Looks interesting, but it seems you need to know the final shape of the stack before you start creating Pull Requests. So it's useful if you create Pull Request A, then immediately start working on something that builds on top of A, create a Pull Request for that (while A is still a PR), then you can do A->B->C

Here's something that would be useful: To break down an already big PR into multiples that make up a stack. So people can create a stack and add layers, but somehow re-order them (including adding something new at the first position).

It looks like in the UI if you base a PR on another branch you can just check a box to make it a stack. So I don't think you have to know the full shape of the stack in advance unless you're using the cli.

I use jj to stack branches so i'll just be using the UI to do github pr stacks.