accessibility

---
name: accessibility
description: Primary accessibility skill for VS Code. REQUIRED for new feature and contribution work, and also applies to updates of existing UI. Covers accessibility help dialogs, accessible views, verbosity settings, signals, ARIA announcements, keyboard navigation, and ARIA labels/roles.
---

## When to Use This Skill

Use this skill for any VS Code feature work that introduces or changes interactive UI.
Use this skill by default for new features and contributions, including when the request does not explicitly mention accessibility.

Trigger examples:
- "add a new feature"
- "implement a new panel/view/widget"
- "add a new command or workflow"
- "new contribution in workbench/editor/extensions"
- "update existing UI interactions"

Do not skip this skill just because accessibility is not named in the prompt.

When adding a **new interactive UI surface** to VS Code — a panel, view, widget, editor overlay, dialog, or any rich focusable component the user interacts with — you **must** provide three accessibility components (if they do not already exist for the feature):

1. **An Accessibility Help Dialog** — opened via the accessibility help keybinding when the feature has focus.
2. **An Accessible View** — a plain-text read-only editor that presents the feature's content to screen reader users (when the feature displays non-trivial visual content).
3. **An Accessibility Verbosity Setting** — a boolean setting that controls whether the "open accessibility help" hint is announced.

Examples of existing features that have all three: the **terminal**, **chat panel**, **notebook**, **diff editor**, **inline completions**, **comments**, **debug REPL**, **hover**, and **notifications**. Features with only a help dialog (no accessible view) include **find widgets**, **source control input**, **keybindings editor**, **problems panel**, and **walkthroughs**.

Sections 4–7 below (signals, ARIA announcements, keyboard navigation, ARIA labels) apply more broadly to **any UI change**, including modifications to existing features.

When **updating an existing feature** — for example, adding new commands, keyboard shortcuts, or interactive capabilities — you must also update the feature's existing accessibility help dialog (`provideContent()`) to document the new functionality. Screen reader users rely on the help dialog as the primary way to discover available actions.

---

## 1. Accessibility Help Dialog

An accessibility help dialog tells the user what the feature does, which keyboard shortcuts are available, and how to interact with it via a screen reader.

### Steps

1. **Create a class implementing `IAccessibleViewImplementation`** with `type = AccessibleViewType.Help`.
   - Set a `priority` (higher = shown first when multiple providers match).
   - Set `when` to a `ContextKeyExpression` that matches when the feature is focused.
   - `getProvider(accessor)` returns an `AccessibleContentProvider`.

2. **Create a content-provider class** implementing `IAccessibleViewContentProvider`.
   - `id` — add a new entry in the `AccessibleViewProviderId` enum in `src/vs/platform/accessibility/browser/accessibleView.ts`.
   - `verbositySettingKey` — reference the new `AccessibilityVerbositySettingId` entry (see §3).
   - `options` — `{ type: AccessibleViewType.Help }`.
   - `provideContent()` — return localized, multi-line help text.

3. **Implement `onClose()`** to restore focus to whatever element was focused before the help dialog opened. This ensures keyboard users and screen reader users return to their previous context.

4. **Register** the implementation:
   ```ts
   AccessibleViewRegistry.register(new MyFeatureAccessibilityHelp());
   ```
   in the feature's `*.contribution.ts` file.

### Example skeleton

The simplest approach is to return an `AccessibleContentProvider` directly from `getProvider()`. This is the most common pattern in the codebase (used by chat, inline chat, quick chat, etc.):

```ts
import { AccessibleViewType, AccessibleContentProvider, AccessibleViewProviderId } from '../../../../platform/accessibility/browser/accessibleView.js';
import { IAccessibleViewImplementation } from '../../../../platform/accessibility/browser/accessibleViewRegistry.js';
import { AccessibilityVerbositySettingId } from '../../../../platform/accessibility/common/accessibilityConfiguration.js';

export class MyFeatureAccessibilityHelp implements IAccessibleViewImplementation {
	readonly priority = 100;
	readonly name = 'my-feature';
	readonly type = AccessibleViewType.Help;
	readonly when = MyFeatureContextKeys.isFocused;

	getProvider(accessor: ServicesAccessor) {
		const helpText = [
			localize('myFeature.help.overview', "You are in My Feature. …"),
			localize('myFeature.help.key1', "- {0}: Do something", '<keybinding:myFeature.doSomething>'),
		].join('\n');
		return new AccessibleContentProvider(
			AccessibleViewProviderId.MyFeature,
			{ type: AccessibleViewType.Help },
			() => helpText,
			() => { /* onClose — refocus whatever was focused before */ },
			AccessibilityVerbositySettingId.MyFeature,
		);
	}
}
```

Alternatively, if the provider needs injected services or must track state (e.g., storing a reference to the previously focused element), create a custom class that extends `Disposable` and implements `IAccessibleViewContentProvider`, then instantiate it via `IInstantiationService` (see `CommentsAccessibilityHelpProvider` for an example):

```ts
class MyFeatureAccessibilityHelpProvider extends Disposable implements IAccessibleViewContentProvider {
	readonly id = AccessibleViewProviderId.MyFeature;
	readonly verbositySettingKey = AccessibilityVerbositySettingId.MyFeature;
	readonly options: IAccessibleViewOptions = { type: AccessibleViewType.Help };

	provideContent(): string { /* … */ }
	onClose(): void { /* … */ }
}

// In getProvider():
getProvider(accessor: ServicesAccessor) {
	return accessor.get(IInstantiationService).createInstance(MyFeatureAccessibilityHelpProvider);
}
```

---

## 2. Accessible View

An accessible view presents the feature's visual content as plain text in a read-only editor. It is required when the feature renders rich or visual content that a screen reader cannot directly read (for example: chat responses, hover tooltips, notifications, terminal output, inline completions).

If the feature is purely keyboard-driven with native text input/output (e.g., a simple input field), an accessible view is not needed — only an accessibility help dialog is required.

### Steps

1. **Create a class implementing `IAccessibleViewImplementation`** with `type = AccessibleViewType.View`.
2. **Create a content-provider** similar to the help dialog, but:
   - `options` — `{ type: AccessibleViewType.View }`, optionally with a `language` for syntax highlighting.
   - `provideContent()` — return the feature's current content as plain text.
   - Optionally implement `provideNextContent()` / `providePreviousContent()` for item-by-item navigation.
   - Implement `onClose()` to restore focus to whatever was focused before the accessible view was opened.
   - Optionally provide `actions` for actions the user can take from the accessible view.
3. **Register** alongside the help dialog:
   ```ts
   AccessibleViewRegistry.register(new MyFeatureAccessibleView());
   ```

### Example skeleton

```ts
export class MyFeatureAccessibleView implements IAccessibleViewImplementation {
	readonly priority = 100;
	readonly name = 'my-feature';
	readonly type = AccessibleViewType.View;
	readonly when = MyFeatureContextKeys.isFocused;

	getProvider(accessor: ServicesAccessor) {
		// Retrieve services, build content from the feature's current state
		const content = getMyFeatureContent();
		if (!content) {
			return undefined;
		}
		return new AccessibleContentProvider(
			AccessibleViewProviderId.MyFeature,
			{ type: AccessibleViewType.View },
			() => content,
			() => { /* onClose — refocus whatever was focused before the accessible view opened */ },
			AccessibilityVerbositySettingId.MyFeature,
		);
	}
}
```

---

## 3. Accessibility Verbosity Setting

A verbosity setting controls whether a hint such as "press Alt+F1 for accessibility help" is announced when the feature gains focus. Users who already know the shortcut can disable it.

### Steps

1. **Add an entry** to `AccessibilityVerbositySettingId` in
   `src/vs/workbench/contrib/accessibility/browser/accessibilityConfiguration.ts`:
   ```ts
   export const enum AccessibilityVerbositySettingId {
       // … existing entries …
       MyFeature = 'accessibility.verbosity.myFeature'
   }
   ```

2. **Register the configuration property** in the same file's `configuration.properties` object:
   ```ts
   [AccessibilityVerbositySettingId.MyFeature]: {
       description: localize('verbosity.myFeature.description',
           'Provide information about how to access the My Feature accessibility help menu when My Feature is focused.'),
       ...baseVerbosityProperty
   },
   ```
   The `baseVerbosityProperty` gives it `type: 'boolean'`, `default: true`, and `tags: ['accessibility']`.

3. **Reference the setting key** in both the help-dialog provider (`verbositySettingKey`) and the accessible-view provider so the runtime can check whether to show the hint.

---

## 4. Accessibility Signals (Sounds & Announcements)

Accessibility signals provide audible and spoken feedback for events that happen visually. Use `IAccessibilitySignalService` to play signals when something important occurs (e.g., an error appears, a task completes, content changes).

### When to use

- **Use an existing signal** when the event already has one defined (see `AccessibilitySignal.*` static members — e.g., `AccessibilitySignal.error`, `AccessibilitySignal.terminalQuickFix`, `AccessibilitySignal.clear`).
- **If no existing signal fits**, reach out to @meganrogge to discuss adding a new one. Do not register new signals without coordinating first.

### How signals work

Each signal has two modalities controlled by user settings:
- **Sound** — a short audio cue, configurable to `auto` (on when screen reader attached), `on`, or `off`.
- **Announcement** — a spoken message via `aria-live`, configurable to `auto` or `off`.

### Usage

```ts
// Inject the service via constructor parameter
constructor(
	@IAccessibilitySignalService private readonly _accessibilitySignalService: IAccessibilitySignalService
) { }

// Play a signal
this._accessibilitySignalService.playSignal(AccessibilitySignal.terminalQuickFix);

// Play with options
this._accessibilitySignalService.playSignal(AccessibilitySignal.error, { userGesture: true });
```

---

## 5. ARIA Alerts vs. Status Messages

Use the `alert()` and `status()` functions from `src/vs/base/browser/ui/aria/aria.ts` to announce dynamic changes to screen readers.

### `alert(msg)` — Assertive live region (`role="alert"`)
- **Use for**: Urgent, important information that the user must know immediately.
- **Examples**: Errors, warnings, critical state changes, results of a user-initiated action.
- **Behavior**: Interrupts the screen reader's current speech.

### `status(msg)` — Polite live region (`aria-live="polite"`)
- **Use for**: Non-urgent, informational updates that should be spoken when the screen reader is idle.
- **Examples**: Progress updates, search result counts, background state changes.
- **Behavior**: Queued and spoken after the screen reader finishes its current output.

### Guidelines

- **Prefer `status()` over `alert()`** unless the information is time-sensitive or the result of a direct user action. Overusing `alert()` creates a noisy, disruptive experience.
- **Keep messages concise.** Screen readers read the entire message; long messages delay the user.
- **Do not duplicate** — if an accessibility signal already announces the event, do not also call `alert()` / `status()` for the same information.
- **Localize** all messages with `nls.localize()`.

---

## 6. Keyboard Navigation

Every interactive UI element must be fully operable via the keyboard.

### Requirements

- **Tab order**: All interactive elements must be reachable via `Tab` / `Shift+Tab` in a logical order.
- **Arrow key navigation**: Lists, trees, grids, and toolbars must support arrow key navigation following WAI-ARIA patterns.
- **Focus visibility**: Focused elements must have a visible focus indicator (VS Code's theme system provides this via `focusBorder`).
- **No mouse-only interactions**: Every action reachable by click or hover must also be reachable via keyboard (context menus, buttons, toggles, etc.).
- **Escape to dismiss**: Overlays, dialogs, and popups must be dismissable with `Escape`, returning focus to the previous element.
- **Focus trapping**: Modal dialogs must trap focus within the dialog until dismissed.

---

## 7. ARIA Labels and Roles

All interactive UI elements must have appropriate ARIA attributes so screen readers can identify and describe them.

### Requirements

- **`aria-label`**: Every interactive element without visible text (icon buttons, icon-only actions, custom widgets) must have a descriptive `aria-label`. Labels should be localized.
- **`aria-labelledby`** / **`aria-describedby`**: Use these to associate elements with existing visible text rather than duplicating strings.
- **`role`**: Custom widgets that do not use native HTML elements must declare the correct ARIA role (e.g., `role="button"`, `role="tree"`, `role="tablist"`).
- **`aria-expanded`**, **`aria-selected`**, **`aria-checked`**: Toggle and selection states must be communicated via the appropriate ARIA state attributes.
- **`aria-hidden="true"`**: Decorative or redundant elements (icons next to text labels, decorative separators) must be hidden from the accessibility tree.

### Guidelines

- Avoid generic labels like "button" or "icon" — describe the action: "Close panel", "Toggle sidebar", "Run task".
- Test with a screen reader (VoiceOver on macOS, NVDA on Windows) to verify labels are spoken correctly in context.
- Lists and trees should use `aria-setsize` and `aria-posinset` when virtualized so screen readers report the correct count.

---

## Checklist for Every New Feature

- [ ] New `AccessibleViewProviderId` entry added in `accessibleView.ts`
- [ ] New `AccessibilityVerbositySettingId` entry added in `accessibilityConfiguration.ts`
- [ ] Verbosity setting registered in the configuration properties with `...baseVerbosityProperty`
- [ ] `IAccessibleViewImplementation` with `type = Help` created and registered
- [ ] Content provider references the correct `verbositySettingKey`
- [ ] Help text is fully localized using `nls.localize()`
- [ ] Keybindings in help text use `<keybinding:commandId>` syntax for dynamic resolution
- [ ] `when` context key is set so the dialog only appears when the feature is focused
- [ ] If the feature has rich/visual content: `IAccessibleViewImplementation` with `type = View` created and registered
- [ ] Registration calls in the feature's `*.contribution.ts` file
- [ ] Accessibility signal played for important events (use existing `AccessibilitySignal.*` or register a new one)
- [ ] `aria.alert()` or `aria.status()` used appropriately for dynamic changes (prefer `status()` unless urgent)
- [ ] All interactive elements reachable and operable via keyboard
- [ ] All interactive elements without visible text have a localized `aria-label`
- [ ] Custom widgets declare the correct ARIA `role` and state attributes
- [ ] Decorative elements are hidden with `aria-hidden="true"`

## Key Files

- `src/vs/platform/accessibility/browser/accessibleView.ts` — `AccessibleViewProviderId`, `AccessibleContentProvider`, `IAccessibleViewContentProvider`
- `src/vs/platform/accessibility/browser/accessibleViewRegistry.ts` — `AccessibleViewRegistry`, `IAccessibleViewImplementation`
- `src/vs/workbench/contrib/accessibility/browser/accessibilityConfiguration.ts` — `AccessibilityVerbositySettingId`, verbosity setting registration
- `src/vs/platform/accessibilitySignal/browser/accessibilitySignalService.ts` — `IAccessibilitySignalService`, `AccessibilitySignal`
- `src/vs/base/browser/ui/aria/aria.ts` — `alert()`, `status()` for ARIA live region announcements