What is the output of $TERM when sitting at the workstation?
What is the output of $TERM when logged in via ssh from the Mac?
If they are different I would look there first.
Then looking at the key error, it could be the fact that your key is being loaded from /tmp. My public key is in ~/.ssh/authorized_keys and my private key is in ~/.ssh/id_rsa. The private key has permissions rw------- and the public key has permissions rw-r–r–
Where is your private key stored?
What are the ownership & permissions on the key in /tmp?
Eureka. Poking a bit more, I remembered I’d set a signing key within my ~/.gitconfig to enable gpg signing. Removing that fixed my git-commit issue over SSH. Still under why gpg signing works locally but not over SSH.