DDI stands for Developer Disk Image according to xcrun devicectl list preferredDDI -h

Thanks! Knowing the per-session caching is expected (not a bug) and that we don't need distinct Key IDs for streaming vs download led us to the fix: we now use two AVContentKeySession instances — one for streaming (non-persistable) and one for downloads/offline playback (persistable). Each has its own cache, so even during non-persistable playback, adding the asset to the download session fires a fresh delegate callback, and the persistable flow works as documented. Works great now!