monorepo-navigator

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

Workspace Analyzer

python3 scripts/monorepo_analyzer.py /path/to/monorepo
python3 scripts/monorepo_analyzer.py /path/to/monorepo --json

Also see references/monorepo-patterns.md for common architecture and CI patterns.

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