modern-csharp-coding-standards

SKILL.md

Modern C# coding standards covering records, pattern matching, value objects, async/await, and high-performance patterns.

Use record types for immutable DTOs and domain entities; readonly record struct for value objects with zero-allocation semantics

Leverage pattern matching with switch expressions, nullable reference types, and composition over inheritance for cleaner, type-safe code

Apply async/await throughout with mandatory CancellationToken parameters; use Span<T>, Memory<T>, and ArrayPool<T> for performance-critical paths

Handle expected business errors with Result<T, TError> types; reserve exceptions for unexpected system failures

Avoid reflection-based metaprogramming (AutoMapper, Mapster) in favor of explicit mapping and composition patterns

Modern C# Coding Standards

When to Use This Skill

Use this skill when:

Writing new C# code or refactoring existing code

Designing public APIs for libraries or services

Optimizing performance-critical code paths

Implementing domain models with strong typing

Building async/await-heavy applications

Working with binary data, buffers, or high-throughput scenarios

Reference Files

value-objects-and-patterns.md: Full value object examples and pattern matching code

performance-and-api-design.md: Span/Memory examples and API design principles

composition-and-error-handling.md: Composition over inheritance, Result type, testing patterns

anti-patterns-and-reflection.md: Reflection avoidance and common anti-patterns