Instead of downloading iCloud assets twice (once to hash, once to upload),
skip local hashing for iCloud-only assets and let the server return its
computed SHA1 checksum in the upload response. The mobile app stores this
checksum locally to prevent re-uploads.
Changes:
- Server returns checksum in upload response (created + duplicate)
- iOS native layer tags iCloud-only assets with ICLOUD_ONLY error
- Hash service skips iCloud assets (allowNetworkAccess: false)
- Upload result carries server checksum back to mobile
- Foreground/background upload services store server checksum
- Backup candidates include unhashed assets (onlyHashed: false)
https://claude.ai/code/session_01LEs74WpkJ1gWcJrFBsp1i2
