PASS new event: HTTP 201 stored
PASS identical replay: HTTP 200 duplicate
PASS wrong token: HTTP 403 rejected-token
PASS missing identity: HTTP 400 missing-or-extra-field
PASS unexpanded variable: HTTP 400 invalid-event
PASS changed same-key event: HTTP 409 conflict
PASS receiver restart: replay remains duplicate; ledger still has one row
PASS 7 loopback HTTP cases; no VICIdial event or CRM request was sent