A release whose last post is 6 hours old gets nothing from the tail, only fragments from neighbouring ranges: settled once unchanged for 30 minutes. Waiting 6 hours after it was read held every history release back from phase 2 after each reset; with the hourly sweeps' resets the prober (and so the par2 merge) never had work. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>