Yargs Scaffolder Skill | Agent Skills

Yargs Scaffolder

Generate a complete Yargs CLI application with TypeScript, middleware support, and best practices.

Capabilities

Generate TypeScript-based Yargs CLI projects
Create command modules with positional arguments
Set up middleware for common operations (logging, config loading)
Configure type coercion and validation
Implement strict mode and fail handlers
Set up build and development workflows

Usage

Invoke this skill when you need to:

Bootstrap a new CLI application using Yargs
Create a CLI with command modules pattern
Set up middleware-based processing
Configure complex argument parsing

Inputs

| Parameter | Type | Required | Description | |-----------|------|----------|-------------| | projectName | string | Yes | Name of the CLI project (kebab-case) | | description | string | Yes | Short description of the CLI | | commands | array | No | List of commands to scaffold | | typescript | boolean | No | Use TypeScript (default: true) | | packageManager | string | No | npm, yarn, or pnpm (default: npm) | | strictMode | boolean | No | Enable strict mode (default: true) |

Command Structure

{
  "commands": [
    {
      "name": "serve",
      "description": "Start the server",
      "aliases": ["s"],
      "positional": [
        { "name": "port", "type": "number", "default": 3000 }
      ],
      "options": [
        { "name": "host", "type": "string", "default": "localhost" },
        { "name": "watch", "type": "boolean", "alias": "w" }
      ]
    }
  ]
}

Output Structure

<projectName>/
├── package.json
├── tsconfig.json
├── .gitignore
├── README.md
├── src/
│   ├── index.ts              # Entry point
│   ├── cli.ts                # Yargs setup
│   ├── commands/
│   │   ├── index.ts          # Command exports
│   │   └── <command>.ts      # Command modules
│   ├── middleware/
│   │   ├── logger.ts         # Logging middleware
│   │   └── config.ts         # Config loading middleware
│   ├── utils/
│   │   └── helpers.ts        # Helper utilities
│   └── types/
│       └── index.ts          # Type definitions
└── tests/
    └── commands/
        └── <command>.test.ts

Generated Code Patterns

Main CLI Entry (src/cli.ts)

import yargs from 'yargs';
import { hideBin } from 'yargs/helpers';
import * as commands from './commands';
import { loggerMiddleware } from './middleware/logger';

export const cli = yargs(hideBin(process.argv))
  .scriptName('<projectName>')
  .usage('$0 <cmd> [args]')
  .middleware([loggerMiddleware])
  .command(commands.serveCommand)
  .command(commands.buildCommand)
  .demandCommand(1, 'You need at least one command')
  .strict()
  .fail((msg, err, yargs) => {
    if (err) throw err;
    console.error(msg);
    console.error(yargs.help());
    process.exit(1);
  })
  .help()
  .alias('help', 'h')
  .version()
  .alias('version', 'v')
  .wrap(Math.min(120, process.stdout.columns || 80));

Command Module Template

import { CommandModule, Argv } from 'yargs';

interface ServeArgs {
  port: number;
  host: string;
  watch: boolean;
}

export const serveCommand: CommandModule<{}, ServeArgs> = {
  command: 'serve [port]',
  aliases: ['s'],
  describe: 'Start the development server',
  builder: (yargs: Argv) => {
    return yargs
      .positional('port', {
        type: 'number',
        default: 3000,
        describe: 'Port to listen on'
      })
      .option('host', {
        type: 'string',
        default: 'localhost',
        describe: 'Host to bind to'
      })
      .option('watch', {
        alias: 'w',
        type: 'boolean',
        default: false,
        describe: 'Enable watch mode'
      });
  },
  handler: async (argv) => {
    console.log(`Starting server on ${argv.host}:${argv.port}`);
  }
};

Dependencies

{
  "dependencies": {
    "yargs": "^17.0.0"
  },
  "devDependencies": {
    "@types/node": "^20.0.0",
    "@types/yargs": "^17.0.0",
    "typescript": "^5.0.0",
    "tsx": "^4.0.0",
    "vitest": "^1.0.0"
  }
}

Workflow

Validate inputs - Check project name, commands structure
Create directory structure - Set up folders and base files
Generate package.json - Configure project metadata
Generate tsconfig.json - TypeScript configuration
Create CLI entry point - Yargs setup with middleware
Generate command modules - Individual command files
Create middleware - Logger, config middleware
Set up tests - Test structure for commands
Initialize git - Optional git initialization

Best Practices Applied

TypeScript strict mode enabled
Command module pattern for scalability
Middleware for cross-cutting concerns
Strict mode with custom fail handler
Proper type definitions for arguments
Completion script support

References

Yargs Documentation: https://yargs.js.org/
Yargs GitHub: https://github.com/yargs/yargs
Command Modules: https://yargs.js.org/docs/#api-reference-commandmodule

Target Processes

cli-application-bootstrap
argument-parser-setup
cli-command-structure-design

Agent Skills: Yargs Scaffolder

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