My notification hook pipes an OSC 777 (title, body) message into /dev/tty, Ghostty handles/ingests it and then emits the event for my terminal app to do things like craft a macOS notif and style the tab/pane of the originating terminal.

    #!/usr/bin/env bash
    MSG=$(cat | jq -r '.last_assistant_message // empty' | head -c 200)
    printf '\e]777;notify;Claude Code;%s\a' "${MSG:-Claude finished responding}" > /dev/tty

I tried the osascript solution first but had some issues, iirc no good way to focus the originating terminal pane on notif click.

Something I never figured out is why Claude Code's "Notification" hook waits minutes to fire. I had to use the "Stop" hook for actual end-of-response timing.