Marks were stored second-granular like index post dates, so opening a thread in the same second its newest post landed left the thread the reader was looking at unread. Marks now carry a fractional part, which makes the two orderable: a post from the view's own second was in the page and reads as seen; any later second re-brightens.

Adds a harness test that walks the whole loop, including the part worth pinning — forum.get does not mark read, only forum.read does. check-in: c7bf7c08f0 user: dmestas tags: trunk