Consider applications with both 1p and 3p sections

[jyasskin]

https://w3ctag.github.io/user-agents/#what says that a (web) UA is "any software entity that interacts with websites outside the entity itself, on behalf of its user". Some applications, like Facebook and the Google Search App, let their users interact with both the application itself (and its creating organization), and also manage users' browsing when they click external links. Arguably, this Finding shouldn't take a position on the Unix philosophy (favoring many small tools): monolithic apps shouldn't intrinsically violate it, and so UA-ness, and the associated duties, shouldn't be viral to parts of an app that don't browse 3p content.

Those apps should still give users clear expectations about what behavior they should expect from different parts of the app. If the distinction between 3p and 1p content is too small, it wouldn't make sense to abandon the UA duties for the 1p content.