Add a repo-level supply-chain incident response playbook for npm/GitHub Actions package-registry incidents, anchored on the May 2026 TanStack compromise and prior Shai-Hulud-style npm incidents.
- add `docs/security/supply-chain-incident-response.md` with exposure checks, immediate response steps, workflow rules, publication rules, and escalation triggers
- link the playbook from `SECURITY.md`
- reject `pull_request_target` workflows that restore or save shared dependency caches
- add a regression test for the new `pull_request_target + actions/cache` guardrail
Validation:
- node tests/ci/validate-workflow-security.test.js (12 passed, 0 failed)
- node scripts/ci/validate-workflow-security.js (validated 7 workflow files)
- npx markdownlint-cli 'SECURITY.md' 'docs/security/supply-chain-incident-response.md'
- npx markdownlint-cli '**/*.md' --ignore node_modules
- git diff --check
- node tests/run-all.js (2377 passed, 0 failed)
- GitHub CI for #1848 green across Ubuntu, Windows, and macOS
No release, tag, npm publish, plugin tag, marketplace submission, or announcement was performed.
Require npm registry signature verification wherever workflow npm audit checks run.
- add npm audit signatures to CI Security Scan and maintenance security audit jobs
- teach the workflow security validator to reject npm audit without signature verification
- keep the repair and Copilot prompt tests portable across Windows path/case and CRLF frontmatter behavior
Validation:
- node tests/run-all.js (2376 passed, 0 failed)
- CI current-head matrix green on #1846
- run non-test workflow installs with npm ci --ignore-scripts where lifecycle scripts are not needed\n- reject plain npm ci in workflows with write permissions\n- reject actions/cache in id-token: write workflows to reduce OIDC publish cache-poisoning risk
