Function crdt_counter_bump 

pub fn crdt_counter_bump(
    current: RuntimeValue,
    amount: i64,
    field_name: &str,
) -> Result<RuntimeValue, String>

One CRDT counter step: current + amount. A CRDT grow-counter is intentionally wrapping (modular) — convergence is defined over the cyclic group, so overflow is a feature here, NOT the silent-corruption footgun that ordinary integer math now promotes away. An absent or Nothing field starts from zero.