The iframe in the centre is the "canvas+API" mock (a stand-in for
Collabora / Figma / Excalidraw). The host page on this side knows
NOTHING about its internals -- it talks to it only through the
NAC.registerPlugin / call / read / subscribe contract.
Buttons on the left exercise the 8 backend types. The right side
shows every nac:plugin:* provenance event the runtime
fires.
backend exercises
postmessage (verb)
sdk-call (verb)
script-bridge (verb, request/response)
same-origin-window (state)
value: -- highlighted: --
fallback chain (state)
resolved: --
subscriptions (events)
no active subscriptions
high-complexity scenarios
iframe loading...target: ./target.html
The iframe is a same-origin mock. The host's plugin manifest
declares verbs/state/events that route through the 8 backends.
Watch the provenance log on the right when you click a button.