Why Agent Event Streams Need Monotonic Ordering Before Real-Time Delivery

A software engineering article on DEV Community argues that real-time delivery alone does not ensure a correct event timeline for long-running agent tasks, as WebSocket reconnections, broker redeliveries, and worker race conditions can cause events to arrive out of order. The author proposes a design using strictly increasing sequence numbers per operation, assigned atomically alongside event writes, to detect duplicates, gaps, and stale events on the consumer side. Consumer logic should buffer out-of-order events briefly and request a replay when gaps are detected, while terminal states such as completed, failed, or cancelled must be locked against further non-audit transitions. Snapshots for client recovery must be generated from a consistent log position to prevent missed events between independent reads, and old progress events should only be compacted after a durable snapshot exists. The author discloses a contribution to the MonkeyCode project, which provided product context, but clarifies the protocol described is an independent reference design not attributed to that system.