monorepo

Monorepo

Project-specific patterns for pnpm workspaces + Turborepo.

Architecture Decisions

Workspace Organization

1. Split apps from packages — apps/ for deployables, packages/ for shared libraries.
2. Namespace packages — Prefix with @org/ to avoid npm conflicts.
3. Single lockfile — pnpm-lock.yaml at root only. Never commit multiple lockfiles.
4. No cross-package file access — Never use ../ to reach into other packages; import via dependencies.

Dependency Management

1. Use workspace:* protocol — Always for internal package dependencies.
2. Hoist common devDependencies — Shared tooling (TypeScript, ESLint) in root.
3. Peer dependencies for frameworks — React, Vue, etc. as peers to avoid version conflicts.
4. Consider Catalogs (pnpm 9.5+) — Centralize versions in pnpm-workspace.yaml for large repos.

Turborepo Tasks

1. Use ^ for build dependencies — "dependsOn": ["^build"] for topological order.
2. Always define outputs — Without outputs, nothing gets cached.
3. Mark dev servers as persistent — "persistent": true, "cache": false.
4. Be explicit about environment — List all build-affecting vars in env or globalEnv.

Gotchas

• Missing outputs in turbo.json silently disables caching for that task. The task runs every time and you won't get an error — just slow builds. Always verify outputs are configured.
• pnpm install does NOT respect --filter for installation — it always installs the entire workspace. Filtering only works for pnpm run and pnpm exec.
• workspace:* resolves to the CURRENT version of the local package, not "latest from npm". If the package has "version": "0.0.0", published packages will have "dependency": "0.0.0" — set meaningful versions before publishing.
• Turborepo's env field in turbo.json uses GLOB patterns, not exact matches. "env": ["API_*"] captures API_KEY, API_URL, etc. Forgetting this causes over-invalidation.
• turbo run build --filter=app-a builds app-a AND all its workspace dependencies. If a dependency fails, app-a won't build. Check transitive deps.
• Adding a package to packages/ requires running pnpm install before the workspace recognizes it. The new package also needs a valid package.json with name matching the workspace pattern.
• TypeScript project references (references in tsconfig.json) must match the workspace dependency graph. Mismatches cause type errors that only appear during tsc --build, not in IDE.
• turbo.json's globalDependencies invalidates ALL tasks when listed files change. Don't put frequently-changed files here — use task-level inputs instead.
• Shared Tailwind configs need @source directives pointing to consuming packages' source directories, otherwise classes used in shared packages are purged.
• pnpm deploy (for production) copies a single package and its dependencies to a target directory. It does NOT run build scripts — build first, then deploy.
• Remote cache (Vercel or self-hosted) requires outputs to be correct. If outputs are wrong, cached artifacts will be incomplete and downstream tasks break silently.
• persistent: true tasks prevent turbo run from exiting. Don't include persistent tasks in CI pipelines unless they have a timeout.