fix: resolve CI failures and address Copilot review comments

- Fix CoreTest/DownloadModelsTests: remove CVP property references, update
  for PackageType + FallbackFull* fields
- Fix CoreTest/ConfigurationModelsTests: same CVP→PackageType migration
- Fix CoreTest/DownloadPlanBuilderTests: replace CVP tests with
  chain/full switch test, update helper signatures
- Fix ClientTest/Program.cs: remove CVP field references (Already fixed in
  fix/chain-fallback-skip-covered-versions)
- Fix HttpDownloadSource.MapVersionEntry: restore MinClientVersion mapping
  (Copilot: prevents premature update to unsupported versions)
- Fix DownloadPlanBuilder: treat PackageType=0 (Unspecified) as Chain for
  backward compatibility (Copilot: prevents empty plan from old servers)
- Fix DownloadPlanBuilder: limit chain size comparison to same AppType as
  bestFull (Copilot: prevents incorrect cross-AppType switching)
- Fix AbstractStrategy: wrap fallback execution in try/catch so a failed
  fallback doesn't abort the entire update loop (Copilot: graceful degradation)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: JusterZhu

src/c#/GeneralUpdate.Core/Download/DownloadPlanBuilder.cs

@@ -136,9 +136,12 @@ public static DownloadPlan Build(
 
         if (candidates.Count == 0) return DownloadPlan.Empty;
 
-        // Separate chain vs full packages
+        // Separate chain vs full packages.
+        // Treat Unspecified (0) as Chain for backward compatibility with older
+        // servers that do not set PackageType yet.
         var chainCandidates = candidates
-            .Where(a => a.PackageType == (int)Configuration.PackageType.Chain)
+            .Where(a => a.PackageType == (int)Configuration.PackageType.Chain
+                        || a.PackageType == (int)Configuration.PackageType.Unspecified)
             .ToList();
 
         var fullCandidates = candidates
@@ -155,7 +158,11 @@ public static DownloadPlan Build(
                 .OrderByDescending(a => { Semver.TryParse(a.Version, out var sv); return sv; })
                 .First();
 
-            long chainTotal = chainCandidates.Sum(a => a.Size);
+            // Only compare against chain packages of the same AppType as bestFull.
+            // Mixing Client and Upgrade sizes together could trigger incorrect switching.
+            long chainTotal = chainCandidates
+                .Where(a => a.AppType == bestFull.AppType)
+                .Sum(a => a.Size);
             var threshold = (long)(bestFull.Size * 0.8);
 
             if (chainTotal >= threshold)

src/c#/GeneralUpdate.Core/Download/Sources/HttpDownloadSource.cs

@@ -176,6 +176,7 @@ private static DownloadAsset MapVersionEntry(VersionEntry v)
             SHA256: v.Hash,
             Version: v.Version ?? "0.0.0",
             PackageType: v.PackageType,
+            MinClientVersion: v.MinClientVersion,
             IsForcibly: v.IsForcibly == true,
             IsFreeze: v.IsFreeze == true,
             RecordId: v.RecordId,

src/c#/GeneralUpdate.Core/Strategy/AbstractStrategy.cs

@@ -209,15 +209,26 @@ public virtual async Task ExecuteAsync()
                         fallbackContext.Add("DiffPipeline", DiffPipeline);
 
                         var fallbackBuilder = BuildPipeline(fallbackContext);
-                        await fallbackBuilder.Build();
-                        status = ReportType.Success;
-                        // Record the fallback full package version so subsequent
-                        // chain packages ≤ this version are skipped.
-                        if (!string.IsNullOrEmpty(version.FallbackFullVersion)
-                            && Semver.TryParse(version.FallbackFullVersion, out var ffv)
-                            && (fallbackEffectiveVersion == null || ffv > fallbackEffectiveVersion))
+                        try
+                        {
+                            await fallbackBuilder.Build();
+                            status = ReportType.Success;
+                            // Record the fallback full package version so subsequent
+                            // chain packages ≤ this version are skipped.
+                            if (!string.IsNullOrEmpty(version.FallbackFullVersion)
+                                && Semver.TryParse(version.FallbackFullVersion, out var ffv)
+                                && (fallbackEffectiveVersion == null || ffv > fallbackEffectiveVersion))
+                            {
+                                fallbackEffectiveVersion = ffv;
+                            }
+                        }
+                        catch (Exception fallbackEx)
                         {
-                            fallbackEffectiveVersion = ffv;
+                            // Fallback itself failed (e.g. missing full zip, decompression error).
+                            // Downgrade to normal failure handling so the loop can continue
+                            // processing remaining versions.
+                            GeneralTracer.Error($"AbstractStrategy.ExecuteAsync: fallback full package also failed for {version.Version}. Error: {fallbackEx.Message}");
+                            status = ReportType.Failure;
                         }
                     }
                     catch (Exception e)

tests/CoreTest/Configuration/ConfigurationModelsTests.cs

@@ -88,30 +88,33 @@ public void DownloadAsset_AllFields_ConstructsCorrectly()
             Assert.Equal("sha256:abc123def456", asset.SHA256);
             Assert.Equal(104857600, asset.Size);
             Assert.Equal(DownloadPriority.Normal, asset.Priority);
-            Assert.False(asset.IsCrossVersion);
+            Assert.Equal(0, asset.PackageType);
             Assert.False(asset.IsForcibly);
             Assert.False(asset.IsFreeze);
         }
 
         [Fact]
-        public void DownloadAsset_CrossVersion_IsForcibly()
+        public void DownloadAsset_ChainWithFallback_PropertiesSet()
         {
             var asset = new DownloadAsset(
-                Name: "critical-patch.zip",
-                Url: "https://cdn.example.com/security/hotfix.zip",
+                Name: "chain-patch.zip",
+                Url: "https://cdn.example.com/chain/patch.zip",
                 Size: 5L * 1024 * 1024,
                 SHA256: null,
-                Version: "2.0.1-hotfix",
+                Version: "2.0.1",
                 Priority: DownloadPriority.High,
-                IsForcibly: true,
-                IsCrossVersion: true,
-                FromVersion: "2.0.0"
+                PackageType: (int)PackageType.Chain,
+                FallbackFullName: "full-v2.0.1",
+                FallbackFullUrl: "https://cdn.example.com/full/v2.0.1.zip",
+                FallbackFullHash: "abc123def456",
+                IsForcibly: true
             );
 
             Assert.Equal(DownloadPriority.High, asset.Priority);
             Assert.True(asset.IsForcibly);
-            Assert.True(asset.IsCrossVersion);
-            Assert.Equal("2.0.0", asset.FromVersion);
+            Assert.Equal((int)PackageType.Chain, asset.PackageType);
+            Assert.Equal("full-v2.0.1", asset.FallbackFullName);
+            Assert.Equal("abc123def456", asset.FallbackFullHash);
         }
 
         #endregion

tests/CoreTest/Download/DownloadModelsTests.cs

@@ -22,8 +22,7 @@ public void DownloadAsset_Defaults_AreSensible()
         Assert.Null(asset.SHA256);
         Assert.Equal("1.0.0", asset.Version);
         Assert.Equal(DownloadPriority.Normal, asset.Priority);
-        Assert.False(asset.IsCrossVersion);
-        Assert.Null(asset.FromVersion);
+        Assert.Equal(0, asset.PackageType);
         Assert.Null(asset.MinClientVersion);
         Assert.False(asset.IsForcibly);
         Assert.False(asset.IsFreeze);
@@ -34,8 +33,12 @@ public void DownloadAsset_FullySpecified_AllPropertiesSet()
     {
         var asset = new DownloadAsset(
             "package.zip", "https://cdn/pkg.zip", 1024, "abc123", "3.0.0",
-            DownloadPriority.High, true, "1.0.0", "2.0.0",
-            "srcHash", "tgtHash", true, false
+            DownloadPriority.High, 0,
+            MinClientVersion: "2.0.0",
+            FallbackFullName: "full-pkg",
+            FallbackFullUrl: "https://cdn/full.zip",
+            FallbackFullHash: "fullhash",
+            IsForcibly: true, IsFreeze: false
         );
 
         Assert.Equal("package.zip", asset.Name);
@@ -44,11 +47,10 @@ public void DownloadAsset_FullySpecified_AllPropertiesSet()
         Assert.Equal("abc123", asset.SHA256);
         Assert.Equal("3.0.0", asset.Version);
         Assert.Equal(DownloadPriority.High, asset.Priority);
-        Assert.True(asset.IsCrossVersion);
-        Assert.Equal("1.0.0", asset.FromVersion);
         Assert.Equal("2.0.0", asset.MinClientVersion);
-        Assert.Equal("srcHash", asset.SourceArchiveHash);
-        Assert.Equal("tgtHash", asset.TargetArchiveHash);
+        Assert.Equal("full-pkg", asset.FallbackFullName);
+        Assert.Equal("https://cdn/full.zip", asset.FallbackFullUrl);
+        Assert.Equal("fullhash", asset.FallbackFullHash);
         Assert.True(asset.IsForcibly);
         Assert.False(asset.IsFreeze);
     }

tests/CoreTest/Download/DownloadPlanBuilderTests.cs

@@ -8,11 +8,10 @@ public class DownloadPlanBuilderTests
 {
     private static DownloadAsset Asset(string name = "a", string version = "2.0.0", string url = "http://u",
         long size = 100, string hash = null, bool isFreeze = false, bool isForcibly = false,
-        bool isCrossVersion = false, string fromVersion = null, string minClientVersion = null)
+        int packageType = (int)PackageType.Chain, string minClientVersion = null)
         => new(name, url, size, hash, version,
               IsFreeze: isFreeze, IsForcibly: isForcibly,
-              IsCrossVersion: isCrossVersion, FromVersion: fromVersion,
-              MinClientVersion: minClientVersion);
+              PackageType: packageType, MinClientVersion: minClientVersion);
 
     [Fact]
     public void Build_AssetsNull_ReturnsEmpty()
@@ -82,40 +81,21 @@ public void Build_NoAssetIsForcibly_IsForciblyFalse()
     }
 
     [Fact]
-    public void Build_CrossVersionIncluded_CvpFirst_ReturnsCvpOnly()
+    public void Build_FullPackageSelected_WhenChainExceedsThreshold()
     {
-        // When a matching CVP exists, the plan selects the CVP and drops
-        // same-AppType chain packages (CVP covers the full range).
+        // Small chain + small full → chain_total >= 80% full → Full selected
         var assets = new[]
         {
-            Asset("cross", "5.0.0", isCrossVersion: true, fromVersion: "1.0.0"),
-            Asset("inc", "2.0.0"), Asset("inc2", "3.0.0")
+            Asset("chain1", "1.1.0", size: 100),
+            Asset("chain2", "2.0.0", size: 100),
+            Asset("full", "2.0.0", packageType: (int)PackageType.Full),
         };
+        // chain_total=200, 80% of full(100) = 80 → 200 >= 80 → full selected
         var result = DownloadPlanBuilder.Build(assets, "1.0.0");
         Assert.True(result.HasAssets);
         Assert.Single(result.Assets);
-        Assert.True(result.Assets[0].IsCrossVersion);
-        Assert.Equal("5.0.0", result.Assets[0].Version);
-    }
-
-    [Fact]
-    public void Build_CvpWithMixedAppTypes_KeepsChainForOtherTypes()
-    {
-        // CVP covers Client (AppType=1). Upgrade chain packages (AppType=2)
-        // should still be included since the CVP doesn't cover that AppType.
-        var assets = new[]
-        {
-            AssetWithType("cvp", "5.0.0", appType: 1, isCrossVersion: true, fromVersion: "1.0.0"),
-            AssetWithType("upgrade1", "2.0.0", appType: 2),
-            AssetWithType("upgrade2", "3.0.0", appType: 2),
-        };
-        var result = DownloadPlanBuilder.Build(assets, "1.0.0");
-        Assert.True(result.HasAssets);
-        Assert.Equal(3, result.Assets.Count);
-        Assert.Equal("5.0.0", result.Assets[0].Version); // CVP first
-        Assert.True(result.Assets[0].IsCrossVersion);
-        Assert.Equal("2.0.0", result.Assets[1].Version); // chain for other AppType
-        Assert.Equal("3.0.0", result.Assets[2].Version);
+        Assert.Equal((int)PackageType.Full, result.Assets[0].PackageType);
+        Assert.Equal("2.0.0", result.Assets[0].Version);
     }
 
     [Fact]
@@ -174,12 +154,11 @@ public void Build_MixedFrozenAndActive_FiltersFrozen()
     private static DownloadAsset AssetWithType(string name = "a", string version = "2.0.0",
         string url = "http://u", long size = 100, string? hash = null,
         bool isFreeze = false, bool isForcibly = false,
-        bool isCrossVersion = false, string? fromVersion = null,
+        int packageType = (int)PackageType.Chain,
         string? minClientVersion = null, int? appType = null)
         => new(name, url, size, hash, version,
               IsFreeze: isFreeze, IsForcibly: isForcibly,
-              IsCrossVersion: isCrossVersion, FromVersion: fromVersion,
-              MinClientVersion: minClientVersion, AppType: appType);
+              PackageType: packageType, MinClientVersion: minClientVersion, AppType: appType);
 
     [Fact]
     public void HasUpdate_EmptyAssets_ReturnsFalse()