[gwnn]

I must be missing something, but

How do constructive natural systems cope with a good GF hand with diamonds after their pds' 1♣ opener? Old school teaches 2♦, but I think most people use 2♦ as WJS nowadays? Or is that the answer? I saw many threads on NMF, invmin, etc etc around here, but none about this particular case.

[awm]

I wouldn't say "most people play 2♦ as a WJS" as there are many alternative treatments (strong, intermediate, criss-cross minor raises, fit-showing, etc) and I'm not even sure that WJS are the plurality choice.

In any case, assuming 2♦ would not show a strong hand with diamonds, the normal thing is to respond 1♦. Then it depends on how the auction develops:

(1) Opener rebids a major. Now you bid 4th suit forcing to game, followed by diamonds.
(2) Opener rebids 2♣. This should deny a 4-card major. You are safe to bid your stronger major to establish a game force (also guaranteeing 5+♦), then rebid diamonds.
(3) Opener rebids 1NT in an up-the-line style. This again denies a 4-card major, and you are safe to bid your stronger major to establish a game force, then rebid diamonds.
(4) Opener rebids 1NT playing Walsh responses. This does not deny a 4-card major since opener would bypass, but 2-way checkback should probably still be on here (you can still sign off in diamonds via 2♣ puppet, and there's not a lot of need to sign off in clubs when opener still frequently has three clubs only). In this case you can bid 2♦ "artificial game force" followed by a diamond rebid.