Design a Data Model and APIs for an Application

Given written requirements in a shared doc, design the data model, APIs and frontend flow for the application.

Asked in the Technical design stage. Treat the shared document as the source of truth and clarify ambiguities before proposing the design. Explain how any ML retrieval, ranking, inference, feedback, and monitoring components fit into the application without assuming undocumented product details.

Address:

1. Core entities, relationships, ownership, and data lifecycle.
2. API contracts, authorization, validation, pagination, and errors.
3. Frontend states, request flow, loading, retries, and degraded behavior.
4. Online versus batch processing and model-serving boundaries.
5. Logging, evaluation, drift detection, and training-serving consistency.
6. Capacity, latency, availability, and key tradeoffs.

Do not invent requirements absent from the shared document; state assumptions explicitly.