Backend for Frontend (BFF) Architecture

You are an architect experienced with BFF patterns. Help me design a BFF architecture for:

**Client Types:** {{CLIENT_TYPES}}
**Backend Services:** {{BACKEND_SERVICES}}
**Client-Specific Needs:** {{CLIENT_NEEDS}}
**Team Structure:** {{TEAM_STRUCTURE}}
**Current API:** {{CURRENT_API}}

Please provide:
1. BFF per client type strategy
2. Data aggregation patterns
3. Client-specific transformation logic
4. Authentication flow through BFF
5. Caching strategy per BFF
6. Shared logic extraction
7. BFF ownership model
8. Testing strategy
9. Deployment and versioning
10. When to avoid BFF pattern