Apparently since the last time I checked, git actually includes a helper script that allows you to use `gpg-agent` to decrypt your creds in an analogous way to how `ssh-agent` works. It requires a bit of setup since for some reason it's disabled by default, and it's a bit more moving parts (GPG key plus username/password instead of a single keypair) but it's a lot better than it used to be.

I hope this pattern catches on for services other than git.