random text when computer idle

[LiamFry]

GNU bash, version 5.2.37(1)-release (x86_64-pc-linux-gnu) [Debian GNU/Linux 13 (trixie)]
ble.sh, version 0.4.0-devel4+8060b7a (noarch) [git 2.47.3, GNU Make 4.4.1, GNU Awk 5.2.1, API 3.2, PMA Avon 8-g1, (GNU MPFR 4.2.2, GNU MP 6.3.0)]
bash-completion, version 2.16.0 (hash:480ffcc6a751e55621ec526eb5dea7a0d86d9e72, 17877 bytes) (noarch)
locale: LANG=en_US.UTF-8
terminal: TERM=screen-256color wcwidth=16.0-west/16.0-2+ri, tmux:0 (84;0;0), vte:8001 (61;8001;1)
options: -emacs -monitor +noclobber +vi +direxpand +extglob +globstar +histappend -hostcomplete +inherit_errexit +login_shell

This is a tricky one to explain ...

My computer's monitor turns off when it has been idle for a period of time. My computer does not sleep nor hibernate; only the monitor goes off. After being in this state for an hour or so, when I return to my computer and wake my screen, any terminal session that was open looks as if someone hit return several times.

If I leave an application running in the terminal, like vim, it is "altered." A perfect example is when I was editing three text files simultaneously, each opened in identical-width vertical splits. I walked away from my computer for about three hours. When I returned, the center frame - the one with focus - had shrunken to 10 characters wide.

I can easily reproduce these behaviors.
It seems to only happen in tmux.
When I remove blesh from my config, none of this happens.
Is there some kind of timer in blesh that periodically does something?

[akinomyoga]

This is most probably caused by the change in the terminal display size. My guess is that, when the monitor of your computer is blacked out, the terminal window size is first shrunken to 10 characters wide, then ble.sh receives the signal SIGWINCH. On receiving the signal, ble.sh redraws the command line, but ble.sh tries to protect the existing contents of the terminal, unlike Readline. That's the difference between the sessions with and without ble.sh that you observed. If you want to turn off the protection, you may change the setting bleopt canvas_winch_action.

# Turn off the protection of existing contents
bleopt canvas_winch_action=redraw-prev

Please read the above link for more details.

[akinomyoga]

Is there some kind of timer in blesh that periodically does something?

To answer this question, ble.sh doesn't do anything about this.

The Vim behavior you observe shouldn't be related to ble.sh. Could you check again if the Vim behavior is really specific in a ble.sh session?