everything-claude-code/rules/csharp/coding-style.md

paths

paths
**/*.cs **/*.csx

C# Coding Style

This file extends common/coding-style.md with C#-specific content.

Standards

• Follow current .NET conventions and enable nullable reference types
• Prefer explicit access modifiers on public and internal APIs
• Keep files aligned with the primary type they define

Types and Models

• Prefer record or record struct for immutable value-like models
• Use class for entities or types with identity and lifecycle
• Use interface for service boundaries and abstractions
• Avoid dynamic in application code; prefer generics or explicit models

public sealed record UserDto(Guid Id, string Email);

public interface IUserRepository
{
    Task<UserDto?> FindByIdAsync(Guid id, CancellationToken cancellationToken);
}

Immutability

• Prefer init setters, constructor parameters, and immutable collections for shared state
• Do not mutate input models in-place when producing updated state

public sealed record UserProfile(string Name, string Email);

public static UserProfile Rename(UserProfile profile, string name) =>
    profile with { Name = name };

Async and Error Handling

• Prefer async/await over blocking calls like .Result or .Wait()
• Pass CancellationToken through public async APIs
• Throw specific exceptions and log with structured properties

public async Task<Order> LoadOrderAsync(
    Guid orderId,
    CancellationToken cancellationToken)
{
    try
    {
        return await repository.FindAsync(orderId, cancellationToken)
            ?? throw new InvalidOperationException($"Order {orderId} was not found.");
    }
    catch (Exception ex)
    {
        logger.LogError(ex, "Failed to load order {OrderId}", orderId);
        throw;
    }
}

Formatting

• Use dotnet format for formatting and analyzer fixes
• Keep using directives organized and remove unused imports
• Prefer expression-bodied members only when they stay readable