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
INLINECODE4 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 TURBOTOKEN and TURBOTEAM 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. 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