GitHub put stacked pull requests into public preview with a gh extension and a Copilot skill.

Announced July 30, stacked PRs split a large change into ordered dependent PRs each targeting the layer below, reviewed in parallel, merged individually or as a whole stack in one click, with automatic rebasing as layers land. Install via gh extension install github/gh-stack; Copilot agents drive the same flow through a gh-stack skill. Existing branch protections and required checks apply. This is the single biggest quality-of-life change for anyone whose agent produces large diffs.