tl;dr: GitHub has launched stacked pull requests in public preview, letting developers break large changes into an ordered series of smaller, independently reviewable PRs that can be merged individually or all at once. The feature works via a new CLI extension (`gh extension install github/gh-stack`), github.com, the mobile app, or Copilot, and integrates with existing branch protections and required checks. Merge queue support is rolling out progressively over the coming weeks.