Bitbucket PM here - thanks for sharing this. We definitely have a lot we can improve around PRs and have some folks looking into it now. We'll definitely take your ideas into consideration.

I'm curious about how you use Bitbucket Cloud. Why did you decide to base your dev flow on forks and bookmarks instead of named branches? Are you working as an individual (and accepting PRs on open source or similar) or as part of a team?

Have you given any thought to moving to named branches -- or even git? Are there other problems there that you're trying to avoid? (As you might imagine, that's where the majority of our customers are today, using various branching models on git rather than forks/bookmarks on hg.)