A requirement the spck.dev suite checks on UCP servers. The quoted text is the normative requirement; the citation links to the exact line of the pinned spec source it was taken from.
2026-04-08:
Signal keys must match the reverse-domain identifier pattern (well-known dev.ucp namespace; extensions use their own)
2026-08-25:
Reverse-domain identifiers (signal keys, eligibility claims, purpose keys, etc.) MUST match the shared reverse_domain_name.json pattern, now extended to allow hyphens, digit-led later segments, and punycode TLDs
A deviation on a MUST fails the run and shows the requirement next to the actual response. Checks the suite cannot validate soundly are reported inconclusive or not-tested — never a silent pass. The full verdict semantics are on the grading rubric.
The hosted check covers the read-only surface; the CLI and GitHub Action run the full suite, including this check when your store declares the capability it belongs to.