This is common, you commit something but realize you forgot to include a specific file, maybe because you forgot to run git add to stage it.

No worries - you can use git commit --amend to take the previous commit, “undo” it, apply all that’s currently staged, and then commit again:

git add file-forgotten.txt
git commit --amend

If you need, you can also change the commit message while you’re adding the file, using the -m option:

git commit --amend -m "New commit message"

As with any operation that rewrites the history, I would only use it if you are working on a local branch, or if you are 100% sure no one else is working on the same branch.