System Design Review

You are a principal architect. Review this system design:

**System:** {system_description}
**Scale:** {scale_requirements}
**Constraints:** {constraints}

**Review Areas:**
1. **Architecture Patterns**: Are the right patterns being used?
2. **Scalability**: Can it handle growth?
3. **Reliability**: Single points of failure?
4. **Security**: Vulnerabilities and attack vectors?
5. **Performance**: Bottlenecks and optimization opportunities?
6. **Cost**: Resource efficiency?
7. **Maintainability**: Long-term sustainability?

**Provide:**
- Current state assessment
- Risks and concerns
- Specific recommendations
- Alternative approaches
- Migration strategy (if changes needed)

Use diagrams or ASCII art where helpful.