FR: Improve "diff" visibility by adding marker before line number

[yerlaser]

Is your feature request related to a problem? Please describe.
The current diff is mostly good, however, when there are small additions on a line those changes are hard to spot.
This happens because unlike red color green color doesn't standout.

Describe the solution you'd like
Add a marker on the lines that contain changes at the very beginning of the line, i.e. before line number.

Describe alternatives you've considered
An alternative would be to highlight the whole line with a background, however, I believe it might not be supported on all terminals

Additional context
I am aware of the existence of --git switch that with an external pager.
However, the default diff seems to be good enough except for this issue and I'd avoid using external tools whenever possible.

[yuja]

Just fyi, you could set diff.color-words.max-inline-alternation=0 to print any changed lines as separate removed/added lines.
https://jj-vcs.github.io/jj/latest/config/#color-words-diff-options

[yerlaser]

Just fyi, you could set diff.color-words.max-inline-alternation=0 to print any changed lines as separate removed/added lines. https://jj-vcs.github.io/jj/latest/config/#color-words-diff-options

Thanks. That suggestion improves the detectability of changes, but at the same time makes it harder to compare them once detected.
The inline word diff is very good at understanding what changed, but when the changes are small the line containing them gets harder to detect.
So, marks on changed lines that standout, e.g. highlight or an asterisk before line number (or both) would be perfect.

[yuja]

marks on changed lines that standout, e.g. highlight or an asterisk before line number (or both) would be perfect.

or make context line numbers dimmed.

Naming aside, maybe we can add "context"/"changed" label to line numbers (or to the whole line.) That's the easiest fix.

[yerlaser]

marks on changed lines that standout, e.g. highlight or an asterisk before line number (or both) would be perfect.

or make context line numbers dimmed.

Naming aside, maybe we can add "context"/"changed" label to line numbers (or to the whole line.) That's the easiest fix.

Now that you suggested it, I think dimming the context line numbers would be the best option of all.
Because, currently, they pop out unnecessarily.
However, given that people might be using tmux or similary software which don't support all color options adding text would be a good fallback mechanism.

[yuja]

The default might have to be underline/bold changed line numbers for compatibility reason, but user can set whatever color/style if line numbers and contents are labeled as "context"/"changed".