Intent to ship: Referrer from Refresh

[Zach Hoffman]

As of Firefox 136, I intend to turn Referrer from Refresh on by default on all platforms. It has been developed behind the network.http.referer.sendFromRefresh pref.

Bug to turn on by default: https://bugzil.la/1928291
Spec: https://html.spec.whatwg.org/multipage/semantics.html#pragma-directives:navigate
Standards body: WHATWG

Other browsers: In terms of the main feature, Chrome and Safari have both been shipping this for years. There are 2 small interop differences remaining:

1. A <meta refresh> to a URL fragment change in Firefox is a "replace" navigation (which matches the current spec) and does not set the referrer. Both Chrome and Safari treat a <meta refresh> to a URL fragment as a "reload" navigation, resulting in the referrer being set. This behavior is up for discussion in spec issue <https://github.com/whatwg/html/issues/6451>.

2. For cross-origin navigations, all 3 browser engines default to the strict-origin-when-cross-origin referrer policy, but in Chrome, pages can override that URL trimming, and in Safari and Firefox, pages can only set a more relaxed referrer policy for top-level navigations. Firefox's implementation of the Referrer from Refresh feature did not change this behavior, and it is still up for discussion in spec issue <https://github.com/privacycg/proposals/issues/13> (see <https://bugzil.la/1800070#c2> for a very brief and incomplete summary of the history of this behavior).

The Referrer from Refresh feature was previously discussed in this "Intent to prototype" thread: <https://groups.google.com/a/mozilla.org/g/dev-platform/c/Eohf1MXoaT4/m/SIMUMom2AwAJ>.

-Zach

[Zach Hoffman]