It is a TPM plugin that uses lifecycle hooks to show working, waiting, idle, and interrupted states. It adds indicators to the window list and pane borders, with an optional popup and sidebar for jumping between agents. It works with your existing tmux theme. Because it is tmux you can customize it the way you want and optimize your workflow.
This is an early version that grew out of my own setup. How do you keep track of agents in tmux? I would like to hear what would make this useful in your workflow. I know herdr exists, but couldnt leave my tmux setup.