Markdown content of the document. Widgets are represented by
placeholders containing a Unicode snowman symbol, e.g.
[[☃ radio 1]]. May contain TeX delimited by dollar signs, e.g.
$\dfrac{1}{2}$. Literal dollar signs are escaped by backslashes.
Information about the configuration and UI state of each widget.
JSON describing a Perseus renderer. Intended for consumption by AI tools. A "renderer" is essentially a Markdown document with embedded interactive widgets.