This interactive collapsible tree visualizes a hierarchical scenario graph, showing step nodes that expand and collapse to reveal child API data. The visualization uses d3.hierarchy and d3.tree to compute node positions, while user clicks trigger transitions that toggle children visibility. SVG circles and labels render each node, with vertical link paths connecting parent-child relationships. Animated transitions use d3's transition system to smoothly move nodes between states, with the root dataset imported from a separate JavaScript data module.