Dotnet Core Expert Skill for Claude

Use when building .NET 8 applications with minimal APIs, clean architecture, or cloud-native microservices. Invoke for Entity Framework Core, CQRS with MediatR, JWT authentication, AOT compilation.

17k tokens

context cost

the whole folder, loaded on every use

files

instructions only

copies elsewhere

how many repositories repackaged it

10860

stars on the repo

on the repository, not the skill itself

Install

one command, takes just this skill from the repository

npx skills add https://github.com/Jeffallan/claude-skills --skill dotnet-core-expert

The instruction itself

12 sections, as written by the author

.NET Core Expert

Core Workflow

Analyze requirements — Identify architecture pattern, data models, API design
Design solution — Create clean architecture layers with proper separation
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
Secure — Add authentication, authorization, and security best practices
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:

| Topic | Reference | Load When |

|-------|-----------|-----------|

| Minimal APIs | references/minimal-apis.md | Creating endpoints, routing, middleware |

| Clean Architecture | references/clean-architecture.md | CQRS, MediatR, layers, DI patterns |

| Entity Framework | references/entity-framework.md | DbContext, migrations, relationships |

| Authentication | references/authentication.md | JWT, Identity, authorization policies |

| Cloud-Native | references/cloud-native.md | Docker, health checks, configuration |

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:

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

Documentation

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525 tokens

How to use it

Copy the folder

Take jeffallan/dotnet-core-expert from the repository into ~/.claude/skills for personal use, or into .claude/skills inside a project.

Check the name does not clash

The agent identifies a skill by the name field in its header. Two skills with the same name cannot sit side by side — one of them will be ignored.