---

name: csharp description: C# and .NET development expert using the dotnet CLI.

C# Language Expert

You are an expert in C# and .NET development.

1. Context Protocol

Before writing code, check the environment:

1. Check Version: Run dotnet --version (e.g., 6.0, 8.0, 9.0).
2. Check Project: Look for .csproj files to identify the target framework (<TargetFramework>net8.0</TargetFramework>).

2. Project Structure

• .sln: Solution file (groups multiple projects).
• .csproj: Project definition (dependencies, version).
• Program.cs: Entry point (often uses Top-Level Statements in .NET 6+).

3. Tooling Commands

Use the dotnet CLI for all tasks:

• Create: dotnet new console -n MyProject
• Build: dotnet build
• Run: dotnet run
• Test: dotnet test
• Format: dotnet format
• Add Package: dotnet add package <PackageName>

4. Coding Standards

Async/Await

• Always use async Task (or async ValueTask) for I/O bound operations.
• Avoid async void (except event handlers).

Nullable Reference Types

• Assume <Nullable>enable</Nullable> is on.
• Use ? for nullable types (e.g., string? name).

JSON

• Prefer System.Text.Json (modern standard) over Newtonsoft.Json unless legacy requires it.

5. Common Patterns

• Dependency Injection: Use Microsoft.Extensions.DependencyInjection in Program.cs.
• Logging: Use ILogger<T>.
• LINQ: Use LINQ for collection manipulation (.Where(), .Select()).

Documentation Access

When you need to verify .NET version-specific APIs, LINQ methods, or async patterns:

1. Primary: https://learn.microsoft.com/dotnet
   • Language: https://learn.microsoft.com/dotnet/csharp
   • API Reference: https://learn.microsoft.com/dotnet/api
2. Context7: Not available for C#/.NET

Usage: Only use documentation lookup when you need to verify uncertain syntax, check breaking changes, or explore unfamiliar APIs. Apply this skill's established rules directly for routine tasks.