Enterprise Policy-as-Code (EPAC) governance architecture on Azure uses GitHub and Azure DevOps to manage Azure Policy assignments across Sandbox and Production Management Groups with automated drift detection. Policy changes flow through a multi-stage pipeline: code commit triggers a plan-only phase, sandbox deployment with validation gates, and production approval before enforcement. Continuous drift detection via scheduled pipelines identifies unauthorized policy changes and automatically restores the desired state, while authorized drifts are tracked as pull requests for audit compliance. This architecture ensures policy consistency, reduces manual governance overhead, and maintains a single source of truth for Azure Policy definitions across your entire tenant.