Commenting on files (including deleted, binary, and renamed files) in a pull request is now generally available on the web and GitHub Mobile! A special thank you to everyone that provided feedback during the public beta.
API support is also now available. See create a review comment (REST API) or
addPullRequestReviewThread (GraphQL mutation) for more details on commenting on files. A new "subject type" field is also now returned by other APIs indicating whether a comment is on a
Learn more about commenting on a pull request.