Show HN: R3 – A Local Code Review Tool for You and Your AI Agent

R3, a local code review tool for AI agents, launched on Hacker News. It enables developers to leave line-specific feedback on agent-generated diffs and documents, tracking comments to resolution outside of chat interfaces. The tool runs fully locally with a web UI and is designed to streamline the review loop between humans and coding agents.

r3 is a review tool for the diffs and docs produced by your coding agents, running locally with a web interface. You leave feedback pinned to the exact line or quote it's about, and track each comment to resolution. r3 fills a gap the chat box can't. Say your agent writes a long planning doc and you want to fix a handful of things. In a chat you copy-paste each passage to quote it, type your feedback, then lose track across turns of what's been handled. Instead of working in a linear, unstructured chat stream, r3 works like the code review tools you're used to, but just for you and your agents, and it runs fully locally. r3-demo-web.mp4 The point of r3 is a tight, copy-paste-free review loop between you and an agent. sequenceDiagram participant A as Agent participant S as r3 server participant U as You browser A- S: 1 r3 create — opens a review, shares the URL loop until you Approve or Abandon A- S: 2 r3 watch blocks for feedback U- S: 3 leave feedback + Submit S-- A: r3 watch prints your feedback to stdout and exits A- S: 4 r3 reply by feedback id S-- U: 5 web UI updates live end - The agent starts a review with and shares the URL. r3 create - The agent runs , which registers as a live watcher and waits for feedback. r3 watch <id - You leave feedback anchored to the exact lines it's about, then click Submit . watch prints your feedback to stdout that's captured by the agent. - The agent works each item and replies by feedback id r3 reply <fid -m "what I changed" , saying what it changed, or the reasoning for why it didn't. - Every reply lands on the web UI through live updates. The agent watch es again until you Approve or Abandon the review. r3 is driven by your coding agent, so the quickest start is to point your agent at it. Drop this into your agent's instructions file AGENTS.md , CLAUDE.md , or your tool's equivalent , or just try it out by pasting it into a new session: This project uses r3 for review. Run it with whichever of these you have: npx @hyperlogue/r3@latest , bunx @hyperlogue/r3@latest , or nix run github:hyperlogue/r3 -- . r3 guide will show how to use it. Then just ask: "put your changes up for review." Your agent runs npx @hyperlogue/r3@latest create … , shares the URL, and waits while you leave feedback in the browser. The launcher lazily starts the web server on localhost and opens the review. One web server spans all your repos on a stable port default 8791 . The first call spawns it automatically, so there's nothing to start by hand; r3 start | stop | status | restart manage it explicitly. Open http://127.0.0.1:8791/ http://127.0.0.1:8791/ to see every project's reviews in one tab. No config needed: reviews live in one global sqlite at $XDG STATE HOME/r3/r3.sqlite keyed by a projects registry so worktrees of one clone are one project and copies stay separate , and the web server announces itself in $XDG RUNTIME DIR/r3/daemon.json so the CLI finds it with zero config. Run the CLI from any git repo, and it tells the web server which project/worktree the call targets. You rarely type the commands yourself — you ask your agent, and it runs the right r3 create : "Put your working changes up for review." → diff review of the working tree "Open a review of the plan doc so I can comment on it." → files review of that file, watched live as the agent keeps editing "Let me review the diff between main and this branch." → diff review of the range "Start a review with a scratch folder and put your draft design doc there." → adhoc scratch review with no git source To install r3 permanently — a persistent command instead of npx / bunx each time — add -g : npm install -g @hyperlogue/r3 or: bun add -g @hyperlogue/r3 Then run r3 … from anywhere. Every review is one of two kinds: - A files review is a live view of a set of files as they are right now. r3 watches them and re-renders on every change, so it fits work in progress: a design doc your agent is still writing, or a few source files you want to read together. - A diff review is a frozen record of a change: a commit, a branch range, your working tree, or any diff. It doesn't move once captured, and follow-up work lands as new rounds you can compare against. Feedback anchors to a quote , not a line number: in a files review your notes follow the code as it's edited; in a diff review the rounds are immutable, so nothing drifts. If you work on a remote dev server, r3 listens on loopback there, and you reach its web UI from your local device through a tunnel. Set one up however you like: an SSH forward ssh -L 8791:localhost:8791 devbox , tailscale serve , or a Cloudflare tunnel. Never bind 0.0.0.0 . Env: R3 PORT default 8791 , R3 BIND default 127.0.0.1 , R3 ALLOWED HOSTS comma-separated exact Host names, never , R3 PUBLIC URL .