Early Design Review: Related Website Partition API

[DCtheTall]

Guten TAG! 🍻

I am requesting an early review for the Related Website Partition (RWP) API, an API which allows third-party embeds to maintain a consistent session only across related sites.

Related Website Sets (RWS) is an effort which aims to introduce a new privacy boundary on the web which allows sites to have access to their unpartitioned cross-site state when they are embedded on other related sites.

Some third-party SaaS developers embed their content on sites which are part of a Related Website Set and wish to maintain a continuous session across multiple sites within that set.

The Related Website Partition (RWP) API is a novel mechanism for providing 3P embeds access to a partitioned, non-cookie storage handle which allows them to continue a single session across multiple domains in the same RWS.

This handle would be available to embeds without prompting the user but is only restricted to activity within that particular RWS. RWS owners must opt into using this technology and may control which sites can use this API using Permissions Policy.

• Explainer: https://github.com/explainers-by-googlers/related-website-partition-api
• User research: N/A
• Security & Privacy self-review: https://github.com/explainers-by-googlers/related-website-partition-api/blob/main/TAG-self-review-questionnaire.md
• GitHub repo: https://github.com/explainers-by-googlers/related-website-partition-api
• Primary contacts (and their relationship to the specification):
• Dylan Cutler (@DCtheTall, Google Chrome, author) Ari Chivukula (@arichiv, Google Chrome, contributor)-
• Organization/project driving the design: Google Chrome
• External status/issue trackers for this feature (publicly visible, e.g. Chrome Status): https://chromestatus.com/feature/5184475929247744

Further details:

[x] I have reviewed the TAG's Web Platform Design Principles

• The group where the incubation/design work on this is being done (or is intended to be done in the future): PrivacyCG
• The group where standardization of this work is intended to be done ("unknown" if not known): unknown
• Existing major pieces of multi-implementer review or discussion of this design:
• Initial public proposal: CHIPS integration with First-Party Sets WICG/first-party-sets#94 (comment)
• Major unresolved issues with or opposition to this design: None so far
• This work is being funded by: Google