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