fix(server): single-clock poll loop + drop dead sync GetReadyWorkerClient (Task 8 review)

src/ZB.MOM.WW.MxGateway.Server/Sessions/GatewaySession.cs

@@ -1672,34 +1672,7 @@ public sealed class GatewaySession
     }
 
     /// <summary>
-    ///     Returns the worker client iff both the gateway-side session state AND
-    ///     the worker client's own state are <see cref="SessionState.Ready"/> /
-    ///     <see cref="WorkerClientState.Ready"/>. The two states can diverge under
-    ///     load: <c>_state</c> only transitions on gateway-driven events (open,
-    ///     close, fault), while <see cref="WorkerClient.State"/> can shift on
-    ///     worker-side signals (heartbeat watchdog, pipe disconnect) before the
-    ///     gateway's session-level reaction observes them. When that happens the
-    ///     in-flight RPC fails fast here with both states surfaced in the
-    ///     diagnostic (Server-030) so the actual mismatch is actionable instead
-    ///     of misleading. The session usually transitions to <c>Faulted</c>
-    ///     shortly after.
-    /// </summary>
-    private IWorkerClient GetReadyWorkerClient()
-    {
-        lock (_syncRoot)
-        {
-            IWorkerClient? ready = EvaluateReadyUnderLock(out string? failureMessage);
-            if (ready is not null)
-            {
-                return ready;
-            }
-
-            throw new SessionManagerException(SessionManagerErrorCode.SessionNotReady, failureMessage!);
-        }
-    }
-
-    /// <summary>
-    ///     Bounded, opt-in async variant of <see cref="GetReadyWorkerClient"/>. When the
+    ///     Bounded, opt-in async variant of the fail-fast readiness check. When the
     ///     session is <see cref="SessionState.Ready"/> but the worker has transiently diverged
     ///     to a non-terminal state (<see cref="WorkerClientState.Handshaking"/>/
     ///     <see cref="WorkerClientState.Created"/>) and the configured worker-ready wait timeout
@@ -1742,7 +1715,11 @@ public sealed class GatewaySession
         DateTimeOffset deadline = _eventStreaming.TimeProvider.GetUtcNow() + _workerReadyWaitTimeout;
         while (true)
         {
-            await Task.Delay(pollIntervalMs, cancellationToken).ConfigureAwait(false);
+            await Task.Delay(
+                    TimeSpan.FromMilliseconds(pollIntervalMs),
+                    _eventStreaming.TimeProvider,
+                    cancellationToken)
+                .ConfigureAwait(false);
 
             lock (_syncRoot)
             {