OptionaldataData URL of the rendered image (persisted for offline/cross-session).
OPTIONAL: an entry persisted without one (e.g. by a data migration that
cannot render PDFs server-side) is rendered lazily on load — resolved
from sourceFileId via the host's onGetFileUrl and composited
client-side, exactly like a peer rebuilding from a pages spec.
OptionalpageFirst PDF page number (1-based). Kept for backward compatibility.
OptionalpageFull list of selected PDF page numbers (1-based). Lets the page-picker restore the user's selection when the same PDF is re-opened.
Source file ID from the file manager
Source file name for display
OptionalthumbSmall preview of the rendered page for the page drawer (~160px wide). Optional — older files have none and the drawer falls back to dataUrl.
'image' for direct images, 'pdf-page' for rendered PDF pages
A background page — an image or rendered PDF page used as the canvas background.