feat: add Retry button for failed model downloads in download manager

Author: NeuralFault

StabilityMatrix.Avalonia/ViewModels/Base/PausableProgressItemViewModelBase.cs

@@ -14,7 +14,8 @@ public abstract partial class PausableProgressItemViewModelBase : ProgressItemVi
         nameof(IsPaused),
         nameof(IsCompleted),
         nameof(CanPauseResume),
-        nameof(CanCancel)
+        nameof(CanCancel),
+        nameof(CanRetry)
     )]
     private ProgressState state = ProgressState.Inactive;
 
@@ -33,9 +34,20 @@ public abstract partial class PausableProgressItemViewModelBase : ProgressItemVi
     public virtual bool SupportsPauseResume => true;
     public virtual bool SupportsCancel => true;
 
+    /// <summary>
+    /// Override to true in subclasses that support manual retry after failure.
+    /// Defaults to false so unrelated progress item types are never affected.
+    /// </summary>
+    public virtual bool SupportsRetry => false;
+
     public bool CanPauseResume => SupportsPauseResume && !IsCompleted && !IsPending;
     public bool CanCancel => SupportsCancel && !IsCompleted;
 
+    /// <summary>
+    /// True only when this item supports retry AND is in the Failed state.
+    /// </summary>
+    public bool CanRetry => SupportsRetry && State == ProgressState.Failed;
+
     private AsyncRelayCommand? pauseCommand;
     public IAsyncRelayCommand PauseCommand => pauseCommand ??= new AsyncRelayCommand(Pause);
 
@@ -51,6 +63,11 @@ public abstract partial class PausableProgressItemViewModelBase : ProgressItemVi
 
     public virtual Task Cancel() => Task.CompletedTask;
 
+    private AsyncRelayCommand? retryCommand;
+    public IAsyncRelayCommand RetryCommand => retryCommand ??= new AsyncRelayCommand(Retry);
+
+    public virtual Task Retry() => Task.CompletedTask;
+
     [RelayCommand]
     private Task TogglePauseResume()
     {

StabilityMatrix.Avalonia/ViewModels/Progress/DownloadProgressItemViewModel.cs

@@ -71,6 +71,11 @@ private void OnProgressStateChanged(ProgressState state)
         }
     }
 
+    /// <summary>
+    /// Downloads support manual retry when they reach the Failed state.
+    /// </summary>
+    public override bool SupportsRetry => true;
+
     /// <inheritdoc />
     public override Task Cancel()
     {
@@ -91,4 +96,13 @@ public override Task Resume()
     {
         return downloadService.TryResumeDownload(download);
     }
+
+    /// <inheritdoc />
+    /// Resets the internal retry counter so the user gets a fresh 3-attempt budget,
+    /// then re-queues the download exactly as if it were being resumed from pause.
+    public override Task Retry()
+    {
+        download.ResetAttempts();
+        return downloadService.TryResumeDownload(download);
+    }
 }

StabilityMatrix.Avalonia/Views/ProgressManagerPage.axaml

@@ -113,6 +113,15 @@
                                         IsVisible="{Binding CanCancel}">
                                         <ui:SymbolIcon Symbol="Cancel" />
                                     </Button>
+
+                                    <!--  Retry button: only visible when download is in Failed state  -->
+                                    <Button
+                                        Classes="transparent-full"
+                                        Command="{Binding RetryCommand}"
+                                        IsVisible="{Binding CanRetry}"
+                                        ToolTip.Tip="Retry download">
+                                        <ui:SymbolIcon Symbol="ArrowCounterclockwise" />
+                                    </Button>
                                 </StackPanel>
 
                                 <ProgressBar

StabilityMatrix.Core/Models/TrackedDownload.cs

@@ -423,6 +423,16 @@ private void OnDownloadTaskCompleted(Task task)
         downloadPauseTokenSource = null;
     }
 
+    /// <summary>
+    /// Resets the internal retry attempt counter back to zero.
+    /// Call this before a user-initiated retry so the download gets
+    /// a fresh budget of automatic retries on the new attempt.
+    /// </summary>
+    public void ResetAttempts()
+    {
+        attempts = 0;
+    }
+
     public void SetDownloadService(IDownloadService service)
     {
         downloadService = service;