WriteAsync published one awaited QoS 1 round-trip per request, so 50 writes to a
stalled broker cost 50 publish deadlines. Different topics now publish concurrently
(at most 8 in flight); same-topic writes stay in request order. A caller cancel still
fills every slot. A successful publish advances LastSuccessfulRead. MiniBroker now
frames packets properly and records/PUBACKs PUBLISHes.
Refs #744
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
A failed SUBSCRIBE (refusal or no broker verdict) used to drop its topic from every
retry set while SubscribeAsync returned a live handle, leaving tags dark behind a
Healthy connection until a redeploy. Failed topics now join a pending set retried by
the next SubscribeAsync and by every reconnect (not counted toward the reconnect's
total-failure verdict, so an ACL-denied topic cannot reconnect-loop). A no-verdict
subscribe degrades its refs then throws so the actor's reconcile re-subscribes. A
subscribe with no transport attached is recorded pending, never established (M-11).
MiniBroker now answers SUBSCRIBE.
Refs #744
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
MQTTnet 5 does not throw on an unsuccessful CONNACK — it returns the reason in
MqttClientConnectResult.ResultCode and v5 removed v4's ThrowOnNonSuccessfulConnectResponse,
so ConnectCoreAsync's unconditional SetState(Connected) sealed a wrong-password deployment
green: DriverState.Healthy / HostState.Running on a session that never authenticated.
Caught by the Task-13 Mosquitto fixture; 240 offline tests missed it.
ConnectCoreAsync now inspects the CONNACK and raises MqttConnectRejectedException.
Credentials/identity/protocol/Last-Will refusals are unrecoverable and set Faulted, which
stops the reconnect supervisor; transient refusals (ServerUnavailable, ServerBusy,
QuotaExceeded, UseAnotherServer, ConnectionRateExceeded, and anything unrecognised) stay
Reconnecting under backoff. MqttDriverProbe now shares the rejection wording, so the
AdminUI Test-connect button and the running driver can no longer disagree.
Claude-Session: https://claude.ai/code/session_01GASWkNEi68FSCtvr6rLoEW
Joseph Doherty