Heartbeat

Liveness ping/pong — HeartbeatPartitionDetector.

The odd one out: heartbeat declares a String prefix ("kuilt.heartbeat.ping") whose first byte happens to be 0x6b, and :kuilt-liveness cannot depend on :kuilt-session to derive from here. The reservation is one-directional and pinned by test, not by construction.

classifies is therefore much narrower than matches — the real test is the whole string, so every ordinary payload beginning with k ("keepalive", "key", …) claims this byte while being a perfectly ordinary application frame.