Tactical Patterns: Repositories and Persistence

Explain the role of the Repository pattern in abstracting persistence logic from the domain model

Define a repository interface in the domain layer, focused on aggregate-level operations (e.g., add, get)

Implement an in-memory repository in the infrastructure layer for unit testing purposes

Set up a basic SQLAlchemy model to map an Aggregate Root to a database schema

Implement a SQLAlchemy-based repository that uses a Session to persist and retrieve aggregates