What problem does it solve? Building ASP.NET Core Web APIs involves many decisions—HTTP status codes, DTO design, OpenAPI wiring, and error handling—that are easy to get wrong or inconsistent. This Skill guides the creation and modification of Web API endpoints so they follow correct HTTP semantics, produce rich OpenAPI documentation, and handle errors uniformly with RFC 7807 Problem Details. ## Core Features & Use Cases - Endpoint Implementation: Adds or modifies endpoints using controllers or minimal APIs, matching the project's existing style and using TypedResults with correct status codes (201 with Location, 204 for deletes, etc.). - DTO & OpenAPI Conventions: Defines sealed record request/response types with XML doc comments, DateTimeOffset, string-serialized enums, and built-in .NET 9+ OpenAPI support instead of Swashbuckle. - Error Handling & Testing: Sets up global exception handling middleware returning Problem Details, a service layer with interfaces, and .http test files for every endpoint. - Use Case: Ask the assistant to add a CRUD products endpoint to your ASP.NET Core project, and it will create the DTOs, minimal API or controller endpoints, OpenAPI metadata, exception handler, service layer, and a .http file—then verify with dotnet build. ## Quick Start Add a new REST endpoint for managing products to my ASP.NET Core project, including DTOs, OpenAPI documentation, error handling, and a .http test file.
