## Scenario Design a small backend service that manages a core entity with **CRUD** operations and also supports an **asynchronous background job** triggered by user actions. To make the problem concrete, assume the core entity is a **Document** that a user can create/update/delete and optionally request an **Export** (a long-running job that generates a downloadable file). ## Requirements ### Functional 1. **CRUD Documents** - Create a document (title + body) - Read/list documents (filter by owner) - Update a document - Delete a document 2. **Async Export Job** - User requests an export for a document. - Export runs asynchronously (may take minutes). - User can query job status. - When done, user can fetch a download URL (or a reference to the exported file). ### Non-functional - Multi-tenant: documents belong to a user/account. - Avoid duplicated exports when users retry the request. - System should be resilient to worker crashes and support retries. ## Deliverables 1. Propose a relational schema (tables, key fields, indexes). 2. Define REST APIs (endpoints, request/response, status codes). 3. Describe the async job workflow (queue, worker, retries, idempotency). 4. Call out important edge cases and operational considerations.