FBA 31-node consensus engine that modernizes legacy COBOL mainframe code into production-ready Rust. Uses Federated Byzantine Agreement (arxiv:2507.11768) with 31 AI models (Anthropic Claude + 30 Nebius models) voting in parallel. Achieves 93%+ confidence with Bayesian-in-Realization guarantee. Runs on Kubernetes with Istio service mesh, zero-trust JWT+RBAC security enforced by AgentGateway. Each model performs k*=89 Chain-of-Thought reasoning steps.