Hi there, Complimentary to https://lists.webkit.org/pipermail/webkit-dev/2021-January/031673.html, Chromium intends to ship the ALPS + ACCEPT_CH HTTP/2 and HTTP/3 frames portions of the Client Hints reliability proposal, and we would like to solicit WebKit's position. As mentioned in the linked thread, the Client Hint Reliability proposal is a set of features aimed at making Client Hints more reliably available and mitigating mis-matches between a site's preferences and the preferences stored in the browser. In particular, The ACCEPT_CH HTTP/2 and HTTP/3 frames, combined with the TLS ALPS extension, are a connection-level optimization to deliver the server’s Client Hint preferences in time for the first HTTP request. Specifications: https://tools.ietf.org/html/draft-davidben-http-client-hint-reliability (section 4) https://tools.ietf.org/html/draft-vvv-httpbis-alps https://tools.ietf.org/html/draft-vvv-tls-alps https://github.com/WICG/client-hints-infrastructure/blob/main/reliability.md... thanks, Mike