The track_url/search session mechanism in Blacklight supports two related but distinct features in Blacklight:

1. Previous/next/back to search navigation in the show view
2. Search history tracking

At the cost of constraining browsing a given search to the tab the search was executed in, the previous/next behavior could be rewritten to use window.sessionStorage and a "window" of offsets into the result set. This would simplify the Blacklight back-end and routing, and eliminate POST/redirect cycles from viewing a result document.

If this entirely replaced the track_url/session mechanism, there would be a legacy data issue and possibly a neglected use case. There is a parallel suggestion to use the ping attribute to replace the existing track mechanism; this could be approached as a complementary change - using sessionStorage to track the search, fetching JSON to populate pagination widgets in the show view, and explicitly configuring a tracking mechanism via the ping attribute if the installation wants to support stored search history.