[fromageGB]

heart76, on 2019-January-25, 16:34, said:

That was probably misleading
My 2♠ promises 6 and the "weak" bid is 2NT, but I believe I would ponder a 2♠ rebid with say AKQJx - xx - Qx - xxx.

Ah, yes, I am with you now!
If you have already shown 6 spades, then your 3rd bid is difficult, and while you might like 4♣ you can't do that if responder might have only a 4-card suit. 3♥ is probably best.

[rmnka447]

fromageGB, on 2019-January-24, 04:31, said:

This is completely wrong. There is no such thing as this rare hand; 2/1 sets up a GF to 4M or 3NT (or 5m for me, I guess others may drop out at 4m). If you are - even rarely - dropping the bidding, then your partnership is opening or responding too lightly. In this bidding, opener is unlimited *, so responder cannot pass. 4♣ is my bid, and then pass 4♥/4♠/5♣.

* (Edit) Well, not unlimited if the 2♠ is limited by agreement, but not for me.

Sorry, but we can disagree about a 2/1 GF being absolutely cast in stone and unchangeable. There are always exceptions. In the case of 2/1, they are very rare and usually involve misfit hands where neither player can bid NT or support partner's suits. Hands like this come up maybe once every couple of years.

Opener's hand is limited by the failure to make other possible bids. Opener has shown 6 ♠ and didn't jump rebid 3 ♠ showing 16-18 or make a jump shift which shows an even stronger hand. If you play 2 ♠ must be a 6 card suit, then 3 ♠ must be a limiting bid. If you play 2 ♠ as a default with minimum hands, then the 3 ♠ must a 6 card suit in a minimum hand. So, being limited, opener is unlikely to have better than a 7 loser hand.

I criticized East's opener and said I'd bid 2 ♠ with it. But given the auction through 3 ♠, West has several things to consider. First of all, the ♠ stiff is a problem because it may add an extra loser into opener's hand unless opener has solid ♠. Even then, if opener holds something like ♠ AKQ543, odds are there is a loser increase. In the remaining suits, West has maybe 3 and a fraction cover cards (♥ A, ♣ KQ plus the fraction for ♦ Qx). Opposite a 7+ loser hand, bidding 4 ♠ doesn't look like a winning continuation.

Oddly, I agree with your 4 ♣ continuation as West's proper continuation. But then East has some considerations to make. First of all, it would be foolish to bid 4 ♠ with a stiff ♠ or less in West's hand as you can no longer pick up the ♠ suit with one loser. Second, since there is a ♣ fit, 5 ♣ might be a continuation, but opposite West's hand, East has only 2 cover cards possibly 3 if East can ruff a heart, that isn't enough to bid 5 ♣ unless responder's hand has 5 or less losers. So, at this point pass seems right.