- Wheel on the main viewer: horizontal deltas always switch examples;
vertical deltas switch only at the modal scroll boundary, then stay in a
sticky session (down = next, up = prev) until the pointer leaves the area
- Touch/pen horizontal swipe switches examples; the synthesized click after
a swipe is swallowed so the media viewer does not open
- '[' / ']' switch examples while the gallery is expanded; ArrowLeft/Right
stay reserved for model-level navigation
- Direction-aware slide transition on every switch for visual feedback
(respects prefers-reduced-motion)