ouch! My auto door is pretty good about stopping for something like that. Nobody needs to see 45 min of chicken kill video. What camera are you using in the coop?
Camera in coop is an Amcrest IP5M-T1179EW-28MM.
The death of the chicken from the door closer was a series of profoundly unlucky events - any one of which, had they not happened, would have prevented the accident.
The door closer has an IR sensor (like the safety beam on garage door openers). It was installed with the factory bracket, which put it about 2" above, and 2" in front of the threshold. It is quite effective, and will prevent the door from closing if something breaks the beam - and will even reverse the door if it's in the process of closing when the beam is broken.
The two chickens lying at the door were the youngest (Easter Eggers) that were just introduced to the flock a few weeks ago. They were still being bullied, and each time they'd jump up on the perch, the other hens would peck at them to get down. So they were sleeping on the floor... The one had its head extended across the threshold.
The closer is very noisy and always startles the whole flock when it operates.
The door closes 45 min after sunset, and the lights inside the coop (and on the exterior awning above the door) ramp down 30 min after that. This is to allow the chickens to have full sight (they have horrible night vision) as the door closes.
With the neck of the chicken being less than 2", with them being bullied to sleep on the floor, with them being so tired as not to wake from the sound of the door - all things conspired for this outcome.
I feel horrible about it since these two Easter Eggers had the best temperament - even running toward us to be petted. When I found her, at first I thought she was sleeping. My 6 yo daughter was with me. Wasn't a fun morning.
But, such is life. It's fragile and delicate. TBH, I'm surprised that of the 13 chickens and 10 ducks we've raised from hatchlings, this was the first (and only) casualty we've had (so far). I've also moved the senor to just above the threshold.
Incidentally, the door closes with less than 1/8" gap at the bottom, and it fully closed on her neck. She was dead immediately. The body kept moving for several minutes afterwards - much as they do when they're decapitated for processing. I take comfort in knowing she didn't suffer.