> For the complete documentation index, see [llms.txt](https://framework.aic.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://framework.aic.io/technical-guidelines-code-standards-and-tech-stack/wpf-standards/wpf-application-architecture.md).

# WPF Application Architecture

## Purpose

WPF applications must remain maintainable as UI complexity grows. AIC uses MVVM, dependency injection and clear separation between UI and business logic.

## Standard Layers

```
Desktop Shell
ViewModels
Application Services
Domain
Infrastructure
```

## Composition Root

The WPF app startup configures services:

```csharp
public partial class App : Application
{
    private IHost? _host;

    protected override async void OnStartup(StartupEventArgs e)
    {
        _host = Host.CreateDefaultBuilder()
            .ConfigureServices((context, services) =>
            {
                services.AddApplication();
                services.AddInfrastructure(context.Configuration);
                services.AddSingleton<MainWindow>();
                services.AddTransient<MainViewModel>();
            })
            .Build();

        await _host.StartAsync();

        var mainWindow = _host.Services.GetRequiredService<MainWindow>();
        mainWindow.Show();
    }
}
```

## Rules

* Views define layout and interaction.
* ViewModels expose state and commands.
* Application services perform use cases.
* Infrastructure handles persistence, files, devices and APIs.
* Domain contains business rules.

## UI Thread Rule

Never block the UI thread with I/O or long-running CPU work.

Use async commands and progress state.

## Error Handling

WPF applications must have:

* user-friendly error messages
* structured logs for diagnostics
* global exception handling
* retry or recovery for transient failures
* safe shutdown behaviour

## Deployment Considerations

Document:

* packaging format
* installation route
* update route
* configuration location
* logs location
* user data location
* rollback or uninstall approach