Simulated e-commerce store used as a live-coding demo during the talk. Sells graphic nerdy t-shirts for work-from-home software engineers. An AI assistant built on langchainrb orchestrates business logic across six tools: customer management, email service, inventory management, order management, payment gateway, and shipping service. Backed by a SQLite database with products, orders, order_items, and customers tables (Active Record-like models). Each tool inherits from Langchain::Tool::Base and is paired with a JSON file describing its functions in the OpenAPI/Swagger spec, which langchainrb ships to the LLM for function calling. Standard operating procedures (create customer if not exists, check inventory, calculate total, charge customer, create order, create shipping label, send email) live in the system prompt. The demo runs order placement, returns, and inventory updates end-to-end against GPT-4 Turbo. Available as a GitHub repo linked from a QR code.