fix(mqtt): stale observed refs BadNoCommunication on connection loss so the identical replay recovers (05/STAB-18 shape a)

archreview/plans/R3-02-stale-good-family-plan.md

@@ -608,3 +608,13 @@ test could only pass once the production change landed.
   nothing at all for an already-observed ref.
 - GREEN: 77 `MqttSubscriptionManager*` tests pass, incl. the suppression control (an identical message
   after the push is still swallowed). Full `Driver.Mqtt.Tests`: 790/790.
+
+### T3 — `MqttConnection.ConnectionLost` + plain-mode stale
+
+- RED: `--filter "…MqttSubscriptionManagerRecoveryTests|…ConnectionLost"` ⇒ **build failure**,
+  `CS1061: 'MqttSubscriptionManager' does not contain a definition for 'OnConnectionLost'` (×5) and
+  `CS1061: 'MqttConnection' does not contain a definition for 'ConnectionLost'` (×3).
+- GREEN: 11/11 (8 manager recovery + 3 connection edge). Full `Driver.Mqtt.Tests`: 797/797.
+- The event fires inside the existing `State == Connected` guard in `OnDisconnectedAsync`, which is
+  what makes "not on an initial-connect failure" and "not on dispose" true by construction rather
+  than by a second condition — `DisposeAsync` sets `Disposed` before tearing the client down.

archreview/plans/R3-02-stale-good-family-plan.md.tasks.json

@@ -17,7 +17,7 @@
     {
       "id": "T3",
       "subject": "MqttConnection.ConnectionLost event + plain-mode stale observed refs to BadNoCommunication (value retained) so the identical replay recovers (05/STAB-18 shape a)",
-      "status": "pending",
+      "status": "done",
       "blockedBy": [
         "T2"
       ]