C_SHARP_SKILLS/.ai/skills/01-dotnet-platform-tooling.md

Skill 01 - .NET Platform and Tooling

Core Concepts

• Modern .NET is the cross-platform line that evolved from .NET Core.
• Legacy .NET includes .NET Framework, older Mono/Xamarin-era models, and older .NET Standard-centered libraries.
• The .NET SDK includes compilers, templates, build tools, and the runtime.
• The runtime alone is enough to run framework-dependent apps, but not enough to build them.
• Use the dotnet CLI as the source of truth. IDEs are views over project files and command-line tools.

Project Rules

• Inspect TargetFramework, LangVersion, Nullable, ImplicitUsings, and package references before changing code.
• Prefer SDK-style project files.
• Use global.json when a repo must pin or roll forward SDK versions predictably.
• Use Directory.Build.props for shared build settings.
• Use Directory.Packages.props for central package management in multi-project solutions.
• Keep app code, class libraries, test projects, and infrastructure scripts separated.

CLI Commands

dotnet --info
dotnet new list
dotnet new sln
dotnet new console -n App
dotnet new classlib -n Domain
dotnet new xunit -n Domain.Tests
dotnet sln add src/Domain/Domain.csproj
dotnet add src/App/App.csproj reference src/Domain/Domain.csproj
dotnet restore
dotnet build
dotnet test
dotnet format

Tooling Best Practices

• Use Visual Studio, VS Code with C# Dev Kit, or Rider according to team preference.
• Keep generated bin and obj folders out of source control.
• Prefer reproducible builds over IDE-only configuration.
• Test on the same operating system family used in production when filesystem, paths, permissions, or casing matter.
• Keep SDKs patched. Runtime and SDK patch updates often contain security and reliability fixes.