Deciphering the Bidding

Just played a hand against GiB, and was faced with the task of trying to picture the opponents' hands.



Obviously, partner has the ace of diamonds. Beyond that, though, what's going on?

4 diamonds was a splinter for spades. GiB alerts 4 hearts as a help suit slam try, but that seems ridiculous. It should be a control showing cue bid. Does it show extras, though, or is it just a courtesy, to show heart control below game?

My first instinct was that 4 spades showed the lack of a first or second round club control. If not that, why not just bid 4 notrump?

East passed. Partner led the 6 of clubs, and dummy came down.



Ok, that's NOT what I was expecting. Maybe, then, 4 hearts was a courtesy, and neither opponent has much more than an opening hand? Granted, if partner has the ace of diamond we already have 11 hcp, but with 9 of those tied up in diamonds, which they've splintered, I don't see the problem, yet.

I'll play out the hand now, and see what it all looked like. From my perspective, though, it sure looks like 6 spades should be making.

...

And the final analysis? Thanks to a void in diamonds and a long running club suit in west, 7 spades is always there.

Interestingly, 5Dx is only down 2, and a good save at all white against 4S+3. Maybe I should have thought of that.