ASP.NET Core Web API

Produce well-structured ASP.NET Core Web API endpoints with proper HTTP semantics, OpenAPI documentation, and error handling.

When to Use

Use this skill when working on ASP.NET Core HTTP APIs, including:

• adding or modifying Web API endpoints implemented with controllers or minimal APIs;
• wiring up OpenAPI/Swagger metadata and endpoint documentation;
• defining request/response DTOs and consistent HTTP status code behavior;
• adding .http files or similar request-based API testing artifacts;
• configuring centralized API error handling middleware or exception mapping.

When Not to Use

Do not use this skill for:

• general C# coding style or non-API refactoring;
• EF Core data modeling or query optimization work; use optimizing-ef-core-queries;
• frontend, Razor, or Blazor UI changes;
• gRPC services;
• SignalR hubs or real-time messaging flows.

Inputs / prerequisites

Before applying this skill, gather the project context needed to match the existing API style and wiring:

• the ASP.NET Core entry point, typically Program.cs;
• any existing controllers, especially classes inheriting ControllerBase or using [ApiController];
• any existing minimal API registrations such as app.MapGet, app.MapPost, app.MapPut, or app.MapDelete;
• related DTO, model, validation, and error-handling types already used by the project;
• available build, run, and test commands so changes can be verified.

If the user asks for a new endpoint, inspect the current project structure first so the implementation follows the established conventions rather than mixing styles.

Workflow

Step 1: Determine the API style

Scan the project for existing endpoint patterns before writing any code.