Cloning one page's design

The design already exists on another page. Your job is to put new content into that design without redrawing it: copy the page, then swap what it says.

Copy-then-edit is the only clone path in this runtime. generate_scene always re-rolls a page from its outline entry — the model invents a fresh element tree every time — so calling it on a copied page destroys exactly the design you came for. Nothing here validates the shape of your result either: the design is preserved because you copied it, and the judgement about which elements are content and which are the skeleton is yours.

The sequence