Function next_producer_identity 

pub fn next_producer_identity(
    verified: bool,
    recovery: bool,
    pid: i64,
    epoch: i16,
    fresh: Option<i64>,
) -> Option<(i64, i16)>

Choose the producer identity exposed after transaction completion.

Verified normal completion reserves i16::MAX for the transaction marker, while a staged recovery identity may use that epoch once before rotating.