She was a laying breed commercial producers have bred them overtime to be over productive and lay once a day for the first year then they are mass slaughtered for dog food or whatever and they start all over again. In the wild they lay about one egg a month.
After the first year they are worn out, so Ivy at five years old just couldn't make egg shell anymore despite all the calcium supplements I gave her and one burst inside her. When that happens they can get egg peritonitis which is an internal infection from retained yolk.
Sometimes with TLC antibiotics and painkillers you can nurse them through it, I've a few retired hens who no longer lay at all. She had it really badly though so there was no hope.
I'll miss her jumping onto my shoulder making two happy "boops" in my ear and immediately hopping down again to dig for worms.