maui-dependency-injection

# Dependency Injection in .NET MAUI .NET MAUI uses the same `Microsoft.Extensions.DependencyInjection` container as ASP.NET Core. All service registration happens in `MauiProgram.CreateMauiApp()` on `builder.Services`. The container is built once at startup and is immutable thereafter. ## When to Use - Registering services, ViewModels, and Pages in `MauiProgram.cs` - Choosing between `AddSingleton`, `AddTransient`, and `AddScoped` - Wiring constructor injection for Pages and ViewModels - Leveraging Shell navigation to auto-resolve DI-registered Pages - Registering platform-specific service implementations with `#if` directives - Designing interfaces for testable service layers ## When Not to Use - XAML data-binding syntax or compiled bindings — use the **maui-data-binding** skill - Shell route registration and query parameters — use the **maui-shell-navigation** skill - Mocking frameworks or test runners — use standard .NET testing tools (xUnit, NUnit, MSTest) and mocking libraries (NSubstitute, Moq) ## Inputs - A .NET MAUI project with a `MauiProgram.cs` file - Knowledge of which services, ViewModels, and Pages need registration - Target platforms (Android, iOS, Mac Catalyst, Windows) for conditional registrations ## Rules That Change the Answer | Situation | Do this | Why | |---|---|---| | Registering a Page or ViewModel | Prefer `AddTransient` | A fresh instance per navigation avoids stale state, and a Singleton page cannot be re-added to the visual tree after it ...