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4A: user-data drives are backup-target-eligible (not role-locked) — surfaced in the drive purpose note. 4B: handleStorageImpact returns backup_copies (apps whose cross-drive backups live on the drive, via backupCopiesOnPath); the wipe/eject modal warns they'd be destroyed (stays customer-confirmable — copies redundant). Cross-drive backup engine remains out of scope. Test: TestBackupCopiesOnPath. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>