Below is a design exploration that places the PR overview into the sidebar using a combination of custom webviews and tree widgets. The main goal is to be able to view the details (commits, changes), write a review, and merge it.

One of the questions that remains is whether we should promote exiting a review by placing it into a view or hide it within a context menu.

Another thing I'm considering is being able to mark a file as "viewed" either via a right-click action or showing a ✔️ on hover that persists when clicked (cc @eamodio):