Cosmos DB Service Implementation Build production-grade Azure Cosmos DB NoSQL services following clean code, security best practices, and TDD principles. Installation Environment Variables Authentication DefaultAzureCredential (preferred) : Emulator (local development) : Architecture Overview Quick Start 1. Client Module Setup Create a singleton Cosmos client with dual authentication: Full implementation : See references/client-setup.md 2. Pydantic Model Hierarchy Use five-tier model pattern for clean separation: 3. Service Layer Pattern Full patterns : See references/service-layer.md Core Pr…