Intent to ship: Clear-Site-Data: "cache" directive for Network cache cleaning

[Manuel Bucher]

Summary: Clear-Site-Data is a HTTP header sent by web servers to clear various browser states for an origin. The "cache" directive indicates to the browser that it should clear the networking cache and various other caches it has for the origin.

We originally shipped “cache” support in Gecko starting with version 63. And unshipped in 93 due to cross-site tracking concerns. The cross-site leak concerns are documented in https://github.com/privacycg/storage-partitioning/issues/11.

The new implementation shipping now has the cross-site leak concerns addressed by only cleaning the partition the header was received in. Tests for them are included in web-platform tests: https://wpt.fyi/results/clear-site-data/clear-cache-partitioning.https.html

Brief history in Gecko:

Shipped in Fx64: https://bugzil.la/1470111

Unshipped in Fx94: https://bugzil.la/1671182, 

Bug: https://bugzil.la/1930500

Specification: https://www.w3.org/TR/clear-site-data/#clear-cache 

Preference: privacy.clearSiteDataHeader.cache.enabled

Web-platform-tests:

• https://wpt.fyi/results/clear-site-data/clear-cache-partitioning.https.html

• https://wpt.fyi/results/clear-site-data/clear-cache.https.html

Other Browsers:

• Blink: Supported since version 61

• WebKit: Supported since version 17

[Mike Taylor]

This is cool to see.

Do you intend to update the spec to match the assertions in your tests?

Other Browsers:

• Blink: Supported since version 61

• WebKit: Supported since version 17

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[Manuel Bucher]

> Do you intend to update the spec to match the assertions in your tests?

Thanks for your interest. Yes, I intend to work on updating the spec.

[Mike Taylor]

On 3/31/25 6:52 AM, Manuel Bucher wrote:

>> Do you intend to update the spec to match the assertions in your tests?
>
> Thanks for your interest. Yes, I intend to work on updating the spec.
>

That's great - Chrome would be interested in making sure we're aligned
there. Looking forward to a future PR to review.

In the meantime, it may make sense to mark the new WPTs as tentative.

later,
Mike

[Manuel Bucher]

On 4/14/25 14:54, Mike Taylor wrote:
> That's great - Chrome would be interested in making sure we're aligned
> there. Looking forward to a future PR to review.
>
> In the meantime, it may make sense to mark the new WPTs as tentative.

Great to hear and thanks for raising. I've opened
https://bugzil.la/1960345 for updating test expectation in the meantime.

Best
Manuel