V3 DDD Architecture

Identify the distinct responsibilities inside the god object, such as task management, session handling, and health monitoring, then extract each into its own domain with entities, value objects, services, and repositories. Wire them together through domain events rather than direct calls.

A microkernel architecture uses a small core kernel that loads and manages domain modules at runtime, exposing them through a registry. Plugins declare dependencies on core domains and register additional services, enabling optional features like swarm coordination without modifying the kernel.

Domain events let one context publish facts, such as TaskCompletedEvent, without knowing its consumers. Handlers in other contexts subscribe via an event bus and react independently, keeping domains isolated and testable.

DDD adds structural overhead, so it is a poor fit for small codebases, simple CRUD applications, or prototypes with few business rules. It pays off mainly when domain logic is complex and multiple teams or modules must evolve independently.

Test entities and services in isolation using mocks for collaborators, verifying state changes and emitted domain events. Because the domain layer has no external dependencies, these unit tests run fast and target high coverage of business rules.