Electrical/RailPolarityMismatch

An explicit voltage source drives both rails opposite their marked polarities: its positive terminal connects to a − rail and its negative terminal to a + rail. The check follows electrical jumper connections and uses rail polarity from the board definition. It does not infer polarity from wire colors or net labels.

board :half
supply :USB, voltage: 5, plus: "B-1", minus: "B+1"

This warning reports the reversed pair once for the source. It skips isolated sources, a source tied to only one marked rail, nets that touch both + and − rails, and rails without declared polarity. Those cases can be valid in bipolar or custom power layouts. In multi-board circuits, the reversed pair must be on the same named board.