fix: resolve Sync API non-Axios response issue

CHANGELOG.md

@@ -2,6 +2,11 @@
 #### Date: Feb-16-2026
 Breaking: Cache persistence is now a separate plugin. When using a cache policy other than `IGNORE_CACHE`, you must pass `cacheOptions.persistenceStore`. Install `@contentstack/persistence-plugin` and use `new PersistenceStore({ ... })` as the store. The SDK no longer bundles persistence code or accepts `storeType` in `cacheOptions`.
 Enhancement: SDK defines only the `PersistenceStore` interface (getItem/setItem); full implementation lives in the plugin for a lighter core package.
+Fix: Sync API returns non-Axios response causing undefined data and recursive sync failure
+
+### Version: 4.11.2
+#### Date: feb-11-2026
+Fix: JS core & axios version bump
 
 
 ### Version: 4.11.2

src/common/types.ts

@@ -127,6 +127,22 @@ export interface SyncType {
   locale?: string;
   startDate?: string;
 }
+
+export interface SyncItem {
+  type: string;
+  event_at: string;
+  content_type_uid: string;
+  data: any;
+}
+
+export interface SyncResponse {
+  items: SyncItem[];
+  skip?: number;
+  limit?: number;
+  total_count?: number;
+  sync_token?: string;
+  pagination_token?: string;
+}
 export type TransformData = { [key: string]: string | string[] };
 
 export enum Format {

src/sync/index.ts

@@ -1 +1,2 @@
 export { synchronization } from './synchronization';
+export type { SyncResponse, SyncItem } from '../common/types';

src/sync/synchronization.ts

@@ -1,9 +1,9 @@
 import { AxiosInstance, getData } from '@contentstack/core';
-import { SyncStack, SyncType, PublishType } from '../common/types';
-import { AxiosRequestConfig, AxiosResponse } from 'axios';
+import { SyncStack, SyncType, PublishType, SyncResponse } from '../common/types';
+import { AxiosRequestConfig } from 'axios';
 import humps from 'humps';
 
-export async function synchronization(client: AxiosInstance, params: SyncStack | SyncType = {}, recursive = false) {
+export async function synchronization(client: AxiosInstance, params: SyncStack | SyncType = {}, recursive = false): Promise<SyncResponse> {
   const config: AxiosRequestConfig = { params };
   const SYNC_URL = '/stacks/sync';
 
@@ -17,18 +17,19 @@ export async function synchronization(client: AxiosInstance, params: SyncStack |
     config.params = { ...config.params, type: type.join(',') };
   }
 
-  let response: AxiosResponse = await getData(client, SYNC_URL, { params: humps.decamelizeKeys(config.params) });
-  const data = response.data;
+  // getData returns response.data directly, not the full AxiosResponse
+  let response: SyncResponse = await getData(client, SYNC_URL, { params: humps.decamelizeKeys(config.params) });
 
-  while (recursive && 'pagination_token' in response.data) {
-    const recResponse: AxiosResponse = await getData(
+  while (recursive && 'pagination_token' in response) {
+    const recResponse: SyncResponse = await getData(
       client,
       SYNC_URL,
-      humps.decamelizeKeys({ paginationToken: data.pagination_token })
+      { params: humps.decamelizeKeys({ paginationToken: response.pagination_token }) }
     );
-    recResponse.data.items = { ...response.data.items, ...recResponse.data.items };
-    response = { ...recResponse };
+    // Merge items from all paginated responses
+    recResponse.items = [...response.items, ...recResponse.items];
+    response = recResponse;
   }
 
-  return response.data;
+  return response;
 }