SSH KeySelect
SSH agent proxy with a tray app for picking which keys an SSH client may offer and sign with.
About
An SSH agent proxy for Windows, macOS and Linux that sits in front of your existing agent and asks which keys each SSH client may see, rejecting signing requests for the rest to limit SSH agent hijacking. Private keys stay in the upstream agent. MyGo builds the tray GUI with its native UI; the ssh-keyselect CLI, which shows the picker in the terminal, is a separate tool.