$ show microsoft/WindowsAppSDK
The Windows App SDK (formerly Project Reunion) is a Microsoft platform SDK for building modern Windows desktop applications. It provides a unified set of WinRT APIs and runtime components that bridge Win32 and UWP development, enabling features like app lifecycle management (single-instance, file/protocol activation), dynamic package dependencies (resolving framework packages at runtime), rich notifications (toast, push, badge), resource management via MRT Core (PRI files with qualifier-based selection), deployment APIs (package sets, validation), environment variable management, OAuth 2.0 authentication, and interop wrappers for storage pickers and camera capture. The architecture is modular: each feature area is implemented as a separate C++/WinRT component (DLL) that can be consumed individually via NuGet packages. The SDK supports both packaged (MSIX) and unpackaged (self-contained) apps, with a bootstrap DLL that initializes the runtime and hooks into the Windows package graph via Detours. Key entry points include MddBootstrapInitialize2 for runtime initialization, the WindowsAppRuntime DLL for COM class factories, and individual component APIs like AppNotificationManager, PushNotificationManager, and PackageDependency. External dependencies include the Windows SDK, C++/WinRT projections, the Windows Implementation Libraries (WIL), and Microsoft Detours for API interception. Data flows involve inter-process communication through shared memory (for activation redirection), named pipes (for OAuth callbacks), and COM out-of-process servers (for push notification long-running tasks). The codebase is heavily instrumented with TraceLogging telemetry and uses feature flags (TerminalVelocity) to gate experimental APIs.
The LLM identified 5 files worth highlighting for reuse:
Provides a RAII wrapper around Windows file-mapping objects for inter-process communication. Encapsulates creation, mapping, and cleanup of shared memory regions with automatic unmapping on destruction. The pattern is self-contained and can be extracted for any Windows IPC scenario requiring efficient data sharing between processes.
Implements a fluent builder pattern for constructing Windows toast notification XML payloads. Methods like AddText, AddButton, AddComboBox, SetProgressBar, and SetScenario return *this for chaining. The builder handles XML serialization internally, insulating callers from raw XML. This pattern is reusable for any notification system requiring structured payload generation.
Uses Microsoft Detours to intercept Windows package graph APIs (GetCurrentPackageInfo, GetCurrentPackageInfo2, GetCurrentPackageInfo3, GetPackageGraphRevisionId) and inject dynamic package dependencies into the process's package graph. The implementation includes version-aware fallback logic and careful detour attach/detach management. This pattern is reusable for any scenario requiring runtime modification of Windows package identity or resource resolution.
Provides an efficient string container that can own or reference string data, with built-in encoding conversion between UTF-8, UTF-16, and ASCII. Supports both buffer ownership (allocated) and non-owning (referenced) modes, with automatic conversion on access. The design is self-contained and can be extracted for any project needing flexible string handling with encoding support.
Implements a thread-safe map (IMap<K,V>) with a lock() method that prevents further modifications while allowing reads. Uses std::recursive_mutex for thread safety. The pattern is reusable for any scenario requiring a concurrent map with a freeze capability, such as configuration stores or caches that need to be populated once and then read-only.