microsoft-extensions-dependency-injection — Claude Code skill

What microsoft-extensions-dependency-injection does

The skill covers registration patterns in Microsoft.Extensions.DependencyInjection built around extension methods on IServiceCollection. Instead of one long Program.cs you get a chain like AddUserServices().AddOrderServices().AddEmailServices(), each method owning one slice of the container. Singleton, Scoped and Transient lifetimes get the same treatment, along with decorators and service interception.

It also sets conventions: naming such as Add{Feature}Services(), Configure{Feature}() and Use{Feature}() for middleware, plus file placement — {Feature}ServiceCollectionExtensions.cs sits next to that feature's services. A testing section shows how to reuse production configuration inside WebApplicationFactory and override only what differs, like the email sender or the payment processor.

The payoff shows up on a team: fewer merge conflicts, visible boundaries between subsystems. Ordering is on you, though. When one module depends on another, calling AddEmailServices() before AddOrderServices() is the caller's job — the skill just says so plainly.