lumen

lumen is an open-source command-line tool by jnsahaj, written in Rust, for reviewing git diffs in a terminal interface. It shows uncommitted changes, commits, branches, or GitHub pull requests side by side. Optional AI helpers generate commit messages, explain changes, and translate natural-language requests into git commands.

What It Is

lumen is a terminal diff viewer and code review TUI that ships as a single static Rust binary. It works with Git and Jujutsu (jj). The diff viewer uses tree-sitter syntax highlighting and runs without any AI configuration.

How the Review Workflow Works

Run lumen diff to view uncommitted changes, a specific commit, a branch range, or a GitHub PR by number or URL. Options let you filter to specific files, watch for file changes, soft-wrap long lines, jump to a file on open, and pick from preset themes. Stacked mode steps through a commit range one commit at a time, tracking viewed files per commit. For PRs, marking a file as viewed syncs with GitHub. Reviewers can annotate a selection, a hunk, or a whole file, then view, edit, copy, or export the annotations.

Optional AI Features

After configuring a provider with lumen configure, lumen draft writes a commit message for staged changes, lumen explain summarizes changes and can answer specific questions, and lumen operate turns a natural-language request into a git command, with a confirmation prompt before it runs. Supported providers include OpenAI, Claude, Gemini, Groq, DeepSeek, xAI, OpenCode Zen, Ollama (local), OpenRouter, and Vercel AI Gateway.

Use With Coding Agents

lumen can serve as the review surface for coding agents. After an agent finishes a turn, you run lumen diff through a shell escape, annotate the diff, and press s to write the formatted annotations to stdout. The agent receives them as its next prompt. The README lists Claude Code and Codex, plus any agent with shell access.

Setup Path

Install with Homebrew on macOS and Linux (brew install jnsahaj/lumen/lumen) or with cargo install lumen. Git is required. fzf and mdcat are optional. Configuration comes from CLI flags, a JSON config file, or environment variables.