Microsoft has built a multi-agent AI system to proactively evaluate and harden its cloud infrastructure, matching the speed, scale, depth, and quality needed for its hyper-scale production environments. This system is part of Microsoft's Secure Future Initiative (SFI), which guides security requirements for a well-defended cloud service. The system evaluates live services against these requirements continuously, incorporating code-level vulnerabilities, configuration, identity, network, and runtime context to assess overall service security posture. It employs a multi-tier agent hierarchy: orchestration agents for workflow management, analysis agents grounded in Microsoft’s threat intelligence, and evidence-gathering agents that investigate across code repositories, infrastructure definitions, identity configurations, runtime settings, network topologies, and live resource states. The system can surface composite vulnerabilities that no single-component review would find, such as a combination of a permissive service-to-service trust relationship, a token scope granting broader access, and a deployment configuration exposing an internal API. This internal capability is not available as a customer-facing product or service, but insights will inform product improvements over time.