Module direction 

The loading direction: what “more load” means for a particular study.

λ_max is a property of the direction, not of the network. Two studies of the same system that stress different buses, or share the pickup differently, get different noses, and neither is more correct than the other. That is why this is an explicit input with named constructors rather than something the solver infers.

Bus stores only net p_spec/q_spec — every importer nets generation and load together before the solver sees them (pgm::accumulate is the clearest example) — so a direction is a per-bus (Δp, Δq) vector, and “load” has to be read off the sign of the net injection unless the caller knows better and supplies its own.

Structs

BaseSpec

The specified injections at the converged base case, captured once.

LoadingDirection

Per-bus (Δp, Δq) in per-unit: the injection change per unit of λ.