activation webhooks), custom webhook delivery engine, and the event routing that connects domain events to external system notifications. Architecture decisions: Service boundaries, event contracts (Kafka), data model evolution (Prisma/PostgreSQL), API design for both public and private endpoints, and the migration strategy from the legacy Next.js monolith … monorepo with 7 microservices (CRM, Billing, Payments, Ledger, Communications, Provisioning, Integrations) TypeScript end‐to‐end PostgreSQL with Prisma ORM (shared database, service‐scoped access) Kafka message bus (migrating from RabbitMQ) for inter‐service communication (send/emit patterns) Redis for caching, queues, rate limiting, and idempotency REST API gateway ...