Trifecta Checker - AI Safety Gate that blocks Lethal Trifecta (Private Data + Untrusted Content + Exfiltration) with 403 block. Live on Vercel with console tests (403/200). Extending to Vultr's Blast Radius Zero challenge: containment-first execution inside Vultr sandbox VM. SDKs: Python + JS. Demo: trifecta-checker.vercel.app GitHub: github.com/altima261/trifecta-checker