Inventory Management API

Build the database layer for an inventory management system using SQLAlchemy and PostgreSQL.

Domain

• Category: name, slug (unique)
• Product: name, SKU (unique), price_cents, belongs to a category
• StockMovement: quantity_change (integer, positive for additions, negative for removals), reason (string), created_at, belongs to a product

Requirements

Produce Python files in a src/ directory:

• src/database.py -- engine configuration, session factory, Base class, and session dependency
• src/models.py -- Category, Product, and StockMovement ORM models with relationships
• src/crud.py -- functions for:
  • add_product(db, name, sku, price_cents, category_id) -- add a product, handle duplicate SKU gracefully
  • record_stock_movement(db, product_id, quantity_change, reason) -- record inventory change
  • get_product_detail(db, product_id) -- return product with its category and recent stock movements

No test files, no migration files, no API framework code.