Expand description
Markdown source turned into an owned tree, before anything is drawn.
Rendering straight from the event stream would mean deciding a block’s layout before its contents are known, and would leave nothing for a test to assert against but pixels. The tree is the seam: parsing is pure and testable on its own, truncation is arithmetic over it, and the renderer only ever walks a finished structure.
Raw HTML survives parsing as Block::Html and Inline::Html. It is
never interpreted and never discarded, because a document that could delete
its own content from the reader’s view by wrapping it in a tag would be a
document nobody could trust.