This skill prevents you from generating code that uses deprecated, obsolete, or removed APIs. Read this before writing any .NET MAUI, Blazor Hybrid, or MauiReactor code.
Reasoning Framework
Follow these steps before generating any MAUI-related code:
Step 1 — Detect the Target Framework
Read the project's .csproj file and find <TargetFramework> or <TargetFrameworks>:
<!-- Single target -->
<TargetFramework>net10.0-android</TargetFramework>
net10.0-android;net10.0-ios;net10.0-maccatalyst;net10.0-windows10.0.19041.0
The version number (`net10.0`, `net9.0`, `net8.0`) determines which APIs are available.
**Always target the version in the project file — never assume a version.**
### Step 2 — Detect Library Versions
Scan `<PackageReference>` entries and `<ItemGroup>` for key packages:
| Package | What it tells you |
|---------|-------------------|
| `Microsoft.Maui.Controls` | MAUI version (if explicit) |
| `CommunityToolkit.Maui` | Toolkit version — APIs change between major versions |
| `CommunityToolkit.Mvvm` | MVVM Toolkit version — needed for `WeakReferenceMessenger` |
| `Reactor.Maui` | MauiReactor version — v3+ has different APIs than v2 |
| `Microsoft.AspNetCore.Components.WebView.Maui` | Blazor Hybrid version |
If no explicit MAUI package version is listed, the MAUI SDK version matches the `<TargetFramework>` .NET version.
### Step 3 — Verify API Currency
Before using any API, ask yourself:
1. **Does this API exist in the detected version?** If you're unsure, prefer the newer pattern.
2. **Is this a Xamarin.Forms API?** MAUI is a different API surface — never assume Xamarin.Forms compatibility.
3. **Is this in the deprecated table below?** If so, use the replacement.
4. **Am I using the Compatibility namespace?** `Microsoft.Maui.Controls.Compatibility.*` types are migration aids, not recommended for new code.
### Step 4 — Apply Decision Rules
- **Always use the newest form** of an API when both old and new exist.
- **Never generate `using Xamarin.Forms`** or `using Xamarin.Essentials` — these are not MAUI.
- **Never use the `Compatibility` namespace** in new projects (`Compatibility.RelativeLayout`, `Compatibility.StackLayout`, etc.).
- **Prefer `async` method names** when both sync-named and async-named versions exist (e.g., `DisplayAlertAsync` over `DisplayAlert`).
- **Check the project's NuGet versions** before using CommunityToolkit or third-party APIs.
---
## Deprecated API Table — .NET MAUI 10
### Controls
| ❌ Deprecated / Removed | ✅ Use Instead | Notes |
|--------------------------|----------------|-------|
| `ListView` | `CollectionView` | `ListView`, `EntryCell`, `ImageCell`, `SwitchCell`, `TextCell`, `ViewCell`, and `Cell` are all deprecated in .NET 10 |
| `TableView` | `CollectionView` or custom layout | Deprecated in .NET 10 |
| `Frame` | `Border` | `Frame` is a Xamarin.Forms legacy control; `Border` is the MAUI replacement with `StrokeShape` support |
| `Compatibility.RelativeLayout` | `Grid` | Migration-only; removed from templates in .NET 10 |
| `Compatibility.StackLayout` | `VerticalStackLayout` / `HorizontalStackLayout` | The compatibility `StackLayout` wraps Xamarin layout logic. Use the native MAUI stack layouts for better performance |
### Gestures & Input
| ❌ Deprecated / Removed | ✅ Use Instead | Notes |
|--------------------------|----------------|-------|
| `ClickGestureRecognizer` | `TapGestureRecognizer` | Removed in .NET 10 |
| `Accelerator` | `KeyboardAccelerator` | Removed from `Microsoft.Maui.Controls` in .NET 10 |
### Page & Navigation
| ❌ Deprecated / Removed | ✅ Use Instead | Notes |
|--------------------------|----------------|-------|
| `Page.IsBusy` | `ActivityIndicator` | `IsBusy` is obsolete in .NET 10; use an explicit activity indicator |
| `DisplayAlert()` | `DisplayAlertAsync()` | Sync-named versions deprecated; use async versions |
| `DisplayActionSheet()` | `DisplayActionSheetAsync()` | Same as above |
| `MessagingCenter` | `WeakReferenceMessenger` (CommunityToolkit.Mvvm) | Made internal in .NET 10 |
### Animation
| ❌ Deprecated / Removed | ✅ Use Instead | Notes |
|--------------------------|----------------|-------|
| `FadeTo()` | `FadeToAsync()` | All animation extension methods renamed to `*Async` in .NET 10 |
| `RotateTo()`, `ScaleTo()`, `TranslateTo()`, etc. | `RotateToAsync()`, `ScaleToAsync()`, `TranslateToAsync()`, etc. | Same pattern — `RelRotateTo` → `RelRotateToAsync`, `RelScaleTo` → `RelScaleToAsync`, `LayoutTo` → `LayoutToAsync` |
### Device & Platform APIs
| ❌ Deprecated / Removed | ✅ Use Instead | Notes |
|--------------------------|----------------|-------|
| `Device.RuntimePlatform` | `DeviceInfo.Platform` | The entire `Device` class is deprecated |
| `Device.BeginInvokeOnMainThread()` | `Dispatcher.Dispatch()` | Use the view's or app's `Dispatcher` property |
| `Device.InvokeOnMainThreadAsync()` | `Dispatcher.DispatchAsync()` | Same |
| `Device.OpenUri()` | `Launcher.OpenAsync()` | Use `Microsoft.Maui.ApplicationModel.Launcher` |
| `Device.StartTimer()` | `Dispatcher.StartTimer()` or `PeriodicTimer` | Use the dispatcher or standard .NET timer |
| `DependencyService` | Constructor injection via `IServiceProvider` | Register services in `MauiProgram.cs` with `builder.Services` |
### XAML & Markup
| ❌ Deprecated / Removed | ✅ Use Instead | Notes |
|--------------------------|----------------|-------|
| `FontImageExtension` (XAML markup extension) | `FontImageSource` (type) | Use `<FontImageSource>` element or property syntax |
| `Color.FromHex()` | `Color.FromArgb()` | `FromHex` is obsolete |
### Safe Area & Layout
| ❌ Deprecated / Removed | ✅ Use Instead | Notes |
|--------------------------|----------------|-------|
| `Page.UseSafeArea` (iOS platform-specific) | `SafeAreaEdges` property | New in .NET 10; `ContentPage` defaults to `None` (edge-to-edge) on all platforms |
| `Layout.IgnoreSafeArea` | `SafeAreaEdges` property | Use the unified safe area API |
### Accessibility
| ❌ Deprecated / Removed | ✅ Use Instead | Notes |
|--------------------------|----------------|-------|
| `AutomationProperties.Name` | `SemanticProperties.Description` | `AutomationProperties` still works but `SemanticProperties` is the MAUI-native approach |
| `AutomationProperties.HelpText` | `SemanticProperties.Hint` | Same |
| iOS `SetAccessibilityHint` / `SetAccessibilityLabel` (Compatibility extensions) | `Microsoft.Maui.Platform.UpdateSemantics()` | Deprecated in .NET 10 |
### NuGet Packages
| ❌ Deprecated Package | ✅ Use Instead | Notes |
|------------------------|----------------|-------|
| `Xamarin.Forms` | `Microsoft.Maui.Controls` | Completely different API surface |
| `Xamarin.Essentials` | Built-in MAUI APIs (`Microsoft.Maui.Devices`, `Microsoft.Maui.ApplicationModel`, etc.) | Essentials is merged into MAUI |
| `Xamarin.CommunityToolkit` | `CommunityToolkit.Maui` | Different namespace and API surface |
| `Microsoft.Toolkit.Mvvm` | `CommunityToolkit.Mvvm` | Package was renamed |
---
## MauiReactor-Specific Guidance
MauiReactor v3+ (for .NET MAUI 9/10):
- **Hot reload**: v3+ uses a feature switch in `.csproj` via `<RuntimeHostConfigurationOption>`. Do NOT use the v2 `EnableMauiReactorHotReload()` call in `MauiProgram.cs`.
- **API wrappers**: MauiReactor auto-generates C# wrappers around MAUI controls. When a MAUI control is deprecated (e.g., `ListView`), the MauiReactor wrapper is also effectively deprecated. Use the MauiReactor wrapper for the replacement control (e.g., `CollectionView`).
- **State management**: Use `State<T>` and `Props<T>` — not older `RxComponent` patterns if they appear in outdated examples.
- **Navigation**: Use MauiReactor's built-in navigation (`Navigation.PushAsync<PageComponent>()`) — do NOT mix in MAUI Shell `GoToAsync` unless deliberately integrating Shell.
---
## Blazor Hybrid-Specific Guidance
- Use **`BlazorWebView`** — not the legacy `WebView` — for hosting Razor components.
- Use **.NET 10 Razor syntax**: `@rendermode` directives, `[SupplyParameterFromQuery]`, and the latest component model.
- **JS interop**: Use `IJSRuntime.InvokeAsync<T>()` — not the obsolete synchronous `IJSInProcessRuntime` patterns for mobile.
- **Safe areas**: In Blazor Hybrid, use CSS `env(safe-area-inset-*)` — do NOT combine XAML `SafeAreaEdges` and CSS safe area padding on the same element (causes double-padding).
- **Web resource interception**: .NET 10 adds `WebResourceRequested` event on `BlazorWebView` and `HybridWebView` for intercepting requests.
---
## Version Detection Cheat Sheet
### Reading the TFM
| TFM Pattern | .NET Version |
|-------------|-------------|
| `net10.0-*` | .NET 10 (latest, current) |
| `net9.0-*` | .NET 9 |
| `net8.0-*` | .NET 8 (LTS) |
### Reading MAUI SDK Version
If the `.csproj` uses `<UseMaui>true</UseMaui>`, the MAUI version matches the TFM:
- `net10.0` → MAUI 10
- `net9.0` → MAUI 9
### Reading MauiReactor Version
Check `<PackageReference Include="Reactor.Maui" Version="X.Y.Z" />`:
- v3.x → .NET MAUI 9/10 compatible, uses feature-switch hot reload
- v2.x → Legacy, uses `EnableMauiReactorHotReload()` builder pattern
### Reading CommunityToolkit Version
Check `<PackageReference Include="CommunityToolkit.Maui" Version="X.Y.Z" />`:
- v11+ → .NET 10 compatible
- v9-10 → .NET 9 compatible
- v5-7 → .NET 8 compatible
---
## Quick Rules
1. **Read the `.csproj` first.** Never generate code without knowing the target framework.
2. **When in doubt, use the newer API.** If two ways exist to do something, the newer way is correct.
3. **Never use `Xamarin.*` namespaces.** They do not exist in MAUI.
4. **Never use `Compatibility.*` types in new projects.** They are migration aids only.
5. **Check this table before using any `Device.*` API.** The `Device` class is fully deprecated.
6. **Use `*Async` method names** for animations, alerts, and action sheets in .NET 10+.
7. **Verify third-party package versions** before using their APIs — CommunityToolkit, MauiReactor, and others break between major versions.