Merge queue

A merge queue is a feature of a Git hosting provider that merges pull requests into a busy branch one group at a time, after testing each against the latest state of that branch and the changes queued ahead of it.

What it is

Two pull requests can each pass CI on their own and still break the branch once both are merged. A merge queue closes that gap. On GitHub (Managing a merge queue):

1. Pull requests join the queue in order.
2. For each, GitHub builds a temporary branch with the latest base branch plus the pull requests ahead of it.
3. Required checks run on that combined state, and the change merges when they pass.
4. If checks fail or the group conflicts, that pull request leaves the queue and the rest are rebuilt without it.

CI must run on the merge_group event for this to work:

on:
  pull_request:
  merge_group:

An administrator turns it on with Require merge queue in the branch's protection rule.

Why it matters

The busier a branch is, the more often "green on its own" stops meaning "green when merged". Teams that let AI agents open many small pull requests hit this sooner.

In AI CodeOps

AI CodeOps doesn't run a merge queue or handle merge_group events. Its release gate judges a pull request on its own checks and findings.