interface
Question type: Propagation Entry: Wave Packets, Relay Propagation, and the Three Thresholds. Canonical lane: start at V03-3.1 (Why a Wave Packet Needs a Volume of Its Own: linking particle structure and Field propagation). Bridge if needed: V01-1.5, V05-5.2. Default retrieval profile: explain_profile. Forbidden shortcut: Do not treat light, fields, and propagation as separate ontologies before installing the Wave Packet grammar.