I wish there was a way to have ssh automatically ssh-add keys you use... with a expiration date. I've tried to get this to work a few times, but I use a unique

I wish there was a way to have ssh automatically ssh-add keys you use... with a expiration date. I've tried to get this to work a few times, but I use a unique key for every login, so I need something to parse ~/.ssh/config to find the right Host def and ssh-add it. The code is obviously in ssh, but it's not exposed to the command line as far as I can tell.