CI / build (pull_request) Successful in 1m8s
CI / lint (pull_request) Successful in 1m23s
CI / unit (pull_request) Successful in 1m23s
CI / frontend (pull_request) Successful in 2m59s
CI / mutation (pull_request) Successful in 6m8s
CI / verify-stack (pull_request) Failing after 7m24s
CI caught my own check falling into the constraint ADR-0028 documents: it looked Objecttypen up by container IP, so the objecttype URL came back IP-addressed and Objecten rejected it as "not one of the available choices". Reach both by service name — compose DNS resolves them, and neither request has OpenZaak's URL-validity constraint that made IPs necessary elsewhere in this script. The 400 also spent the full 60s timeout disguised as "transport:" because HTTPError is a URLError subclass. Handle it separately: a 4xx now fails immediately with the response body, which is where the real reason was. Verified both ways against a live Objecten: absent record → exit 1 with the reason, present record → exit 0.