[Marc-André Moreau (mamoreau-devolutions)]

Summary

Improves the Avalonia-to-Rust authoring surface across both code-first UI and managed AXAML + Rust view-model interop while keeping all published COM IIDs and vtable layouts unchanged:

• Hierarchy-Aware Wrappers (Upcast<Target>, Downcast<Target>, Deref):
  • Marks generated control wrappers #[repr(transparent)] and ComPtr<T> #[repr(C)].
  • Emits Deref<Target = ParentType>, static Upcast<Ancestor> / AsRef<Ancestor>, and safe runtime Downcast<Sub> (is::<T>(), cast::<T>()) across the control hierarchy, plus object_id(), same_object(), and NonOwningRef<T>.
• Ergonomic Property Conversions & Inline Attached Properties:
  • Adds tuple/scalar/array From conversions for Thickness, CornerRadius, Size, Point, Vector, Rect, PixelPoint, Color (including Color::parse_hex), Brush, and Paint.
  • Emits content_text / header_text helpers and inline attached-property builders (.grid_row(...), .grid_column(...), .dock_panel_dock(...), .canvas_left(...), .tool_tip_tip(...), etc.) on controls.
• Declarative El<T> Builders, rsx! Macro & Reactive Control Flow (Show / For):
  • Adds deferred El<T> descriptors (Control::el(), AppScope::mount_view, mount_into_*, ControlSlot) and the rsx! declarative macro supporting attached properties (Grid.row: 1), ref: node_ref, class: "...", string/expression children, and if/for blocks.
  • Adds Show::when / Show::when_else and keyed For::each (KeyedListReconciler, .children_for(...), .items_for(...)) that reuse realized controls and update per-item Signal<T> handles in place.
• Fine-Grained Scoped Reactivity, Context Injection, Safe Command & Async Resource<T>:
  • Adds Copy arena-backed Signal<T>, Memo<T>, Effect, NodeRef<T>, TwoWay<T>, ReactiveScope (with automatic subtree effect disposal), provide_context<T> / use_context<T>, Command::with_can_execute, Resource<T> (AppScope::create_resource), theme_variant_signal, resource_signal, theme_brush, and data_template_reactive container pooling.
  • Implements IntoValue<T> and IntoProp<T, Marker> so El<T> setters accept static values, signals, memos, closures, and signal.two_way().
• Compile-Time AXAML-to-Rust Transpiler (compile_axaml / --compile-axaml):
  • Adds rustolonia-bindgen --compile-axaml <input.axaml> <output.rs> to compile .axaml markup into typed El<T> builders, <ViewName>Refs, <ViewName>Bindings, and <ViewName>Handlers.
• Declarative View-Model Macros & Rust Source Scanner (--scan-rust):
  • Adds reactive_view_model!, prop!, when_any!, and ViewModelRustScanner (Avalonia.ViewModelProjection.Tool --scan-rust) supporting #[view_model], #[view_model_enum], #[prop], #[derived], #[collection], and #[command].

Validation

• cargo test --manifest-path .\rust\Cargo.toml -p rustolonia-bindgen --locked
• cargo test --manifest-path .\rust\Cargo.toml -p rustolonia --locked
• cargo check --manifest-path .\rust\Cargo.toml -p rustolonia --examples --locked
• dotnet build .\projection\Avalonia.ViewModelProjection.Tool\Avalonia.ViewModelProjection.Tool.csproj -c Release
• pwsh .\rust\tests\test-build-app.ps1