I did a search in the Li Product Ideas board and found this thread:
It looks like it was archived due to not getting enough kudos to make it onto the product roadmap. I'd like to see this make it onto our roadmap, but unfortunately it is not my call. I'd recommend either lobbying to re-open this idea, or add a new idea for this (and maybe link to the old one) and getting some users to kudo it.
I agree that it's not ideal to have to code something to keep retrieving more messages when not enough unread messages are retrieved, and that seems like it gives us some more weight to implement this.
Yeah its probably taken everyone longer to type the replies here than to implement this.
Given the field already exists in the message collection it would just simply be allowing it to be a constraint in a Liql query.
