# KB: Domain Router

The **Domain Router** is the traffic controller of the EbookBuilder ecosystem, responsible for directing requests to the correct agent or service based on the context of the task.

## Functions
- **Contextual Routing**: Analyzes incoming user prompts to determine if they need a "Creative Writer", an "API Wizard", or a "Technical Editor".
- **Multi-Tenant Support**: Maps custom subdomains (e.g., `user-1.ebookbuilder.com`) to specific Hugging Face Space instances.
- **Load Balancing**: Distributes heavy generation tasks across multiple backend model endpoints to maintain responsiveness.

## Architecture
- **Layer 7 Routing**: Operates at the application level to inspect headers and path parameters.
- **Failover Logic**: If a specific model provider is down, the router automatically switches to a fallback (e.g., switching from Vertex AI to Hugging Face Inference Endpoints).