Nx Monorepo Agent Skill

Nx Monorepo

Overview

Provides guidance for Nx monorepo management in TypeScript/JavaScript projects. Covers workspace creation, project generation, task execution, caching strategies, Module Federation, and CI/CD integration.

When to Use

Use this skill when:

• Creating a new Nx workspace or initializing Nx in an existing project
• Generating applications, libraries, or components with Nx generators
• Running affected commands or executing tasks across multiple projects
• Setting up CI/CD pipelines for Nx projects (GitHub Actions, CircleCI, etc.)
• Configuring Module Federation with React or Next.js
• Implementing NestJS backend applications within Nx
• Managing TypeScript package libraries with buildable and publishable libs
• Setting up remote caching or Nx Cloud
• Optimizing monorepo build times and caching strategies
• Debugging dependency graph issues or circular dependencies

Trigger phrases: "create Nx workspace", "Nx monorepo", "generate Nx app", "Nx affected", "Nx CI/CD", "Module Federation Nx", "Nx Cloud"

Instructions

Workspace Creation

• Create a new workspace with interactive setup:

   npx create-nx-workspace@latest

Follow prompts to select preset (Integrated, Standalone, Package-based) and framework stack.

• Initialize Nx in an existing project:

   nx@latest init

• Create with specific preset (non-interactive):

   npx create-nx-workspace@latest my-workspace --preset=react

Verify: nx show projects lists the new workspace projects

Project Generation

• Generate a React application:

   nx g @nx/react:app my-app

• Generate a library:

   # React library
   nx g @nx/react:lib my-lib

   # TypeScript library
   nx g @nx/js:lib my-util

Verify: nx show projects lists the new lib

• Generate a component in lib:

   nx g @nx/react:component my-comp --project=my-lib

• Generate NestJS backend:

   nx g @nx/nest:app my-api

Verify: nx show projects lists my-api and nx run my-api:build succeeds

Task Execution

• Run tasks for affected projects only:

   nx affected -t lint test build

• Run tasks across all projects:

   # Build all projects
   nx run-many -t build

   # Test specific projects
   nx run-many -t test -p=my-app,my-lib

   # Test by pattern
   nx run-many -t test --projects=*-app

• Run specific target on single project:

   nx run my-app:build

• Visualize dependency graph:

   nx graph

Project Configuration

Each project has a project.json defining targets, executor, and configurations:

{
  "name": "my-app",
  "projectType": "application",
  "sourceRoot": "apps/my-app/src",
  "targets": {
    "build": {
      "executor": "@nx/react:webpack",
      "outputs": ["{workspaceRoot}/dist/apps/my-app"],
      "configurations": {
        "production": {
          "optimization": true
        }
      }
    },
    "test": {
      "executor": "@nx/vite:test"
    }
  },
  "tags": ["type:app", "scope:frontend"]
}

Dependency Management

• Set up project dependencies:

   {
     "targets": {
       "build": {
         "dependsOn": [
           { "projects": ["shared-ui"], "target": "build" }
         ]
       }
     }
   }

• Use tags for organization:

   { "tags": ["type:ui", "scope:frontend", "platform:web"] }

Module Federation (Nx 17+)

• Generate a remote (micro-frontend):

   nx g @nx/react:remote checkout --host=dashboard

• Generate a host:

   nx g @nx/react:host dashboard

CI/CD Setup

Use affected commands in CI to only build/test changed projects:

# .github/workflows/ci.yml
- run: npx nx affected -t lint --parallel
- run: npx nx affected -t test --parallel
- run: npx nx affected -t build --parallel

Examples

Example 1: Create New React Workspace

Input: "Create a new Nx workspace with React and TypeScript"

Steps:

npx create-nx-workspace@latest my-workspace
# Select: Integrated Monorepo → React → Integrated monorepo (Nx Cloud)

Verify: cd my-workspace && nx show projects lists the created app

Expected Result: Workspace created with:

• apps/ directory with React app
• libs/ directory for shared libraries
• nx.json with cache configuration
• CI/CD workflow files ready

Example 2: Run Tests for Changed Projects

Input: "Run tests only for projects affected by recent changes"

Command:

nx affected -t test --base=main~1 --head=main

Expected Result: Only tests for projects affected by changes between commits are executed, leveraging cached results from previous runs.

Example 3: Generate and Build a Shared Library

Input: "Create a shared UI library and use it in the app"

Steps:

# Generate library
nx g @nx/react:lib shared-ui

# Generate component in library
nx g @nx/react:component button --project=shared-ui

# Import in app (tsconfig paths auto-configured)
import { Button } from '@my-workspace/shared-ui'

Verify: nx run shared-ui:build completes successfully and nx graph shows the dependency link to your app

Expected Result: Buildable library at libs/shared-ui with proper TypeScript path mapping configured.

Example 4: Set Up Module Federation

Input: "Configure Module Federation for micro-frontends"

Steps:

# Create host app
nx g @nx/react:host dashboard

# Add remote to host
nx g @nx/react:remote product-catalog --host=dashboard

# Start dev servers
nx run dashboard:serve
nx run product-catalog:serve

Verify: Both servers start without errors and nx graph shows dashboard → product-catalog remote connection

Expected Result: Two separate applications running where product-catalog loads dynamically into dashboard at runtime.

Example 5: Debug Build Dependencies

Input: "Why is my app rebuilding when unrelated lib changes?"

Diagnosis:

# Show project graph
nx graph --focused=my-app

# Check implicit dependencies
nx show project my-app --json | grep implicitDependencies

Solution: Add explicit dependency configuration or use namedInputs in nx.json to exclude certain files from triggering builds.

Verify Fix Worked: Make a change to the unrelated lib, run nx affected -t build — my-app should not appear in the affected projects list.

Best Practices

• Always use nx affected in CI to only test/build changed projects
• Organize libs by domain/business capability, not by technical layer
• Use tags consistently (type:app|lib, scope:frontend|backend|shared)
• Prevent circular dependencies by configuring workspaceLayout boundaries in nx.json
• Enable remote caching with Nx Cloud for team productivity
• Keep project.json simple - use defaults from nx.json when possible
• Leverage generators instead of manual file creation for consistency
• Configure namedInputs to exclude test files from production cache keys
• Use Module Federation for independent deployment of micro-frontends
• Keep workspace generators in tools/ for project-specific scaffolding

Constraints and Warnings

• Node.js 18.10+ is required for Nx 17+
• Windows users: Use WSL or Git Bash for best experience
• First-time setup may take longer due to package installation
• Large monorepos (50+ projects) should use distributed task execution
• Module Federation requires webpack 5+ and specific Nx configuration
• Some generators require additional plugins to be installed first
• Cache location: Default ~/.nx/cache can grow large; configure cacheDirectory in nx.json if needed
• Circular dependencies will cause build failures; use nx graph to visualize
• Preset migration: Converting between Integrated/Standalone/Package-based requires manual effort

Reference Files

For detailed guidance on specific topics, consult:

| Topic | Reference File |

|-------|----------------|

| Workspace setup, basic commands | references/basics.md |

| Generators (app, lib, component) | references/generators.md |

| React, Next.js, Expo patterns | references/react.md |

| NestJS backend patterns | references/nestjs.md |

| TypeScript packages | references/typescript.md |

| CI/CD (GitHub, CircleCI, etc.) | references/ci-cd.md |

| Caching, affected, advanced | references/advanced.md |