diff --git a/.github/agents/test-developer.md b/.github/agents/test-developer.md
index ab09044..1b2b752 100644
--- a/.github/agents/test-developer.md
+++ b/.github/agents/test-developer.md
@@ -55,6 +55,32 @@ public void ClassName_MethodUnderTest_Scenario_ExpectedBehavior()
 - Clear failure messages for assertions
 - Consider edge cases and error conditions
 
+### Tests and Requirements
+
+- **All requirements MUST have linked tests** - this is enforced in CI
+- **Not all tests need requirements** - tests may be created for:
+  - Exploring corner cases not explicitly stated in requirements
+  - Testing design decisions and implementation details
+  - Failure-testing and error handling scenarios
+  - Verifying internal behavior beyond requirement scope
+
+### Test Source Filters
+
+Test links in `requirements.yaml` can include a source filter prefix to restrict which test results count as
+evidence. These filters are critical for platform and framework requirements - **do not remove them**.
+
+- `windows@TestName` - proves the test passed on a Windows platform
+- `ubuntu@TestName` - proves the test passed on a Linux (Ubuntu) platform
+- `net8.0@TestName` - proves the test passed under the .NET 8 target framework
+- `net9.0@TestName` - proves the test passed under the .NET 9 target framework
+- `net10.0@TestName` - proves the test passed under the .NET 10 target framework
+- `dotnet8.x@TestName` - proves the self-validation test ran on a machine with .NET 8.x runtime
+- `dotnet9.x@TestName` - proves the self-validation test ran on a machine with .NET 9.x runtime
+- `dotnet10.x@TestName` - proves the self-validation test ran on a machine with .NET 10.x runtime
+
+Removing a source filter means a test result from any environment can satisfy the requirement, which invalidates
+the evidence-based proof that the tool works on a specific platform or framework.
+
 ### SpdxTool-Specific
 
 - **NOT self-validation tests** - those are handled by Software Developer Agent
@@ -97,8 +123,18 @@ Common anti-patterns to avoid (not exhaustive):
    // ✅ Good: Assert.HasCount(3, collection);
    ```
 
+5. **Avoid Assert.IsTrue for string prefix checks** - Use `Assert.StartsWith` instead of wrapping
+   `string.StartsWith` in `Assert.IsTrue`, as it produces clearer failure messages that show the expected prefix
+   and actual value:
+
+   ```csharp
+   // ❌ Bad: Assert.IsTrue(value.StartsWith("prefix"));
+   // ✅ Good: Assert.StartsWith("prefix", value);
+   ```
+
 ## Defer To
 
+- **Requirements Agent**: For test strategy and coverage requirements
 - **Software Developer Agent**: For self-validation tests and production code issues
 - **Technical Writer Agent**: For test documentation in markdown
 - **Code Quality Agent**: For test linting and static analysis
diff --git a/src/DemaConsulting.SpdxTool/DemaConsulting.SpdxTool.csproj b/src/DemaConsulting.SpdxTool/DemaConsulting.SpdxTool.csproj
index 3145dca..e4023b7 100644
--- a/src/DemaConsulting.SpdxTool/DemaConsulting.SpdxTool.csproj
+++ b/src/DemaConsulting.SpdxTool/DemaConsulting.SpdxTool.csproj
@@ -3,7 +3,7 @@
   <PropertyGroup>
     <OutputType>Exe</OutputType>
     <TargetFrameworks>net8.0;net9.0;net10.0</TargetFrameworks>
-    <LangVersion>12</LangVersion>
+    <LangVersion>latest</LangVersion>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
 
@@ -46,11 +46,27 @@
     <SBOMPackageSupplier>Organization: $(Company)</SBOMPackageSupplier>
   </PropertyGroup>
 
+  <!-- Runtime Dependencies -->
   <ItemGroup>
     <PackageReference Include="DemaConsulting.SpdxModel" Version="2.5.0" />
     <PackageReference Include="DemaConsulting.TestResults" Version="1.5.0" />
+    <PackageReference Include="YamlDotNet" Version="16.3.0" />
+  </ItemGroup>
+
+  <!-- Build Tool Dependencies -->
+  <ItemGroup>
     <PackageReference Include="Microsoft.Sbom.Targets" Version="4.1.5" PrivateAssets="All" />
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="10.0.103" PrivateAssets="All" />
+    <PackageReference Include="Polyfill" Version="9.12.0" PrivateAssets="All" />
+  </ItemGroup>
+
+  <!-- Code Analysis Dependencies -->
+  <ItemGroup>
+    <!-- Analyzer packages use child-element form to configure both PrivateAssets and IncludeAssets:
+         - PrivateAssets="all" prevents these build-time analyzers from becoming transitive dependencies
+           in packages that consume this tool.
+         - IncludeAssets lists all asset types (including 'analyzers' and 'buildtransitive') to ensure
+           Roslyn analyzers and MSBuild targets are fully activated during the build. -->
     <PackageReference Include="Microsoft.CodeAnalysis.NetAnalyzers" Version="10.0.103">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
@@ -59,7 +75,6 @@
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
-    <PackageReference Include="YamlDotNet" Version="16.3.0" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/test/DemaConsulting.SpdxTool.Targets.Tests/DemaConsulting.SpdxTool.Targets.Tests.csproj b/test/DemaConsulting.SpdxTool.Targets.Tests/DemaConsulting.SpdxTool.Targets.Tests.csproj
index fc2dd0c..ce0f06d 100644
--- a/test/DemaConsulting.SpdxTool.Targets.Tests/DemaConsulting.SpdxTool.Targets.Tests.csproj
+++ b/test/DemaConsulting.SpdxTool.Targets.Tests/DemaConsulting.SpdxTool.Targets.Tests.csproj
@@ -42,8 +42,10 @@
     </PackageReference>
   </ItemGroup>
 
+  <!-- Implicit Usings -->
   <ItemGroup>
     <Using Include="Microsoft.VisualStudio.TestTools.UnitTesting" />
+    <Using Include="Polyfills" />
   </ItemGroup>
 
 </Project>
diff --git a/test/DemaConsulting.SpdxTool.Tests/DemaConsulting.SpdxTool.Tests.csproj b/test/DemaConsulting.SpdxTool.Tests/DemaConsulting.SpdxTool.Tests.csproj
index 849df90..980bafb 100644
--- a/test/DemaConsulting.SpdxTool.Tests/DemaConsulting.SpdxTool.Tests.csproj
+++ b/test/DemaConsulting.SpdxTool.Tests/DemaConsulting.SpdxTool.Tests.csproj
@@ -50,8 +50,10 @@
     </ProjectReference>
   </ItemGroup>
 
+  <!-- Implicit Usings -->
   <ItemGroup>
     <Using Include="Microsoft.VisualStudio.TestTools.UnitTesting" />
+    <Using Include="Polyfills" />
   </ItemGroup>
 
 </Project>
\ No newline at end of file