GitHub Ships Stacked Pull Requests in Public Preview

GitHub moved stacked pull requests into public preview on July 30, letting one PR target another PR's branch instead of main.

That lets a schema change, an API change, and a UI change ship as three separately reviewed layers instead of one sprawling diff. The chain runs A to main, B to A, C to B, with each layer merging in one click once its own review clears. GitHub says research across 1.5 million pull requests found PRs under 200 lines get reviewed three times faster, with 40% fewer defects reaching production.

The bigger draw is agent-generated code, the natural output size that's too big to review in one pass. Teams have been reaching for outside tools to slice that output into reviewable diffs. GitHub built the slicing into the platform itself.

The changelog doesn't say whether coding agents will start generating output pre-split into stacks. It also doesn't say whether engineers will keep slicing by hand after the fact instead. That gap decides whether stacking becomes a default workflow or stays a power-user trick.