Sky

Sky is the workbench UI for Editor.Land. It is built with Astro and runs inside the OS WebView when the editor is launched in native mode: WKWebView on macOS, WebView2 on Windows. Sky consumes typed service interfaces from Wind (the Effect-TS service layer) for all state that crosses the UI boundary, including open files, panel layout, extension contributions, and language server results.

Sky communicates with Mountain (the Rust kernel) exclusively through Tauri’s typed IPC. It does not call the file system, spawn terminals, or talk to the Debug Adapter Protocol directly. Every native operation is a typed IPC call that Mountain fulfils. This strict boundary means the same Sky component tree can run in a browser during development (with Wind stubs) and in the real desktop application without any code change.

Source Layout

Sky’s source tree is compact and purpose-built:

Source/
├── Workbench/
│   ├── Mountain.astro       ← primary desktop entry-point (Tauri / native)
│   ├── Browser.astro        ← browser dev-mode entry-point
│   ├── BrowserTest.astro    ← browser test harness
│   ├── Default.astro        ← shared workbench shell (layout, panels)
│   ├── NLS.astro            ← National Language Support injection
│   ├── TelemetryBridge.astro← telemetry bridge to Mountain
│   ├── BrowserProxy/        ← dev proxy for browser debug profile
│   ├── Bundled/             ← bundled workbench module output
│   └── Electron/            ← Electron compatibility profile
├── Function/            ← pure functional utilities
├── pages/               ← Astro page routing
└── env.d.ts             ← Astro environment type declarations

Mountain.astro is the file that matters most for the native desktop experience. It bootstraps the Tauri WebView context, loads Wind’s Layer stack, and hands control to Default.astro which renders the workbench shell. All Wind service subscriptions, IPC channel initialization, and the SkyEvent listener registry are wired in Mountain.astro before the first frame paints.

NLS.astro injects the National Language Support data bundle into the workbench so that VS Code’s UI string catalog is available to extensions and platform modules that call vscode.l10n.*.

TelemetryBridge.astro connects Sky’s in-page telemetry events to Mountain’s PostHog reporter (behind the Telemetry feature flag).

Bundled/ holds the output of the Rest/Output build pipeline — the bundled VS Code workbench module graph that Sky loads inside the WebView.

Sky and Wind

Sky and Wind are two distinct layers that work together. Wind defines the Effect-TS service interfaces: the typed contracts for workbench state. Sky consumes those interfaces to render the actual UI components. The separation means UI components do not hold raw state. They subscribe to Wind services and re-render when those services emit changes.

This is the same model VS Code uses internally (a service container with injected dependencies), implemented with Effect-TS’s typed Layer system rather than VS Code’s untyped createDecorator approach. The practical result is that every Sky component is testable without a running desktop window.

The SkyEvent Registry

Mountain and Sky coordinate through a typed event URI registry called SkyEvent. The registry is maintained in two places that must stay in sync: Source/IPC/SkyEvent.ts in Wind (the TypeScript side) and Source/IPC/SkyEvent.rs in Mountain (the Rust side). When Mountain emits an event it uses the Rust enum variant; when Wind subscribes it uses the TypeScript constant. Drift between the two sides would cause listeners to never fire, so both files are updated together whenever a new event is added.

The registry currently defines 95 event URIs across the following domains:

Editor: sky://editor/applyEdits, sky://editor/openDocument, sky://editor/saveAll
Terminal: sky://terminal/create, sky://terminal/data, sky://terminal/resize, sky://terminal/processId, sky://terminal/show, sky://terminal/hide, sky://terminal/closed, sky://terminal/opened, sky://terminal/exit
Tree view: sky://tree-view/create, sky://tree-view/refresh, sky://tree-view/node-expanded, sky://tree-view/selection-changed, sky://tree-view/reveal, sky://tree-view/restore-state, sky://tree-view/set-badge, sky://tree-view/set-message, sky://tree-view/set-title, sky://tree-view/dispose
Status bar: sky://statusbar/create, sky://statusbar/set-entry, sky://statusbar/set-message, sky://statusbar/update, sky://statusbar/dispose, sky://statusbar/dispose-entry, sky://statusbar/dispose-message
Output: sky://output/create, sky://output/append, sky://output/replace, sky://output/clear, sky://output/show, sky://output/reveal, sky://output/dispose
Webview: sky://webview/create, sky://webview/created, sky://webview/set-html, sky://webview/post-message, sky://webview/message, sky://webview/options-changed, sky://webview/dispose, sky://webview/disposed, sky://webview/revealed
Notifications: sky://notification/show, sky://notification/progress-begin, sky://notification/progress-update, sky://notification/progress-end
SCM: sky://scm/register, sky://scm/provider/added, sky://scm/provider/changed, sky://scm/provider/removed, sky://scm/group/changed, sky://scm/updateGroup
Debug: sky://debug/register, sky://debug/start, sky://debug/stop
Test: sky://test/registered, sky://test/run-started, sky://test/run-status-changed
Documents, Diagnostics, Configuration, Language, Lifecycle, Progress, Task, Theme, UI, VFS, Window, Workspace: each with dedicated typed channels.

All URI strings follow a canonical kebab-case pattern (sky://domain/action). Older camelCase variants have been migrated to the canonical form so Sky only ever sees a single consistent shape per event.

Build Profile Behaviour

Sky’s runtime environment depends on which build profile is active:

debug — Sky runs as a plain web app in the browser. Browser.astro is the entry point; no Tauri WebView, no Mountain process. Astro’s dev server with HMR is active so component changes reflect without a full page reload. File system, terminal, and debug APIs are unavailable. Used for rapid UI iteration.
debug-mountain — Sky runs inside WKWebView (macOS) or WebView2 (Windows) via Mountain.astro. Mountain is running; all Tauri IPC calls resolve through the Rust kernel. This is the primary development target for both platforms and the only profile where the full editor experience is available.
debug-electron — Workbench/Electron/ provides compatibility shims for running Sky inside Electron’s renderer. This profile exists for compatibility testing and is not actively maintained.

Current Status

Sky is the active UI layer for the debug-mountain profile on macOS and Windows. The workbench builds, installs, and runs correctly on both platforms.

Verified working in debug-mountain:

The editor window opens and renders the full workbench UI via WKWebView (macOS) or WebView2 (Windows).
The VS Code-compatible editor surface (Monaco or equivalent) is active.
Panel layout, command palette, and status bar render through Sky components driven by Wind service subscriptions.
Terminal panels open, receive data on sky://terminal/data, and resize correctly via sky://terminal/resize.
Tree-view panels populate via $provideTreeChildren through Cocoon and refresh via sky://tree-view/refresh.
Output channels create, append, and clear correctly.
Status bar entries create and update without flicker.
Webview panels open and receive HTML via sky://webview/set-html.
Wind service subscriptions drive UI state updates without full-page reloads.
NLS data bundle loads correctly, making VS Code UI strings and extension localisation available via vscode.l10n.*.
TelemetryBridge connects in-page events to Mountain’s reporter.

Optimisation roadmap:

The workbench module graph currently consists of 3,385 dynamically imported modules loaded sequentially at cold boot. The application is fully functional today. The Rest/Output pipeline is being extended to bundle this graph into a single pre-linked module, which is projected to cut cold-boot time by ~550 ms. This is a well-scoped, in-progress optimisation — not a blocker.
Notebook UI, chat panel, and language model UI panels are on the roadmap, consistent with the planned vscode.notebook.*, vscode.chat.*, and vscode.lm.* API work in Cocoon.

VS Code UI Compatibility

Sky reimplements the VS Code workbench UI rather than forking it. The goal is behavioural compatibility: panels, tabs, the command palette, the status bar, and the activity bar behave as a VS Code user expects, without carrying Electron’s renderer process or VS Code’s original webpack bundle. The surfaces that are complete work correctly today. Incomplete surfaces are absent rather than silently broken.

Sky