It's back!
It's an RSS feed reader, and there's a browser extension with which you can add articles to your library directly. You can of course also add articles manually in the web UI.
If I understood you correctly this may be what you're looking for.
RSS readers show content based on the feed they're coming from, and show read and unread items in the same list. That makes it difficult to know which items you've already seen, and is especially annoying for managing items that you want to read at some point but not anytime soon.
Lighthouse splits it into Inbox (new items) and Library (bookmarked items). This makes it possible to process new items quickly, and take your time with reading them.