.NET Core Expert

What it does

When your agent uses it

• Starting a new .NET 8 minimal API project with a layered structure
• Adding CQRS handlers with MediatR to an existing .NET service
• Setting up JWT authentication and authorization policies
• Modeling data and migrations with Entity Framework Core
• Preparing a .NET service for containers with health checks

Example prompts

• “Create a .NET 8 minimal API for managing orders with EF Core and a clean architecture solution layout.”
• “Add a GetCustomerQuery handler using MediatR and return a record DTO instead of the entity.”
• “Protect the admin endpoints with JWT bearer auth and a role-based policy.”
• “Write WebApplicationFactory integration tests for the products endpoints.”

Requirements

• The .NET 8 SDK with the `dotnet` CLI

Workflow steps

5 steps, taken from the first numbered list in SKILL.md.

1. 1Analyze requirements — Identify architecture pattern, data models, API design
2. 2Design solution — Create clean architecture layers with proper separation
3. 3Implement — Write high-performance code with modern C# features; run dotnet build to verify compilation — if build fails, review errors…
4. 4Secure — Add authentication, authorization, and security best practices
5. 5Test — Write comprehensive tests with xUnit and integration testing; run dotnet test to confirm all tests pass — if tests fail, diagnose…

What it can do on your machine

Read from SKILL.md and the folder at commit 1be15d8. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  Shell commands in SKILL.md call:

  • dotnet

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  Links to these hosts (documentation or services it may open):

  • github.com
  • synergetic.solutions
  • jeffallan.github.io

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

.NET Core Expert loads about 1.3k tokens when it runs, and up to ~17k if it reads all its reference files. Until then it costs about 54 tokens; SKILL.md has 292 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~54

When it runs · the whole SKILL.md, loaded when a task matches

~1.3k

With references · SKILL.md plus every file in references/, read only if the agent opens them

~17k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from Jeffallan/claude-skills at commit 1be15d8, republished under its MIT licence (© Jeffallan). 292 words, ~1,310 tokens.

name

dotnet-core-expert

description

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.

license

MIT

metadata.author

https://github.com/Jeffallan

metadata.company

https://synergetic.solutions

metadata.version

1.1.0

metadata.domain

backend

metadata.triggers

.NET Core, .NET 8, ASP.NET Core, C# 12, minimal API, Entity Framework Core, microservices .NET, CQRS, MediatR

metadata.role

specialist

metadata.scope

implementation

metadata.output-format

code

metadata.related-skills

fullstack-guardian, microservices-architect, cloud-architect, test-master

// 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();

// 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);
}

// 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);

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

© Jeffallan, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 5 other files (references) in skills/dotnet-core-expert of Jeffallan/claude-skills.

• SKILL.md
• references/authentication.md
• references/clean-architecture.md
• references/cloud-native.md
• references/entity-framework.md
• references/minimal-apis.md

Open the folder on GitHubat commit 1be15d8