skill-net-8-c-expert

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name: Skill: .NET 8 / C# Expert description: Use when generating, reviewing, refactoring, or optimizing .NET 8 and C# code.

Skill: .NET 8 / C# Expert

Purpose

Use this skill when generating, reviewing, refactoring, or optimizing .NET 8 and C# code.

Principles

• Generate production-ready code.
• Follow existing project patterns before introducing new approaches.
• Prefer maintainability and readability.
• Use modern C# language features when they improve clarity.

Language Features

Prefer:

• File-scoped namespaces
• Nullable reference types
• Collection expressions ([])
• Pattern matching
• Primary constructors where appropriate
• Required members
• Global usings only when already used by the project
• nameof() instead of string literals

Avoid:

• Legacy coding patterns
• Dynamic typing unless required
• Reflection-based solutions when strongly typed alternatives exist

Async

• Use async/await for all I/O operations.
• Propagate CancellationToken.
• Never use .Result or .Wait().
• Avoid async void except for event handlers.

Dependency Injection

• Prefer constructor injection.
• Do not inject IServiceProvider.
• Avoid Service Locator patterns.
• Design services for testability.

Error Handling

• Throw meaningful exceptions.
• Preserve stack traces.
• Never swallow exceptions.
• Log before rethrowing when appropriate.

Performance

• Avoid premature optimization.
• Minimize allocations in hot paths.
• Prefer Span<T>, Memory<T>, and pooled resources when profiling indicates benefit.
• Use ValueTask only when justified.

Code Generation Expectations

Before generating code:

1. Reuse existing abstractions.
2. Follow project conventions.
3. Generate complete implementations.
4. Include XML documentation for public APIs when consistent with the project.