This is an extension to git-branchless that automates the creation and management of stacked pull requests on GitHub.

• GitHub CLI
• Git Branchless

cargo install --git 'https://github.com/FergusYip/merge-mate' --locked --force

The main and most useful merge-mate command is mm update. It looks at your current stack(.) and will update the pull requests of every branch in the stack.

Suppose you have the following stack and every branch has its own pull request.

❯ git sl
◇ 809e18c 3m (main) initial commit
┃
◯ fc6d3ce 2m (feature-foo) add foo
┃
◯ 940199e 2m (feature-bar) add bar
┃
● 08d8ee7 2m (feature-foobar) add foobar

Now, let's say that we actually need to refactor some code before introducing foo, bar, and foobar. So, we add a new commit before add foo, which results in the following revised stack.

❯ git sl
◇ 809e18c 7m (main) initial commit
┃
● ff34308 29s (refactor-code) refactor code
┃
◯ 1d18550 10s (feature-foo) add foo
┃
◯ 6d8214d 10s (feature-bar) add bar
┃
◯ 79506b6 10s (feature-foobar) add foobar

We want to merge refactor-code first so we force push the entire stack and create a new pull request for it.

❯ git submit -c
❯ gh pr create

But now we encounter a problem: the diff of the feature-foo pull request against main includes the refactor-code commit. Typically, you would manually update the base branch of the feature-foo pull request to be refactor-code. And if you have a pull request table of contents, you would have to update it too for every single pull request.

This is where mm update comes in. Simply run it to update the base branches and table of contents of every pull request in the stack.

mm update

Let's say that we've merged the head of our pull request stack into the main branch.

❯ git sl
◇ 809e18c 25m initial commit
┣━┓
⋮ ● 6e45530 44s (refactor-code) refactor code
⋮ ┃
⋮ ◯ b355aaa 44s (feature-foo) add foo
⋮ ┃
⋮ ◯ 6068fda 44s (feature-bar) add bar
⋮ ┃
⋮ ◯ 9ac0be3 44s (feature-foobar) add foobar
⋮
◇ 71f5662 1m (main) Merge branch 'refactor-code' into 'main'

The advancement of main has caused the diff of the feature-foo pull request to become incorrect.

In this scenario, we must rebase feature-foo and its descendant on top of main.

git move -s b355aaa -d main

Which results in

❯ git sl
◇ 809e18c 28m initial commit
┣━┓
⋮ ◯ 6e45530 3m (refactor-code) refactor code
⋮
◇ 71f5662 4m (main) Merge branch 'refactor-code' into 'main'
┃
● c56d427 16s (feature-foo) add foo
┃
◯ 87c9f38 16s (feature-bar) add bar
┃
◯ 0f1e2c9 16s (feature-foobar) add foobar

Then we need to push our local changes to GitHub. Make sure you have checked out one of the commits in the stack.

git submit && mm update

We chain mm update behind git submit to ensure that the head of the feature-foo pull request is changed from refactor-code to main.

In some instances, merged pull requests will not be deleted if they are squashed into main.

❯ git sl
◇ 809e18c 28m initial commit
┣━┓
⋮ ◯ 6e45530 3m (refactor-code) refactor code
⋮
◇ 71f5662 4m (main) Merge branch 'refactor-code' into 'main'

In this case, you would run the mm cleanup command. The mm cleanup command will look at every branch that is older than main and ask if you want to hide it.

❯ mm cleanup
Hide "refactor-code"? [Y/n]