Function reduction_total_bytes 

pub fn reduction_total_bytes(
    log: &ReductionLog,
    minted_view: &[ChatMessage],
    recorded: Option<&[ChatMessage]>,
    id: &str,
) -> Result<usize>

Total byte length of the original content behind reduction id — what ExpandOutcome::total_bytes would report — without slicing anything. Used by the agent’s argument-validation error path so a malformed byte_range error can name the true size the caller is ranging over.