agents-inc/infra-monorepo-turborepo

Monorepo Orchestration with Turborepo

Quick Guide: Turborepo 2.x for monorepo orchestration. Task pipelines with dependency ordering. Local + remote caching for massive speed gains. Workspaces for package linking. Syncpack for dependency version consistency. Internal packages use @repo/* naming, explicit exports fields, and workspace:* protocol.

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<critical_requirements>

CRITICAL: Before Using This Skill

All code must follow project conventions in CLAUDE.md (kebab-case, named exports, import ordering, import type, named constants)

(You MUST define task dependencies using dependsOn: ["^build"] in turbo.json to ensure topological ordering)

(You MUST declare all environment variables in the env array of turbo.json tasks for proper cache invalidation)

(You MUST set cache: false for tasks with side effects like dev servers and code generation)

(You MUST use Bun workspaces protocol workspace:* for internal package dependencies)

(You MUST use @repo/* naming convention for ALL internal packages)

(You MUST define explicit exports field in package.json - never allow importing internal paths)

(You MUST mark React as peerDependencies NOT dependencies in component packages)

</critical_requirements>

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Auto-detection: Turborepo configuration, turbo.json, monorepo setup, workspaces, Bun workspaces, syncpack, task pipelines, @repo/* packages, package.json exports, workspace dependencies, shared configurations

When to use:

• Configuring Turborepo task pipeline and caching strategies
• Setting up workspaces for monorepo package linking
• Enabling remote caching for team/CI cache sharing
• Synchronizing dependency versions across workspace packages
• Creating new internal packages in packages/
• Configuring package.json exports for tree-shaking
• Setting up shared configuration packages (@repo/eslint-config, @repo/typescript-config)

When NOT to use:

• Single application projects (use standard build tools directly)
• Projects without shared packages (no monorepo benefits)
• Very small projects where setup overhead exceeds caching benefits
• Polyrepo architecture is preferred over monorepo
• Projects already using Nx or Lerna (don't mix monorepo tools)
• App-specific code that won't be shared (keep in app directory)

Key patterns covered:

• Turborepo 2.x task pipeline (dependsOn, outputs, inputs, cache)
• Local and remote caching strategies
• Bun workspaces for package linking
• Syncpack for dependency version consistency
• Environment variable handling in turbo.json
• Package structure and @repo/* naming conventions
• package.json exports for tree-shaking
• Named exports and barrel file patterns
• Internal dependencies with workspace protocol

Detailed Resources:

• For code examples, see examples/core.md (always start here)
  • examples/caching.md - Remote caching, CI/CD integration
  • examples/workspaces.md - Workspace protocol, syncpack, dependency boundaries
  • examples/packages.md - Internal package conventions, exports, creating packages
• For decision frameworks and anti-patterns, see reference.md

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<philosophy>

Philosophy

Turborepo is a high-performance build system designed for JavaScript/TypeScript monorepos. It provides intelligent task scheduling, caching, and remote cache sharing to dramatically reduce build times. Combined with Bun workspaces, it enables efficient package management with automatic dependency linking.

When to use Turborepo:

• Managing monorepos with multiple apps and shared packages
• Teams need to share build cache across developers and CI
• Build times are slow and need optimization through caching
• Projects with complex task dependencies requiring topological ordering

When NOT to use Turborepo:

• Single application projects (use standard build tools)
• Projects without shared packages (no monorepo needed)
• Very small projects where setup overhead exceeds benefits
• Polyrepo architecture is preferred over monorepo

</philosophy>

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<patterns>

Core Patterns

Pattern 1: Turborepo Task Pipeline with Dependency Ordering

Define task dependencies and caching behavior in turbo.json to enable intelligent build orchestration and caching.

Key Concepts

• dependsOn: ["^build"] - Run dependency tasks first (topological order)
• outputs - Define what files to cache
• inputs - Specify which files trigger cache invalidation
• cache: false - Disable caching for tasks with side effects
• persistent: true - Keep dev servers running

Configuration

// Good Example - Proper task configuration with dependencies
{
  "tasks": {
    "build": {
      "dependsOn": ["^build"],
      "env": ["DATABASE_URL", "NODE_ENV"],
      "outputs": ["dist/**", ".next/**", "!.next/cache/**"]
    },
    "test": {
      "dependsOn": ["^build"],
      "inputs": [
        "$TURBO_DEFAULT$",
        "src/**/*.tsx",
        "src/**/*.ts",
        "test/**/*.ts",
        "test/**/*.tsx"
      ]
    },
    "dev": {
      "cache": false,
      "persistent": true
    },
    "generate": {
      "dependsOn": ["^generate"],
      "cache": false
    },
    "lint": {}
  }
}

Why good: dependsOn: ["^build"] ensures topological task execution (dependencies build first), env array includes all environment variables for proper cache invalidation, cache: false prevents caching tasks with side effects (dev servers, code generation), outputs specifies cacheable artifacts while excluding cache directories

See examples/core.md for good/bad comparison examples.

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Pattern 2: Caching Strategies

Turborepo's caching system dramatically speeds up builds by reusing previous task outputs when inputs haven't changed.

What Gets Cached

• Build outputs (dist/, .next/)
• Test results (when cache: true)
• Lint results

What Doesn't Get Cached

• Dev servers (cache: false)
• Code generation (cache: false - generates files)
• Tasks with side effects

Cache Invalidation Triggers

• Source file changes
• Dependency changes
• Environment variable changes (when in env array)
• Global dependencies changes (.env, tsconfig.json)

Setup: Link Vercel account, set TURBO_TOKEN and TURBO_TEAM environment variables to enable remote cache sharing.

See examples/caching.md for remote caching configuration and CI integration examples.

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Pattern 3: Bun Workspaces for Package Management

Configure Bun workspaces to enable package linking and dependency sharing across monorepo packages.

Workspace Configuration

// Good Example - Properly configured workspaces
{
  "workspaces": ["apps/*", "packages/*"],
  "dependencies": {
    "@repo/ui": "workspace:*",
    "@repo/types": "workspace:*"
  }
}

Why good: workspace:* protocol links local packages automatically, glob patterns apps/* and packages/* discover all packages dynamically, Bun hoists common dependencies to root reducing duplication

Directory Structure

my-monorepo/
├── apps/
│   ├── web/              # Frontend application
│   ├── admin/            # Admin dashboard
│   └── server/           # Backend server
├── packages/
│   ├── ui/               # Shared UI components
│   ├── api/              # API client
│   ├── eslint-config/    # Shared ESLint config
│   ├── prettier-config/  # Shared Prettier config
│   └── typescript-config/ # Shared TypeScript config
├── turbo.json            # Turborepo configuration
└── package.json          # Root package.json with workspaces

See examples/workspaces.md for workspace protocol good/bad comparison examples.

</patterns>

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<performance>

Performance Optimization

Cache Hit Metrics:

• First build: ~45s (5 packages, no cache)
• Cached build: ~1s (97% faster with local cache)
• Affected build: ~12s (73% faster, only changed packages rebuild)
• Team savings: Hours per week with remote cache enabled

Optimization Strategies:

• Set globalDependencies for files affecting all packages (.env, tsconfig.json) to prevent unnecessary cache invalidation
• Use inputs array to fine-tune what triggers cache invalidation for specific tasks
• Enable remote caching to share artifacts across team and CI
• Use --filter with affected detection (--filter=...[HEAD^]) to only run tasks for changed packages
• Set outputs carefully to exclude cache directories (e.g., !.next/cache/**)

Force Cache Bypass:

# Ignore cache when needed
bun run build --force

# Only build affected packages
bun run build --filter=...[HEAD^1]

</performance>

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<decision_framework>

Decision Framework

When to Create a New Package

New code to write?
├─ Is it a deployable application? → apps/
├─ Is it shared across 2+ apps? → packages/
├─ Is it app-specific? → Keep in app directory
└─ Is it a build tool? → tools/

When to Use Turborepo

Is this a monorepo with multiple packages/apps?
├─ NO → Use standard build tools
└─ YES → Do builds take > 30s or is caching important?
    ├─ YES → Use Turborepo
    └─ NO → Standard tools may suffice

For comprehensive decision trees and package creation criteria, see reference.md.

</decision_framework>

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<red_flags>

RED FLAGS

High Priority Issues:

• Missing dependsOn: ["^build"] for build tasks (breaks topological ordering)
• Missing env array in turbo.json (causes cache misses across environments)
• Caching dev servers or code generation (incorrect outputs reused)
• Default exports in library packages (breaks tree-shaking)
• Missing exports field in package.json (allows internal path imports)

Common Mistakes:

• Hardcoded versions instead of workspace:* for internal deps
• React in dependencies instead of peerDependencies
• Giant barrel files re-exporting everything (negates tree-shaking)
• Running full test suite without --filter=...[HEAD^] affected detection

Gotchas:

• dependsOn: ["^task"] runs dependencies' tasks; dependsOn: ["task"] runs same package's task
• --filter=...[HEAD^] requires fetch-depth: 2 in GitHub Actions
• Exclude cache directories in outputs: !.next/cache/**

For detailed anti-patterns and checklists, see reference.md.

</red_flags>

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<critical_reminders>

CRITICAL REMINDERS

All code must follow project conventions in CLAUDE.md

(You MUST define task dependencies using dependsOn: ["^build"] in turbo.json to ensure topological ordering)

(You MUST declare all environment variables in the env array of turbo.json tasks for proper cache invalidation)

(You MUST set cache: false for tasks with side effects like dev servers and code generation)

(You MUST use Bun workspaces protocol workspace:* for internal package dependencies)

(You MUST use @repo/* naming convention for ALL internal packages)

(You MUST define explicit exports field in package.json - never allow importing internal paths)

(You MUST mark React as peerDependencies NOT dependencies in component packages)

Failure to follow these rules will cause incorrect builds, cache misses, broken dependency resolution, and tree-shaking failures.

</critical_reminders>