[Kungsgeten]

Yesterday I held:

JTx
KT97
K9xxx
A

I chose to open 1D (4+D, 11-19, unbalanced but could have longer clubs). The bidding went like this:

1D-1S;
2H-3H;
4H-5D;
5NT-All pass.

This is how I interpreted the auction:

1D-1S; (both natural)
2H-3H; (2H shows three-card support, either 11-14 or 18-19. 3H was undiscussed, but should be GF if natural, and generally we play third-suit as (semi)natural)
4H-5D; (I bid 4H as an offer to play. Our general agreement is that after establishing a trump fit, a five-level bid is voidwood)
5NT-Pass; (Two keycards, no trump queen. Something has gone wrong)

This was partner's hand:

AKxx
x
Axxx
Jxxx

The 3H bid was what threw us off the rails. Partner intended this as a sort of fourth-suit forcing, asking for a stopper (even though it was the third suit). Our agreements over 1D-1S; 2H are:

2S = To play vs 11-14.
2NT = Natural INV, only 4S.
3C = Artificial GF. Sets spades as trump suit and asks for shortness.
3D = Natural INV.
3S = Natural INV.
3NT = To play
4CDH = Splinter
4S = Fast arrival, worse than 3C. Partner may pass even with 18-19.

The forcing bids are few here, so perhaps we should give up on 2NT or 3D being an invite? Part of the idea is that GF hands with 4S may respond 1NT (almost GF relay) instead of 1S, perhaps if diamonds is an alternative contract or similar. This might wrong-side NT though, and we currently have no way to ask for stoppers after our relays.

[helene_t]

It's probably ok if you just change 3♣ to just being GF, not setting spades as trump.

With this hand it's either 3♣ or 3♦, then, depending on your degree of optimism.

[nullve]

I don't think you need to be able to invite over 1♦-1♠; 2♥ if the weaker range is "11-13" instead of "11-14". (And with 14, 3451 you can open 1N.)