One instance per browser. The service worker makes SilverBullet offline-capable: it caches and serves the client code, embeds the Sync engine that keeps a local copy of your files, and implements the HTTP API locally by intercepting calls bound for the Architecture/Server.

By default, sync.documents is disabled, so non-Markdown documents are not copied into IndexedDB. A /.fs request for such a document misses local storage and is proxied with the original request object. During initial sync, a document already present locally may use the local fast path instead.

When sync.documents is enabled and a document exists locally, IndexedDB still stores and returns the complete value.