I think https://zellij.dev/ covers all of these? But it isn't an "agent native", and `herdr` seems to support importing existing agent sessions.
I use zellij a lot and created myself a zellij skill for an agent to manage my sessions/layouts in zellij directly.
So for a new worktree the agent can create a tab in zellij with multiple panes, properly named etc.
It works really nicely.
Although since I got the 52 inch Dell monitor I tend to just put everything visible at all once most of the time.
seamlessly jumping from local to remote sessions is something ive been hoping for in zellij for quite a while so if herdr supports this it could be interesting.
Until I try it, though, I don't think I'll understand why it needs a specific feature for running an agent tool in a side panel, which is appartently one of it's main selling point.