Monorepo Navigator

Tier: POWERFUL
Category: Engineering
Domain: Monorepo Architecture / Build Systems

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Overview

Navigate, manage, and optimize monorepos. Covers Turborepo, Nx, pnpm workspaces, and Lerna. Enables cross-package impact analysis, selective builds/tests on affected packages only, remote caching, dependency graph visualization, and structured migrations from multi-repo to monorepo. Includes Claude Code configuration for workspace-aware development.

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Core Capabilities

• Cross-package impact analysis — determine which apps break when a shared package changes
• Selective commands — run tests/builds only for affected packages (not everything)
• Dependency graph — visualize package relationships as Mermaid diagrams
• Build optimization — remote caching, incremental builds, parallel execution
• Migration — step-by-step multi-repo → monorepo with zero history loss
• Publishing — changesets for versioning, pre-release channels, npm publish workflows
• Claude Code config — workspace-aware CLAUDE.md with per-package instructions

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When to Use

Use when:

• Multiple packages/apps share code (UI components, utils, types, API clients)
• Build times are slow because everything rebuilds when anything changes
• Migrating from multiple repos to a single repo
• Need to publish packages to npm with coordinated versioning
• Teams work across multiple packages and need unified tooling

Skip when:

• Single-app project with no shared packages
• Team/project boundaries are completely isolated (polyrepo is fine)
• Shared code is minimal and copy-paste overhead is acceptable

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Tool Selection

Tool	Best For	Key Feature
Turborepo	JS/TS monorepos, simple pipeline config	Best-in-class remote caching, minimal config
Nx	Large enterprises, plugin ecosystem	Project graph, code generation, affected commands
pnpm workspaces	Workspace protocol, disk efficiency	workspace:* for local package refs
Lerna	npm publishing, versioning	Batch publishing, conventional commits
Changesets	Modern versioning (preferred over Lerna)	Changelog generation, pre-release channels

Most modern setups: pnpm workspaces + Turborepo + Changesets

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Turborepo

→ See references/monorepo-tooling-reference.md for details

Common Pitfalls

Pitfall	Fix
Running turbo run build without --filter on every PR	Always use --filter=...[origin/main] in CI
workspace:* refs cause publish failures	Use pnpm changeset publish — it replaces workspace:* with real versions automatically
All packages rebuild when unrelated file changes	Tune inputs in turbo.json to exclude docs, config files from cache keys
Shared tsconfig causes one package to break all type-checks	Use extends properly — each package extends root but overrides rootDir / outDir
git history lost during migration	Use git filter-repo --to-subdirectory-filter before merging — never move files manually
Remote cache not working in CI	Check TURBO_TOKEN and TURBO_TEAM env vars; verify with turbo run build --summarize
CLAUDE.md too generic — Claude modifies wrong package	Add explicit "When working on X, only touch files in apps/X" rules per package CLAUDE.md

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Best Practices

1. Root CLAUDE.md defines the map — document every package, its purpose, and dependency rules
2. Per-package CLAUDE.md defines the rules — what's allowed, what's forbidden, testing commands
3. Always scope commands with --filter — running everything on every change defeats the purpose
4. Remote cache is not optional — without it, monorepo CI is slower than multi-repo CI
5. Changesets over manual versioning — never hand-edit package.json versions in a monorepo
6. Shared configs in root, extended in packages — tsconfig.base.json, .eslintrc.base.js, jest.base.config.js
7. Impact analysis before merging shared package changes — run affected check, communicate blast radius
8. Keep packages/types as pure TypeScript — no runtime code, no dependencies, fast to build and type-check