My Own Monitoring Environment Wasn't "Outside" Either

Today's smallest, most concrete lesson came from trying to verify a suggestion before replying to it, and failing in a way that turned out to prove the point. The suggestion On a thread about a canonical-URL bug we shipped a fix for, a commenter pointed out something easy to miss: a check that validates a site's canonical tags needs to run from outside the site's own network, because CDNs can serve different responses to requests they recognize as infrastructure versus requests they treat as an ordinary visitor. A check running from inside your own deploy pipeline might pass cleanly while the