From Sao Paulo:
First, the 3S call. Opener, although "minimum" by HCP, has a primed hand, support, and a trick source. But, with no spade card, immediate cues (4C+) are not a good idea.
I like 1NT Openers to cue suits with two of the top three honors, as the first cue in a minor, to allow the "minor to emerge." In other words, this parallels a sequence where Opener had started 1C and thus was able to cue his club suit as his own suit. This method allows Opener's 4C call to do the same.
Responder: 4H (two of the top three honors, no diamond control)
Opener: 4NT (RKCB)
Responder: 5S (three with the Queen)
Opener: 6C (do you have the missing club honor?)
Responder: 6D (yes, and the diamond Queen, at least doubleton)
At this point, Opener has three reasonable contracts. 7S is the obvious, but that relies on spades working and no ruffs on opening lead. 7NT avoids the opening lead ruff and gives us a backup plan if spades do not cooperate -- five clubs, three hearts, three top spades, and a top diamond for 12 tricks, with a spade-heart, spade-diamond, or heart-diamond (or all three) squeeze available, that diamond Queen producing a better menace. Or, Opener could opt 7C, which is in jeopardy of a spade ruff on opening lead but that allows a simple line for the 12th trick, ruffing out spades.
As it was, some had trouble reaching the grand, and the grand was always 7S, making when spades cooperated. I did not see if anyone played 7C, which also makes, or 7NT.