Something I want to know and all users of CKSyncEngine care about I'm going to build a full stack solution using CKSyncEngine, but what's the near future and the support and maintenance priorities inside Apple for CKSyncEngine? There is only one short video for CKSyncEngine, in 2023, no updates after that, no future plans mentioned. I'm worried that this technology be deprecated or not activity maintained. This is a complex technology, without being activity maintained (or open-sourced) there will be fatal production issues we the developer cannot solve. The CK developer in the video stated that "many apps" were using the framework, but he did not list any. The only named is NSUbiquitousKeyValueStore, but NSUbiquitousKeyValueStore is too simple a use case. I wonder is apple's Notes.app using it, or going to use it? Is SwiftData using it? API Problems The API design seems a little bit tricky, not designed from a user's perspective. handleEvent doesn't contain any context information about which batch. How do I react the event properly? Let's say our sync code and CKSyncEngine, and callbacks are all on a dedicated thread. Consider this: in nextRecordZoneChangeBatch you provided a batch of changes, let's call this BATCH 1, including an item in database with uuid "***" and name "yyy" before the changes are uploaded, there are new changes from many OTHER BACKGROUND THREADS made to the database. item "***"'s name is now "zzz" handle SentRecordZoneChanges event: I get records that uploaded or failed, but I don't know which BATCH the records belong to. How do I decide if i have to mark "***" as finished uploading or not? If I mark *** as finished that's wrong, the new name "zzz" is not uploaded. I have to compare every field of *** with the savedRecord to decide if I finished uploading or not? That is not acceptable as the performance and memory will be bad. Other questions I have to add recordIDs to state, and wait for the engine to react. I don't think this is a good idea, because recordID is a CloudKit concept, and what I want to sync is a local database. I don't see any rational for this, or not documented. If the engine is going to ask for a batch of records, you can get all record ids from the batch?