Should there be a header feature?
Headers are very common on Less Wrong, unfortunately, they interfere with the summary by taking up most of the space. I’d suggest the creation of a feature to mark certain content as a header which would then exclude it from this summary.
I presume by the “summary” you refer to the hover preview?
Our current vision was more something along the lines of “allow users to provide an explicit abstract of a post that shows on hover and in other contexts where summaries are useful”
I’d still like the ability to make the explicit abstract just read off the text after a certain point, but I suppose it would require a lot of work to support that functionality.