Build a Reconnecting SSE Task Stream With Node.js

A long-running AI task needs to report more than “loading.” It may be queued, editing, testing, waiting for input, retrying, or complete.

For a learning project, Server-Sent Events (SSE) are a small way to study that state flow. The server sends UTF-8 events over one HTTP response, the client remembers an event ID, and a reconnect can continue after the last accepted event.

Important scope note: MonkeyCode uses WebSocket, not SSE, for the task streams I reviewed. Its mobile task-stream client includes reconnection, queued replies, and deduplication behavior. I used those reliability concerns as inspiration for this smaller SSE exercise, not as a description of MonkeyCode's transport.

Prerequisites

You need Node.js 20 or newer. There are no packages to install.