Inputs
Supply network
MV cable (at MV potential)
Transformer
LV cable
—
three-phase prospective fault current
Calculation report
Where the impedance actually is
The gate re-runs the engine against a worked example published in a freely-downloadable source, and compares against its printed answer — not against a number this app chose for itself. The 0.5 % band exists because the source prints its intermediate impedances rounded; full-precision arithmetic lands a little under the printed figure, and a tolerance tighter than the source's own rounding would fail correct code.
Every stage in the spine says where a model was allowed to sit and what holds authority instead. The short version: a model may draft almost every artefact here, and none of its drafts decide anything — at runtime no model is on the compute path at all.