fn read_zone_output(conn: &Connection, block_oid: &str) -> Option<Vec<u8>>Expand description
Reassemble a zone’s output file bytes directly from db_file_data
(read-only, avoids opening a second writable FileStore on another channel).
Returns None when absent or empty. Agent output is non-circular, so
concatenating parts in partidx order matches FileStore::read_file.