I propose adding a new command show-diff-change to show the previous version of the git hunk under the cursor. This would allow for a quick, inline preview of what has been changed at a specific point in the file.

I believe this feature fits as part of the Helix core rather than being a plugin considering that:

• the vision for git-related features, as expressed in this comment on #2261 , is that read-only operations are fine for core
• it's intrinsically coupled with the gutter implementation and the :reset-diff-change command, as the hunks should be exactly the same for consistency

I have a draft implementation in this PR, of course open to any feedback.