Thanks, Chris! And yeah, limiting violations to only changed lines is going to be the principal theme of my next blog post. I came across the same gist I think you did, and attempted to rework its monkey patching to get it to work with modern RuboCop — and then just as I was wondering whether to package that work up into a gem, I discovered that you had already done all that! I had already planned to include rubocop_lineup in that post…

I haven’t implemented differential checks as part of a PR review stage yet. That’s mainly because I’ve got code running at the individual commit stage, using overcommit to prevent checking in code where edited lines violate our style guide. A confirmatory guard within the PR, especially one that could flag violations using GitHub’s checks API, would be useful too, though — in a dev room where every developer is free to use their own editing workflow of choice, we found that overcommit didn’t sit nicely with at least one contractor’s preferred vim/Git combo.