Referencing this similar issue, which had good suggestions:
macOS keeps asking my ssh passphrase since I updated to Sierra
but this solution isn't working for Sonoma, and using git on a server. Used the following in .ssh/config:
AddKeysToAgent yes
UseKeychain yes
I removed the ssh key and started over - also tried the following:
ssh-add --apple-use-keychain ~/.ssh/id_rsa
is there some identity requirement here?