Reddit mentions of Stanley Hardware S760-814 1271 Sliding Bolt Door/Gate Latches in Zinc

you could get an automatic coop door:

https://www.amazon.com/gp/product/B00TONTHRG/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

We have a coop run that is highly secured, and a main coop that is also secured. We close the coop run manually, and the main coop house closes automatically. All it took was closing the girls in the main coop run then letting themselves get locked out overnight a few times for them to learn to get in the house. Now we have gone down after dark more than once and all the girls are in the house and the door closed.

you would need to secure the main run area better to use our approach though. Our run is enclosed on all sides (including bottom) with 1/2" hardware cloth. Right next to the main house door (where the girls tend to sit if they get locked out) is #8 mesh. All mesh is secured between pieces of cedar framing with screws running through the cedar and the mesh.

We use the slide type doors which I feel are more secure than other options. one I made myself with diamond plate aluminum (if you can get flat aluminum I recommend it) that slides between rails of flat bar aluminum that have a gap created by washers. You can also buy a very similar design if you want to:

https://www.amazon.com/gp/product/B018KIVUC0/ref=oh_aui_search_detailpage?ie=UTF8&psc=1


The biggest thing you need to do to secure your coop/run area is enclose the entire thing in hardware cloth. It needs to be the small 1/2" hardware cloth like here: https://www.amazon.com/Hardware-Galvanized-Chicken-Supports-Poultry/dp/B015PD9F52/ref=sr_1_1?s=lawn-garden&ie=UTF8&qid=1499439834&sr=1-1-spons&keywords=hardware+cloth&psc=1.

When I say enclose, I mean fully enclose on all sides including top and bottom. The cloth must be screwed/anchored in place (not just stapled). If you use larger cloth then animals such as racoons can reach through and grab the chickens. You should include the house in the enclosure. If you do not secure the bottom then they will just dig under and in.

I've had animals try and fail to get into my coop. I came out one day to find blood all over one side of the coop where an animal had tried to scratch its way in and lost claws. I also have come out to find that animals had tried to dig under the coop only to find hardware cloth there as well. you MAY be able to get away with just putting a hardware cloth skirt a few feet out from the coop but I prefer to just have the floor be hardware cloth.

Finally, all latches that allow us to get into the coop are safety latches since racoons can figure out normal latches. we mostly use hook and eyes like these (I use stainless though): https://www.amazon.com/Zinc-Plated-Wire-Safety-4-Pack/dp/B01LYNKFIL/ref=sr_1_1?s=hi&ie=UTF8&qid=1499440049&sr=1-1&keywords=hook+and+eye+safety+latch

Though our main coop door does have this sort of latch (which we intend to add a padlock to if there are signs of animals getting in through it): https://www.amazon.com/Stanley-National-Hardware-CD1271-Sliding/dp/B009YNW3QS/ref=sr_1_12?s=hi&ie=UTF8&qid=1499440093&sr=1-12&keywords=gate+latch+lock