Use PortableRuntimeIdentifierGraph in ToolPackage

Author: am11

src/Cli/dotnet/ToolPackage/ToolPackageDownloaderBase.cs

@@ -57,7 +57,15 @@ protected ToolPackageDownloaderBase(
         _currentWorkingDirectory = currentWorkingDirectory;
 
         _localToolAssetDir = new DirectoryPath(_fileSystem.Directory.CreateTemporarySubdirectory());
-        _runtimeJsonPath = runtimeJsonPathForTests ?? Path.Combine(AppContext.BaseDirectory!, "RuntimeIdentifierGraph.json");
+
+        // Tools target modern (net8.0+) frameworks, for which the SDK resolves RIDs using the simplified
+        // "portable" RID graph by default (UseRidGraph=false). Prefer that graph here so tool RID-asset
+        // selection matches normal restore/build; fall back to the legacy graph if the portable one isn't
+        // present in the layout.
+        string portableRuntimeJsonPath = Path.Combine(AppContext.BaseDirectory!, "PortableRuntimeIdentifierGraph.json");
+        string legacyRuntimeJsonPath = Path.Combine(AppContext.BaseDirectory!, "RuntimeIdentifierGraph.json");
+        _runtimeJsonPath = runtimeJsonPathForTests
+            ?? (File.Exists(portableRuntimeJsonPath) ? portableRuntimeJsonPath : legacyRuntimeJsonPath);
     }
 
     protected abstract INuGetPackageDownloader CreateNuGetPackageDownloader(