The site has a newsletter, and the weekly ranking. There is no digest of the forum, and a digest is the thing that would make a forum worth coming back to when you only have twenty minutes.
What I mean. A weekly email with the threads that were worth reading: the new topics, the ones that got replies, and the ones that were solved. Not every post, not the whole thread — a link, the title, and one or two lines about why it is worth your time.
Why a weekly rhythm and not a daily one. A forum is not a news site. The conversations take a day or two to become interesting, and a daily digest of a forum is a list of questions from yesterday that nobody has answered yet. Once a week, the threads have had time to gather replies, and the list is a set of finished things.
The newsletter already does the work. We have a weekly list of projects, the growth ranking, and a newsletter that goes out. A forum digest is the same machinery pointed at a different list. The reason it does not exist is that there was no forum worth digesting yet.
The one design decision that matters. What goes in it. A digest that lists every thread teaches people to ignore it. I would want about five items, chosen the way the weekly ranking is chosen: by what people actually read and replied to, with a little editorial judgement about what is worth a summary. Five items a week is a habit; twenty is a chore.