Handled it: declined to negotiate when only the classical X25519 was offered, which is a deliberate post-quantum floor. No RFC requires this and none forbids it.
The client did what the clause requires.
What was measured
- Client
- quinn — quinn + h3 (our fork), noq fork
- Test
- Server negotiates only classical X25519 against a hybrid offer —
t-classical-only - Clause
- RFC 8446 §4.1.1, draft-ietf-tls-hybrid-design §5 (MAY)
- Class
- discretionary — The RFC permits either behaviour; the report says which was chosen.
- Required behaviour
- Either outcome is conformant and the report says which was taken. A client that proceeds has chosen availability: the connection is classically secure and it accepted that. A client that refuses has chosen a post-quantum floor, which is a policy some deployments now require and no RFC yet mandates. No grade is attached, because attaching one would invent a requirement. What is worth knowing is that the answer is a deliberate choice rather than an accident, and today most clients cannot express it either way.
- Measured
- 2026-09-18
Reproduce it
The suite is the judge, so the reproduction is to point the same client at the same test and let the server report what it saw.
SESSION=$(curl -sX POST https://conformance.pqcrypta.com/session | jq -r .id)
# then drive quinn at the test URL and read the verdict:
curl -s https://conformance.pqcrypta.com/report/$SESSION.json | jq '.results["t-classical-only"]'