Rex has "sessions" which are like groups of tabs and it is scriptable, I made a little plugin that when invoked pops open a floating terminal asks for a worktree name and sets up a new worktree.

i'm not sure what you're referring to - if herdr had worktree management features, I never used them. that's not something i'd want my terminal multiplexer to do anyway, our worktree automation is part of the repo.