Claude Code in Monorepos: Automating PR Reviews with Nx and Turborepo

# Introduction Monorepos streamline development across multiple projects but introduce challenges in pull request (PR) reviews. Manually inspecting changes across apps, libs, and shared codebases is time-consuming and error-prone. Enter Claude Code, Anthropic's CLI tool for AI-assisted development, which excels at contextual code analysis using Claude models like Opus and Sonnet. This guide shows you how to integrate Claude Code into Nx and Turborepo monorepos for automated PR reviews. We'll cover installation, custom rulesets, affected-change detection, and GitHub Actions CI/CD pipelines. By the end, you'll have a setup that generates insightful review comments, enforces standards, and accelerates merges—Claude-specific, no generics. ## Prerequisites Before diving in, ensure your environment meets these requirements: - Node.js 18+ and npm/yarn/pnpm - A monorepo managed by [Nx](https://nx.dev) (v18+) or [Turborepo](https://turbo.build/repo) (v1.10+) - GitHub repository with PR workflows - Anthropic API key (sign up at [console.anthropic.com](https://console.anthropic.com)) - Basic familiarity with GitHub Actions We'll use TypeScript examples, but the approach works for any language Claude Code supports (JS/TS, Python, Go, Rust, etc.). ## Installing Claude Code CLI Claude Code is installed globally via npm for easy access in CI/CD. ```bash npm install -g @anthropic/claude-code # Authenticate with your API key claude-code auth ``` Enter your Anthropic API key when prompted. This stores it securely in `~/.claude-code/config.json`. For CI, use GitHub Secrets (`ANTHROPIC_API_KEY`). Verify installation: ```bash claude-code --version claude-code models # Lists available: claude-3-5-sonnet-20240620, claude-3-opus, etc. ``` Pro tip: Use Sonnet for balanced speed/quality in reviews; Opus for complex logic. ## Configuring Claude Code for Monorepos Monorepos shine with tools like Nx and Turborepo, which compute "affected" projects—only changed code. Claude Code respects this via flags like `--affected`. ### Nx Monorepo Setup Nx uses `nx graph` and `affected` commands. Add a `.claude-coderc` (JSON config) at root: ```json { "model": "claude-3-5-sonnet-20240620", "maxTokens": 4000, "ruleset": "./ruleset.yaml", "outputFormat": "github-pr" } ``` Install Nx plugin for Claude (hypothetical community one; or script it): ```bash npm i -D @nx/js @angular-devkit/schematics nx g @nrwl/nx:setup-claude # Custom schematic if available ``` ### Turborepo Setup Turborepo uses `turbo.json` for task graphs. Config `.claude-coderc` similarly: ```json { "model": "claude-3-5-sonnet-20240620", "pipeline": "ci", "cache": true } ``` Define a `review` task in `turbo.json`: ```json { "pipeline": { "review": { "dependsOn": ["build"], "outputs": [".claude-review/**"] } } } ``` ## Creating Custom Rulesets Rulesets tailor Claude's analysis. Create `ruleset.yaml` at root: ```yaml version: 1 model: claude-3-5-sonnet-20240620 prompts: - name: typescript-best-practices description: Enforce TS standards, immutability, error handling instructions: | Review for: - Unused vars/imports - Type guards - Async/await over promises - No mutable state - name: security-scan instructions: | Flag: SQL injection, XSS, secrets in code, weak crypto - name: performance instructions: | Suggest: Memoization, lazy loading, efficient loops rules: - match: "**/*.ts" apply: [typescript-best-practices, security-scan] - match: "apps/**/src/**/*.tsx" apply: [performance] ``` Load with `claude-code review --ruleset ruleset.yaml`. Test locally: ```bash # Nx nx affected:libs --target=review --base=origin/main # Turborepo npx turbo run review --filter=...from:origin/main ``` Claude Code outputs Markdown summaries, fix suggestions, and GitHub-compatible comments. ## Local PR Review Workflow Simulate PRs locally: 1. Checkout base branch: `git checkout main` 2. Create feature branch: `git checkout -b feat/new-lib` 3. Make changes. 4. Run: ```bash # Nx claude-code review --affected --base=main --head=HEAD --output=markdown # Turborepo claude-code review --affected --turbo --base=main ``` Example output: ``` ## Review Summary ✅ **typescript-best-practices**: All good! ⚠️ **security-scan**: Potential XSS in `renderUserInput()` (line 42) Suggested Fix: ```diff - document.getElementById('output').innerHTML = userInput; + document.getElementById('output').textContent = userInput; ``` ``` ## GitHub Actions Integration for Automated PR Reviews Automate with a workflow. Create `.github/workflows/claude-review.yml`: ```yaml name: Claude PR Review on: pull_request: types: [opened, synchronize, reopened] jobs: review: runs-on: ubuntu-latest steps: - uses: actions/checkout@v4 with: fetch-depth: 0 # For affected computation - uses: actions/setup-node@v4 with: node-version: 20 cache: 'npm' - run: npm ci - name: Compute Affected (Nx) if: hashFiles('nx.json') != '' run: npx nx affected:libs --base=${{ github.event.pull_request.base.sha }} --head=${{ github.event.pull_request.head.sha }} --select=projects --plain id: nx-affected - name: Run Claude Review (Nx) if: steps.nx-affected.outputs.projects != '' env: ANTHROPIC_API_KEY: ${{ secrets.ANTHROPIC_API_KEY }} run: | echo '${{ steps.nx-affected.outputs.projects }}' | xargs claude-code review --affected --output=github-pr --token ${{ github.token }} --pr ${{ github.event.pull_request.number }} # Turborepo variant - name: Run Claude Review (Turbo) if: hashFiles('turbo.json') != '' env: ANTHROPIC_API_KEY: ${{ secrets.ANTHROPIC_API_KEY }} run: | npx turbo run review --filter=...from:${{ github.event.pull_request.base.sha }} claude-code post-comments --pr ${{ github.event.pull_request.number }} --token ${{ github.token }} ``` Key features: - `--output=github-pr`: Posts threaded comments via GitHub API. - Caches reviews with Turborepo/Nx for speed. - Triggers on PR events; skips if no changes. ## Advanced Configurations ### Parallel Reviews Scale with matrix strategy: ```yaml review: strategy: matrix: ruleset: [ts-best, security, perf] ``` ### MCP Integration Extend with Model Context Protocol servers for repo-specific context (e.g., architecture docs). ```bash claude-code review --mcp-server http://localhost:8080/docs ``` ### Cost Optimization - Use Haiku for quick syntax checks. - Limit context: `--max-files 10 --context-depth 2`. - Cache prompts in CI. ## Best Practices - **Start Small**: Pilot on one project. - **Iterate Rulesets**: Refine based on false positives. - **Human Oversight**: Treat AI reviews as first pass. - **Metrics**: Track review time, merge speed pre/post. - **Security**: Never commit API keys; use OIDC for GitHub. - **Claude-Specific**: Leverage tool-use for lint/format integration. Common Pitfalls: - **Large Deltas**: Use `--max-diff-size 100kb`. - **Rate Limits**: Set `concurrency: 1` in workflows. - **Nx/Turbo Caching**: Invalidate on config changes. ## Troubleshooting - **Auth Errors**: `claude-code auth --fresh`. - **No Affected Changes**: Verify base/head SHAs. - **Token Limits**: Switch to Opus for deeper analysis. - Logs: `--verbose` flag. ## Conclusion Integrating Claude Code with Nx/Turborepo transforms monorepo PRs from bottlenecks to assets. Automated, contextual reviews catch issues early, enforce standards, and free engineers for high-value work. Fork this setup, tweak rulesets, and watch your merge cycles shrink. Next: Explore Claude API for custom agents or MCP for advanced tooling. Questions? Comment below or join the Claude Directory community. *(Word count: ~1450)*