diff --git a/apps/web/vitest.setup.ts b/apps/web/vitest.setup.ts
index 4523022..92165be 100644
--- a/apps/web/vitest.setup.ts
+++ b/apps/web/vitest.setup.ts
@@ -24,3 +24,33 @@ Object.defineProperty(window, "matchMedia", {
     dispatchEvent: () => false,
   }),
 });
+
+// Ensure localStorage exists with a full Storage API for tests.
+// Avoid touching the built-in accessor (which emits warnings in Node).
+let storageStore: Record<string, string> = {};
+const storageMock: Storage = {
+  getItem: (key: string): string | null => storageStore[key] ?? null,
+  setItem: (key: string, value: string): void => {
+    storageStore[key] = value;
+  },
+  removeItem: (key: string): void => {
+    // eslint-disable-next-line @typescript-eslint/no-dynamic-delete
+    delete storageStore[key];
+  },
+  clear: (): void => {
+    storageStore = {};
+  },
+  get length(): number {
+    return Object.keys(storageStore).length;
+  },
+  key: (index: number): string | null => {
+    const keys = Object.keys(storageStore);
+    return keys[index] ?? null;
+  },
+};
+
+Object.defineProperty(window, "localStorage", {
+  value: storageMock,
+  writable: true,
+  configurable: true,
+});