Update WinGet catalog snapshot and ensure successful index refresh

src/UniGetUI.PackageEngine.Managers.WinGet/ClientHelpers/NativeWinGetHelper.cs

@@ -448,19 +448,27 @@ nativePackage.AvailableVersions is { } versions
 
     private IReadOnlyList<CatalogPackage> GetCachedLocalWinGetPackages(int? cacheSeconds = null)
     {
-        if (_localPackagesProvider is not null)
-        {
-            return _localPackagesProvider();
-        }
+        long sourceIndexGeneration = WinGet.SourceIndexGeneration;
 
         return cacheSeconds is null
-            ? TaskRecycler<IReadOnlyList<CatalogPackage>>.RunOrAttach(GetLocalWinGetPackages)
+            ? TaskRecycler<IReadOnlyList<CatalogPackage>>.RunOrAttach(
+                EnumerateLocalWinGetPackages,
+                sourceIndexGeneration
+            )
             : TaskRecycler<IReadOnlyList<CatalogPackage>>.RunOrAttach(
-                GetLocalWinGetPackages,
+                EnumerateLocalWinGetPackages,
+                sourceIndexGeneration,
                 cacheSeconds.Value
             );
     }
 
+    private IReadOnlyList<CatalogPackage> EnumerateLocalWinGetPackages(long sourceIndexGeneration)
+    {
+        return _localPackagesProvider is not null
+            ? _localPackagesProvider()
+            : GetLocalWinGetPackages();
+    }
+
     private IReadOnlyList<Package> GetAvailableUpdatesFromSystemCli(Exception ex)
     {
         var unwrappedException = UnwrapException(ex);

src/UniGetUI.PackageEngine.Managers.WinGet/WinGet.cs

@@ -92,6 +92,13 @@ public void Dispose()
             }
         }
 
+        private static long _sourceIndexGeneration;
+
+        internal static long SourceIndexGeneration => Volatile.Read(ref _sourceIndexGeneration);
+
+        internal static void MarkSourceIndexRefreshed() =>
+            Interlocked.Increment(ref _sourceIndexGeneration);
+
         public WinGet()
         {
             Capabilities = new ManagerCapabilities
@@ -811,12 +818,19 @@ public override void RefreshPackageIndexes()
                 p.StartInfo.Environment["TMP"] = WinGetTemp;
             }
 
-            p.Start();
-            logger.AddToStdOut(p.StandardOutput.ReadToEnd());
-            logger.AddToStdErr(p.StandardError.ReadToEnd());
-            logger.Close(p.ExitCode);
-            p.WaitForExit();
-            p.Close();
+            try
+            {
+                p.Start();
+                logger.AddToStdOut(p.StandardOutput.ReadToEnd());
+                logger.AddToStdErr(p.StandardError.ReadToEnd());
+                logger.Close(p.ExitCode);
+                p.WaitForExit();
+                p.Close();
+            }
+            finally
+            {
+                MarkSourceIndexRefreshed();
+            }
         }
 
         private string GetCliToolProxyArgument()

src/UniGetUI.PackageEngine.PackageManagerClasses/Manager/PackageManager.cs

@@ -463,7 +463,10 @@ private IReadOnlyList<IPackage> _getAvailableUpdates(bool SecondAttempt)
             }
             try
             {
-                RefreshPackageIndexesSafely();
+                if (!SecondAttempt)
+                {
+                    RefreshPackageIndexesSafely();
+                }
 
                 var packages = RunListingTaskWithTimeout(
                     GetAvailableUpdates_UnSafe,

src/UniGetUI.PackageEngine.Tests/PackageManagerTests.cs

@@ -266,7 +266,7 @@ public void FindPackagesRetriesOnceAfterFailure()
     }
 
     [Fact]
-    public void GetAvailableUpdatesRetriesOnceAndRefreshesIndexesPerAttempt()
+    public void GetAvailableUpdatesRetriesOnceWithoutRefreshingIndexesAgain()
     {
         var manager = CreateReadyManager();
         var attempts = 0;
@@ -283,7 +283,7 @@ public void GetAvailableUpdatesRetriesOnceAndRefreshesIndexesPerAttempt()
         var package = Assert.Single(packages);
         Assert.Equal("Contoso.Update", package.Id);
         Assert.Equal(1, manager.AttemptFastRepairCalls);
-        Assert.Equal(2, manager.RefreshPackageIndexesCalls);
+        Assert.Equal(1, manager.RefreshPackageIndexesCalls);
     }
 
     [Fact]

src/UniGetUI.PackageEngine.Tests/WinGetManagerTests.cs

@@ -735,6 +735,65 @@ public void NativeWinGetHelperUsesSystemCliFallbackForUpdatesWhenCompositeCatalo
         Assert.Equal("2.0.0", package.NewVersionString);
     }
 
+    [Fact]
+    public void NativeWinGetHelperTakesANewCatalogSnapshotAfterTheSourceIndexIsRefreshed()
+    {
+        WinGet.MarkSourceIndexRefreshed();
+        int snapshots = 0;
+        var helper = new NativeWinGetHelper(
+            new TestableWinGet(),
+            systemCliHelperFactory: null,
+            skipInitialization: true,
+            localPackagesProvider: () =>
+            {
+                snapshots++;
+                return [];
+            }
+        );
+
+        helper.GetInstalledPackages_UnSafe();
+        Assert.Equal(1, snapshots);
+
+        WinGet.MarkSourceIndexRefreshed();
+        helper.GetAvailableUpdates_UnSafe();
+
+        Assert.Equal(2, snapshots);
+    }
+
+    [Fact]
+    public void NativeWinGetHelperReusesTheCatalogSnapshotWhileTheSourceIndexIsUnchanged()
+    {
+        WinGet.MarkSourceIndexRefreshed();
+        int snapshots = 0;
+        var helper = new NativeWinGetHelper(
+            new TestableWinGet(),
+            systemCliHelperFactory: null,
+            skipInitialization: true,
+            localPackagesProvider: () =>
+            {
+                snapshots++;
+                return [];
+            }
+        );
+
+        helper.GetInstalledPackages_UnSafe();
+        helper.GetAvailableUpdates_UnSafe();
+        helper.GetAvailableUpdates_UnSafe();
+
+        Assert.Equal(1, snapshots);
+    }
+
+    [Fact]
+    public void RefreshPackageIndexesAdvancesTheSourceIndexGenerationWhenTheCliCallFails()
+    {
+        var manager = new TestableWinGet();
+        long generationBefore = WinGet.SourceIndexGeneration;
+
+        Assert.ThrowsAny<Exception>(manager.RefreshPackageIndexes);
+
+        Assert.NotEqual(generationBefore, WinGet.SourceIndexGeneration);
+    }
+
     [Fact]
     public void NativeWinGetHelperSelectReachableCatalogsSkipsUnavailableSources()
     {