lgtm

LGTM

A browser-based code review UI for collaborating with Claude Code. Claude registers a project, seeds inline comments on the diff, adds documents for review, and runs analysis to prioritize files. You review everything in the browser and submit feedback that Claude reads and acts on.

Install as a Claude Code plugin

The simplest way to use LGTM is as a Claude Code plugin. This gives you the /lgtm command, auto-starts the server, and connects MCP tools automatically.

In a Claude Code session, register the marketplace and install the plugin:

/plugin marketplace add tomplex/lgtm
/plugin install lgtm@tomplex-lgtm

Once installed, the server starts automatically when you open a Claude Code session (via a SessionStart hook). No manual MCP configuration needed - the plugin bundles its own .mcp.json. Just type /lgtm or ask Claude to review your changes.

Channels (real-time feedback)

For submitted reviews and direct questions to push back to Claude immediately (rather than requiring Claude to poll with read_feedback), start Claude Code with the development channels flag:

claude --dangerously-load-development-channels plugin:lgtm@tomplex-lgtm

Without this flag, everything still works - Claude just needs to call read_feedback to see your review comments.

What the plugin provides

• /lgtm command - registers the current project and opens the review UI
• /lgtm analyze skill - dispatches agents to classify files by priority and generate a review strategy
• /lgtm walkthrough skill - generates a narrated tour of the diff as ordered "stops" you step through in the UI
• /lgtm prepare skill - chains analyze + walkthrough so a review session opens fully primed
• MCP tools - Claude can claim reviews, post comments, add documents, set analysis and walkthroughs, read your feedback
• SessionStart hook - auto-starts the LGTM server on port 9900 if it isn't already running
• Sub-agents - file-classifier, synthesizer, and walkthrough-author agents power the analysis and walkthrough pipelines

Requirements

• Node.js 20+
• Claude Code CLI
• ripgrep on PATH — required for symbol lookup. Install with brew install ripgrep (macOS), apt install ripgrep (Debian/Ubuntu), or apk add ripgrep (Alpine). The server logs a prominent warning at startup if rg is missing, and symbol-lookup requests throw a clear error rather than returning empty results.

Node dependencies are installed automatically on first session start. No manual build step needed.

How it works

You're working with Claude on a feature branch. When you're ready for review (or want Claude to review its own work), Claude registers the project with LGTM and opens a browser tab. The diff viewer shows your branch changes with syntax highlighting, word-level change detection, and inline commenting.

Claude can seed comments on specific lines before you even start reading. You reply, resolve, or dismiss those comments inline. When you're done, you submit your review - Claude reads the structured feedback and can act on it in the same session.

The review loop is iterative. Claude addresses feedback, you refresh the diff, post more comments. Back and forth until it's right.

Analysis

Claude can also run an analysis pass that classifies every file in the diff by priority (critical / important / normal / low) and review phase (review / skim / rubber-stamp), then groups files thematically with a suggested review strategy. The sidebar switches between flat, grouped and phased views based on this analysis.

Walkthrough

For larger or more architectural changes, Claude can generate a narrated walkthrough — an ordered sequence of "stops" through the diff, each with a title, narrative, and references to the specific lines and files it covers. You step through it in the UI like a guided tour. Stops are tracked as visited, the sidebar shows stop-coverage badges per file, and you can still leave comments and use peek-definition while inside walkthrough mode.

Press W from the diff to enter walkthrough mode. Enter and Shift+Enter step forward and back; g followed by a digit jumps directly to a stop; d exits back to the diff.

Features

Diff review