diff --git a/tests/samples/slay-the-spire-like/grid-inventory.test.ts b/tests/samples/slay-the-spire-like/grid-inventory.test.ts
index 94077cf..5d7ed1d 100644
--- a/tests/samples/slay-the-spire-like/grid-inventory.test.ts
+++ b/tests/samples/slay-the-spire-like/grid-inventory.test.ts
@@ -15,6 +15,48 @@ import {
   type GridInventory,
   type InventoryItem,
 } from "@/samples/slay-the-spire-like/system/grid-inventory";
+import { createItemIn } from "@/samples/slay-the-spire-like/system/grid-inventory/factory";
+import type { GameItemMeta } from "@/samples/slay-the-spire-like/system/grid-inventory/types";
+import type {
+  CardData,
+  ItemData,
+} from "@/samples/slay-the-spire-like/system/types";
+
+/**
+ * Helper: create a minimal CardData for testing.
+ */
+function createTestCardData(id: string, name: string, desc: string): CardData {
+  return {
+    id,
+    name,
+    desc,
+    type: "item",
+    costType: "energy",
+    costCount: 1,
+    targetType: "single",
+    effects: [],
+  };
+}
+
+/**
+ * Helper: create a minimal ItemData for testing.
+ */
+function createTestItemData(
+  id: string,
+  name: string,
+  shapeStr: string,
+  desc: string,
+): ItemData {
+  return {
+    id,
+    type: "weapon",
+    name,
+    shape: shapeStr,
+    card: createTestCardData(id, name, desc),
+    price: 10,
+    description: desc,
+  };
+}
 
 /**
  * Helper: create a test inventory item.
@@ -535,4 +577,81 @@ describe("grid-inventory", () => {
       expect(adjShield.has("sword")).toBe(true);
     });
   });
+
+  describe("createItemIn", () => {
+    it("should place item at first valid position", () => {
+      const inv = createGridInventory<GameItemMeta>(6, 4);
+      const itemData = createTestItemData("sword", "长剑", "oee", "攻击");
+
+      const result = createItemIn(inv, "sword-1", itemData);
+
+      expect(result).toEqual({ success: true });
+      expect(inv.items.size).toBe(1);
+      expect(inv.occupiedCells.size).toBe(3); // shape "oee" has 3 cells
+      expect(inv.items.get("sword-1")?.meta?.itemData.id).toBe("sword");
+    });
+
+    it("should skip occupied cells and find next valid position", () => {
+      const inv = createGridInventory<GameItemMeta>(6, 4);
+
+      // Place first item manually at origin
+      const firstItem = createTestItem("existing", "oee");
+      placeItem(inv, firstItem);
+
+      const itemData = createTestItemData("shield", "盾牌", "o", "防御");
+
+      const result = createItemIn(inv, "shield-1", itemData);
+
+      expect(result).toEqual({ success: true });
+      // Shield should be at x=3, y=0 (first available spot after "oee" at x=0-2)
+      const placedItem = inv.items.get("shield-1");
+      expect(placedItem?.transform.offset).toEqual({ x: 3, y: 0 });
+    });
+
+    it("should return error when no valid placement exists", () => {
+      const inv = createGridInventory<GameItemMeta>(3, 3);
+
+      // Fill the grid completely with 1x1 items
+      for (let i = 0; i < 9; i++) {
+        const itemData = createTestItemData(`item${i}`, `物品${i}`, "o", "");
+        createItemIn(inv, `item-${i}`, itemData);
+      }
+
+      // Try to place one more item
+      const itemData = createTestItemData("overflow", "溢出", "oee", "");
+      const result = createItemIn(inv, "overflow-1", itemData);
+
+      expect(result).toEqual({ success: false, reason: "无可用位置" });
+    });
+
+    it("should handle multi-cell items correctly", () => {
+      const inv = createGridInventory<GameItemMeta>(4, 4);
+      const itemData = createTestItemData("lshape", "L形", "oes", "特殊");
+
+      const result = createItemIn(inv, "lshape-1", itemData);
+
+      expect(result).toEqual({ success: true });
+      expect(inv.items.size).toBe(1);
+      // Shape "oes" has 3 cells
+      expect(inv.occupiedCells.size).toBe(3);
+    });
+
+    it("should not place item when inventory is completely full", () => {
+      const inv = createGridInventory<GameItemMeta>(2, 2);
+
+      // Fill with 1x1 items
+      const itemData = createTestItemData("small", "小物品", "o", "");
+      createItemIn(inv, "small-1", itemData);
+      createItemIn(inv, "small-2", itemData);
+      createItemIn(inv, "small-3", itemData);
+      createItemIn(inv, "small-4", itemData);
+
+      // Grid is now full
+      const overflowItem = createTestItemData("overflow", "溢出", "o", "");
+      const result = createItemIn(inv, "overflow-5", overflowItem);
+
+      expect(result).toEqual({ success: false, reason: "无可用位置" });
+      expect(inv.items.size).toBe(4);
+    });
+  });
 });