These buttons fire mock GA4 hits at google-analytics.com/g/collect.
The real request to Google will fail (expected) — what matters is that the
collector captures a copy and POSTs it to ingest. Watch the Network tab for
the ingest POST, then check Firestore.
Failed requests: Failing request sends a fetch and an XHR to
/wt-probe-missing. The test server answers 404 (expect two
http_error docs with status 404 and no hint). If the request
is blocked or the browser is offline, expect status 0 and a hint.
Fire and leave sends a fetch to an address that never answers, and
then opens about:blank.
Load order modes: ?siteId=…&preload=1 fires a page_view
before injecting the collector (expect partialCapture:true on the
health doc and an event with transport:"observer");
&consent=1 pushes a Consent Mode default before load (expect
consentPending:true).
Health report: the full report goes about 3 s after the start. If you close
or hide the tab before that, the collector sends an Early report (expect
early:true on the health doc). A full report has no
early key.