What is sidenote?

sidenote lets you review your own markdown-based website the way you would review a document in Google Docs or Word, but with an AI coding agent doing the actual editing for you. Instead of switching back and forth between a browser tab showing your rendered page and a terminal window where you talk to an AI assistant, sidenote brings both into the same place. You look at your live site, select a passage of text you want changed, and leave a comment right there, and a local AI agent, either Claude or Codex, handles the rest. Once you leave a comment, it appears pinned in a sidebar next to your page. From there you have two options. You can ask a question about that passage, and the agent will answer directly in the comment thread without touching any files at all. Or you can resolve the comment into an actual change, in which case the agent edits the underlying markdown source and shows you a real git diff right there in the browser, which you can then accept or reject. If a passage's source text has changed since you left the comment, sidenote refuses to apply an outdated patch rather than risk editing the wrong thing. Importantly, sidenote describes itself as not an editor. You are only annotating your intent, and the markdown files remain the single source of truth, the AI agent is the one making changes, always as a reviewable diff rather than a silent edit. Setting it up requires Node.js 18 or newer, either the Claude or Codex command line tool installed and available on your system, and a site that renders its markdown through a tool called remark, such as a typical Next.js-powered blog. It is aimed at people who write and maintain content-heavy sites, like blog authors and documentation writers, who already use AI coding tools and want a faster way to request edits without leaving their browser.