To drop redunance we can put in ```.page``` just the page content.
Regarding the manifest question I see two solutions:
1) code frames in HTML directly (through ```$pages``` or a new element)
2) render frames client-side by JavaScript basing on informations passed by json or a variable.

Maybe first solution is cleaner and faster (despite a slightly bigger file size, that anyway is highly gzippable by the web server).

Ps: sure I will add me to the authoers, thanks Lu.