Fix Mosswort Bridge hideaway card visible to opponent (#4828)

client/src/components/board/PermanentCard.tsx

@@ -30,6 +30,7 @@ import {
   boardChoiceMaxSelection,
   buildBoardChoiceAction,
   getBoardChoiceView,
+  isFaceDownExileCardVisibleToViewer,
   isBoardChoiceImmediate,
   type BoardChoiceIntent,
 } from "../../viewmodel/gameStateView.ts";
@@ -1045,7 +1046,9 @@ interface ExileGhostCardProps {
 }
 
 const ExileGhostCard = memo(function ExileGhostCard({ objectId, offset }: ExileGhostCardProps) {
-  const obj = useGameStore((s) => s.gameState?.objects[objectId]);
+  const gameState = useGameStore((s) => s.gameState);
+  const obj = gameState?.objects[objectId];
+  const viewerId = usePlayerId();
   const { handlers: hoverHandlers } = useCardHover(objectId);
   const battlefieldCardDisplay = usePreferencesStore((s) => s.battlefieldCardDisplay);
   const controllerIdentity = useGameStore(
@@ -1054,6 +1057,9 @@ const ExileGhostCard = memo(function ExileGhostCard({ objectId, offset }: ExileG
 
   if (!obj) return null;
 
+  const hiddenFromViewer =
+    obj.face_down && !isFaceDownExileCardVisibleToViewer(gameState ?? null, obj, viewerId);
+
   const isLand = obj.card_types.core_types.includes("Land");
   const displayColors = getCardDisplayColors(
     obj.color,
@@ -1074,9 +1080,13 @@ const ExileGhostCard = memo(function ExileGhostCard({ objectId, offset }: ExileG
       {/* Purple exile tint */}
       <div className="absolute inset-0 z-10 rounded-lg bg-purple-600/30 pointer-events-none" />
       {useArtCrop ? (
-        <ArtCropCard objectId={objectId} />
+        hiddenFromViewer ? (
+          <CardImage cardName={imgName} size="small" faceDown />
+        ) : (
+          <ArtCropCard objectId={objectId} />
+        )
       ) : (
-        <CardImage cardName={imgName} faceIndex={imgFace} oracleId={imgOracleId} faceName={imgFaceName} size="small" colors={displayColors} isToken={obj.display_source === "Token"} tokenFilters={obj.display_source === "Token" ? tokenFiltersForObject(obj) : undefined} tokenImageRef={obj.token_image_ref} oracleText={obj.display_source === "Token" ? obj.token_rules_text : undefined} faceDown={obj.face_down} />
+        <CardImage cardName={imgName} faceIndex={imgFace} oracleId={imgOracleId} faceName={imgFaceName} size="small" colors={displayColors} isToken={obj.display_source === "Token"} tokenFilters={obj.display_source === "Token" ? tokenFiltersForObject(obj) : undefined} tokenImageRef={obj.token_image_ref} oracleText={obj.display_source === "Token" ? obj.token_rules_text : undefined} faceDown={hiddenFromViewer} />
       )}
     </div>
   );

client/src/components/board/__tests__/issue_4828_hideaway_exile_ghost.test.tsx

@@ -0,0 +1,155 @@
+import { cleanup, render } from "@testing-library/react";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+
+import type { GameObject, GameState } from "../../../adapter/types.ts";
+import { useGameStore } from "../../../stores/gameStore.ts";
+import { BoardInteractionContext } from "../BoardInteractionContext.tsx";
+import { PermanentCard } from "../PermanentCard.tsx";
+
+vi.mock("../../card/CardImage.tsx", () => ({
+  CardImage: ({ cardName, faceDown }: { cardName: string; faceDown?: boolean }) => (
+    <div
+      aria-label={faceDown ? "Face-down card" : cardName}
+      data-face-down={faceDown ? "true" : "false"}
+    />
+  ),
+}));
+
+function makeObject(overrides: Partial<GameObject> = {}): GameObject {
+  return {
+    id: 1,
+    card_id: 100,
+    owner: 0,
+    controller: 0,
+    zone: "Battlefield",
+    tapped: false,
+    face_down: false,
+    flipped: false,
+    transformed: false,
+    damage_marked: 0,
+    dealt_deathtouch_damage: false,
+    attached_to: null,
+    attachments: [],
+    counters: {},
+    name: "Host",
+    power: null,
+    toughness: null,
+    loyalty: null,
+    card_types: { supertypes: [], core_types: ["Land"], subtypes: [] },
+    mana_cost: { type: "NoCost" },
+    keywords: [],
+    abilities: [],
+    trigger_definitions: [],
+    replacement_definitions: [],
+    static_definitions: [],
+    color: [],
+    base_power: null,
+    base_toughness: null,
+    base_keywords: [],
+    base_color: [],
+    timestamp: 1,
+    entered_battlefield_turn: null,
+    ...overrides,
+  };
+}
+
+function makeState(objects: GameObject[], exileLinks: NonNullable<GameState["exile_links"]>): GameState {
+  return {
+    active_player: 0,
+    priority_player: 0,
+    players: [
+      {
+        id: 0,
+        life: 20,
+        poison_counters: 0,
+        mana_pool: { mana: [] },
+        library: [],
+        hand: [],
+        graveyard: [],
+        has_drawn_this_turn: false,
+        lands_played_this_turn: 0,
+        turns_taken: 0,
+      },
+      {
+        id: 1,
+        life: 20,
+        poison_counters: 0,
+        mana_pool: { mana: [] },
+        library: [],
+        hand: [],
+        graveyard: [],
+        has_drawn_this_turn: false,
+        lands_played_this_turn: 0,
+        turns_taken: 0,
+      },
+    ],
+    objects: Object.fromEntries(objects.map((o) => [o.id, o])),
+    battlefield: objects.filter((o) => o.zone === "Battlefield").map((o) => o.id),
+    exile: objects.filter((o) => o.zone === "Exile").map((o) => o.id),
+    stack: [],
+    combat: null,
+    exile_links: exileLinks,
+    waiting_for: { type: "Priority", data: { player: 0 } },
+  } as unknown as GameState;
+}
+
+describe("PermanentCard Hideaway exile ghost (issue #4828)", () => {
+  afterEach(() => cleanup());
+
+  beforeEach(() => {
+    window.matchMedia = ((query: string) => ({
+      matches: query === "(any-hover: hover)",
+      media: query,
+      onchange: null,
+      addEventListener: vi.fn(),
+      removeEventListener: vi.fn(),
+      addListener: vi.fn(),
+      removeListener: vi.fn(),
+      dispatchEvent: vi.fn(),
+    })) as unknown as typeof window.matchMedia;
+  });
+
+  it("hides an opponent's Hideaway-exiled card on the source permanent's exile ghost", () => {
+    const source = makeObject({
+      id: 1,
+      owner: 1,
+      controller: 1,
+      name: "Mosswort Bridge",
+    });
+    const hidden = makeObject({
+      id: 2,
+      owner: 1,
+      controller: 1,
+      zone: "Exile",
+      name: "Ghalta, Primal Hunter",
+      face_down: true,
+    });
+    const gameState = makeState(
+      [source, hidden],
+      [{ exiled_id: 2, source_id: 1, kind: "HideawayLookable" }],
+    );
+    useGameStore.setState({ gameState, waitingFor: gameState.waiting_for });
+
+    const { queryByLabelText } = render(
+      <BoardInteractionContext.Provider
+        value={{
+          activatableObjectIds: new Set(),
+          boardChoiceObjectIds: new Set(),
+          committedAttackerIds: new Set(),
+          incomingAttackerCounts: new Map(),
+          manaTappableObjectIds: new Set(),
+          selectableSacrificeObjectIds: new Set(),
+          selectableManaCostCreatureIds: new Set(),
+          undoableTapObjectIds: new Set(),
+          validAttackerIds: new Set(),
+          validTargetObjectIds: new Set(),
+        }}
+      >
+        <PermanentCard objectId={1} />
+      </BoardInteractionContext.Provider>,
+    );
+
+    expect(queryByLabelText("Face-down card")).not.toBeNull();
+    expect(queryByLabelText("Ghalta, Primal Hunter")).toBeNull();
+  });
+});