I had been assuming that the June 13 date written on the citation was the make or break date that I had to show up unless the court gave me a meaningful response to my request for a continuance, that I made as part of my informal request for discovery. I didn't actually notice the modified due date on the courtesy notice until it was pointed out to me by the baliff at the traffic court when I showed up there that day. Oh well.
Object lesson: read all your legal documents very, very carefully and follow the instructions precisely.
On June 19, I received their response
to my request for a court order for
discovery - another three-business-day bulk-mail delay for a letter
dated June 14.