For some positions, the hiring process includes a technical interview.
This technical interview revolves around a merge request to a small Rails application created for the interview.
A day before the call, we will send you a link to the merge request and ask you to spend up to 30 minutes of your time reviewing it, as you would for any contribution to a project you were working on. The merge request is self-contained, so you shouldn't need to look elsewhere in the project.
This technical interview is a 1-hour video call and screen sharing session with the interviewer(s), where they will ask you to walk them through your review, and where you will also write some code to improve the merge request.