I have found many thread and feature requests talking about keeping read news items.
One of the features that none of the reader on OSX have is being able to bookmark and categorise bookmarked items. E.g save a bookmark of an article about world cup in a bookmarks folder called World Cup. This may get aorund the need to retain lots of news items which impact performance while allowing the saving of key news items.
You mean saving an article of a feed into a bookmark? Please give an example.