Generate XML documentation from DocumentationAttribute for IDE IntelliSense

[Copilot]

Custom attributes don't render in IDE tooltips. The DocumentationAttribute contains rich metadata (description, parameters, examples) but IDEs show only the raw attribute syntax since they require XML documentation files.

Implementation

XmlDocGenerator MSBuild Package

• Roslyn-based post-build tool extracts DocumentationAttribute from compiled assemblies
• Augments XML documentation with <summary>, <remarks>, <example> elements
• Packaged as MSBuild SDK with automatic target integration
• Runs AfterTargets="Build" to process final output assemblies

Integration Points

• XmlDocGeneratorLocal.props - Local development (path resolution for net9.0 runtime)
• build/*.targets - NuGet consumer integration via MSBuild extensibility
• OmegaLeo.HelperLib.Documentation package dependency - transitive installation

Test Infrastructure

• 42 unit tests covering MathExtensions, IListExtensions, BenchmarkUtility, NeoDictionary
• xUnit framework integration
• CI workflow already configured for automatic PR validation

XML Generation Example

// Source code (clean, attribute only)
[Documentation("Start", "Starts or restarts the stopwatch for the given key.")]
public static void Start(string key)

// Generated XML (IDE consumes this)
<member name="M:OmegaLeo.HelperLib.Helpers.BenchmarkUtility.Start(System.String)">
    <summary>Starts or restarts the stopwatch for the given key.</summary>
</member>

Configuration Updates

• Added <GenerateDocumentationFile>true</GenerateDocumentationFile> to Changelog and Game projects (missing baseline XML generation)
• Fixed tool path resolution from net8.0 to net9.0 (matches runtime)
• Updated $(IntermediateOutputPath) to $(TargetDir) (IDEs read from bin, not obj)

Behavior

Library developers (ProjectReference): IDEs show source code, attributes visible in context
Package consumers (DLL reference): IDEs read XML files, rich IntelliSense from DocumentationAttribute

Works with Visual Studio, Rider, VS Code. Zero configuration for consumers - MSBuild targets auto-import from NuGet package cache.

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