fix(v2.1): re-enable Zstd on net11 - .NET 11 RC1 DOES ship ZstandardStream

Previous commit wrongly disabled Zstd: the ref-pack XML search missed the type, but reflection against System.IO.Compression.dll (11.0.0-rc.1) confirms ZstandardStream(Stream, CompressionLevel, bool) and ZstandardCompressionOptions exist. Restore the original #if NET11_0_OR_GREATER implementation; Zstd tests now pass on net11 (0 skipped). net10.0 unchanged (PlatformNotSupportedException fallback, 1679 tests green).

Author: MPCoreDeveloper

src/SharpCoreDB/Services/BlockCompressor.cs

@@ -55,17 +55,25 @@ public static byte[] Decompress(ReadOnlySpan<byte> data, BlockCompressionMode mo
     {
         BlockCompressionMode.Brotli => new BrotliStream(output, level, leaveOpen: false),
         BlockCompressionMode.GZip => new GZipStream(output, level, leaveOpen: false),
+#if NET11_0_OR_GREATER
+        BlockCompressionMode.Zstd => new ZstandardStream(output, level, leaveOpen: false),
+#else
         BlockCompressionMode.Zstd => throw new PlatformNotSupportedException(
-            "Zstd compression is not available in the current .NET runtime (System.IO.Compression does not ship a Zstandard stream yet)."),
+            "Zstd compression requires .NET 11 or later. Current runtime: " + Environment.Version),
+#endif
         _ => throw new ArgumentOutOfRangeException(nameof(mode))
     };
 
     private static Stream CreateDecompressor(Stream input, BlockCompressionMode mode) => mode switch
     {
         BlockCompressionMode.Brotli => new BrotliStream(input, CompressionMode.Decompress, leaveOpen: false),
         BlockCompressionMode.GZip => new GZipStream(input, CompressionMode.Decompress, leaveOpen: false),
+#if NET11_0_OR_GREATER
+        BlockCompressionMode.Zstd => new ZstandardStream(input, CompressionMode.Decompress, leaveOpen: false),
+#else
         BlockCompressionMode.Zstd => throw new PlatformNotSupportedException(
-            "Zstd decompression is not available in the current .NET runtime (System.IO.Compression does not ship a Zstandard stream yet)."),
+            "Zstd decompression requires .NET 11 or later. Current runtime: " + Environment.Version),
+#endif
         _ => throw new ArgumentOutOfRangeException(nameof(mode))
     };
 

src/SharpCoreDB/Storage/BlockCompressionMode.cs

@@ -30,9 +30,8 @@ public enum BlockCompressionMode
     /// <summary>
     /// Zstandard compression (excellent speed/ratio balance).
     /// Best for: general-purpose database blocks, telemetry, mixed workloads.
-    /// NOTE: .NET 11 RC1 does not ship a Zstandard stream in System.IO.Compression yet
-    /// (only ZLib streams), so this mode currently throws PlatformNotSupportedException
-    /// on all runtimes; it is reserved for a future runtime that adds native Zstandard.
+    /// Requires .NET 11+ (System.IO.Compression.ZstandardStream).
+    /// On .NET 10, using this mode will throw NotSupportedException.
     /// </summary>
     Zstd = 3
 }

tests/SharpCoreDB.Tests/Storage/CompressionLevelTests.cs

@@ -93,34 +93,10 @@ public void BlockCompressor_GZip_HigherEffortDoesNotIncreaseSize()
             $"SmallestSize ({smallest.Length}) should be smaller than raw ({data.Length})");
     }
 
-    /// <summary>
-    /// Skips Zstd-only tests until a .NET runtime ships a native Zstandard stream
-    /// (verified: .NET 11 RC1's System.IO.Compression has no ZstandardStream yet).
-    /// No-op on runtimes without Zstandard support; the covered tests are net11-gated anyway.
-    /// </summary>
-    private static void SkipIfZstdUnsupported()
-    {
-#if NET11_0_OR_GREATER
-        Assert.Skip("Zstandard compression is not available in the current .NET runtime (System.IO.Compression has no ZstandardStream yet).");
-#endif
-    }
-
-    private static void SkipIfZstd(BlockCompressionMode mode)
-    {
-#if NET11_0_OR_GREATER
-        if (mode == BlockCompressionMode.Zstd)
-        {
-            SkipIfZstdUnsupported();
-        }
-#endif
-    }
-
 #if NET11_0_OR_GREATER
     [Fact]
     public void BlockCompressor_Zstd_HigherEffortDoesNotIncreaseSize()
     {
-        SkipIfZstdUnsupported();
-
         var data = RealisticCompressiblePayload();
 
         var fastest = BlockCompressor.Compress(data, BlockCompressionMode.Zstd, OptionalCompressionLevel.Fastest);
@@ -141,8 +117,6 @@ public void BlockCompressor_Zstd_HigherEffortDoesNotIncreaseSize()
     [InlineData(OptionalCompressionLevel.SmallestSize)]
     public void BlockCompressor_Zstd_Roundtrip_PreservesData(OptionalCompressionLevel level)
     {
-        SkipIfZstdUnsupported();
-
         var data = RealisticCompressiblePayload();
 
         var compressed = BlockCompressor.Compress(data, BlockCompressionMode.Zstd, level);
@@ -315,8 +289,6 @@ private static string GenerateRealisticMetadata(int tableCount)
 #endif
     public void GetReadStream_CompressedBlock_NoEncryption_ReturnsDecompressedData(BlockCompressionMode mode)
     {
-        SkipIfZstd(mode);
-
         var path = Path.Combine(Path.GetTempPath(), $"readstream_{mode}_{Guid.NewGuid():N}.scdb");
         var originalData = RealisticCompressiblePayload();
 
@@ -366,8 +338,6 @@ public void GetReadStream_CompressedBlock_NoEncryption_ReturnsDecompressedData(B
 #endif
     public void GetReadSpan_CompressedBlock_NoEncryption_ReturnsDecompressedData(BlockCompressionMode mode)
     {
-        SkipIfZstd(mode);
-
         var path = Path.Combine(Path.GetTempPath(), $"readspan_{mode}_{Guid.NewGuid():N}.scdb");
         var originalData = RealisticCompressiblePayload();