AppAlling 🧩

AppAlling is a pluggable, reactive WinForms shell written in .NET 9.
It provides a minimal, opinionated host that loads external plugins to compose:

• Menus and commands
• Tool windows and views
• Reactive global state shared across plugins
• Services and background tasks

The shell itself contains almost no business logic.
Everything is contributed by plugins through well-defined contracts.

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✨ Features

• Plugin-first design — Drop *.dll plugins into /plugins and they light up the shell
• Centralized state management — Redux-style Store<T> with Rx observables
• Dependency injection — Microsoft.Extensions.DependencyInjection powers DI
• Data-driven UI — Menus and commands are described declaratively (no hard-coded WinForms controls)

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📦 Solution Layout

AppAlling/
├─ src/
│  ├─ AppAlling.Abstractions/       # Contracts for plugins (no UI deps)
│  ├─ AppAlling.Application/        # State store, command bus, DI extensions
│  ├─ AppAlling.PluginHost/         # Assembly discovery and composition
│  ├─ AppAlling.UI.WinForms/        # Shell (minimal WinForms host)
│  └─ AppAlling.Plugins.HelloWorld/ # Example plugin (menus + tool window)
└─ plugins/                         # Runtime plugin folder (copied here at build)

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🚀 Getting Started

Prerequisites

• .NET 9 SDK
• Windows (WinForms)

Build & Run

dotnet build
dotnet run --project src/AppAlling.UI.WinForms

On build, sample plugins are copied to /plugins, so they’ll load automatically.

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🧩 Writing a Plugin

Create a new class library referencing AppAlling.Abstractions:

dotnet new classlib -n MyCoolPlugin
dotnet add MyCoolPlugin reference src/AppAlling.Abstractions/AppAlling.Abstractions.csproj

Implement IAppallingPlugin and optional contribution interfaces:

public sealed class MyPlugin : IAppallingPlugin, IMenuModelContribution, ICommandContribution
{
    public PluginMetadata Metadata => new("my.plugin", "My Plugin", "1.0.0");

    public void ConfigureServices(IServiceCollection services, IPluginContext ctx)
    {
        // Register any services, command handlers, or tool window factories
        services.AddSingleton<ICommandExec>(new Exec("myPlugin.sayHi", _ =>
        {
            MessageBox.Show("Hello from MyPlugin!");
            return Task.CompletedTask;
        }));
    }

    public IEnumerable<CommandDescriptor> DescribeCommands() => new[]
    {
        new CommandDescriptor("myPlugin.sayHi", "Say Hi")
    };

    public IEnumerable<MenuItemDescriptor> BuildMenuModel() => new[]
    {
        new MenuItemDescriptor("&Tools", Children: new []
        {
            new MenuItemDescriptor("Say &Hi", "myPlugin.sayHi")
        })
    };

    private sealed class Exec(string id, Func<IServiceProvider, Task> run) : ICommandExec
    {
        public bool CanHandle(string commandId) => commandId == id;
        public Task ExecuteAsync(IServiceProvider sp) => run(sp);
    }
}

Build your plugin and copy the DLL to plugins/. Launch AppAlling — your menu item will appear instantly.

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🏗 Extensibility Points

Contract	Purpose
ICommandContribution	Declare commands (metadata)
IMenuModelContribution	Contribute to menu tree (data-driven)
IToolWindowContribution	Register tool windows by command ID
ICommandExec	Provide execution logic for commands
IToolWindowFactory	Build Form/UserControl instances
IStore<AppState>	Access centralized, reactive state

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📜 License

MIT — do whatever you want, but a link back or credit is appreciated.