Customer.io Reference Architecture Overview Enterprise-grade reference architecture for Customer.io: a service layer separating Track and App API concerns, event-driven processing with message queues, repository pattern for user-to-CIO sync, webhook event bus, and infrastructure as code. Architecture Principles 1. Two Clients, Two Concerns — for behavioral data in, for messages out 2. Event-Driven — Message queues decouple your app from Customer.io API availability 3. Idempotent Operations — All writes safely retryable via content hashing 4. Service Layer — Business logic never calls Customer…