diff --git a/src/samples/slay-the-spire-like/grid-inventory/index.ts b/src/samples/slay-the-spire-like/grid-inventory/index.ts
index 936bd7f..d926b78 100644
--- a/src/samples/slay-the-spire-like/grid-inventory/index.ts
+++ b/src/samples/slay-the-spire-like/grid-inventory/index.ts
@@ -1,4 +1,4 @@
-export type { CellCoordinate, GridInventory, InventoryItem, PlacementResult } from './types';
+export type { CellCoordinate, CellKey, GridInventory, InventoryItem, MutationResult, PlacementResult } from './types';
 export {
     createGridInventory,
     flipItem,
diff --git a/src/samples/slay-the-spire-like/grid-inventory/transform.ts b/src/samples/slay-the-spire-like/grid-inventory/transform.ts
index 624c894..d29094f 100644
--- a/src/samples/slay-the-spire-like/grid-inventory/transform.ts
+++ b/src/samples/slay-the-spire-like/grid-inventory/transform.ts
@@ -8,36 +8,36 @@ import {
     rotateTransform,
     transformShape,
 } from '../utils/shape-collision';
-import type { GridInventory, InventoryItem, PlacementResult } from './types';
+import type { CellKey, GridInventory, InventoryItem, MutationResult, PlacementResult } from './types';
 
 /**
  * Creates a new empty grid inventory.
  * Note: When used inside `.produce()`, call this before returning the draft.
  */
-export function createGridInventory(width: number, height: number): GridInventory {
+export function createGridInventory<TMeta = Record<string, unknown>>(width: number, height: number): GridInventory<TMeta> {
     return {
         width,
         height,
-        items: new Map<string, InventoryItem>(),
-        occupiedCells: new Set<string>(),
+        items: new Map<string, InventoryItem<TMeta>>(),
+        occupiedCells: new Set<CellKey>(),
     };
 }
 
 /**
  * Builds a Set of occupied cell keys from a shape and transform.
  */
-function getShapeCellKeys(shape: ParsedShape, transform: Transform2D): Set<string> {
+function getShapeCellKeys(shape: ParsedShape, transform: Transform2D): Set<CellKey> {
     const cells = transformShape(shape, transform);
-    return new Set(cells.map(c => `${c.x},${c.y}`));
+    return new Set(cells.map(c => `${c.x},${c.y}` as CellKey));
 }
 
 /**
  * Validates whether an item can be placed at the given transform.
  * Checks bounds and collision with all other items.
  */
-export function validatePlacement(
-    inventory: GridInventory,
-    shape: InventoryItem['shape'],
+export function validatePlacement<TMeta = Record<string, unknown>>(
+    inventory: GridInventory<TMeta>,
+    shape: InventoryItem<TMeta>['shape'],
     transform: Transform2D
 ): PlacementResult {
     if (!checkBounds(shape, transform, inventory.width, inventory.height)) {
@@ -56,7 +56,7 @@ export function validatePlacement(
  * **Mutates directly** — call inside a `.produce()` callback.
  * Does not validate; call `validatePlacement` first.
  */
-export function placeItem(inventory: GridInventory, item: InventoryItem): void {
+export function placeItem<TMeta = Record<string, unknown>>(inventory: GridInventory<TMeta>, item: InventoryItem<TMeta>): void {
     const cells = getShapeCellKeys(item.shape, item.transform);
     for (const cellKey of cells) {
         inventory.occupiedCells.add(cellKey);
@@ -68,7 +68,7 @@ export function placeItem(inventory: GridInventory, item: InventoryItem): void {
  * Removes an item from the grid by its ID.
  * **Mutates directly** — call inside a `.produce()` callback.
  */
-export function removeItem(inventory: GridInventory, itemId: string): void {
+export function removeItem<TMeta = Record<string, unknown>>(inventory: GridInventory<TMeta>, itemId: string): void {
     const item = inventory.items.get(itemId);
     if (!item) return;
 
@@ -84,11 +84,11 @@ export function removeItem(inventory: GridInventory, itemId: string): void {
  * **Mutates directly** — call inside a `.produce()` callback.
  * Validates before applying; returns result indicating success.
  */
-export function moveItem(
-    inventory: GridInventory,
+export function moveItem<TMeta = Record<string, unknown>>(
+    inventory: GridInventory<TMeta>,
     itemId: string,
     newTransform: Transform2D
-): { success: true } | { success: false; reason: string } {
+): MutationResult {
     const item = inventory.items.get(itemId);
     if (!item) {
         return { success: false, reason: '物品不存在' };
@@ -127,11 +127,11 @@ export function moveItem(
  * **Mutates directly** — call inside a `.produce()` callback.
  * Validates before applying; returns result indicating success.
  */
-export function rotateItem(
-    inventory: GridInventory,
+export function rotateItem<TMeta = Record<string, unknown>>(
+    inventory: GridInventory<TMeta>,
     itemId: string,
     degrees: number
-): { success: true } | { success: false; reason: string } {
+): MutationResult {
     const item = inventory.items.get(itemId);
     if (!item) {
         return { success: false, reason: '物品不存在' };
@@ -146,11 +146,11 @@ export function rotateItem(
  * **Mutates directly** — call inside a `.produce()` callback.
  * Validates before applying; returns result indicating success.
  */
-export function flipItem(
-    inventory: GridInventory,
+export function flipItem<TMeta = Record<string, unknown>>(
+    inventory: GridInventory<TMeta>,
     itemId: string,
     axis: 'x' | 'y'
-): { success: true } | { success: false; reason: string } {
+): MutationResult {
     const item = inventory.items.get(itemId);
     if (!item) {
         return { success: false, reason: '物品不存在' };
@@ -166,19 +166,19 @@ export function flipItem(
 /**
  * Returns a copy of the occupied cells set.
  */
-export function getOccupiedCellSet(inventory: GridInventory): Set<string> {
+export function getOccupiedCellSet<TMeta = Record<string, unknown>>(inventory: GridInventory<TMeta>): Set<CellKey> {
     return new Set(inventory.occupiedCells);
 }
 
 /**
  * Finds the item occupying the given cell, if any.
  */
-export function getItemAtCell(
-    inventory: GridInventory,
+export function getItemAtCell<TMeta = Record<string, unknown>>(
+    inventory: GridInventory<TMeta>,
     x: number,
     y: number
-): InventoryItem | undefined {
-    const cellKey = `${x},${y}`;
+): InventoryItem<TMeta> | undefined {
+    const cellKey = `${x},${y}` as CellKey;
     if (!inventory.occupiedCells.has(cellKey)) {
         return undefined;
     }
@@ -197,30 +197,31 @@ export function getItemAtCell(
  * Gets all items adjacent to the given item (orthogonally, not diagonally).
  * Returns a Map of itemId -> item for deduplication.
  */
-export function getAdjacentItems(
-    inventory: GridInventory,
+export function getAdjacentItems<TMeta extends Record<string, unknown> = Record<string, unknown>>(
+    inventory: GridInventory<TMeta>,
     itemId: string
-): Map<string, InventoryItem> {
+): Map<string, InventoryItem<TMeta>> {
     const item = inventory.items.get(itemId);
     if (!item) {
         return new Map();
     }
 
     const ownCells = getShapeCellKeys(item.shape, item.transform);
-    const adjacent = new Map<string, InventoryItem>();
+    const adjacent = new Map<string, InventoryItem<TMeta>>();
 
     for (const cellKey of ownCells) {
         const [cx, cy] = cellKey.split(',').map(Number);
-        const neighbors = [
-            `${cx + 1},${cy}`,
-            `${cx - 1},${cy}`,
-            `${cx},${cy + 1}`,
-            `${cx},${cy - 1}`,
+        const neighbors: CellKey[] = [
+            `${cx + 1},${cy}` as CellKey,
+            `${cx - 1},${cy}` as CellKey,
+            `${cx},${cy + 1}` as CellKey,
+            `${cx},${cy - 1}` as CellKey,
         ];
 
         for (const neighborKey of neighbors) {
             if (inventory.occupiedCells.has(neighborKey) && !ownCells.has(neighborKey)) {
-                const neighborItem = getItemAtCell(inventory, ...neighborKey.split(',').map(Number) as [number, number]);
+                const [nx, ny] = neighborKey.split(',').map(Number);
+                const neighborItem = getItemAtCell(inventory, nx, ny);
                 if (neighborItem) {
                     adjacent.set(neighborItem.id, neighborItem);
                 }
diff --git a/src/samples/slay-the-spire-like/grid-inventory/types.ts b/src/samples/slay-the-spire-like/grid-inventory/types.ts
index ff0866a..f022b9e 100644
--- a/src/samples/slay-the-spire-like/grid-inventory/types.ts
+++ b/src/samples/slay-the-spire-like/grid-inventory/types.ts
@@ -1,6 +1,11 @@
 import type { ParsedShape } from '../utils/parse-shape';
 import type { Transform2D } from '../utils/shape-collision';
 
+/**
+ * String key representing a grid cell in "x,y" format.
+ */
+export type CellKey = `${number},${number}`;
+
 /**
  * Simple 2D coordinate for grid cells.
  */
@@ -11,8 +16,9 @@ export interface CellCoordinate {
 
 /**
  * An item placed on the grid inventory.
+ * @template TMeta - Optional metadata type for game-specific data
  */
-export interface InventoryItem {
+export interface InventoryItem<TMeta = Record<string, unknown>> {
     /** Unique item identifier */
     id: string;
     /** Reference to the item's shape definition */
@@ -20,7 +26,7 @@ export interface InventoryItem {
     /** Current transformation (position, rotation, flips) */
     transform: Transform2D;
     /** Optional metadata for game-specific data */
-    meta?: Record<string, unknown>;
+    meta?: TMeta;
 }
 
 /**
@@ -28,17 +34,23 @@ export interface InventoryItem {
  */
 export type PlacementResult = { valid: true } | { valid: false; reason: string };
 
+/**
+ * Result of a mutation operation (move, rotate, flip).
+ */
+export type MutationResult = { success: true } | { success: false; reason: string };
+
 /**
  * Grid inventory state.
  * Designed to be mutated directly inside a `mutative .produce()` callback.
+ * @template TMeta - Optional metadata type for items
  */
-export interface GridInventory {
+export interface GridInventory<TMeta = Record<string, unknown>> {
     /** Board width in cells */
     width: number;
     /** Board height in cells */
     height: number;
     /** Map of itemId -> InventoryItem for all placed items */
-    items: Map<string, InventoryItem>;
+    items: Map<string, InventoryItem<TMeta>>;
     /** Set of occupied cells in "x,y" format for O(1) collision lookups */
-    occupiedCells: Set<string>;
+    occupiedCells: Set<CellKey>;
 }