Use when building or reviewing an ASP.NET Core (.NET 8/9) HTTP service in a touchstone repo — minimal APIs vs controllers, DI lifetimes, options/config, ProblemDetails, EF Core, auth policies, middleware, resilience, integration tests. Triggers on `Microsoft.AspNetCore` in a .csproj, `WebApplication.CreateBuilder` / `app.MapGet` in Program.cs, `[ApiController]` controllers, `DbContext`. C#-language rules (nullable, async, analyzers, packaging) live in the csharp skill.
