specrail-pr-gate

# SpecRail PR Gate Use this skill before saying a PR is merge-ready. ## Steps 1. Collect current PR evidence. Prefer the read-only adapter when available: ```sh python3 checks/github_pr_evidence.py --github-repo <owner/repo> --pr <pr-number> --review-source independent_lane --json > <evidence.json> ``` For a partial slice with a standalone `Refs #<issue-number>` directive, pass the expected issue explicitly: ```sh python3 checks/github_pr_evidence.py --github-repo <owner/repo> --pr <pr-number> --issue <issue-number> --review-source independent_lane --json > <evidence.json> ``` The expected issue must exist in the same repository and remain open. Other closing references may coexist; the adapter records all of them without redirecting the explicit target. A verified `partial` relation satisfies only linked-work evidence and never authorizes final completion or issue closure. 2. Run the offline gate: ```sh python3 checks/pr_gate.py --repo . --evidence <evidence.json> --json ``` 3. Confirm evidence includes linked issue and, for new adapter output, a self-consistent `issue_reference`; also confirm current PR head SHA, gate-query completion timestamp, gate-query head SHA, CI/check rollup, review decision, review source, lane failures, review-thread resolution, merge state, and human merge authorization. 4. Interpret decisions precisely: - `allowed`: evidence satisfies the local merge-readiness policy. - `needs_human`: deterministic evidence passed, but...