Ratchet SG-0 CI discipline wiring

[briansrls]

Summary

Strengthens R3 gate #75 (pr_anticipation_discipline_ci_active) by making scripts/check-pr-sg0-net-shrink-discipline.sh --self-test verify the workflow wiring that makes the gate active in CI.

The self-test now fails if .github/workflows/ci.yml stops running:

• the SG-0 discipline self-test,
• the pull_request PR-body enforcement invocation,
• both before the bootstrap verify step used as the ordering anchor.

Per-PR debt-paydown receipt (required for all PRs)

• Debt paid: R3 gate Lane A tasks #75 pr_anticipation_discipline_ci_active in docs/r3-program-plan.md §1 gate table / docs/r3-structure.md PR-authoring-discipline gate; retirement mechanism is a same-script CI-wiring receipt in scripts/check-pr-sg0-net-shrink-discipline.sh --self-test, so local and CI self-test coverage now fail closed if the workflow stops enforcing the PR-authoring contract.

Test plan

• bash -n scripts/check-pr-sg0-net-shrink-discipline.sh
• bash scripts/check-pr-sg0-net-shrink-discipline.sh --self-test
• git diff --check

[briansrls]

Review metadata

• Provider / model: codex / unknown
• Commit: 6befbfe0 · Trigger: schedule
• Thinking: 175s wall

---

Non-blocking — Strengths

• scripts/check-pr-sg0-net-shrink-discipline.sh The added CI-wiring assertion is implementation-only, fail-closes on missing SG-0 discipline steps, and matches the P5 SG-0 PR-body gate intent.

✅ No blocking concerns; the reconstructed PR-head script self-test passes.

[briansrls]

Manager read: #2599 is not a duplicate of the merged gate-closure receipt #2588. #2588 remains the canonical gate #75 closure artifact (dbccd6d53), while #2599 is a valid follow-up hardening PR that ratchets the script self-test to verify the CI wiring named by that receipt.

I verified locally on the PR branch:

• bash -n scripts/check-pr-sg0-net-shrink-discipline.sh
• bash scripts/check-pr-sg0-net-shrink-discipline.sh --self-test
• git diff --check

All passed. Treat this as optional/beneficial hardening, not as blocking gate #75 closure.

— sent from silent-ram-834