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
Closes the connect-vs-connect defect: MQTTnet throws (and raises no DisconnectedAsync)
on a connect-while-connected, so a caller's ConnectAsync and the reconnect supervisor
corrupted each other in both directions. Both paths now check first; when the supervisor
finds the session already restored it stands down WITHOUT firing Reconnected.
Reconnected becomes Func<CancellationToken, Task>, fed from the lifetime token and capped
at ConnectTimeoutSeconds, so a hung re-subscribe can no longer park the supervisor.
Connected is published only after the re-subscribe succeeds; a supervisor that dies now
reports Faulted instead of Reconnecting forever.
Claude-Session: https://claude.ai/code/session_01GASWkNEi68FSCtvr6rLoEW
Review follow-ups on MqttConnection (Task 3):
- Every certificate test asserted rejection, so the accept branch was
unreachable-by-regression. Adds a leaf genuinely issued by the pinned CA and
asserts acceptance.
- ValidateAgainstPinnedCa never seeded ChainPolicy.ExtraStore from the incoming
chain, so a leaf behind an intermediate delivered during the handshake failed
despite a legitimate path to the pinned root. Seeds from both the incoming
chain's elements and its ExtraStore; CustomRootTrust still means only the
pinned roots may terminate the chain.
- A DisposeAsync racing an in-flight connect escaped as an unclassified
exception; it now folds into ObjectDisposedException.
- Promotes the single-caller concurrency invariant into the type remarks, with
the accurate blast radius (a leaked live connection, not a benign throw).
Serialising the lifecycle remains Task 4's job.
- X509Chain.Build can throw; an exception escaping a TLS validation callback is
an opaque handshake crash, so it is caught and refused.
- Adds a connect-retry test (Task 4's reconnect loop reuses the instance) and a
disposed-then-connect test.
Claude-Session: https://claude.ai/code/session_01GASWkNEi68FSCtvr6rLoEW
Joseph Doherty