Translate user journeys into low/mid-fidelity wireframes and interactive prototypes. Validate the interaction model BEFORE pixel polish — the wireframe is the design's contract; the prototype is its validation. Lives downstream of `ux-journey-mapping` (which provides the friction inventory and opportunity hotspots to wireframe first) and upstream of `design-system` (which provides the tokens and components the wireframes resolve to). The UX Designer runs this. Use whenever a slice's UI is being designed before implementation begins.
