One thing I love using ThoughtStreams for is thoughts on films and books but that immediately leads to concerns about spoilers.
While someone can always avoid a stream, I'm particularly worried about spoilers appearing on the home page or in other places like search results once we implement more features like that.
One possible solution would be to have a flag on a stream that the author uses to indicate it contains spoilers.
It could be at a card level too, but I wonder if that would be too cumbersome.
If a stream (or card) is flagged as containing spoilers, a reader must opt-in to see it.
That would be fairly easy to implement. From a data model point of view, it's just a relation of stream (or card) and user and a boolean. Or you could even drop the boolean and have the existence of the tuple in the relation be enough.
Perhaps the lead card of the stream would always be shown so the author can explain what the stream is about.
The rest of the cards would effectively act like they were unpublished to people who had not yet opted-in to see the stream.