Authors should be able to publish a blog post and have it show up in their followers’ feeds shortly after. The create-post operation must be fast and should not wait on fan-out. After the post is saved, emit an event with postId and authorId to Kafka so a downstream service can insert the post into each follower’s feed in a time-ordered DynamoDB store (partition by userId, sort by timestamp). Build the write path only: a Spring Boot GraphQL mutation that persists the post and reliably publishes the Kafka message.