<home> <end> keys don't work inside neovim inside tmux

[kiyoon]

What Operating System(s) are you seeing this problem on?

Linux X11

Which Wayland compositor or X11 Window manager(s) are you using?

No response

WezTerm version

20230123-190635-dd28dbae

Did you try the latest nightly build to see if the issue is better (or worse!) than your current version?

Yes, and I updated the version box above to show the version of the nightly that I tried

Describe the bug

home and end keys do not work in neovim when using TERM=wezterm terminfo inside tmux.

My tmux configuration:

# 256 colour
set -g default-terminal "tmux-256color"
set -ag terminal-overrides ",xterm-256color:RGB"
set -as terminal-overrides ',*:Smulx=\E[4::%p1%dm'  # undercurl support
set -as terminal-overrides ',*:Setulc=\E[58::2::%p1%{65536}%/%d::%p1%{256}%/%{255}%&%d::%p1%{255}%&%d%;m'  # underscore colours - needs tmux-3.0

I tried to change the default-terminal to wezterm but it introduces another problem: and doesn't work in zsh and the cursor changes to box (not |)

If I don't pass TERM=wezterm it works well in neovim.

To Reproduce

No response

Configuration

I don't think any config is relevant here.

local wezterm = require("wezterm")

return {
	color_scheme = "Dracula (Official)",

	font = wezterm.font_with_fallback({
		"JetBrainsMono Nerd Font",
		"Fira Code Nerd Font",
	}),
	font_size = 14.3,

	hyperlink_rules = {
		-- Linkify things that look like URLs and the host has a TLD name.
		-- Compiled-in default. Used if you don't specify any hyperlink_rules.
		{
			regex = "\\b\\w+://[\\w.-]+\\.[a-z]{2,15}\\S*\\b",
			format = "$0",
		},

		-- linkify email addresses
		-- Compiled-in default. Used if you don't specify any hyperlink_rules.
		{
			regex = [[\b\w+@[\w-]+(\.[\w-]+)+\b]],
			format = "mailto:$0",
		},

		-- file:// URI
		-- Compiled-in default. Used if you don't specify any hyperlink_rules.
		{
			regex = [[\bfile://\S*\b]],
			format = "$0",
		},

		-- Linkify things that look like URLs with numeric addresses as hosts.
		-- E.g. http://127.0.0.1:8000 for a local development server,
		-- or http://192.168.1.1 for the web interface of many routers.
		{
			regex = [[\b\w+://(?:[\d]{1,3}\.){3}[\d]{1,3}\S*\b]],
			format = "$0",
		},

		-- Make task numbers clickable
		-- The first matched regex group is captured in $1.
		-- {
		-- 	regex = [[\b[tT](\d+)\b]],
		-- 	format = "https://example.com/tasks/?t=$1",
		-- },

		-- Make username/project paths clickable. This implies paths like the following are for GitHub.
		-- ( "nvim-treesitter/nvim-treesitter" | wbthomason/packer.nvim | wez/wezterm | "wez/wezterm.git" )
		-- As long as a full URL hyperlink regex exists above this it should not match a full URL to
		-- GitHub or GitLab / BitBucket (i.e. https://gitlab.com/user/project.git is still a whole clickable URL)
		{
			regex = [[["]?([\w\d]{1}[-\w\d]+)(/){1}([-\w\d\.]+)["]?]],
			format = "https://www.github.com/$1/$3",
		},
	},

	-- undercurl becomes ugly if underline_position < -4
	underline_position = -4,
	keys = {
		{
			key = "Enter",
			mods = "ALT",
			action = wezterm.action.DisableDefaultAssignment,
		},
	},
}

Expected Behavior

No response

Logs

No response

Anything else?

No response

[wez]

I'm not clear on what term is set to or where in your configuration.

The way things should be configured is:

The value of TERM should be either xterm-256color or wezterm (the latter only if you have installed the wezterm terminfo file) when you launch tmux, so that tmux knows what terminal it is interacting with and so it can translate accordingly.

For programs spawned inside tmux, TERM must be set to tmux-256color as that is the terminal which they communicating with. It is not valid to set TERM to xterm-256color or wezterm for processes running inside tmux.

[kiyoon]

Thanks for the clear explanation. I was putting TERM to wezterm for nvim process and it was the problem.

I added this in wezterm.lua. I need to make sure I have this terminfo file every computer I ssh into.

  term = 'wezterm',

And now echo $TERM prints wezterm outside tmux.

This should be in .tmux.conf

set -g default-terminal "tmux-256color"
set -ag terminal-overrides ",xterm-256color:RGB"
set -as terminal-overrides ',*:Smulx=\E[4::%p1%dm'  # undercurl support
set -as terminal-overrides ',*:Setulc=\E[58::2::%p1%{65536}%/%d::%p1%{256}%/%{255}%&%d::%p1%{255}%&%d%;m'  # underscore colours - needs tmux-3.0

echo $TERM prints tmux-256color inside tmux.
Finally, do not change the TERM variable for processes separately.

[kiyoon]

Out of curiosity, is it not valid to set set -g default-terminal "xterm-256color"? I saw many people doing this in tmux configuration. And also in iTerm2 tmux-256color didn't work and I had to use xterm-256color.

[kiyoon]

I'm sorry, but my configuration introduced another problem. Now in neovim I can use home and end keys, but it does not show undercurl. Why is this happening?

[kiyoon]

I originally followed here to set the undercurl (env TERM=wezterm nvim). And I believe this is setting the process TERM value to wezterm?

Which the explicit TERM=wezterm the undercurl works, however the home and end keys don't

[wez]

The thing to understand is that tmux is a separate terminal emulator program; the programs running inside it must use a terminfo entry that is valid for use in tmux, otherwise they won't understand each other.

tmux maintains its own model of all of the panes that it manages. The tmux client will then attempt to translate that information to output into the terminal that the client runs in. The client needs to be set to use the terminfo that matches that hosting terminal.

Changing TERM doesn't change any behavior in wezterm; it is just a string to use as a key to lookup data from the terminfo database.

When you press a key, wezterm will encode that key according to the settings you have configured in your wezterm.lua, modified by escape sequences that may have been emitted by the application(s) running inside it. See: https://wezfurlong.org/wezterm/config/key-encoding.html

The application running inside wezterm then decodes that key press, perhaps based on its understanding of the terminfo database (using TERM) and reacts to it.

When you're running tmux, the tmux client will then internally dispatch that keypress by re-encoding it according to tmux's rules and send it to the program running inside tmux.

is it not valid to set set -g default-terminal "xterm-256color"? I saw many people doing this in tmux configuration.

It's not technically valid, as tmux is a different terminal from xterm. Many terminals have some common behaviors so it may kinda work, but certain functions will be using the wrong definitions and you'll experience misbehaviors.

[wez]

In terms of reaching a resolution on this issue, can you remove tmux from the equation?

I'm interested to hear whether the home/end keys work for you when using TERM=wezterm and the default TERM=xterm-256color when you run nvim directly in wezterm.

If they both work outside of tmux, then I think you'll need to follow up with the tmux folks to troubleshoot your tmux configuration.

[kiyoon]

Yes, it works outside of tmux.

Based on your description I think I configured it correctly. wezterm.lua has term = "wezterm" and setting tmux-256color to tmux. I guess I need to talk to tmux folks instead