After much delay I finally got tmux-continuum & tmux-resurrect going. Which I think are very well known plugins for this.

https://github.com/tmux-plugins/tmux-continuum https://github.com/tmux-plugins/tmux-resurrect

Also used tpm, the plugin manager. There's some variants. I went with ahiru-tpm which is pretty drop in compatible but not seeing much action, and tpm seems more active again. https://github.com/tmux-plugins/tpm https://github.com/x3rAx/ahiru-tpm

One of the weird cool (but also, wish I'd known, has risks!) things I wasn't expecting is that captures the screen buffer. The program is dead, but there it is, whatever was last there, when you reboot. Wild.

I've had some system instability some, alas (blast you ram crunch), and did everything under the sun to build tools to capture my workspace. This, this was way way easier.