Context - I have an application which shows a feed of stories, with new stories coming in live.
Definition - Seen: When a particular story card has come on the screen it is marked as "seen". User might or might not have interacted with the story using any button.
Problem statement -
User goes through the feed and scrolls through say top 4 messages out of 10 in his feed. Then closes the app. While the app was closed 3 new messages came in.
What can be the best way to show 6+3 un-seen messages next time he opens the app. Ensuring that he the 4 seen messages are not completely lost to him (i.e. he can still find it later if he wants to)?