GitHub webhook entry — launches Platform EM review on every non-draft PR.

Subscribed events: pull_request with actions opened, synchronize, reopened, ready_for_review. Non-matching events return 200 with a no-op response so the webhook delivery stays healthy in GitHub's UI.

ready_for_review (2026-09-05): a PR opened as a draft and later marked ready never carried a reviewable delivery — its opened / synchronize events all arrived with draft: true and were skipped, and GitHub sends no further synchronize until the next push. PRs #1169 and #1192 had to be woken by hand with scripts/wake_em.py. The draft skip below still applies to every action, so draft pushes never burn a review.

Security: HMAC-SHA256 signature required via X-Hub-Signature-256. Configured by setting GITHUB_WEBHOOK_SECRET in Secrets Manager.

Filtering (2026-04-27): no author filter. Per Gib's principle — "any pr where both reviewers are green, we should merge — why wouldn't we" — code quality is the gate, not author identity. Two genuinely different model families (Platform EM Claude + Code Judgment Codex) agreeing IS the multi-eye guarantee. Draft PRs are skipped — that is the work-in-progress opt-out.