Expand description
The command queue: the channel between a host and the app.
A host calls AutomationQueue::submit with an Envelope and gets a
receiver for the Reply. The app drains the queue at three fixed points
in the frame (§4.4): drain_input in
raw_input_hook, then drain_app for
Phase::Mutate at the top of ui and for Phase::Read at the bottom. A
command waits in the queue until its phase comes round.