Modification time of the source note (picker ordering).
Identity of the note inside the wiki: its path relative to its root (posix separators), prefixed with the root's folder name when the wiki packs several roots. Deliberately not an absolute path — the wiki file must not carry the exporting machine's directory layout.
Folder name of the served root the note belongs to.
Document title (front-matter title or file basename).
The updateHtml payload the shell replays into the page when it
finishes loading (same message the serve server would broadcast), so
the preview app initializes exactly like in crossnote serve.
The complete preview page document for the note — the exact page the serve server would render at
/preview?file=…— with shared assets referenced ascrossnote-wiki-asset:<id>tokens.