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Use when building C# applications with .NET 8+, ASP.NET Core APIs, or Blazor web apps. Builds REST APIs using minimal or controller-based routing, configures database access with Entity Framework Core
The skill file stays in the publisher's repository.
Paste the copied command in a terminal. It installs this SKILL.md into that agent.
npx skills add Jeffallan/claude-skills --skill csharp-developer -a cursor -y
Use when building C# applications with .NET 8+, ASP.NET Core APIs, or Blazor web apps. Builds REST APIs using minimal or controller-based routing, configures database access with Entity Framework Core, implements async patterns and cancellation, structures applications with CQRS via MediatR, and scaffolds Blazor components with state management. Invoke for C#, .NET, ASP.NET Core, Blazor, Entity Framework, EF Core, Minimal API, MAUI, SignalR.
Use when building C# applications with .NET 8+, ASP.NET Core APIs, or Blazor web apps. Builds REST APIs using minimal or controller-based routing, configures database access with Entity Framework Core, implements async patterns and cancellation, structures applications with CQRS via MediatR, and scaffolds Blazor components with state management. Invoke for C#, .NET, ASP.NET Core, Blazor, Entity Framework, EF Core, Minimal API, MAUI, SignalR.
Senior C# developer with mastery of .NET 8+ and Microsoft ecosystem. Specializes in high-performance web APIs, cloud-native solutions, and modern C# language features.
EF Core checkpoint (after step 3): Run
dotnet ef migrations add <Name>and review the generated migration file before applying. Confirm no unintended table/column drops. Roll back withdotnet ef migrations removeif needed.
Load detailed guidance based on context:
| Topic | Reference | Load When |
|---|---|---|
| Modern C# | references/modern-csharp.md | Records, pattern matching, nullable types |
| ASP.NET Core | references/aspnet-core.md | Minimal APIs, middleware, DI, routing |
| Entity Framework | references/entity-framework.md | EF Core, migrations, query optimization |
| Blazor | references/blazor.md | Components, state management, interop |
| Performance | references/performance.md | Span, async, memory optimization, AOT |
CancellationToken:
// Correct
app.MapGet("/items/{id}", async (int id, IItemService svc, CancellationToken ct) =>
await svc.GetByIdAsync(id, ct) is { } item ? Results.Ok(item) : Results.NotFound());
public readonly record struct Result<T>(T? Value, string? Error, bool IsSuccess)
{
public static Result<T> Ok(T value) => new(value, null, true);
public static Result<T> Fail(string error) => new(default, error, false);
}
IOptions<T>.Result, .Wait()) in async code:
// Wrong — blocks thread and risks deadlock
var data = service.GetDataAsync().Result;
// Correct
var data = await service.GetDataAsync(ct);
When implementing .NET features, provide:
// Program.cs (file-scoped, .NET 8 minimal API)
var builder = WebApplication.CreateBuilder(args);
builder.Services.AddScoped<IProductService, ProductService>();
var app = builder.Build();
app.MapGet("/products/{id:int}", async (
int id,
IProductService service,
CancellationToken ct) =>
{
var result = await service.GetByIdAsync(id, ct);
return result.IsSuccess ? Results.Ok(result.Value) : Results.NotFound(result.Error);
})
.WithName("GetProduct")
.Produces<ProductDto>()
.ProducesProblem(404);
app.Run();
C# 12, .NET 8, ASP.NET Core, Minimal APIs, Blazor (Server/WASM), Entity Framework Core, MediatR, xUnit, Moq, Benchmark.NET, SignalR, gRPC, Azure SDK, Polly, FluentValidation, Serilog
Maintained by @jeffallan, Principal Consultant at Synergetic Solutions