2h ago
Setting "retentionDays" to -1 silently deletes the entire history
-1 is what the per-type settings use for "Forever", so it's the natural value to try for the global one. Instead the sweep appears to do date math on it, putting the cutoff a day ahead and deleting every item on next launch. A large finite value like 36500 works fine, so clamping it or adding a real "Forever" option would avoid the data loss.
Pending