I like the idea, but we already have the terminal bell. In my setup, when an agent is done or needs something, it emits a bell. Based on config, this results in a desktop notification if I’m not in the terminal, or a toast from my multiplexer if I’m in the terminal. The terminal pane gets a colored “bell” icon in its title that is cleared when I attach to it.

The total lack of mention of the terminal bell in the article is weird. I think it needs to be addressed for the protocol to be taken seriously. More granular info sounds nice, but also nice is the simplicity of the bell.