WPT details: WPT tests do not currently check the value itself; rather it checks for the existence of the value. We do not plan to extend it further given the platform-specific aspect and limited ability for a WPT test to infer about what the appropriate version value would be.
Updates the version provided via the Sec-CH-UA-Platform-Version on Windows to provide a reasonable level of fidelity to allow sites to identify meaningful Windows platform changes. This aligns with the current definition in the proposal in the UA Client Hints WICG repo. This enables sites to deliver appropriate binary executables and help content specific to that OS version.
This enables sites to deliver appropriate binary executables and help content specific to that OS version. The current UA string and existing Sec-CH-UA-Platform-Version implementation provides the "major" and "minor" version Windows components. However, as of Windows 10, Windows generally doesn't increase either of these numbers across significant releases. Notably, Windows 11 does not increase either of these numbers. The updated UA Client Hints proposal text specifies that the value on Windows should instead be derived based on the Windows.Foundation.UniversalApiContract version. This version revises when the set of APIs exposed on Windows changes in a significant way while not being particularly identifying (e.g. a typical security update will not revise it). A table of value mappings to Windows releases can be seen in the UA Client Hints' repo issue 220.
Explainers: https://github.com/WICG/ua-client-hints/commit/5c1be8772eaf3b823c3c07d6baa6d7348a77627d