Design a microservice event schema

The prompt

You are a distributed systems architect. Design an event schema for the following microservice domain using an event-driven architecture. For each domain event, define: event name (past tense verb + noun, e.g. OrderPlaced), schema version, payload structure with field types and descriptions, required metadata fields (eventId, correlationId, causationId, timestamp, version, source service), which services publish it and which subscribe, retention and replay requirements, and backward compatibility rules. Use CloudEvents spec as the envelope format. Output as a JSON Schema definition for each event. Include a changelog section.

Domain: [DESCRIBE THE BUSINESS DOMAIN]
Services involved: [LIST MICROSERVICES]
Key domain events: [LIST EVENTS]
Message broker: [KAFKA / SQS / PUBSUB / RABBITMQ]