Support immediate payments in group travel deals

game/public-deals.ts

@@ -190,9 +190,9 @@ export function validatePublicDeals(value: unknown, players: readonly PublicDeal
       requireDeal(travel.dueTurn === undefined || travel.dueTurn >= (deal.turn as number),
         'Choose a travel turn no earlier than the offer turn.');
       requireDeal(!Object.hasOwn(deal, 'paymentStatus') && (multi
-        ? !!travel.actor && travel.actor !== deal.from && parties.includes(travel.actor) && !payment
+        ? !!travel.actor && travel.actor !== deal.from && parties.includes(travel.actor) && (!payment || payment.kind === 'immediateBribe')
         : !Object.hasOwn(travel, 'actor') && (!payment || payment.kind === 'immediateBribe')),
-      'Choose an invited traveler; payment is available only as a two-party immediate bribe.');
+      'Choose an invited traveler and an optional immediate bribe between participants.');
       // The actor's final acceptance is checked privately. An unfinished offer
       // cannot already contain that vote, even after a decline or withdrawal.
       if (multi && deal.status !== 'active' && deal.status !== 'released')
@@ -253,7 +253,8 @@ export function setPublicDealTravel(deal: PublicDeal, value: unknown, players: r
   validatePublicDeals([deal], players);
   requireDeal(deal.status === 'offered' && !Object.hasOwn(deal, 'travel') &&
     !Object.hasOwn(deal, 'paymentStatus') && (deal.participants
-      ? !!deal.acceptVotes && deal.acceptVotes.length === 1 && deal.acceptVotes[0] === deal.from && !deal.payment
+      ? !!deal.acceptVotes && deal.acceptVotes.length === 1 && deal.acceptVotes[0] === deal.from &&
+        (!deal.payment || deal.payment.kind === 'immediateBribe')
       : !Object.hasOwn(deal, 'acceptVotes') && (!deal.payment ||
         deal.payment.kind === 'immediateBribe')),
   'Only a fresh offer may add a travel term with a supported payment.');