Improve xplat dump test work item naming

src/native/managed/cdac/tests/DumpTests/DumpTestBase.cs

@@ -34,13 +34,14 @@ public static IEnumerable<object[]> TestConfigurations
     {
         get
         {
+            string? dumpSource = GetDumpSource();
             foreach (string r2rMode in GetR2RModes())
             {
                 if (!IsVersionSkipped("local"))
-                    yield return [new TestConfiguration("local", r2rMode)];
+                    yield return [new TestConfiguration("local", r2rMode, dumpSource)];
 
                 if (!IsVersionSkipped("net10.0"))
-                    yield return [new TestConfiguration("net10.0", r2rMode)];
+                    yield return [new TestConfiguration("net10.0", r2rMode, dumpSource)];
             }
         }
     }
@@ -176,6 +177,28 @@ private static string GetDumpRoot()
         return Path.Combine(repoRoot, "artifacts", "dumps", "cdac");
     }
 
+    /// <summary>
+    /// Returns the dump source platform from dump-info.json (e.g., "windows_x64"),
+    /// or null for local runs where CDAC_DUMP_ROOT is not set.
+    /// </summary>
+    private static string? GetDumpSource()
+    {
+        string? dumpRoot = Environment.GetEnvironmentVariable("CDAC_DUMP_ROOT");
+        if (string.IsNullOrEmpty(dumpRoot))
+            return null;
+
+        // Try loading dump-info.json from any version directory to get OS/Arch
+        foreach (string versionDir in new[] { "local", "net10.0" })
+        {
+            DumpInfo? info = DumpInfo.TryLoad(Path.Combine(dumpRoot, versionDir));
+            if (info is not null)
+                return $"{info.Os}_{info.Arch}";
+        }
+
+        // Fall back to the directory name if dump-info.json isn't available
+        return Path.GetFileName(dumpRoot.TrimEnd(Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar));
+    }
+
     /// <summary>
     /// Returns the R2R modes to test against. Both modes are always tested;
     /// dumps that don't exist for a given mode are skipped via <see cref="SkipTestException"/>.

src/native/managed/cdac/tests/DumpTests/TestConfiguration.cs

@@ -26,25 +26,35 @@ public sealed class TestConfiguration : IXunitSerializable
     /// </summary>
     public string R2RMode { get; set; } = "r2r";
 
+    /// <summary>
+    /// The platform that produced the dump (e.g., "windows_x64", "linux_arm64").
+    /// Null for local runs where the host and dump source are the same.
+    /// </summary>
+    public string? DumpSource { get; set; }
+
     public TestConfiguration() { }
 
-    public TestConfiguration(string runtimeVersion, string r2rMode)
+    public TestConfiguration(string runtimeVersion, string r2rMode, string? dumpSource = null)
     {
         RuntimeVersion = runtimeVersion;
         R2RMode = r2rMode;
+        DumpSource = dumpSource;
     }
 
-    public override string ToString() => $"{RuntimeVersion}/{R2RMode}";
+    public override string ToString() =>
+        DumpSource is not null ? $"{RuntimeVersion}/{R2RMode} ({DumpSource})" : $"{RuntimeVersion}/{R2RMode}";
 
     public void Serialize(IXunitSerializationInfo info)
     {
         info.AddValue(nameof(RuntimeVersion), RuntimeVersion);
         info.AddValue(nameof(R2RMode), R2RMode);
+        info.AddValue(nameof(DumpSource), DumpSource, typeof(string));
     }
 
     public void Deserialize(IXunitSerializationInfo info)
     {
         RuntimeVersion = info.GetValue<string>(nameof(RuntimeVersion));
         R2RMode = info.GetValue<string>(nameof(R2RMode));
+        DumpSource = info.GetValue<string>(nameof(DumpSource));
     }
 }

src/native/managed/cdac/tests/DumpTests/cdac-dump-xplat-test-helix.proj

@@ -18,6 +18,7 @@
       TestHostPayload    — Path to testhost shared framework directory
       DumpTestsPayload   — Path to payload directory (tests/ + dumps/)
       TargetOS           — Target OS (windows, linux, osx)
+      TargetArchitecture — Target architecture (x64, x86, arm64, arm)
       SourcePlatforms    — Semicolon-separated source platform names
                            (e.g. "windows_x64;linux_x64;osx_arm64")
   -->
@@ -97,7 +98,7 @@
     <WriteLinesToFile File="$(_HelixCommandFile)" Lines="@(_HelixCommandLines)" Overwrite="true" />
 
     <ItemGroup>
-      <HelixWorkItem Include="CdacXPlatDumpTests_%(_SourcePlatform.Identity)">
+      <HelixWorkItem Include="CdacXPlatDumpTests_host_$(TargetOS)_$(TargetArchitecture)_dumps_%(_SourcePlatform.Identity)">
         <PayloadDirectory>$(DumpTestsPayload)</PayloadDirectory>
         <Command>$([System.IO.File]::ReadAllText('$(_HelixCommandFile)'))</Command>
         <Timeout>$(WorkItemTimeout)</Timeout>