Is it possible for an engineer from PhotoKit team to take a look at this question and provide guidance here?

Thanks for the detailed response, Albert. Our server API has a strict payload limit of 250 MB per request. Because of this constraint, our existing upload infrastructure uses chunked uploads for large files — splitting videos into smaller byte ranges and uploading each chunk separately via the BITS protocol (CreateSession → Fragment → CloseSession). However, I don't see any API surface in PHAssetResourceUploadJobChangeRequest to: Specify byte ranges for partial uploads Create multiple sequential jobs for chunks of the same resource Provide a callback/delegate pattern for "give me the next upload destination" Given that the system daemon handles uploads out-of-process (as you explained), it seems this API assumes the destination endpoint can accept the entire file in a single HTTP request. My question then becomes: For services with server-side payload limits, is PHBackgroundResourceUploadExtension the wrong tool for the job? Should we instead: Continue using our existing NSURLSession background upload approach (where we control chunking)? Is there a roadmap consideration for chunked upload support in this API? Any guidance from the team would be appreciated. We'd love to adopt this new API for its battery/lifecycle benefits, but the 250 MB server limit is a hard constraint we can't easily change.