astrolabe/src/app/infrastructure/storage-estimate.ts

/**
 * Storage origin-usage adapter (spec §02 → Storage Monitor; docs/architecture/02 §6).
 *
 * The ONLY module that touches the Storage Manager API. We read `usage` — the bytes
 * actually stored for the origin, which is reliable — and deliberately ignore
 * `quota`, a padded, browser-decided approximation that is not a real free-space
 * figure (web.dev → storage-for-the-web). Snippet/dataset bytes are measured in the
 * component from our own stores; this just supplies the whole-origin total so the
 * "App" remainder can be derived. Returns undefined when the API is absent or the
 * call rejects; never throws.
 */

export async function readOriginUsage(): Promise<number | undefined> {
  const storage = typeof navigator !== 'undefined' ? navigator.storage : undefined;
  if (!storage || typeof storage.estimate !== 'function') return undefined;
  try {
    const { usage } = await storage.estimate();
    return typeof usage === 'number' ? usage : undefined;
  } catch {
    return undefined;
  }
}