diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 434f467..6772790 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -147,7 +147,7 @@ jobs:
               exit 1
           }
 
-          & $vstest "RandomNumberGenerator.Test\bin\Release\Random Number Generator.Test.dll" /Logger:"console;verbosity=minimal"
+          & $vstest "tests\RandomNumberGenerator.Test\bin\Release\Random Number Generator.Test.dll" /Logger:"console;verbosity=minimal"
           if ($LASTEXITCODE -ne 0)
           {
               Write-Host "::error::The tests did not pass, so nothing is released."
diff --git a/CLAUDE.md b/CLAUDE.md
index 27a9f6e..265c721 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -11,7 +11,10 @@ the results. The device access layer is a native C++ DLL (`TruRNGpro`) called th
 Three projects in `RandomNumberGenerator.sln`:
 - `RandomNumberGenerator.csproj` — WinForms app, AnyCPU (64-bit; `Prefer32Bit=false`)
 - `TruRNGpro/TruRNGpro.vcxproj` — native C++ DLL, **x64 only** (solution maps `Any CPU` → `x64`)
-- `RandomNumberGenerator.Test/` — MSTest + Moq unit tests
+- `tests/RandomNumberGenerator.Test/` — MSTest + Moq unit tests
+
+Both kinds of test live under `tests/`: the unit tests above, and `tests/manual/`, which drives the built
+application and is described in its own README.
 
 ## Build and test
 
@@ -28,12 +31,12 @@ nuget restore RandomNumberGenerator.sln
 & $msbuild RandomNumberGenerator.sln /p:Configuration=Debug /p:Platform="Any CPU"
 
 # Run all tests
-& $vstest "RandomNumberGenerator.Test\bin\Debug\Random Number Generator.Test.dll"
+& $vstest "tests\RandomNumberGenerator.Test\bin\Debug\Random Number Generator.Test.dll"
 
 # Run a single test / class / category
-& $vstest "RandomNumberGenerator.Test\bin\Debug\Random Number Generator.Test.dll" /Tests:WriteDataPoint_ValidWriter_Success
-& $vstest "RandomNumberGenerator.Test\bin\Debug\Random Number Generator.Test.dll" /TestCaseFilter:"FullyQualifiedName~RNGXMLWriterTests"
-& $vstest "RandomNumberGenerator.Test\bin\Debug\Random Number Generator.Test.dll" /TestCaseFilter:"TestCategory=Component"
+& $vstest "tests\RandomNumberGenerator.Test\bin\Debug\Random Number Generator.Test.dll" /Tests:WriteDataPoint_ValidWriter_Success
+& $vstest "tests\RandomNumberGenerator.Test\bin\Debug\Random Number Generator.Test.dll" /TestCaseFilter:"FullyQualifiedName~RNGXMLWriterTests"
+& $vstest "tests\RandomNumberGenerator.Test\bin\Debug\Random Number Generator.Test.dll" /TestCaseFilter:"TestCategory=Component"
 ```
 
 Build ordering matters. The native project copies `TruRNGpro.dll` to `<sln>\bin\`, and both the app and the
@@ -241,7 +244,7 @@ here (`DeviceInterfaces` supplies the `USBDeviceNotification` constants used in
 
 ## Coding conventions
 
-`CODING_GUIDELINES.md` (app), `RandomNumberGenerator.Test/CODING_GUIDELINES_TESTS.md` (tests), and
+`CODING_GUIDELINES.md` (app), `tests/RandomNumberGenerator.Test/CODING_GUIDELINES_TESTS.md` (tests), and
 `TruRNGpro/CODING_GUIDELINES_CPP.md` (native) are authoritative and are actually followed throughout. The
 non-obvious rules new code is expected to match:
 
diff --git a/README.md b/README.md
index 3e89578..c86af0b 100644
--- a/README.md
+++ b/README.md
@@ -135,7 +135,8 @@ stopping the recording.
 |---|---|
 | `RandomNumberGenerator.csproj` | The application. Windows Forms, .NET Framework 4.8, AnyCPU |
 | `TruRNGpro/TruRNGpro.vcxproj` | Native DLL holding the device interface and the simulator. x64 |
-| `RandomNumberGenerator.Test/` | Unit tests. MSTest and Moq |
+| `tests/RandomNumberGenerator.Test/` | Unit tests. MSTest and Moq |
+| `tests/manual/` | Suites that drive the built application, some needing the device attached |
 
 The application talks to the native DLL through two exported functions, `Initialize` and
 `GetRandomBitAverage`, which sit behind an interface implemented by both the real device and the simulator.
@@ -143,7 +144,7 @@ The application talks to the native DLL through two exported functions, `Initial
 ## Tests
 
 ```
-vstest.console.exe "RandomNumberGenerator.Test\bin\Debug\Random Number Generator.Test.dll"
+vstest.console.exe "tests\RandomNumberGenerator.Test\bin\Debug\Random Number Generator.Test.dll"
 ```
 
 `vstest.console.exe` is under the Visual Studio installation, in
@@ -162,7 +163,7 @@ in place.
 The coding standards are written down and are followed throughout:
 
 - `CODING_GUIDELINES.md` for the application
-- `RandomNumberGenerator.Test/CODING_GUIDELINES_TESTS.md` for the tests
+- `tests/RandomNumberGenerator.Test/CODING_GUIDELINES_TESTS.md` for the tests
 - `TruRNGpro/CODING_GUIDELINES_CPP.md` for the native code
 
 `CLAUDE.md` describes the architecture and the build for anyone, or anything, new to the codebase.
diff --git a/RandomNumberGenerator.sln b/RandomNumberGenerator.sln
index d5cf5e6..17b103d 100644
--- a/RandomNumberGenerator.sln
+++ b/RandomNumberGenerator.sln
@@ -10,7 +10,7 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "RandomNumberGenerator", "Ra
 EndProject
 Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "TruRNGpro", "TruRNGpro\TruRNGpro.vcxproj", "{983F2AF3-825E-4283-B55C-D0401CDA780B}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "RandomNumberGenerator.Test", "RandomNumberGenerator.Test\RandomNumberGenerator.Test.csproj", "{0507DC94-C63E-4C0A-8659-B18BC37DDE25}"
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "RandomNumberGenerator.Test", "tests\RandomNumberGenerator.Test\RandomNumberGenerator.Test.csproj", "{0507DC94-C63E-4C0A-8659-B18BC37DDE25}"
 	ProjectSection(ProjectDependencies) = postProject
 		{983F2AF3-825E-4283-B55C-D0401CDA780B} = {983F2AF3-825E-4283-B55C-D0401CDA780B}
 	EndProjectSection
diff --git a/RandomNumberGenerator.Test/CODING_GUIDELINES_TESTS.md b/tests/RandomNumberGenerator.Test/CODING_GUIDELINES_TESTS.md
similarity index 100%
rename from RandomNumberGenerator.Test/CODING_GUIDELINES_TESTS.md
rename to tests/RandomNumberGenerator.Test/CODING_GUIDELINES_TESTS.md
diff --git a/RandomNumberGenerator.Test/DeviceUpdateThread.Test.cs b/tests/RandomNumberGenerator.Test/DeviceUpdateThread.Test.cs
similarity index 100%
rename from RandomNumberGenerator.Test/DeviceUpdateThread.Test.cs
rename to tests/RandomNumberGenerator.Test/DeviceUpdateThread.Test.cs
diff --git a/RandomNumberGenerator.Test/GeneratorForm.Test.cs b/tests/RandomNumberGenerator.Test/GeneratorForm.Test.cs
similarity index 99%
rename from RandomNumberGenerator.Test/GeneratorForm.Test.cs
rename to tests/RandomNumberGenerator.Test/GeneratorForm.Test.cs
index 7273045..ba1f34f 100644
--- a/RandomNumberGenerator.Test/GeneratorForm.Test.cs
+++ b/tests/RandomNumberGenerator.Test/GeneratorForm.Test.cs
@@ -100,6 +100,16 @@ public TestContext TestContext
         [TestCleanup]
         public void Cleanup()
         {
+            // Let go of the form this test built, the way DeviceUpdateThreadTests does and for the same
+            // reason. Building a form points the device search at it and queues a search on the thread pool,
+            // and that search reports back by assigning the device list to whichever form is the parent when
+            // it finishes - which is a later test's form, or one that is being written to at that moment.
+            // The search guards that assignment with InvokeRequired, but a form that was never shown has no
+            // window handle, and InvokeRequired on a handleless control is false rather than true, so the
+            // report is made from the pool thread instead of being marshalled. Leaving the parent set is
+            // what let a search outlive the test that started it.
+            DeviceUpdateThread.Parent = null;
+
             // Delete test files if they exist to ensure clean state for next test
             string[] testFiles = {
                 m_sBASELINE_TEST_FILE,
diff --git a/RandomNumberGenerator.Test/HistogramChart.Test.cs b/tests/RandomNumberGenerator.Test/HistogramChart.Test.cs
similarity index 100%
rename from RandomNumberGenerator.Test/HistogramChart.Test.cs
rename to tests/RandomNumberGenerator.Test/HistogramChart.Test.cs
diff --git a/RandomNumberGenerator.Test/Properties/AssemblyInfo.cs b/tests/RandomNumberGenerator.Test/Properties/AssemblyInfo.cs
similarity index 100%
rename from RandomNumberGenerator.Test/Properties/AssemblyInfo.cs
rename to tests/RandomNumberGenerator.Test/Properties/AssemblyInfo.cs
diff --git a/RandomNumberGenerator.Test/RNGChart.Test.cs b/tests/RandomNumberGenerator.Test/RNGChart.Test.cs
similarity index 100%
rename from RandomNumberGenerator.Test/RNGChart.Test.cs
rename to tests/RandomNumberGenerator.Test/RNGChart.Test.cs
diff --git a/RandomNumberGenerator.Test/RNGDevice.Test.cs b/tests/RandomNumberGenerator.Test/RNGDevice.Test.cs
similarity index 100%
rename from RandomNumberGenerator.Test/RNGDevice.Test.cs
rename to tests/RandomNumberGenerator.Test/RNGDevice.Test.cs
diff --git a/RandomNumberGenerator.Test/RNGDeviceTimer.Test.cs b/tests/RandomNumberGenerator.Test/RNGDeviceTimer.Test.cs
similarity index 100%
rename from RandomNumberGenerator.Test/RNGDeviceTimer.Test.cs
rename to tests/RandomNumberGenerator.Test/RNGDeviceTimer.Test.cs
diff --git a/RandomNumberGenerator.Test/RNGSessionData.Test.cs b/tests/RandomNumberGenerator.Test/RNGSessionData.Test.cs
similarity index 100%
rename from RandomNumberGenerator.Test/RNGSessionData.Test.cs
rename to tests/RandomNumberGenerator.Test/RNGSessionData.Test.cs
diff --git a/RandomNumberGenerator.Test/RNGSessionDataFile.Test.cs b/tests/RandomNumberGenerator.Test/RNGSessionDataFile.Test.cs
similarity index 100%
rename from RandomNumberGenerator.Test/RNGSessionDataFile.Test.cs
rename to tests/RandomNumberGenerator.Test/RNGSessionDataFile.Test.cs
diff --git a/RandomNumberGenerator.Test/RNGSessionTimer.Test.cs b/tests/RandomNumberGenerator.Test/RNGSessionTimer.Test.cs
similarity index 100%
rename from RandomNumberGenerator.Test/RNGSessionTimer.Test.cs
rename to tests/RandomNumberGenerator.Test/RNGSessionTimer.Test.cs
diff --git a/RandomNumberGenerator.Test/RNGXMLReader.Test.cs b/tests/RandomNumberGenerator.Test/RNGXMLReader.Test.cs
similarity index 100%
rename from RandomNumberGenerator.Test/RNGXMLReader.Test.cs
rename to tests/RandomNumberGenerator.Test/RNGXMLReader.Test.cs
diff --git a/RandomNumberGenerator.Test/RNGXMLWriter.Test.cs b/tests/RandomNumberGenerator.Test/RNGXMLWriter.Test.cs
similarity index 100%
rename from RandomNumberGenerator.Test/RNGXMLWriter.Test.cs
rename to tests/RandomNumberGenerator.Test/RNGXMLWriter.Test.cs
diff --git a/RandomNumberGenerator.Test/RandomNumberGenerator.Test.csproj b/tests/RandomNumberGenerator.Test/RandomNumberGenerator.Test.csproj
similarity index 76%
rename from RandomNumberGenerator.Test/RandomNumberGenerator.Test.csproj
rename to tests/RandomNumberGenerator.Test/RandomNumberGenerator.Test.csproj
index 8faf58b..89000f4 100644
--- a/RandomNumberGenerator.Test/RandomNumberGenerator.Test.csproj
+++ b/tests/RandomNumberGenerator.Test/RandomNumberGenerator.Test.csproj
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Project ToolsVersion="15.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
-  <Import Project="..\packages\MSTest.TestAdapter.2.2.10\build\net46\MSTest.TestAdapter.props" Condition="Exists('..\packages\MSTest.TestAdapter.2.2.10\build\net46\MSTest.TestAdapter.props')" />
+  <Import Project="..\..\packages\MSTest.TestAdapter.2.2.10\build\net46\MSTest.TestAdapter.props" Condition="Exists('..\..\packages\MSTest.TestAdapter.2.2.10\build\net46\MSTest.TestAdapter.props')" />
   <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
   <PropertyGroup>
     <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
@@ -43,29 +43,29 @@
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="Castle.Core, Version=5.0.0.0, Culture=neutral, PublicKeyToken=407dd0808d44fbdc, processorArchitecture=MSIL">
-      <HintPath>..\packages\Castle.Core.5.1.1\lib\net462\Castle.Core.dll</HintPath>
+      <HintPath>..\..\packages\Castle.Core.5.1.1\lib\net462\Castle.Core.dll</HintPath>
     </Reference>
     <Reference Include="MathNet.Numerics, Version=5.0.0.0, Culture=neutral, processorArchitecture=MSIL">
-      <HintPath>..\packages\MathNet.Numerics.5.0.0\lib\net48\MathNet.Numerics.dll</HintPath>
+      <HintPath>..\..\packages\MathNet.Numerics.5.0.0\lib\net48\MathNet.Numerics.dll</HintPath>
     </Reference>
     <Reference Include="Microsoft.VisualStudio.TestPlatform.TestFramework, Version=14.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
-      <HintPath>..\packages\MSTest.TestFramework.2.2.10\lib\net45\Microsoft.VisualStudio.TestPlatform.TestFramework.dll</HintPath>
+      <HintPath>..\..\packages\MSTest.TestFramework.2.2.10\lib\net45\Microsoft.VisualStudio.TestPlatform.TestFramework.dll</HintPath>
     </Reference>
     <Reference Include="Microsoft.VisualStudio.TestPlatform.TestFramework.Extensions, Version=14.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
-      <HintPath>..\packages\MSTest.TestFramework.2.2.10\lib\net45\Microsoft.VisualStudio.TestPlatform.TestFramework.Extensions.dll</HintPath>
+      <HintPath>..\..\packages\MSTest.TestFramework.2.2.10\lib\net45\Microsoft.VisualStudio.TestPlatform.TestFramework.Extensions.dll</HintPath>
     </Reference>
     <Reference Include="Moq, Version=4.20.70.0, Culture=neutral, PublicKeyToken=69f491c39445e920, processorArchitecture=MSIL">
-      <HintPath>..\packages\Moq.4.20.70\lib\net462\Moq.dll</HintPath>
+      <HintPath>..\..\packages\Moq.4.20.70\lib\net462\Moq.dll</HintPath>
     </Reference>
     <Reference Include="System" />
     <Reference Include="System.Configuration" />
     <Reference Include="System.Core" />
     <Reference Include="System.Drawing" />
     <Reference Include="System.Runtime.CompilerServices.Unsafe, Version=4.0.4.1, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
-      <HintPath>..\packages\System.Runtime.CompilerServices.Unsafe.4.5.3\lib\net461\System.Runtime.CompilerServices.Unsafe.dll</HintPath>
+      <HintPath>..\..\packages\System.Runtime.CompilerServices.Unsafe.4.5.3\lib\net461\System.Runtime.CompilerServices.Unsafe.dll</HintPath>
     </Reference>
     <Reference Include="System.Threading.Tasks.Extensions, Version=4.2.0.1, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
-      <HintPath>..\packages\System.Threading.Tasks.Extensions.4.5.4\lib\net461\System.Threading.Tasks.Extensions.dll</HintPath>
+      <HintPath>..\..\packages\System.Threading.Tasks.Extensions.4.5.4\lib\net461\System.Threading.Tasks.Extensions.dll</HintPath>
     </Reference>
     <Reference Include="System.Windows.Forms" />
     <Reference Include="System.Windows.Forms.DataVisualization" />
@@ -94,7 +94,7 @@
     <None Include="packages.config" />
   </ItemGroup>
   <ItemGroup>
-    <ProjectReference Include="..\RandomNumberGenerator.csproj">
+    <ProjectReference Include="..\..\RandomNumberGenerator.csproj">
       <Project>{58f5fb77-99e5-4212-a46f-af3a18d46b17}</Project>
       <Name>RandomNumberGenerator</Name>
     </ProjectReference>
@@ -105,10 +105,10 @@
     <PropertyGroup>
       <ErrorText>This project references NuGet package(s) that are missing on this computer. Use NuGet Package Restore to download them.  For more information, see http://go.microsoft.com/fwlink/?LinkID=322105. The missing file is {0}.</ErrorText>
     </PropertyGroup>
-    <Error Condition="!Exists('..\packages\MSTest.TestAdapter.2.2.10\build\net46\MSTest.TestAdapter.props')" Text="$([System.String]::Format('$(ErrorText)', '..\packages\MSTest.TestAdapter.2.2.10\build\net46\MSTest.TestAdapter.props'))" />
-    <Error Condition="!Exists('..\packages\MSTest.TestAdapter.2.2.10\build\net46\MSTest.TestAdapter.targets')" Text="$([System.String]::Format('$(ErrorText)', '..\packages\MSTest.TestAdapter.2.2.10\build\net46\MSTest.TestAdapter.targets'))" />
+    <Error Condition="!Exists('..\..\packages\MSTest.TestAdapter.2.2.10\build\net46\MSTest.TestAdapter.props')" Text="$([System.String]::Format('$(ErrorText)', '..\..\packages\MSTest.TestAdapter.2.2.10\build\net46\MSTest.TestAdapter.props'))" />
+    <Error Condition="!Exists('..\..\packages\MSTest.TestAdapter.2.2.10\build\net46\MSTest.TestAdapter.targets')" Text="$([System.String]::Format('$(ErrorText)', '..\..\packages\MSTest.TestAdapter.2.2.10\build\net46\MSTest.TestAdapter.targets'))" />
   </Target>
-  <Import Project="..\packages\MSTest.TestAdapter.2.2.10\build\net46\MSTest.TestAdapter.targets" Condition="Exists('..\packages\MSTest.TestAdapter.2.2.10\build\net46\MSTest.TestAdapter.targets')" />
+  <Import Project="..\..\packages\MSTest.TestAdapter.2.2.10\build\net46\MSTest.TestAdapter.targets" Condition="Exists('..\..\packages\MSTest.TestAdapter.2.2.10\build\net46\MSTest.TestAdapter.targets')" />
   <PropertyGroup>
     <PostBuildEvent>xcopy /Y "$(SolutionDir)bin\TruRNGpro.dll" "$(TargetDir)"
 if errorlevel  1 goto end
diff --git a/tests/RandomNumberGenerator.Test/RandomNumberGenerator.sln b/tests/RandomNumberGenerator.Test/RandomNumberGenerator.sln
new file mode 100644
index 0000000..5f28270
--- /dev/null
+++ b/tests/RandomNumberGenerator.Test/RandomNumberGenerator.sln
@@ -0,0 +1 @@
+
\ No newline at end of file
diff --git a/RandomNumberGenerator.Test/SignificanceTest.Test.cs b/tests/RandomNumberGenerator.Test/SignificanceTest.Test.cs
similarity index 100%
rename from RandomNumberGenerator.Test/SignificanceTest.Test.cs
rename to tests/RandomNumberGenerator.Test/SignificanceTest.Test.cs
diff --git a/RandomNumberGenerator.Test/StatisticalAnalysis.Test.cs b/tests/RandomNumberGenerator.Test/StatisticalAnalysis.Test.cs
similarity index 100%
rename from RandomNumberGenerator.Test/StatisticalAnalysis.Test.cs
rename to tests/RandomNumberGenerator.Test/StatisticalAnalysis.Test.cs
diff --git a/RandomNumberGenerator.Test/TargetValues.Test.cs b/tests/RandomNumberGenerator.Test/TargetValues.Test.cs
similarity index 100%
rename from RandomNumberGenerator.Test/TargetValues.Test.cs
rename to tests/RandomNumberGenerator.Test/TargetValues.Test.cs
diff --git a/RandomNumberGenerator.Test/XMLDataPoint.Test.cs b/tests/RandomNumberGenerator.Test/XMLDataPoint.Test.cs
similarity index 100%
rename from RandomNumberGenerator.Test/XMLDataPoint.Test.cs
rename to tests/RandomNumberGenerator.Test/XMLDataPoint.Test.cs
diff --git a/RandomNumberGenerator.Test/packages.config b/tests/RandomNumberGenerator.Test/packages.config
similarity index 100%
rename from RandomNumberGenerator.Test/packages.config
rename to tests/RandomNumberGenerator.Test/packages.config
diff --git a/tests/manual/README.md b/tests/manual/README.md
index ed02f62..7fe0fe4 100644
--- a/tests/manual/README.md
+++ b/tests/manual/README.md
@@ -1,6 +1,6 @@
 # Manual test suites
 
-These drive the built application rather than its classes. The unit tests in `RandomNumberGenerator.Test`
+These drive the built application rather than its classes. The unit tests in `tests/RandomNumberGenerator.Test`
 cover the layers underneath the window; nothing in them builds the form's event wiring, and nothing in them
 can reach the device at all. Everything here exists because a fault got past a clean unit run.