Function lift_thread_membership 

fn lift_thread_membership(bytes: &[u8], threads: &mut [ReviewThread])

Attribute a pre-per-turn row’s history: a thread filed as a whole has its user turns stamped with that review, so they read as the round they were actually part of instead of as unfiled. Positional - the mirror decode ignores every other key, so it aligns with threads. Only applies where no turn is filed yet, leaving a re-saved row’s own membership alone; the new shape persists on the thread’s next write.