at the bottom. We’ve had this happen twice.
Just fyi