Fix UI thread deadlock in fleet alert acknowledgment

- Acknowledgment now marks locally first, then posts to server in background
- Status check timer runs async properly without blocking UI thread
- Both changes use Task.Run to avoid .GetAwaiter().GetResult() deadlocks
- Bump tray to 1.6.4, agent to 1.13.3

agent/ShopDbEndpointAgent.Tray/FleetAlertForm.cs

@@ -68,26 +68,33 @@ internal sealed class FleetAlertForm : Form
         statusCheckTimer.Start();
     }
 
-    private async void StatusCheckTimer_Tick(object? sender, EventArgs e)
+    private void StatusCheckTimer_Tick(object? sender, EventArgs e)
     {
         if (client == null || hostname == null)
             return;
 
-        try
+        Task.Run(async () =>
         {
-            var alerts = await client.FetchAlertsAsync(hostname, CancellationToken.None);
+            try
-            var stillActive = alerts?.Any(a => a.NotificationId == alert.NotificationId) ?? false;
-
-            if (!stillActive)
             {
-                statusCheckTimer?.Stop();
+                var alerts = await client.FetchAlertsAsync(hostname, CancellationToken.None)
-                Close();
+                    .ConfigureAwait(false);
+                var stillActive = alerts?.Any(a => a.NotificationId == alert.NotificationId) ?? false;
+
+                if (!stillActive)
+                {
+                    BeginInvoke(new Action(() =>
+                    {
+                        statusCheckTimer?.Stop();
+                        Close();
+                    }));
+                }
             }
-        }
+            catch
-        catch
+            {
-        {
+                // Ignore errors - keep the form open if we can't check status
-            // Ignore errors - keep the form open if we can't check status
+            }
-        }
+        });
     }
 
     private void ApplyRoundedCorners()

agent/ShopDbEndpointAgent.Tray/FleetAlertWorker.cs

@@ -159,24 +159,25 @@ internal sealed class FleetAlertWorker : IDisposable
 
     private void OnAlertAcknowledged(FleetAlert alert, CancellationToken token)
     {
-        try
+        logger.LogInformation(
-        {
+            "Fleet alert {NotificationId} acknowledged; queuing server post.", alert.NotificationId);
-            logger.LogInformation(
-                "Fleet alert {NotificationId} acknowledged; posting to server.", alert.NotificationId);
 
-            client.AcknowledgeAlertAsync(alert.NotificationId, assetId, hostname, token)
+        store.MarkAcknowledged(alert.NotificationId);
-                .GetAwaiter()
-                .GetResult();
 
-            store.MarkAcknowledged(alert.NotificationId);
+        Task.Run(async () =>
-            logger.LogInformation("Fleet alert {NotificationId} recorded.", alert.NotificationId);
-        }
-        catch (Exception exception)
         {
-            logger.LogWarning(exception,
+            try
-                "Could not acknowledge fleet alert {NotificationId}; will retry on next poll.",
+            {
-                alert.NotificationId);
+                await client.AcknowledgeAlertAsync(alert.NotificationId, assetId, hostname, token);
-        }
+                logger.LogInformation("Fleet alert {NotificationId} posted to server.", alert.NotificationId);
+            }
+            catch (Exception exception)
+            {
+                logger.LogWarning(exception,
+                    "Could not post acknowledgment for fleet alert {NotificationId}; already marked locally.",
+                    alert.NotificationId);
+            }
+        });
     }
 
     public void Dispose()

agent/ShopDbEndpointAgent.Tray/ShopDbEndpointAgent.Tray.csproj

@@ -79,7 +79,10 @@
 	<!-- 1.6.3: auto-close when notification becomes inactive. Fleet alert forms now
 	     check every 30 seconds if the notification is still active on the server and
 	     automatically close if it has ended or been deactivated. -->
-	<Version>1.6.3</Version>
+	<!-- 1.6.4: fix UI thread deadlock. Acknowledgment and status checks now run async
+	     properly without blocking the UI thread. Acknowledgment is marked locally first,
+	     then posted to server in background to prevent lockups. -->
+	<Version>1.6.4</Version>
 	<InvariantGlobalization>true</InvariantGlobalization>
 	<RuntimeIdentifier>win-x64</RuntimeIdentifier>
 	<SelfContained>true</SelfContained>

agent/ShopDbEndpointAgent/ShopDbEndpointAgent.csproj

@@ -175,7 +175,9 @@
 	     No agent code changes, but deployed together for version consistency. -->
 	<!-- 1.13.2: coordinated release with tray 1.6.3 (auto-close when inactive, crash fix).
 	     No agent code changes, but deployed together for version consistency. -->
-	<Version>1.13.2</Version>
+	<!-- 1.13.3: coordinated release with tray 1.6.4 (deadlock fix).
+	     No agent code changes, but deployed together for version consistency. -->
+	<Version>1.13.3</Version>
 	<InvariantGlobalization>true</InvariantGlobalization>
 	<RuntimeIdentifier>win-x64</RuntimeIdentifier>
 	<SelfContained>true</SelfContained>