fn private_read_row_stream<'a>(
map: &'a Arc<Map>,
room_id: &'a RoomId,
user_id: &'a UserId,
) -> impl Stream<Item = Result<(SmallString<[u8; 48]>, u64, Option<u64>)>> + Send + 'aExpand description
Per-thread marker rows under (room, user) in map.
Active markers in the live store and announced markers in the sync mirror share one row shape, keyed by thread kind.