Feat: Add ability to toggle zsh-integration title change

[EightBitBoot]

When changing the current surface's title via ANSI escape escape sequences (\e]0;My Custom Title Here\a or \e]2;My Custom Title Here\a), the zsh shell integration's _ghostty_precmd and _ghostty_preexec functions automatically overwrite it (I spent the better part of today tearing my head out and searching through the code thinking this was a bug in the terminal itself). This functionality can be disabled, however it must be disabled before the shell finishes loading and cannot be re-enabled (or disabled) at a later point.

To work around this, a new environment variable has been added (only to the zsh integration for now): GHOSTTY_SHELL_INTEGRATION_TOGGLE_TITLE_OFF. This is settable by scripts and commands to disable the zsh integration's overwriting of the title and can be unset to re-enable the functionality.

To take advantage of this, I have the following functions enabled in my .zshrc:

function unset_title() {
    echo -ne "\x1b]0;\x07"
    if [[ $TERM == "xterm-ghostty" ]]; then
        unset GHOSTTY_SHELL_INTEGRATION_TOGGLE_TITLE_OFF
    fi
}

function set_title() {
    if [ $# -eq 0 -o ${#1} -eq 0 ]; then
        # If the title isn't provided or is an empty string, reset the title to factory settings
        unset_title
    else
        echo -ne "\x1b]0;${1}\x07"
        if [[ $TERM == "xterm-ghostty" ]]; then
            GHOSTTY_SHELL_INTEGRATION_TOGGLE_TITLE_OFF=1
        fi
    fi
}

After taking a cursory look at the bash I don't believe this same method will be possible there (as it works by setting $PS0 and $PS1 to send the escape sequences).

For elvish I don't know enough to add the desired functionality.

If someone wants to add the code for the other supported shells, or suggest how I might go about fixing them I would be more than happy to include / create it.

[anund]

While I wrap my head around how precmd/prexec is supposed to work in zsh would you mind helping me understand why you don't just turn the integration off and handle the title entirely yourself? (which bits of the current integration do you want to work when you aren't manually setting the title?)

[nivkner]

in elvish you can modify report-pwd to only change the title conditionally when GHOSTTY_SHELL_INTEGRATION_TOGGLE_TITLE_OFF isnt on, like this:

fn report-pwd {
    var title_disabled = (eq 1 $E:GHOSTTY_SHELL_INTEGRATION_TOGGLE_TITLE_OFF)
    if (not $title_disabled) { printf "\e]7;file://%s%s\a" (hostname) (pwd) }
}

(not sure why all the double negatives, but I'm sticking with the convention)

[anund]

I've got the pieces for all 4 shells in my head now.

The evlish suggestion is correct though I suggest just reusing the envvar. Bash is already dynamic from what I can see reading the code. Fish doesn't do anything around the title and relies on the builtin just running. (indeed the defaults for my distro also set the term title for zsh/bash)

It feels a bit like even after making this dynamic for zsh/elvish you should probably just turn the feature off and control the terminal title completely. Is there a reason why you prefer spiting responsibility between ghostty and your own scripts?

[anund]

I think the only reason the original code, ~3 years back in kitty, chose to add the title code here via an append was stylistic. Rather than bending over backward with read please add the ifs to their original functions. Switching on the original envvar would be better too.