Adversarial review: survived a hostile reviewer plus two independent refuters, each told to assume the PR was broken and to default to refuting when uncertain. 19 of 62 PRs cleared that bar.
The back-link validator compared bare slugs, so a same-slug page in another source masked a genuinely missing reverse edge — silent under-reporting in exactly the multi-source setup where it matters. Now keyed on the full 4-tuple, per the `(source_id, slug)` uniqueness invariant. Verified on real Docker Postgres with 28/28 parity, which the PR itself had skipped.
Verified before merge: the PR's own tests fail when the production change is reverted; typecheck clean; MERGEABLE/CLEAN on the current base after batches 1 and 2 landed, not a stale one.
Known gap, recorded rather than hidden: remote MCP serialization of the additive Link fields is untested; the fields are additive JSON.