Request for position on an emerging web specification

• WebKittens who can provide input: @johnwilander @annevk

Information about the spec

• Spec Title: First-Party Sets
• GitHub repository: https://github.com/WICG/first-party-sets

Design reviews and vendor positions

• Mozilla standards-positions issue: First-Party Sets mozilla/standards-positions#350

Anything else we need to know

First-Party Sets proposes a new web-platform mechanism to declare that a collection of related domains is a First-Party Set.

This proposal has previously been discussed in PrivacyCG and WebKit has indicated a position in May 2022. However, the First-Party Sets proposal has undergone some significant changes since that position was published, in particular:

• We've introduced the notion of "subsets" to categorize set member domains, and allow the UA to handle them differently and impose different requirements according to their declared type.
• We've abandoned the SameParty cookie attribute.
• We've indicated support for the Storage Access API for sites to request cross-site cookie access, within the bounds of a First-Party Set.

These changes were introduced in WICG/first-party-sets#92. They align the proposal with other browsers' approaches of using the Storage Access API to mediate sites' requests for cross-site cookie access.

Given the extent of the changes (particularly as they relate to some more recent WebKit comments), I'd like to request a "re-"review of the First-party Sets proposal. Thanks!