SSH key management for a multi-server fleet: ed25519, ssh-agent, ProxyJump, YubiKey FIDO2, and when agent forwarding is the wrong tool
You manage five servers. Each has a different SSH key in ~/.ssh/authorized_keys from the day you set it up — one’s an old id_rsa from 2018, two have your laptop’s current ed25519 key, one has an ancient ECDSA key from …