Function restore_backup_reader 

pub fn restore_backup_reader<R: BufRead>(
    lmpg: &Lmpg,
    reader: R,
) -> Result<(u64, u64), String>

Restore a JSONL backup incrementally from a buffered reader. The reader is consumed line-by-line, so callers can restore large logical exports without first materializing the complete artifact as one String.

Errors

Returns an error when a line cannot be read/decoded or an engine operation fails. A caller must discard its target if restoration stops after a prefix.