feat: upgrade-aware snapshots — surface RemovedFiles/Keys in UI and CLI

Author: SysAdminDoc

src/DeepPurge.App/ViewModels/MainViewModel.Extensions.cs

@@ -328,9 +328,16 @@ private async Task RunWinapp2Async()
             var delta = await new InstallSnapshotEngine().TraceInstallAsync(programName, installerPath, args);
             _dispatcher.Invoke(() =>
             {
-                SnapshotStatus = $"{programName}: +{delta.AddedFiles.Count} files, " +
-                                 $"+{delta.AddedRegistryKeys.Count} keys, " +
-                                 $"+{FormatSize(delta.TotalAddedBytes)}";
+                var parts = new List<string>
+                {
+                    $"+{delta.AddedFiles.Count} files (+{FormatSize(delta.TotalAddedBytes)})",
+                    $"+{delta.AddedRegistryKeys.Count} keys"
+                };
+                if (delta.RemovedFiles.Count > 0)
+                    parts.Add($"-{delta.RemovedFiles.Count} removed files");
+                if (delta.RemovedRegistryKeys.Count > 0)
+                    parts.Add($"-{delta.RemovedRegistryKeys.Count} removed keys");
+                SnapshotStatus = $"{programName}: {string.Join(", ", parts)}";
             });
             return delta;
         }

src/DeepPurge.Cli/Program.cs

@@ -314,10 +314,11 @@ private static async Task<int> CmdSnapshotAsync(ParsedArgs a, CancellationToken
 
         var engine = new InstallSnapshotEngine();
         var delta = await engine.TraceInstallAsync(name, installer, extraArgs, ct);
-        Console.WriteLine($"Added files: {delta.AddedFiles.Count} ({FormatBytes(delta.TotalAddedBytes)})");
-        Console.WriteLine($"Added regkeys: {delta.AddedRegistryKeys.Count}");
-        Console.WriteLine($"Removed files: {delta.RemovedFiles.Count}");
-        Console.WriteLine($"Removed regkeys: {delta.RemovedRegistryKeys.Count}");
+        if (delta.IsUpgrade) Console.WriteLine("[upgrade detected — showing diff against prior version]");
+        Console.WriteLine($"Added files:      {delta.AddedFiles.Count,5} ({FormatBytes(delta.TotalAddedBytes)})");
+        Console.WriteLine($"Added regkeys:    {delta.AddedRegistryKeys.Count,5}");
+        Console.WriteLine($"Removed files:    {delta.RemovedFiles.Count,5}");
+        Console.WriteLine($"Removed regkeys:  {delta.RemovedRegistryKeys.Count,5}");
         return 0;
     }
 

src/DeepPurge.Core/InstallMonitor/InstallSnapshotEngine.cs

@@ -25,6 +25,7 @@ public class InstallDelta
     public List<string>        RemovedFiles       { get; set; } = new();
     public List<string>        RemovedRegistryKeys{ get; set; } = new();
     public long TotalAddedBytes => AddedFiles.Sum(f => f.SizeBytes);
+    public bool IsUpgrade => RemovedFiles.Count > 0 || RemovedRegistryKeys.Count > 0;
 }
 
 /// <summary>