DesktopFramework.Core 1.0.0

WOS — Blazor Web Desktop Framework on .NET Aspire

A reusable, browser-based "web desktop" shell built with Blazor (Interactive Server), .NET 10 and .NET Aspire. Any Blazor component can be registered as an app and opened inside a movable, resizable, minimizable / maximizable window — like a Windows / Ubuntu desktop running in the browser, with a glass (acrylic) look, a taskbar, a start menu, notifications and theming.

Demo

<video src="media/file0.webm" controls width="100%"></video>

If the player above doesn't appear, watch it here: media/file0.webm

Features

• 🪟 Windowing — open/close, focus & z-ordering, move, resize (8 handles), minimize, maximize/restore, single- and multi-instance apps, window cascade.
• 🖱️ Smooth drag & resize — handled by a JS module (pointer events) so gestures never round-trip to the server; final geometry is committed back to Blazor on gesture end.
• 🧩 Dynamic apps — register any Razor component as an app; it renders in a window via DynamicComponent, with parameters passed in.
• 🟦 Taskbar — a button per open window (active highlighted), click to focus / minimize, start button, system tray with clock, theme toggle and a live notification badge.
• 🔍 Start menu — apps grouped by category, live search.
• 🖥️ Desktop icons — launch apps by double-click (or Enter/Space).
• 🔔 Notifications — a client-side store, a bell panel (click an item to dismiss, "clear all"), and toasts that pop bottom-right then fade out while the item stays in the list.
• 🎨 Glassmorphism theming — translucent acrylic surfaces (backdrop-filter), light/dark themes via CSS variables, persisted to localStorage.
• 🆎 Font Awesome 6 (free) icons throughout (app icons are just FA class strings).
• ⛶ Fullscreen toggle button (top-right) using the browser Fullscreen API.
• ⏳ Busy/loading cursor — BusyService flips the whole desktop to the OS wait cursor while async work runs (e.g. a slow API call).
• 🔐 Login + roles — a configurable two-step sign-in (step 1: credentials → step 2: pick company / role) that calls an auth API and stores the session in sessionStorage. The whole flow is driven by LoginFlowOptions, so a project can disable step 2 (EnableContextStep = false) for a plain single-step login, or toggle/require each selector. Apps can require roles (AppDescriptor.RequiredRoles) and are hidden for users who lack them.
• 🛡️ Resilient errors — API failures (400/401/403/404/408/429/5xx, timeouts, network down) return as data and render a friendly in-window error panel with Retry; an ErrorBoundary around each window contains unexpected crashes to that window — the desktop never goes down.
• 💾 Persistence — window layout (position/size/state/z-order) and theme survive reloads via localStorage, behind an IDesktopPersistence seam that can later move to a backend.
• ☁️ Aspire-native — orchestration, service discovery, health, OpenTelemetry and resilient HttpClients from day one. The Blazor app calls the API by logical name, not a hardcoded URL.

Quick start

Prerequisites: .NET 10 SDK.

dotnet run --project DesktopFramework.AppHost

This boots the Aspire dashboard plus both resources (web + api). Open the web endpoint listed in the dashboard. The desktop loads its welcome content and notifications from DesktopFramework.Api through Aspire service discovery.

The Font Awesome stylesheet is loaded from a CDN, so the first run needs internet access for icons to appear. (See Offline icons below to self-host.)

Build / test only:

dotnet build WOS.slnx

Solution structure

Reference flow: AppHost → web, api · ServiceDefaults ← web, api · Contracts ← api, web, core · Core ← Components, SampleApps, Web · Components ← SampleApps, Web · SampleApps ← Web.

Core concepts

Services (in DesktopFramework.Core, all scoped — one desktop per circuit)

Seams the host implements (in DesktopFramework.Web): IDesktopContentService → DesktopApiClient (typed HttpClient), IDesktopPersistence → LocalStoragePersistence (JS localStorage), IPermissionService → default AllowAllPermissionService (auth-ready for later).

Backend API

Registering an app

Icons are Font Awesome class strings (or an emoji — both work).

registry.Register(new AppDescriptor
{
    Id = "customers",
    Title = "Customers",
    Icon = "fa-solid fa-user",
    ComponentType = typeof(CustomerApp),
    Category = DesktopAppCategory.Productivity,
    AllowMultipleInstances = true,
    DefaultWindowOptions = new WindowOptions { InitialSize = new(480, 340) },
});

Open it (optionally with parameters / a de-dup key):

windowManager.OpenApp("customers", new AppLaunchOptions
{
    InstanceKey = "42",
    Parameters = new Dictionary<string, object?> { ["CustomerId"] = 42 },
});

The component renders inside its window via DynamicComponent; Parameters keys must match the target component's [Parameter] properties. Single-instance apps refocus instead of duplicating; multi-instance apps open separate windows (de-duped by InstanceKey when provided).

The bundled sample apps are Welcome, About, Settings (single-instance), Customers (multi-instance with a CustomerId parameter), Notification Demo, and Data Loader (loads from a slow endpoint to show the busy cursor) — registered in SampleApps/SampleAppRegistration.cs and wired from Web/Components/Pages/Home.razor.

Showing the busy cursor during async work

@inject BusyService Busy
...
_data = await Busy.RunAsync(() => Content.GetReportAsync());
// Desktop shows the OS wait cursor for the whole duration; reference-counted,
// so concurrent operations behave correctly.

Pushing a notification from an app

@inject NotificationService Notifications
...
Notifications.Add("Saved", "Customer #42 updated.", severity: "success");
// → appears as a toast bottom-right, then settles into the bell panel.

severity is one of info | success | warning | error.

Theming

All chrome reads CSS variables defined in Components/wwwroot/css/desktop-framework.css; [data-theme="dark"] swaps the set. Override the variables (e.g. --wos-accent, --wos-desktop-bg, --wos-glass-blur) to reskin the desktop without touching components. The sun/moon button in the tray toggles dark mode and persists it.

Offline icons

Font Awesome is currently referenced from a CDN in Web/Components/App.razor. To work fully offline, install the free package (e.g. via libman/npm) and point the <link> at the local copy under wwwroot.

Architecture notes

• Render mode: Interactive Server. API calls live server-side so Aspire service discovery "just works"; drag/resize stays smooth because JS owns the gesture.
• State flow: components mutate state only through services; services raise events; components re-render. No component-to-component mutation.
• Per-circuit state: services are scoped, so each connected user gets their own desktop.
• Persistence v1: window layout + theme in localStorage. Notifications are in-memory per session. The IDesktopPersistence seam lets this move to an Aspire backend service later.

See .claude/plans/ for the full technical plan, phase breakdown and the future-services design (Settings/Notifications/Identity/Files APIs).

Project layout (key files)

DesktopFramework.Core/
  Windowing/        WindowInstance, WindowOptions, WindowState, geometry, WindowCommand
  Apps/             AppDescriptor, AppLaunchOptions, DesktopAppCategory, IDesktopApp
  Services/         WindowManager, AppRegistry, ZIndexManager, DesktopStateService,
                    ThemeService, NotificationService, WindowPersistenceService, interfaces
DesktopFramework.Components/
  Desktop/          DesktopShell, DesktopBackground, DesktopIcon, Taskbar, FullscreenButton
  Windowing/        WindowHost, AppWindow, WindowTitleBar, WindowContent
  Layout/           StartMenu, ContextMenu, NotificationArea, NotificationToasts
  Widgets/          WelcomeWidget
  Icon.razor
  wwwroot/js/window-interop.js     (drag, resize, localStorage, theme, fullscreen)
  wwwroot/css/desktop-framework.css
DesktopFramework.Web/
  Services/         DesktopApiClient, LocalStoragePersistence
  Components/Pages/Home.razor       (hosts <DesktopShell/>, registers apps)
  Program.cs

Roadmap

• Persist notifications and per-icon positions.
• Right-click context menus on desktop / icons / taskbar (component exists, not yet wired).
• Pinned taskbar apps, Alt-Tab switcher.
• Real Aspire backend services behind the existing seams (Settings, Notifications, Identity, Files).
• Authentication + permission enforcement (the AppDescriptor already carries RequiredRoles/Claims/Permissions).