I'd like to get WebKit's position on Markup based Client Hints delegation for third-party content. https://groups.google.com/a/chromium.org/g/blink-dev/c/FTNrw03Xs9s/m/O74Mp6b... https://docs.google.com/document/d/1U3P9yvaT1NXG_qRmY3Lp6Me7M5kTnd3QrBb1yFUV... https://wicg.github.io/client-hints-infrastructure/#accept-ch-state-algo This is to support content negotiation use cases such as differential serving of variable fonts, color vector fonts, responsive images, and other third-party content which requires client information lost by user agent reduction (an ongoing project). For example: variable fonts allow significantly less font information to be transferred without loss of functionality, but only works on specific operating systems. It’s already possible to set a Permissions Policy in the HTTP response header, but for sites without the ability to modify HTTP headers a HTML solution would be ideal. This proposes a meta tag which allows delegation of client hints to third-party origins. These tags could be included in code-snippets for embedded third-party content for ease of use. For example, to specify third party requests to https://foo.bar must include sec-ch-width you could include: <meta name="accept-ch" content="sec-ch-width=('self' 'https://foo.bar')"> You may still omit the permission policy and rely on the default allowlist as follows: <meta name="accept-ch" content="sec-ch-width"> Note that this is the equivalent of the following today: <meta http-equiv="accept-ch" content="sec-ch-width"> ~ Ari Chivukula (Their/There/They're)