Share of cache hits that served text from a changed section. Cited sections are edited at random and the questions that hit before the edits are replayed (179 on WixQA, 274 on QASPER).
The text cache serves what it stored, so its error grows with every edit. ragtrail never served a changed section. The price is fewer prefetches: on WixQA they drop from 110 with no edits to 50 with half the sections edited, and the rest become hints or misses.