fix(storage): avoid calling setItem with the state just retrieved

src/middleware/persist.ts

@@ -459,27 +459,34 @@ const newImpl: PersistImpl = (config, baseOptions) => (set, get, api) => {
             deserializedStorageValue.version !== options.version
           ) {
             if (options.migrate) {
-              return options.migrate(
-                deserializedStorageValue.state,
-                deserializedStorageValue.version,
-              )
+              return [
+                true,
+                options.migrate(
+                  deserializedStorageValue.state,
+                  deserializedStorageValue.version,
+                ),
+              ] as const
             }
             console.error(
               `State loaded from storage couldn't be migrated since no migrate function was provided`,
             )
           } else {
-            return deserializedStorageValue.state
+            return [false, deserializedStorageValue.state] as const
           }
         }
+        return [false, undefined] as const
       })
-      .then((migratedState) => {
+      .then((migrationResult) => {
+        const [migrated, migratedState] = migrationResult
         stateFromStorage = options.merge(
           migratedState as S,
           get() ?? configResult,
         )
 
         set(stateFromStorage as S, true)
-        return setItem()
+        if (migrated) {
+          return setItem()
+        }
       })
       .then(() => {
         // TODO: In the asynchronous case, it's possible that the state has changed

tests/persistSync.test.tsx

@@ -738,4 +738,26 @@ describe('persist middleware with sync configuration', () => {
       undefined,
     )
   })
+
+  it('does not call setItem when hydrating from its own storage', async () => {
+    const setItem = vi.fn()
+    const storage = {
+      getItem: (name: string) => ({
+        state: { count: 42, name },
+        version: 0,
+      }),
+      setItem,
+      removeItem: () => {},
+    }
+
+    const useBoundStore = create(
+      persist(() => ({}), {
+        name: 'test-storage',
+        storage: storage,
+      }),
+    )
+
+    expect(useBoundStore.persist.hasHydrated()).toBe(true)
+    expect(setItem).toBeCalledTimes(0)
+  })
 })