GitHub stacked pull requests reach general availability with 9% more code merged

GitHub stacked pull requests were a public preview, and the repositories that adopted them merged 9 percent more code than their peers. GitHub moved the feature to general availability, and the GA release adds five changes to how stacks merge, rebase and pass through a merge queue.

GitHub's own figures from the preview period name three numbers in one paragraph. Repositories using stacks saw a 9 percent increase in merged code compared with peers. Two-thirds of the top 1 percent of repositories now use stacked pull requests. Those same adopters saw a 5 percent improvement in time to merge. The company published the figures without a method note, so a reader should treat them as GitHub's own measurement of its own preview.

What stacks change for a reviewer

A stack breaks one large change into a chain of small pull requests. Each pull request targets the one before it. The reviewer reads one layer at a time, and the author can start the next layer without waiting for the first to merge. The design is older than GitHub's version of it: Graphite and ghstack have built on top of a Git host for years. The GA release is the point at which a team can use the pattern without a third-party tool.

Five changes in the GA release

Rebase stack now preserves approvals when a stack is otherwise unchanged and the base branch moves ahead, even in repositories that dismiss stale approvals. Rebased commits stay signed, and automatic rebases after a partial merge sign the replacement commits when branch rules require signatures. A user with permission to bypass repository rules can use that permission to merge the lowest unmerged pull request in a stack. A stack enters the merge queue as one merge group, and the merge commit method now creates one merge commit per pull request. A branching stack retargets automatically when its base branch is deleted, so the bottom pull request stays open.

Auto-merge for stacks rolls out over the next few weeks. The persistent header on a pull request page now shows which stack it belongs to, and Shift plus J and Shift plus K move between pull requests in a stack. The gh stack CLI extension gains support for Git worktrees. The pull_request webhook gains a stacked action that fires when a pull request joins a stack.

What a team actually gets

A reviewer who opens a 40 file pull request one scroll at a time runs out of attention long before the end of the diff. Stacking the change is the structural fix. Until the preview ended, that structural fix was in a tool outside GitHub, or in a workflow built on top of GitHub's branches. The GA release puts the structural fix inside the review and merge screens a team already uses, and inside the merge queue, which is where the signed commit and bypass rules choices get tested in production. Stacked pull requests are available on all github.com plans, and will arrive in an upcoming GitHub Enterprise Server release.

Source

Stacked pull requests generally available, GitHub Changelog.