For now, the AudioWorklet text uses things that need an event loop to work (postMessage, onmessage, new Promises, that kind of thing), but it's not defined how it all works.

It must be defined, otherwise it can't be implemented properly.

For example, does onmessage execute before or after the call to process? On which thread? When does resolved promises execute?

This was discussed but forgotten about in #1193 (comment).