trackPlayCounts was rekeyed to just the track title, discarding the artist half of the composite key used everywhere else (trackFirstListen, trackCounts). Two different artists' same-titled tracks (a very common occurrence — "Intro", "Home", "Breathe", ...) silently overwrote each other's count, so buildDiscoveredTracks could show a completely unrelated artist's play count next to a "recently discovered" track. Now keyed by the same trackKey ("name|||artist") used by trackFirstListen, and discovery.ts looks up by that key instead of the name it had already parsed back out of it.