Two treasures, one square: the taker names their prize

pickUpTreasure grabbed whichever treasure the list offered first —
with two on a square, no choice and sometimes the wrong one. The
command now takes an optional treasureId (absent in every stored
ledger, so old replays keep their old grab), and when the square
holds more than one, the button asks "whose?" before dispatching.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

packages/engine/test/terrain-objects-control.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, it } from "vitest";
-import { applyCommand, activePlayer, boardView, gameLos, sustainedOn } from "../src/game";
+import { applyCommand, activePlayer, boardView, createGame, gameLos, sustainedOn } from "../src/game";
 import { cellKey, edgeKey, neighbor, SIDES } from "../src/board";
 import type { CardInstance } from "../src/cards";
 import { newGame, must, giveCard, toRound2, faceOff, castAt, emptyNeighborCell } from "./helpers";
@@ -277,3 +277,17 @@ describe("control effects", () => {
     expect(state.players.find((p) => p.id === me.id)!.hand.some((c) => c.cardId === "create-wall")).toBe(true);
   });
 });
+
+describe("picking one of two treasures", () => {
+  it("a named treasure is the one taken", () => {
+    let { state } = createGame({ playerIds: ["a", "b"], seed: 42, sets: ["basic"], deckRev: 16 });
+    state = toRound2(state);
+    const p = activePlayer(state);
+    const [t1, t2] = state.treasures.filter((t) => t.owner !== p.id);
+    t1!.position = { ...p.position }; t1!.carriedBy = null;
+    t2!.position = { ...p.position }; t2!.carriedBy = null;
+    const r = applyCommand(state, p.id, { type: "pickUpTreasure", treasureId: t2!.id });
+    if (!r.ok) throw new Error(r.error);
+    expect(r.state.players.find((q) => q.id === p.id)!.carriedTreasureId).toBe(t2!.id);
+  });
+});