Function apply_bus_load_active_power 

pub fn apply_bus_load_active_power<T>(
    module: &mut PioModule<T>,
    bus: BusId,
    total: ActivePower,
    allocation: LoadAllocation,
) -> Result<UpdateReport, Error>
where
    T: BalancedCalculationInstance,

The calculation types used by solver consumers. The full problem vocabulary lives in powerio_prob; these types sit at the facade root so a consumer does not need a second PowerIO dependency to name its boundary. Replace the aggregate active demand at one bus using an explicit allocation rule, then apply the resulting load updates atomically to the module.

Only in service loads participate. The returned report names every load whose active demand changed. No load is selected by table position.

Errors

The bus is unknown, the bus has no in service load, a participating load lacks a persistent identity, or the selected allocation rule has no valid basis.