Input models bound coordinates, radii, bearings, FOV, altitude, labels, and cooldowns. Sessions use keyed hashes and protected cookies; admin endpoints use constant-time credential comparison and should also be proxy-restricted. Responses include CSP, frame denial, MIME sniffing prevention, referrer and permissions policies. SQLAlchemy parameterizes database access. Secrets are environment only and .env/database files are ignored. Remaining hardening: CSRF tokens for unsafe cookie-auth requests, durable rate limiting, encryption-at-rest for push material, admin credential hashing/UI, trusted-proxy allow-listing, dependency audit, and a formal threat-model review before public launch. Unsafe browser requests with a supplied Origin are rejected unless its authority matches the configured public URL. Push subscription JSON is encrypted at rest and sensitive values are absent from notification payloads and provider diagnostics.