diff --git a/.github/workflows/validate-task.yml b/.github/workflows/validate-task.yml
index 33062ea..af67422 100644
--- a/.github/workflows/validate-task.yml
+++ b/.github/workflows/validate-task.yml
@@ -24,9 +24,11 @@ jobs:
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
       # Builds with TreatWarningsAsErrors, so analyzer and code-style warnings fail here.
-      # --collect drives coverlet.collector to emit Cobertura XML into ./coverage/<guid>/.
+      # global.json opts dotnet test into Microsoft.Testing.Platform (MTP) mode, the .NET 10 SDK's replacement for
+      # the VSTest runner; --coverlet drives coverlet.MTP (coverlet.collector's VSTest data collector is silently
+      # ignored under MTP) to emit Cobertura XML into ./coverage/.
       - name: Run unit tests step
-        run: dotnet test --collect:"XPlat Code Coverage" --results-directory ./coverage
+        run: dotnet test --coverlet --coverlet-output-format cobertura --results-directory ./coverage
 
       # Report-only: fail_ci_if_error is false so a Codecov hiccup or an absent token never fails the gate.
       - name: Upload coverage to Codecov step
diff --git a/Directory.Packages.props b/Directory.Packages.props
index f8074c3..8aa51c4 100644
--- a/Directory.Packages.props
+++ b/Directory.Packages.props
@@ -1,10 +1,12 @@
 <Project>
   <ItemGroup>
-    <PackageVersion Include="AwesomeAssertions" Version="9.5.0" />
-    <PackageVersion Include="coverlet.collector" Version="10.0.1" />
-    <PackageVersion Include="Microsoft.CodeAnalysis.CSharp" Version="5.6.0" />
+    <PackageVersion Include="AwesomeAssertions" Version="9.6.0" />
+    <!-- coverlet.MTP replaces coverlet.collector: the VSTest data collector is silently ignored
+         under Microsoft.Testing.Platform (MTP0001), so coverage needs the MTP-native extension. -->
+    <PackageVersion Include="coverlet.MTP" Version="10.0.1" />
+    <PackageVersion Include="Microsoft.CodeAnalysis.CSharp" Version="5.9.0" />
     <PackageVersion Include="Microsoft.Extensions.Logging.Abstractions" Version="10.0.11" />
-    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.8.1" />
+    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.9.0" />
     <PackageVersion Include="Microsoft.SourceLink.GitHub" Version="10.0.400" />
     <PackageVersion Include="ptr727.Utilities" Version="4.0.28" />
     <PackageVersion Include="Serilog" Version="4.4.0" />
@@ -13,8 +15,7 @@
     <PackageVersion Include="Serilog.Sinks.Console" Version="6.1.1" />
     <PackageVersion Include="Serilog.Sinks.File" Version="7.0.0" />
     <PackageVersion Include="System.CommandLine" Version="2.0.11" />
-    <PackageVersion Include="xunit.analyzers" Version="1.27.0" />
-    <PackageVersion Include="xunit.runner.visualstudio" Version="3.1.5" />
-    <PackageVersion Include="xunit.v3" Version="3.2.2" />
+    <PackageVersion Include="xunit.analyzers" Version="2.0.0" />
+    <PackageVersion Include="xunit.v3" Version="4.0.0" />
   </ItemGroup>
 </Project>
diff --git a/LanguageTagsTests/LanguageTagsTests.csproj b/LanguageTagsTests/LanguageTagsTests.csproj
index 544a84d..1c44906 100644
--- a/LanguageTagsTests/LanguageTagsTests.csproj
+++ b/LanguageTagsTests/LanguageTagsTests.csproj
@@ -11,12 +11,15 @@
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
-    <PackageReference Include="xunit.runner.visualstudio" PrivateAssets="All" />
     <PackageReference Include="xunit.v3" />
-    <PackageReference Include="coverlet.collector">
-      <PrivateAssets>all</PrivateAssets>
-      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
-    </PackageReference>
+    <!-- coverlet.MTP is a native Microsoft.Testing.Platform extension, not a build-time-only tool
+         like the VSTest coverlet.collector was: its self-registration codegen needs the package on
+         this project's own compile-time closure, so IncludeAssets must not exclude "compile" (the
+         collector's restricted list omitted it, which is fine for a VSTest data collector but
+         breaks a compiled-against library). PrivateAssets is unrelated to that and stays unset,
+         since it only controls exposure to downstream consumers, which this test project has none
+         of. -->
+    <PackageReference Include="coverlet.MTP" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\LanguageTags\LanguageTags.csproj" />
diff --git a/global.json b/global.json
new file mode 100644
index 0000000..7ec050f
--- /dev/null
+++ b/global.json
@@ -0,0 +1,5 @@
+{
+  "test": {
+    "runner": "Microsoft.Testing.Platform"
+  }
+}