thisisme | Create cool images containing useful information | Generator Utils library

That represents the line in the file you want the comment to appear on. For Merge Requests, comments can either be on the code or general discussions (though the API names seem to be backwards).

To add a general discussion comment, you can use the Notes API: https://docs.gitlab.com/ee/api/notes.html#create-new-merge-request-note. This will look like the comment here: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/52673#note_495396729

To add a comment to the changed code in a Merge Request, you can use the Discussions API here: https://docs.gitlab.com/ee/api/discussions.html#create-new-merge-request-thread. This operation has options to set the file path and line number a comment should start on, a range that a comment applies to, etc. This is an example of a comment on the code itself: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/52673/diffs#2eda52c44979de93f257b305ada778372eacba0b_6_5