To be clear on the GUI point, since my last reply here answered a different question: this is a terminal tool and it won't convert you. The reason I stay in one is that the agents already live in terminals, so the manager is a view over what's running rather than a second place things live.
herdr's a whole runtime, own multiplexer, plugins, socket api. mine sits on tmux and doesn't try to replace it, sessions stay normal tmux sessions.
overlap on the status sidebar is real. two things I lean on that I couldn't find a key for over there: space on a blocked agent types the answer into its pane without attaching, and ctrl+r opens its repo as full-file diffs where a comment on a line goes back to that agent as a prompt. herdr's socket api can push text into a pane, so the first one is scriptable at least. correct me if I missed something.