Wrong delta diff background color in Ghostty

[ComplexPlane]

Describe the bug

When using the delta pager in lazygit specifically in Ghostty, the background color for line-wise additions is gray instead of green.

Here's a summary of the background color values I observe in different situations (using the terminal inspector in Ghostty), including running delta outside lazygit, overriding TERM, and in kitty:

Terminal	Command	Background Color	Correct
ghostty	lg	Palette 235 (#262626)	No
ghostty	TERM=xterm-kitty lg	#002800	Yes
ghostty	delta	#002800	Yes
ghostty	delta --true-color never	Palette 22 (#005f00)	Yes
kitty	lg	#002800 (color picker)	Yes

Is this related? #2962

To Reproduce

Install Ghostty and delta, and use this lazygit config:

git:
  paging:
    colorArg: always
    pager: delta --dark --paging=never --line-numbers --hyperlinks --hyperlinks-file-link-format="lazygit-edit://{path}:{line}"

Screenshots

It should look like:

Actual:

Version info:
commit=611fabde11d24d9acc71ee26077b9a1101f59f27, build date=2024-09-18T10:56:10Z, build source=binaryRelease, version=0.44.1, os=darwin, arch=arm64, git version=2.39.5 (Apple Git-154)

git version 2.39.5 (Apple Git-154)

This issue is also present on master.

[yudai0804]

I am struggling with the same issue.
There was no issue when using delta on its own. However, it doesn't work properly when using delta with lazygit.

[tdimeco]

Same issue here. Running TERM=xterm-256color lg seems to fix the issue.

Is this related to this post? https://mitchellh.com/writing/ghostty-devlog-004
Especially the following part:

We found other upstream bugs, and I'm proud that Ghostty community have been not only reporting issues, but also providing fixes. Tim made a PR to the popular Go library tcell to fix a particularly bad issue. This is an important library since it is used by popular TUI applications such as lazygit, lazydocker, etc. Without this fix, all of those programs spew garbage unless you run them explicitly with TERM=xterm-256color. I hope this can be accepted soon!

[joshgoebel]

Related: #4149

I've upstreamed the fix to tcell and waiting for it to be accepted there before we can pull it back into lazygit properly. My PR builds today and fixes this though if anyone is interested.

[tdimeco]

Many thanks 🙏

[gdamore]

The tcell fix was merged yesterday.