Look for `macos-option-as-alt`. The Ghostty docs use the term "Alt" here to mean using the key as a terminal input modifier rather than for macOS text input. This setting allows you to specify only one option key to use this behavior for.

Was just looking for how to configure this globally. You can create a keybind for every key[0][1] but that's a bit silly faff nonsense in current year 2024.

[0] e.g. `keybind = alt+f=esc:f`

[1] Which affects both option keys, sadly.

I have this as a system-wide mapping with Karabiner. Complex modifications, "Post esc if left_alt is pressed alone".

There's never a time when I wouldn't want this to work, may as well enable it everywhere.

Edit: It looks like I misunderstood what that setting in iTerm does. But hey if you do want left option to send Esc by itself, that's how to get it.