To my knowledge, stacked diffs were first done in the Linux kernel as stacks of patches sent over email. From there they spread to Google and Facebook. (Source: I worked on Facebook's source control team from 2012-2018 and did a lot of work to enable stacked diffs there.)
Congrats and thank you. You helped build one of the best devex experiences I've ever had the pleasure of working with :)
At some point, a derivative idea becomes so different from the original one that it’s a novel idea in essence. Just like SMS is ultimately a derivative of cuneiform tablets, and yet it isn’t in any meaningful sense.
Right, I was thinking from a web-based UI. The "pull request" term is from git (AFAIK), but git itself was built to accommodate the earlier concept of mailing patches around. (Source: I've been using version control since RCS/SCCS days and contributed here and there to git in its infancy. Also an early user/contributor to Gerrit.)