Auto-merge by default: every same-repo PR that references an issue gets squash auto-merge #9086

The owner, 2026-10-11 (translated): "make auto-merge the default!"

On 2026-10-11, none of the 215 open bee and port PRs had auto-merge, so a PR that went green still sat until someone merged it by hand. GitHub has no repository setting that turns auto-merge on for every PR; it has to be enabled per PR. The Issue Gate already runs on every PR event (pull_request_target: opened, edited, reopened, synchronize) and already knows whether the PR references an issue, so the step belongs there.

User Scenarios

• Given a PR from a branch of gHashTag/t27 whose body says Closes #N, when the Issue Gate passes, then squash auto-merge is enabled on it and it merges as soon as the required checks are green.
• Given a draft PR, a PR from a fork, or a PR labelled no-auto-merge, when the gate runs, then auto-merge is not enabled.
• Given a PR with no issue reference, when the gate fails, then the auto-merge step does not run.

Requirements

• FR-001: The step MUST run only after the issue reference check passed, and only for non-draft PRs whose head repository is gHashTag/t27 and that lack the label no-auto-merge.
• FR-002: It MUST use GH_AGENT_TOKEN, as queen-publish.yml does, so that the merge commit starts master's workflows. A merge made with GITHUB_TOKEN starts none.
• FR-003: The PR MUST be net <= 0 in hand-written lines (policy: hand-written code in any language but t27 may only shrink (Closes #8227) #8236).

Success Criteria

• grep -c 'Auto-merge by default' .github/workflows/issue-gate.yml prints 1.
• With the criterion above satisfied, the first PR opened after the merge shows autoMergeRequest set, as reported by gh pr view N --json autoMergeRequest.
• git diff --numstat of the PR shows .github/workflows/issue-gate.yml with deletions >= additions.

Boundary

• .github/workflows/issue-gate.yml