Agent skill
yargs-scaffolder
Generate Yargs-based CLI applications with commands, positional args, middleware, and TypeScript support. Creates a complete scaffolded CLI application with modern patterns.
Install this agent skill to your Project
npx add-skill https://github.com/a5c-ai/babysitter/tree/main/library/specializations/cli-mcp-development/skills/yargs-scaffolder
SKILL.md
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
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