ci: gate pull requests on an accepted issue and signed commits

[dev-jodee]

Linked issue

Linked issue: trivial

What and why

Replaces the contributor canary word with checks that do not depend on an agent opting into them, and adds the issue-first gate from solana-mobile/templates#64.

• The canary only fires when an agent both reads CLAUDE.md and follows a request to self-incriminate. It catches nothing adversarial and little honest. Removed from CLAUDE.md, AGENTS.md and the hygiene patterns. The rest of the attribution scan is untouched and still labels ai-unreviewed, comments and fails the check without closing anything.
• New Accepted issue linked job: the description must reference an issue a maintainer has labelled accepted. Without one the PR is labelled needs-issue, commented on once and closed. Once the issue is accepted and linked, reopening the PR reruns the check and clears the label. Linked issue: trivial exempts typos, broken links and comment-only fixes. Bots and authors with write, maintain or admin access skip.
• New Commits signed job: an unverified commit gets one changes-requested review naming the shas, dismissed automatically once all commits verify and replaced when a force-push changes which commits are unsigned. The review carries a marker with the digest of that list, so the job only ever dismisses a review it wrote itself. This enforces a rule CONTRIBUTING already stated but nothing checked.
• PR template gains the required Linked issue field.

Both jobs run under a per-PR concurrency group, so overlapping opened/edited/synchronize runs cannot race on the label or file duplicate reviews. No third-party action is involved: pull_request_target with pull-requests: write is the worst place to carry one, and the logic is a handful of gh calls.

Testing

bash -n on both new job scripts, YAML parsed. The jobs themselves only run once this is on main, since pull_request_target reads the workflow from the base branch.

AI disclosure

• No AI tooling was used beyond editor autocomplete.
• AI tooling was used. Tool and extent: Claude Code drafted the two jobs and the label config, I reviewed and edited before opening.

[greptile-apps]

Confidence Score: 5/5

The PR appears safe to merge; no outstanding correctness or repository-rule violations remain.

Findings

1.  Reopening bypasses automatic closure ▶
2.  Review ownership is ambiguous ▶

Summary

The PR replaces the contributor canary with enforceable pull-request hygiene checks.

• Requires external contributors to reference an accepted issue or declare an eligible trivial change.
• Labels, comments on, and closes noncompliant pull requests directly from the hygiene workflow.
• Requests changes for unsigned commits and identifies its own reviews with a durable marker.
• Updates the pull-request template and contribution guidance to document the new requirements.
• Since the previous review, the workflow now closes reopened noncompliant PRs directly and scopes signing-review dismissal to reviews created by this gate.

_{Reviews (2) · Last reviewed commit: "ci: gate pull requests on an accepted is..."}

[amilz]

CI hardening: adds accepted-issue + signed-commits gates to pr-hygiene, retires marzipan canary. LGTM.