So it turns out that amfora copies Bombadillo and only scrolls some of the page. Half-page scrolling can be problematic as the new content may be hard to find in the middle of the terminal. Half-page might be good if you're quickly skimming the text; two impressions might help you spot something that was missed when it was elsewhere on the page, and in that case you're glancing around and not following the prose. One option here is to patch amfora for full-page motion; probably these should be distinct commands like less, mutt, and vi have for full- or half-page motions.

amfora-pager.patch

There is some variance in full-page motions in other commands whether they show a previous line or not; the above includes one line from the previous page, but that might be another option the user could set, "context lines" or something like that.

vi and w3m have the complication that the cursor is somewhere in the view, and motions can be made relative to the cursor in addition to moving the page view around. There can be variance where the cursor ends up after various motions: w3m jumps the cursor to the middle of the page if you cursor down at the bottom; vi instead keeps the cursor at the bottom of the screen. Some code changes later and my w3m now behaves more like vi, hopefully without breaking anything else.

It might be nice if there were a standard paging library, but said library would need to know all sorts of things and thus could be too big or not suitable for all use cases, and might end up with a configuration file a mile long. Maybe in some other operating system…