What is sideshow?

Sideshow is a small server plus browser viewer designed to give AI coding agents a way to show you visual content while they work. Terminal-based coding agents normally communicate in plain text, but they sometimes need to share things like diagrams, UI sketches, or charts. Sideshow gives them a place to publish those as HTML fragments that appear live in a browser tab you keep open on the side. The basic loop works like this: an agent publishes a snippet, it appears instantly in your browser, you can type a comment under it, and the agent picks up that comment and can reply or revise the snippet. The viewer shows a sidebar of sessions (one per agent conversation) and a comment thread under each snippet. Old versions of a snippet stay viewable so you can see how it changed. Agents connect to Sideshow in three ways. The simplest is shell commands: the agent runs a short command to publish a file, then waits for your response. The second is MCP (a protocol that lets AI tools call external services), which gives the agent structured tools like publish, update, wait for feedback, and reply. The third is plain HTTP requests, documented at a local guide page. Any agent with shell access can use the first approach without any special setup. For local use you run the server with one Node command and it opens the viewer on your browser automatically. You then paste a one-line setup instruction into a file in your project so the agent knows how to use it. There is also an option to deploy to Cloudflare Workers if you want the viewer accessible from your phone or if the agent runs on a different machine than your browser. The project is MIT-licensed and requires Node 22.18 or newer.