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.NET Core Expert

Core Workflow

1. Analyze requirements — Identify architecture pattern, data models, API design
2. Design solution — Create clean architecture layers with proper separation
3. Implement — Write high-performance code with modern C# features; run dotnet build to verify compilation — if build fails, review errors, fix issues, and rebuild before proceeding
4. Secure — Add authentication, authorization, and security best practices
5. Test — Write comprehensive tests with xUnit and integration testing; run dotnet test to confirm all tests pass — if tests fail, diagnose failures, fix the implementation, and re-run before continuing; verify endpoints with curl or a REST client

Reference Guide

Load detailed guidance based on context:

Constraints

MUST DO

• Use .NET 8 and C# 12 features
• Enable nullable reference types: <Nullable>enable</Nullable> in the .csproj
• Use async/await for all I/O operations — e.g., await dbContext.Users.ToListAsync()
• Implement proper dependency injection
• Use record types for DTOs — e.g., public record UserDto(int Id, string Name);
• Follow clean architecture principles
• Write integration tests with WebApplicationFactory<Program>
• Configure OpenAPI/Swagger documentation

MUST NOT DO

• Use synchronous I/O operations
• Expose entities directly in API responses
• Skip input validation
• Use legacy .NET Framework patterns
• Mix concerns across architectural layers
• Use deprecated EF Core patterns

Code Examples

Minimal API Endpoint

// Program.cs
var builder = WebApplication.CreateBuilder(args);
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();
builder.Services.AddMediatR(cfg => cfg.RegisterServicesFromAssembly(typeof(Program).Assembly));

var app = builder.Build();
app.UseSwagger();
app.UseSwaggerUI();

app.MapGet("/users/{id}", async (int id, ISender sender, CancellationToken ct) =>
{
    var result = await sender.Send(new GetUserQuery(id), ct);
    return result is null ? Results.NotFound() : Results.Ok(result);
})
.WithName("GetUser")
.Produces<UserDto>()
.ProducesProblem(404);

app.Run();

MediatR Query Handler

// Application/Users/GetUserQuery.cs
public record GetUserQuery(int Id) : IRequest<UserDto?>;

public sealed class GetUserQueryHandler : IRequestHandler<GetUserQuery, UserDto?>
{
    private readonly AppDbContext _db;

    public GetUserQueryHandler(AppDbContext db) => _db = db;

    public async Task<UserDto?> Handle(GetUserQuery request, CancellationToken ct) =>
        await _db.Users
            .AsNoTracking()
            .Where(u => u.Id == request.Id)
            .Select(u => new UserDto(u.Id, u.Name))
            .FirstOrDefaultAsync(ct);
}

EF Core DbContext with Async Query

// Infrastructure/AppDbContext.cs
public sealed class AppDbContext(DbContextOptions<AppDbContext> options) : DbContext(options)
{
    public DbSet<User> Users => Set<User>();

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.ApplyConfigurationsFromAssembly(typeof(AppDbContext).Assembly);
    }
}

// Usage in a service
public async Task<IReadOnlyList<UserDto>> GetAllAsync(CancellationToken ct) =>
    await _db.Users
        .AsNoTracking()
        .Select(u => new UserDto(u.Id, u.Name))
        .ToListAsync(ct);

DTO with Record Type

public record UserDto(int Id, string Name);
public record CreateUserRequest(string Name, string Email);

Output Templates

When implementing .NET features, provide:

1. Project structure (solution/project files)
2. Domain models and DTOs
3. API endpoints or service implementations
4. Database context and migrations if applicable
5. Brief explanation of architectural decisions

Weekly Installs

1.1K

Repository

jeffallan/claude-skills

GitHub Stars

7.2K

First Seen

Jan 21, 2026

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