C# Coding Skill

Mandatory patterns and idioms for writing modern C#. All items in this skill are requirements, not suggestions. Use for new code; opportunistically refactor existing code when revisiting.

Framework Detection

Before writing code, check TargetFramework in the project's csproj to determine the available C# language version. If the csproj has no TargetFramework, look for a Directory.Build.props (or other *.props file) that defines it; these files spread common properties across multiple projects. Only use features whose minimum version tag (e.g., C# 12+) is satisfied by the project. When a mandated feature is unavailable, fall back to the idiomatic alternative for that version.

Required Language Features