diff --git a/.github/workflows/validate-task.yml b/.github/workflows/validate-task.yml
index e0567d2..db8bca1 100644
--- a/.github/workflows/validate-task.yml
+++ b/.github/workflows/validate-task.yml
@@ -24,9 +24,14 @@ 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>/.
+      # dotnet test runs on native Microsoft.Testing.Platform (global.json test.runner); --coverage
+      # drives Microsoft.Testing.Extensions.CodeCoverage to emit Cobertura XML into ./coverage/.
+      # --coverage-output names the file explicitly: the default is a GUID basename that
+      # codecov-action's file finder does not match, so the upload step would silently find nothing.
       - name: Run unit tests step
-        run: dotnet test --collect:"XPlat Code Coverage" --results-directory ./coverage
+        run: >-
+          dotnet test --coverage --coverage-output-format cobertura
+          --coverage-output coverage.cobertura.xml --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 1813bcb..d4c69f3 100644
--- a/Directory.Packages.props
+++ b/Directory.Packages.props
@@ -1,16 +1,16 @@
 <Project>
   <ItemGroup>
     <PackageVersion Include="AwesomeAssertions" Version="9.5.0" />
-    <PackageVersion Include="coverlet.collector" Version="10.0.1" />
     <PackageVersion Include="Microsoft.Extensions.Http.Resilience" Version="10.8.0" />
     <PackageVersion Include="Microsoft.Extensions.Logging.Abstractions" Version="10.0.10" />
-    <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="10.0.301" />
+    <PackageVersion Include="Microsoft.Testing.Extensions.CodeCoverage" Version="18.9.0" />
     <PackageVersion Include="Serilog" Version="4.4.0" />
     <PackageVersion Include="Serilog.Extensions.Logging" Version="10.0.0" />
     <PackageVersion Include="Serilog.Sinks.Console" Version="6.1.1" />
-    <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.runner.visualstudio" Version="4.0.0" />
+    <PackageVersion Include="xunit.v3" Version="4.0.0" />
   </ItemGroup>
 </Project>
diff --git a/Utilities.slnx b/Utilities.slnx
index a0cdada..fe43668 100644
--- a/Utilities.slnx
+++ b/Utilities.slnx
@@ -9,6 +9,7 @@
         <File Path="cspell.json" />
         <File Path="Directory.Build.props" />
         <File Path="Directory.Packages.props" />
+        <File Path="global.json" />
         <File Path="LICENSE" />
         <File Path="README.md" />
         <File Path="version.json" />
diff --git a/UtilitiesTests/ExtensionsTests.cs b/UtilitiesTests/ExtensionsTests.cs
index 63e61d8..aa22f7b 100644
--- a/UtilitiesTests/ExtensionsTests.cs
+++ b/UtilitiesTests/ExtensionsTests.cs
@@ -93,7 +93,7 @@ public void StringExtension_Compress_WithNullString_ShouldThrow()
         string? nullString = null;
 
         _ = FluentActions
-            .Invoking(() => nullString.Compress())
+            .Invoking(() => nullString!.Compress())
             .Should()
             .Throw<ArgumentNullException>();
     }
@@ -211,7 +211,7 @@ public async Task StringExtension_CompressAsync_WithNullString_ShouldThrow()
         string? nullString = null;
 
         _ = await FluentActions
-            .Awaiting(() => nullString.CompressAsync())
+            .Awaiting(() => nullString!.CompressAsync())
             .Should()
             .ThrowAsync<ArgumentNullException>();
     }
@@ -222,7 +222,7 @@ public async Task StringExtension_DecompressAsync_WithNullString_ShouldThrow()
         string? nullString = null;
 
         _ = await FluentActions
-            .Awaiting(() => nullString.DecompressAsync())
+            .Awaiting(() => nullString!.DecompressAsync())
             .Should()
             .ThrowAsync<ArgumentNullException>();
     }
diff --git a/UtilitiesTests/UtilitiesTests.csproj b/UtilitiesTests/UtilitiesTests.csproj
index 6d87d47..210db32 100644
--- a/UtilitiesTests/UtilitiesTests.csproj
+++ b/UtilitiesTests/UtilitiesTests.csproj
@@ -2,6 +2,10 @@
   <PropertyGroup>
     <IsTestProject>true</IsTestProject>
     <RootNamespace>ptr727.Utilities.Tests</RootNamespace>
+    <!-- .NET 10 SDK dropped the VSTest bridge for dotnet test; run xunit.v3 through native
+         Microsoft.Testing.Platform instead (paired with global.json's "test.runner" setting). -->
+    <OutputType>Exe</OutputType>
+    <UseMicrosoftTestingPlatformRunner>true</UseMicrosoftTestingPlatformRunner>
   </PropertyGroup>
   <ItemGroup>
     <PackageReference Include="AwesomeAssertions" />
@@ -12,9 +16,13 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
     <PackageReference Include="xunit.runner.visualstudio" PrivateAssets="All" />
-    <PackageReference Include="coverlet.collector">
+    <!-- coverlet.collector is VSTest-only; Microsoft.Testing.Extensions.CodeCoverage is the
+         native MTP coverage provider (drives the dotnet test coverage flag). -->
+    <!-- Unlike coverlet.collector, this extension's self-registration code is compiled in, so
+         "compile" must stay in IncludeAssets. -->
+    <PackageReference Include="Microsoft.Testing.Extensions.CodeCoverage">
       <PrivateAssets>all</PrivateAssets>
-      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <IncludeAssets>compile; runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
   </ItemGroup>
   <ItemGroup>
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"
+  }
+}