I just had a post-surgery followup appointment with the urologist, and I'm recording the results mostly for my own benefit, but I'll put the details behind a cut tag so that it's there to read for those who might be interested.
The doctor confirmed that the kidneystones had definitely gone by the time he got there in surgery. His theory is that the previous stone (the one that caused me all that hassle in April when it got stuck) served to stretch the ureter somewhat, which allowed the smaller stones to pass by themselves shortly afterward. All well and good, so far as it goes. The potentially tricky bit is that the stones were the result of infection, and the sort of infection that causes them can sometimes linger dormant for a long time, flaring up every so often to generate more stones. So we'll have to keep a careful watch to see if that is happening in my case. I'm to have an annual ultrasound for the next 3 years or so (starting in 6 months) to see if any more stones have formed. My GP is going to be informed that any time I'm treated for a urinary tract infection ever, cultures need to be taken of the infection to check what bug is causing it, certain specific antibiotics need to be used to treat it (and IIRC, I will need to have an ultrasound to check for new kidneystones), and I'll need more tests afterward to confirm that the infection's fully clear.
He also said that from now on I will need to be extra-careful about hydration. I need to drink enough each day to ensure that I pee at least 2 litres daily, and initially at least, I need to measure both input and output so that I can work out what's required intake-wise to make this happen. He also recommended that I drink at least 2 glasses of citrus juice a day, since citrus juice apparently can help prevent these kinds of infections. (It seems that the traditional cranberry juice treatment for UTIs isn't so useful in this specific case - apparently while it helps knock out E. coli infections, it doesn't do much for the urea-splitting bacteria I'm dealing with.) Oh, and if I suspect a UTI, it turns out that pharmacies sell over-the-counter urine test sticks to check for infections. That's handy to know.
So that's the story so far. If there's evidence of recurring infection down the track, at that point we'll consider whether being put on urinary antiseptics or rotating antibiotics on a (semi?)permanent basis is appropriate. I hope I can avoid that, myself. But it'd be better than periodic rounds of kidneystones and kidney infections, so I'll do it if necessary.