ASP.NET Core minimal API - endpoint mechanics

This skill owns the shape of a minimal API endpoint: where it is registered, what it returns, how parameters bind, and how a cross-cutting concern hangs off it. It stops at the endpoint boundary. The pipeline-wide concerns - validation library choice, resilience, observability, response caching - belong to the ASP.NET Core cross-cutting hub, the failure-to-ProblemDetails contract to the HTTP error-handling skill, OpenAPI document generation and the docs UI to the OpenAPI skill, and auth configuration to the .NET authentication skill; the controller-based counterpart is the skill covering controller-based Web APIs. Where your skill list has none of them, the endpoint rules below still execute - keep the concern out of the lambda and report the surrounding wiring as unowned rather than inventing a second convention for it. Floor is .NET 8 / C# 12; anything newer is marked optional.

When to use

• Covers how an endpoint is shaped and wired, not what surrounds it: MapGroup registration, TypedResults and Results-of-T outcome unions, IEndpointFilter, parameter binding, endpoint metadata, and hardened IFormFile uploads.
• Later additions (beyond the .NET 8 floor) are flagged optional.
• Do NOT use for MVC or API controllers (that is the controller-based Web API skill), gRPC, SignalR, or non-HTTP code.

Where endpoints live

Program.cs is for wiring, not for routes. Each feature or resource owns one registration extension method that maps its group: