• TLS on all traffic; HTTP redirects to HTTPS; certificates auto-renew
• Encryption at rest for stored content and indexes
• Per-tenant key derivation. Cross-tenant access is not a check that could be wrong; it is a different key and a different physical path
• In a real deployment the root secret belongs in a key management service or HSM, never in the application. We say that here because the shortcut is common and invisible from outside

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