Replace KeyFromEnv with AgentKeyFromEnv/AdminKeyFromEnv reading EMCLI_KEY and EMCLI_ADMIN_KEY; add NewDEK for envelope encryption. Seal/Open double as DEK wrap/unwrap. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>