I have a separate VS Code window connected to a dev container for each project that stays open for days, weeks or months at a time. Does the tmux approach materially improve upon that setup? Genuinely curious if I’m missing out on something here.

You can end up pretty deep down the rabbit hole with tmux and configuring it in different ways. One thing you can do that you might not be able to do with your vscode set up is have a script, written in tmux commands, that generates a complicated windowing environment. I am not familiar with the capabilities of your setup though, since I don't use vscode. I would guess tmux is more comfortable than vscode for using it with just the keyboard too.

There's a ton written on tmux as you can imagine by this point. This page seems pretty comprehensive on the advanced features including tmux scripting:

https://github.com/tmux/tmux/wiki/Advanced-Use

Maybe, you can SSH to GNU Screen and attach where you were, perhaps from your phone to just read. You could do the same with rdesktop to something x11, but you'd need more than a 256MB VM for that. If you have this running 24x365 then you'd spend more energy/money.

To all above: but machines reboot, also, not? Even our coorp Linuxes now succumb to ugly IT update reboot cycles, Cloud VMs even more ephemeral, and lets not even start with dev containers... One can script tmux sessions to some degree, but still loosing a lot of state (editor open ther, shell history here..).

I hardly reboot a machine unless I am intending to, but there are plugins for tmux for this too.

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

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

Rebooting my dev boxes for security updates or kernel upgrades once every few months/year isn't a big deal, and I generally know when it's going down. The laptop is an ssh terminal/browser/doc reader only!

Me too, that's why I don't care how old it is anymore.