fix(auditlog): do not log a graceful-stop OperationCanceledException at Error in the telemetry drains (review 2026-10-21 06/COR-2)

src/ZB.MOM.WW.ScadaBridge.AuditLog/Site/Telemetry/SiteAuditTelemetryActor.cs

@@ -163,8 +163,8 @@ public class SiteAuditTelemetryActor : ReceiveActor
         // Route every async dependency call through the
         // per-actor lifecycle token so PostStop cancellation actually
         // propagates into the queue read, the gRPC push, and the
-        // mark-forwarded write. OperationCanceledException is swallowed by
+        // mark-forwarded write. A shutdown-driven OperationCanceledException is
-        // the catch-all below.
+        // swallowed silently by the dedicated catch below.
         var ct = _lifecycleCts.Token;
         try
         {
@@ -204,6 +204,12 @@ public class SiteAuditTelemetryActor : ReceiveActor
                     .ConfigureAwait(false);
             }
         }
+        catch (OperationCanceledException) when (ct.IsCancellationRequested)
+        {
+            // Graceful stop: PostStop cancelled the lifecycle token while the drain
+            // was awaiting the queue / gRPC push. Expected on every orderly shutdown or
+            // failover — not an error (review 2026-10-21 06/COR-2).
+        }
         catch (Exception ex)
         {
             // Catch-all so a SQLite hiccup or mapper bug never crashes the
@@ -382,6 +388,10 @@ public class SiteAuditTelemetryActor : ReceiveActor
                     .ConfigureAwait(false);
             }
         }
+        catch (OperationCanceledException) when (ct.IsCancellationRequested)
+        {
+            // Graceful stop mid-drain — see OnDrainAsync (review 2026-10-21 06/COR-2).
+        }
         catch (Exception ex)
         {
             _logger.LogError(ex,

tests/ZB.MOM.WW.ScadaBridge.AuditLog.Tests/Site/Telemetry/SiteAuditTelemetryActorTests.cs

@@ -717,4 +717,47 @@ public class SiteAuditTelemetryActorTests : TestKit
             }, TimeSpan.FromSeconds(10));
         });
     }
+
+    /// <summary>
+    /// Review 2026-10-21 06/COR-2: a graceful stop while a drain is parked on its
+    /// queue read surfaces as an <see cref="OperationCanceledException"/>; it must not
+    /// be logged at Error ("Unexpected error during ... drain") on every orderly shutdown.
+    /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
+    [Fact]
+    public async Task GracefulStop_MidDrain_DoesNotLogError()
+    {
+        var reads = new System.Collections.Concurrent.ConcurrentQueue<int>();
+        async Task<IReadOnlyList<AuditEvent>> Parked(CancellationToken ct)
+        {
+            reads.Enqueue(1);
+            await Task.Delay(Timeout.Infinite, ct).ConfigureAwait(false);
+            return Array.Empty<AuditEvent>();
+        }
+        _queue.ReadPendingAsync(Arg.Any<int>(), Arg.Any<CancellationToken>())
+            .Returns(c => Parked(c.Arg<CancellationToken>()));
+        _queue.ReadPendingCachedTelemetryAsync(Arg.Any<int>(), Arg.Any<CancellationToken>())
+            .Returns(c => Parked(c.Arg<CancellationToken>()));
+
+        var logger = new CapturingLogger<SiteAuditTelemetryActor>();
+        var actor = Sys.ActorOf(Props.Create(() => new SiteAuditTelemetryActor(
+            _queue, _client, Opts(), logger, (IOperationTrackingStore?)_trackingStore)));
+
+        await AwaitConditionAsync(() => Task.FromResult(reads.Count >= 1), TimeSpan.FromSeconds(10));
+        Watch(actor);
+        Sys.Stop(actor);
+        await ExpectTerminatedAsync(actor);
+        await Task.Delay(300);
+
+        Assert.DoesNotContain(logger.Levels, l => l >= Microsoft.Extensions.Logging.LogLevel.Error);
+    }
+
+    private sealed class CapturingLogger<T> : Microsoft.Extensions.Logging.ILogger<T>
+    {
+        public System.Collections.Concurrent.ConcurrentQueue<Microsoft.Extensions.Logging.LogLevel> Levels { get; } = new();
+        public IDisposable? BeginScope<TState>(TState state) where TState : notnull => null;
+        public bool IsEnabled(Microsoft.Extensions.Logging.LogLevel logLevel) => true;
+        public void Log<TState>(Microsoft.Extensions.Logging.LogLevel logLevel, Microsoft.Extensions.Logging.EventId eventId,
+            TState state, Exception? exception, Func<TState, Exception?, string> formatter) => Levels.Enqueue(logLevel);
+    }
 }