Settings Service

8.5 `SettingsService` — Persistent key-value storage

Runs in: view only. The legacy settings API is exposed in the view proxy bag — for new code, prefer StorageService (both worker and view) for namespaced persistence.

Permission required: None (namespaced to your extension's section).

interface ISettingsService {
  get<T>(section: string, key: string): Promise<T>;
  set<T>(section: string, key: string, value: T): Promise<void>;
  onChanged<T>(section: string, callback: (settings: T) => void): () => void;
}

Usage:

const settings = context.getService<ISettingsService>('settings');

// Read a setting (with TypeScript type inference)
const theme = await settings.get<string>('com.yourname.myext', 'theme');
const count = await settings.get<number>('com.yourname.myext', 'itemCount');

// Write a setting
await settings.set('com.yourname.myext', 'theme', 'dark');
await settings.set('com.yourname.myext', 'lastUsed', Date.now());

// Subscribe to changes (reactive — fires when value changes from any source)
const unsubscribe = settings.onChanged<{ theme: string }>(
  'com.yourname.myext',
  (newSettings) => {
    console.log('Theme changed to:', newSettings.theme);
  }
);

// Call the returned function to stop listening
unsubscribe();

Pro Tip: Use StorageService (Section 8.12) for general-purpose data persistence — it's backed by SQLite and scoped to your extension. Use SettingsService when you need reactive change subscriptions or host-visible configuration. For transient local state within a session, localStorage works fine inside the iframe.

#8.5 SettingsService — Persistent key-value storage

8.5 `SettingsService` — Persistent key-value storage