ESC]0;stringBEL -- Set icon name and window title to string ESC]1;stringBEL -- Set icon name to string ESC]2;stringBEL -- Set window title to string via https://tldp.org/HOWTO/Xterm-Title-3.html

This is achieved by calling `autosave_hook' in interesting places, like new_tab or free_tab. It'll set up a timer to later persist the session. This is particularly useful to avoid loosing tabs on the event of a crash or unexpected system halt, or other similar event.