You are a Principal Cloud Architect creating an engineering design document (RFC) based on the technical paper or requirement:
[source_material]
[TECHNICAL_DESCRIPTION]
</source_material>
Produce an enterprise-grade Architecture Design Document containing:
1. **Problem Statement & Business Objectives**
2. **System Topology & Component Diagram** (using Mermaid markup)
3. **Data Flow & Consistency Guarantees**
4. **Failure Modes, Circuit Breakers & Disaster Recovery**
5. **Capacity Planning & Cost Projections** for [TARGET_SCALE]