Swap Meet trades treasures — a carried treasure is a carried item

The trade grammar gains a 'treasure' token (never present in stored
ledgers, so no gate needed): a dagger can buy back the treasure in a
thief's arms, or two armfuls of gold can change hands outright. The
one-treasure carry limit and WEAKNESS both hold in a trade as at a
grab — a one-way treasure needs an open slot and an able back. The
picker offers each side's carried treasure alongside displayed items,
withholding theirs when your own arms are already full.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0138A8CjeQRpvzKxuMfz1Bqc

packages/web/src/App.svelte

@@ -834,14 +834,36 @@
   }
 
   // SWAP MEET: pick one of your carried items, then one of theirs you can
-  // see (their displayed items — hidden hand cards are not on the table).
+  // see (their displayed items and any treasure in their arms — hidden
+  // hand cards are not on the table).
   let swapMeetTarget = $state<string | null>(null);
   let swapMine = $state<string | null>(null);
-  const myTradables = $derived(view ? view.yourHand.filter((c) => isMovableObject(c.cardId)) : []);
+  const myTradables = $derived.by(() => {
+    if (!view) return [];
+    const opts = new Map<string, string>();
+    for (const c of view.yourHand) {
+      if (isMovableObject(c.cardId)) opts.set(c.cardId, cardDef(c.cardId).name);
+    }
+    if (me?.carriedTreasureId) {
+      const t = view.treasures.find((t) => t.id === me.carriedTreasureId);
+      opts.set("treasure", `${t?.owner ?? "the"}'s treasure (carried)`);
+    }
+    return [...opts].map(([key, label]) => ({ key, label }));
+  });
   const theirTradables = $derived.by(() => {
     if (!view || !swapMeetTarget) return [];
-    const t = view.players.find((p) => p.id === swapMeetTarget);
-    return t ? t.displayed.filter((c) => isMovableObject(c.cardId)) : [];
+    const them = view.players.find((p) => p.id === swapMeetTarget);
+    if (!them) return [];
+    const opts = new Map<string, string>();
+    for (const c of them.displayed) {
+      if (isMovableObject(c.cardId)) opts.set(c.cardId, cardDef(c.cardId).name);
+    }
+    // Their treasure is claimable unless your arms are already full.
+    if (them.carriedTreasureId && (swapMine === "treasure" || !me?.carriedTreasureId)) {
+      const t = view.treasures.find((t) => t.id === them.carriedTreasureId);
+      opts.set("treasure", `${t?.owner ?? "the"}'s treasure (carried)`);
+    }
+    return [...opts].map(([key, label]) => ({ key, label }));
   });
   function castSwapMeet(theirs: string) {
     if (!selectedCard || !swapMeetTarget || !swapMine) return;
@@ -1706,15 +1728,15 @@
                 <span>— you carry no items to trade</span>
               {:else if !swapMine}
                 <span>— trade away your:</span>
-                {#each myTradables as c (c.instanceId)}
-                  <button class="stamp tiny" onclick={() => (swapMine = c.cardId)}>{cardDef(c.cardId).name}</button>
+                {#each myTradables as c (c.key)}
+                  <button class="stamp tiny" onclick={() => (swapMine = c.key)}>{c.label}</button>
                 {/each}
               {:else if theirTradables.length === 0}
                 <span>— they show no item you could claim</span>
               {:else}
                 <span>— and take their:</span>
-                {#each theirTradables as c (c.instanceId)}
-                  <button class="stamp tiny" onclick={() => castSwapMeet(c.cardId)}>{cardDef(c.cardId).name}</button>
+                {#each theirTradables as c (c.key)}
+                  <button class="stamp tiny" onclick={() => castSwapMeet(c.key)}>{c.label}</button>
                 {/each}
               {/if}
             {/if}