fix(undo-redo): address review feedback

- Gate setItem/removeItem on migration completion via shared
  awaitMigration() helper. Previously only getItem awaited the one-time
  localStorage -> IndexedDB migration; a setItem racing the migration
  could be overwritten when migration completed (Cursor Bugbot, high).
- Use `typeof window` for the SSR guard to match
  apps/sim/stores/terminal/console/storage.ts (Greptile).
- Add error-swallowing test for removeItem to mirror the existing
  coverage on getItem and setItem (Greptile).
- Switch storage.test.ts to `@vitest-environment jsdom` since the
  module-load IIFE depends on `typeof window`.

Signed-off-by: JaeHyung Jang <jaehyung.jang@navercorp.com>

Author: Sprexatura

apps/sim/stores/undo-redo/storage.test.ts

@@ -1,5 +1,5 @@
 /**
- * @vitest-environment node
+ * @vitest-environment jsdom
  */
 import { beforeEach, describe, expect, it, vi } from 'vitest'
 
@@ -137,6 +137,14 @@ describe('undo-redo IndexedDB storage adapter', () => {
       expect(idbStore.has(STORE_KEY)).toBe(false)
     })
 
+    it('removeItem swallows IndexedDB errors', async () => {
+      const { indexedDBStorage, migrationReady } = await loadFreshModule()
+      await migrationReady
+
+      idbDel.mockRejectedValueOnce(new Error('idb delete failed'))
+      await expect(indexedDBStorage.removeItem(STORE_KEY)).resolves.toBeUndefined()
+    })
+
     it('getItem swallows IndexedDB read errors and returns null', async () => {
       const { indexedDBStorage, migrationReady } = await loadFreshModule()
       await migrationReady

apps/sim/stores/undo-redo/storage.ts

@@ -17,7 +17,7 @@ let migrationPromiseInternal: Promise<void> | null = null
  * for the other persisted Zustand stores that share it.
  */
 async function migrateFromLocalStorage(): Promise<void> {
-  if (typeof localStorage === 'undefined') return
+  if (typeof window === 'undefined') return
 
   try {
     const migrated = await get<boolean>(MIGRATION_KEY)
@@ -36,26 +36,29 @@ async function migrateFromLocalStorage(): Promise<void> {
   }
 }
 
-if (typeof localStorage !== 'undefined') {
+if (typeof window !== 'undefined') {
   migrationPromiseInternal = migrateFromLocalStorage().finally(() => {
     migrationPromiseInternal = null
   })
 }
 
 /**
  * Resolves when the one-time localStorage → IndexedDB migration finishes.
- * Exposed for tests; production code reads through `indexedDBStorage.getItem`
- * which already awaits this promise.
+ * Exposed for tests; production code reads through `indexedDBStorage`
+ * methods which already await this promise.
  */
 export const migrationReady: Promise<void> = migrationPromiseInternal ?? Promise.resolve()
 
+async function awaitMigration(): Promise<void> {
+  if (migrationPromiseInternal) {
+    await migrationPromiseInternal
+  }
+}
+
 export const indexedDBStorage: StateStorage = {
   getItem: async (name: string): Promise<string | null> => {
-    if (typeof localStorage === 'undefined') return null
-
-    if (migrationPromiseInternal) {
-      await migrationPromiseInternal
-    }
+    if (typeof window === 'undefined') return null
+    await awaitMigration()
 
     try {
       const value = await get<string>(name)
@@ -67,7 +70,9 @@ export const indexedDBStorage: StateStorage = {
   },
 
   setItem: async (name: string, value: string): Promise<void> => {
-    if (typeof localStorage === 'undefined') return
+    if (typeof window === 'undefined') return
+    await awaitMigration()
+
     try {
       await set(name, value)
     } catch (error) {
@@ -76,7 +81,9 @@ export const indexedDBStorage: StateStorage = {
   },
 
   removeItem: async (name: string): Promise<void> => {
-    if (typeof localStorage === 'undefined') return
+    if (typeof window === 'undefined') return
+    await awaitMigration()
+
     try {
       await del(name)
     } catch (error) {