Add new PR to bottom of stack

[ajilani]

I'm playing around with GitHub stacks, which is now in public preview. I see how to add a new PR on top of an existing stack, but is there a way to add a new PR to the bottom of the stack? The use case for this is that the bottom PR is too large, so I create a new branch halfway through the commits of the bottom PR, open a PR for it, and then re-target the original bottom PR to target the new PR branch. But I don't see a way to change the base of a stacked PR; the UI locks it. I ended up deleting the stack, which allowed me to change the base and then create a new stack.

[tt-a1i]

There are two slightly different cases here.

If you only need a new empty layer below the current bottom branch, recent versions have gh stack modify. Put the cursor on the bottom branch, press i to insert below it, then save with Ctrl+S and run:

gh stack submit

For the actual case you described—splitting the commits of an existing bottom PR—the documented limitation is that modify cannot split a branch. You still need to create the split branches in Git first, then rebuild the stack from those existing branches:

gh stack unstack
gh stack init new-bottom old-bottom
gh stack submit

init can adopt existing branches. So your delete/recreate workaround was basically the right approach for a real split; modify only avoids it when inserting an empty layer is enough.