Tracking issue for user-agent string/etc. upstreaming into HTML / Fetch

[domenic]

The work in https://compat.spec.whatwg.org/#ua-string-section is very exciting.

I think the Compat Standard is the right place for this kind of work to happen in the near- and medium-term. But IMO in the long-term, if things settle down into a cross-browser equilibrium, we should migrate much of this into HTML (specifically the section on the various navigator properties) and Fetch (to give more guidance on the default User-Agent value).

For example, it would be good to normatively specify in HTML the relationship between navigator.userAgent, navigator.appVersion, and navigator.platform. Today I learned from https://www.chromium.org/updates/ua-reduction/ that appVersion is "everything after the Mozilla/" in userAgent, which is not captured in any spec today. Similarly, I assume there is some relationship between platform and the <oscpu> and/or <platform> tokens in the Compat Standard?

I'm unsure whether we'd want to go further and move the stuff about specific browsers and platforms from into HTML, or leave that in Compat.

[miketaylr]

Thanks for filing! Yes, agree that ideally this work ends up elsewhere (both Fetch and HTML make sense) once we clean it up sufficiently.

[domenic]

We could also probably say something useful about the crossover with the navigator compatibility mode.