The engine's own health dashboard, published: the quality-assurance self-test that gates every morning's site publish, per-source data freshness for every connector (BLS, EIA, Zillow, AAA and the rest), and the timestamp of the last successful publish.
A data site should show its plumbing. If a source stalls or a check fails, it appears here before anyone has to ask — and the publish gate holds the last good snapshot live rather than shipping a wrong number. Transparency about failures is part of the methodology.
Zillow data: Data Provided by Zillow Group.