feat: add unloading of AgentClient on switch

src/paradigm-ehb.CommandCenter.Core/Models/AgentClient.cs

@@ -8,7 +8,7 @@
 
 namespace paradigm_ehb.CommandCenter.Core.Models
 {
-    public sealed class AgentClient : IDisposable
+    public sealed class AgentClient : IDisposable, IAsyncDisposable
     {
         private bool disposedValue;
         private AgentHealthWatcher? _healthWatcher;
@@ -16,19 +16,19 @@
         /// <summary>
         /// Gets or sets the network endpoint information for the agent connection.
         /// </summary>
         public AgentEndpoint Endpoint { get; set; }
 
         public GrpcChannel Channel { get; init; }
 
         public Health.HealthClient Health { get; init; }
 
         public Greeter.GreeterClient Greeter { get; init; }
 
         public JournalService.JournalServiceClient Journal { get; init; }
 
         public HandlerService.HandlerServiceClient Service { get; init; }
 
         public ResourcesService.ResourcesServiceClient Resources { get; init; }
 
         public bool HealthWatchEnabled { get; set; } = true;
 
@@ -63,6 +63,7 @@
                     {
                         StopHealthWatch();
                         _healthWatcher?.Dispose();
+                        Channel.ShutdownAsync().Wait();
                         Channel?.Dispose();
                     }
                     catch
@@ -77,7 +78,33 @@
         public void Dispose()
         {
             Dispose(disposing: true);
-            GC.SuppressFinalize(this);
+        }
+
+        private async Task DisposeAsync(bool disposing)
+        {
+            if (!disposedValue)
+            {
+                if (disposing)
+                {
+                    try
+                    {
+                        StopHealthWatch();
+                        _healthWatcher?.Dispose();
+                        await Channel.ShutdownAsync().ConfigureAwait(false);
+                        Channel?.Dispose();
+                    }
+                    catch
+                    {
+                        // ignore
+                    }
+                }
+                disposedValue = true;
+            }
+        }
+
+        public async ValueTask DisposeAsync()
+        {
+            await DisposeAsync(true);
         }
     }
 }

src/paradigm-ehb.CommandCenter.WinUI/srvMgnt/ServerMainPage.xaml.cs

@@ -38,6 +38,15 @@ protected override void OnNavigatedTo(NavigationEventArgs e)
             _ = InitializeForNavigationAsync(e);
         }
 
+        protected override async void OnNavigatedFrom(NavigationEventArgs e)
+        {
+            base.OnNavigatedFrom(e);
+
+            AgentClient? agentClient = await _agentClientRegistry.GetAsync(serverObj.Id);
+            if (agentClient is not null) await agentClient.DisposeAsync();
+            await _agentClientRegistry.DeregisterAsync(serverObj.Id);
+        }
+
         private async Task InitializeForNavigationAsync(NavigationEventArgs e)
         {
             try

src/paradigm-ehb.CommandCenter.WinUI/srvMgnt/Views/ServicesPage.xaml.cs

@@ -360,7 +360,8 @@ private async Task LoadAllServices(CancellationToken cancellationToken = default
             GetUnitsReply? response = await client.Service.GetAllUnitsAsync(request: new GetUnitsRequest(), cancellationToken: cancellationToken);
             if (response is null)
             {
-                throw new InvalidOperationException("Received null response from ActionAsync.");
+                await ShowErrorInfoBarAsync("Failed to retrieve services: received null response from agent.");
+                return;
             }
 
             foreach (LoadedUnit? unit in response.Units)