Run the budgeted sync handler on the content thread while blocking network calls retain their worker. This keeps ownership checks, backups, replacements and deletions ordered with savefile lifetime changes.
Keep a local save in place until its download is complete. If the completion cannot be handed to the handler, discard the temporary file and carry the manifests forward instead of committing on the callback thread.
Exercise threaded and unthreaded queues, both replacement modes, ownership acquired during transfer, backup contents and failed completion allocation.
