Left column (left_html)
This page is built with layout: "split" in PAGE. The generator passes this body to split_page(..., left_html=…). Use it for playgrounds, live components, or embedded previews alongside prose.
Example panel
Same pattern as preview-split.html, but routed through the normal showcase sidebar and assets.
Right column (right_html)
Defined by render_right() in generator/pages/split_layout_demo.py. Pair with API tables, props, or long-form notes while keeping the demo visible on the left.