fix(live-preview): foreign postMessage events reset client-side state #12925
+5
−1
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Needed for #12860.
If the admin panel broadcasts foreign postMessage events, i.e. those without the
payload-live-preview
signature, client-side live preview subscriptions will reset back to initial state.This is because we dispatch two postMessage events in the admin panel, one for client-side live preview to catch (
payload-live-preview
), and the other for server-side live preview (payload-document-event
). This was not previously noticeable because both events would only get called simultaneously on initial render, where initial state is already the expected result.Now that Live Preview can be freely toggled on and off, both events are frequently dispatched and very obviously disregard the current working state.