Dotnet 10 Csharp 14

Diagnoses and fixes .NET MAUI development environment issues. Validates .NET SDK, workloads, Java JDK, Android SDK, Xcode, and Windows SDK. All version requirements discovered dynamically from NuGet WorkloadDependencies.json — never hardcoded. Use when: setting up MAUI development, build errors mentioning SDK/workload/JDK/Android, "Android SDK not found", "Java version" errors, "Xcode not found", environment verification after updates, or any MAUI toolchain issues. Do not use for: non-MAUI .NET projects, Xamarin.Forms apps, runtime app crashes unrelated to environment setup, or app store publishing issues. Works on macOS, Windows, and Linux.

Baseline C# skill loaded for every .NET code path. Guides language patterns (records, pattern matching, primary constructors, C# 8-15), coding standards, async/await, DI, LINQ, serialization, domain modeling, concurrency, Roslyn analyzers, globalization, native interop (P/Invoke, LibraryImport, ComWrappers), WASM interop (JSImport/JSExport), and type design. Spans 25 topics. Do not use for ASP.NET endpoint architecture, UI framework patterns, or CI/CD guidance.

Run file-based C# apps with the .NET CLI when the user explicitly wants C#/.NET code without creating a project. Use for C# language/API experiments, one-file C# apps, small multi-file C# apps composed with `#:include`/`#:exclude`, or C# file-based apps linked with `#:ref`. Do not use for language-agnostic throwaway scripts, generic computations, Python/PowerShell-style automation, full projects, or existing app integration.

Guidance for .NET MAUI XAML and C# data bindings — compiled bindings, INotifyPropertyChanged / ObservableObject, value converters, binding modes, multi-binding, relative bindings, fallbacks, and MVVM best practices. USE FOR: setting up compiled bindings with x:DataType, implementing INotifyPropertyChanged or CommunityToolkit ObservableObject, creating IValueConverter / IMultiValueConverter, choosing binding modes, configuring BindingContext, relative bindings, binding fallbacks, StringFormat, code-behind SetBinding with lambdas, and enforcing XC0022/XC0025 warnings. DO NOT USE FOR: CollectionView item templates and layouts (use maui-collectionview), Shell navigation data passing (use maui-shell-navigation), dependency injection (use maui-dependency-injection), or animations triggered by property changes (use .NET MAUI animation APIs).

Guide for theming .NET MAUI apps — light/dark mode via AppThemeBinding, ResourceDictionary theme switching, DynamicResource bindings, system theme detection, and user theme preferences. Use when: "dark mode", "light mode", "theming", "AppThemeBinding", "theme switching", "ResourceDictionary theme", "dynamic resources", "system theme detection", "color scheme", "app theme", "DynamicResource". Do not use for: localization or language switching (see .NET MAUI localization documentation), accessibility visual adjustments (see .NET MAUI accessibility documentation), app icons or splash screens (see .NET MAUI app icons documentation), or Bootstrap-style class theming (see Plugin.Maui.BootstrapTheme NuGet package).

.NET MAUI safe area and edge-to-edge layout guidance for .NET 10+. Covers the new SafeAreaEdges property, SafeAreaRegions enum, per-edge control, keyboard avoidance, Blazor Hybrid CSS safe areas, migration from legacy iOS-only APIs, and platform-specific behavior for Android, iOS, and Mac Catalyst. USE FOR: "safe area", "edge-to-edge", "SafeAreaEdges", "SafeAreaRegions", "keyboard avoidance", "notch insets", "status bar overlap", "iOS safe area", "Android edge-to-edge", "content behind status bar", "UseSafeArea migration", "soft input keyboard", "IgnoreSafeArea replacement". DO NOT USE FOR: general layout or grid design (use Grid and StackLayout), app lifecycle handling (use maui-app-lifecycle), theming or styling (use maui-theming), or Shell navigation structure.