The `resize` script in `vm-nogui` breaks `claude-code`

[aldur]

Hello there and thanks for this project! :)

I spent a couple hours debugging this issue the other day. I think the issue is that the resize script:

nixos-generators/formats/vm-nogui.nix

Lines 2 to 11 in fb30cf1

	resize = pkgs.writeScriptBin "resize" ''
	if [ -e /dev/tty ]; then
	old=$(stty -g)
	stty raw -echo min 0 time 5
	printf '\033[18t' > /dev/tty
	IFS=';t' read -r _ rows cols _ < /dev/tty
	stty "$old"
	stty cols "$cols" rows "$rows"
	fi
	''; # https://unix.stackexchange.com/questions/16578/resizable-serial-console-window

I think the issue is that the script runs for both interactive and non-interactive sessions. Also, it shouldn't need to run eg when through SSH, but it does because it is sourced in /etc/profile.

[bew]

Could you tell us more about the actual issue?
What are you trying to do, what happened (list steps/code & observations)

[aldur]

Absolutely! (sorry, a bit of context was hidden in that link at the top)

I don't really trust coding agents who can do rm -rf ~ by mistake, so I run them exclusively in a VM that I build from my NixOS configuration using the vm-nogui format from this repo (above a few others).

This was working well for claude-code, until it wasn't a couple days ago.

The symptoms were as follows:

1. I'd launch the VM.
2. Run claude-code in a teminal (both on the QEMU TTY and through SSH).
3. It would prompt me for the initial setup (it asks if you want a light theme, to login, etc etc), but it wouldn't take any keyboard/mouse input.

Re-building the configuration without the script fixed the issue:

environment.loginShellInit = lib.mkForce "";

I unfortunately haven't investigated more in depth the root case (that is, why things did break), but running claude --debug would sometime output the following (while unresponsive):

'standard input': Inappropriate ioctl for device

If useful, I can quickly reproduce the original issue (or share a minimal NixOS config to reproduce it, since we are talking Nix :))