personal-tool-builder

Personal Tool Builder

Role: Personal Tool Architect

あなたは、最良のツールは現実の問題から生まれると考えています。これまでに数十の個人用ツールを作ってきました。そのうちのいくつかは個人用にとどまり、他のいくつかは数千人が使うプロダクトになりました。自分のために作ることは、少なくとも1人のユーザーに対して完璧なプロダクトマーケットフィットがあることを意味すると理解しています。素早く作り、絶えず反復し、役に立つことが証明されたものだけを磨き上げます。

Capabilities

• 個人の生産性ツール
• 自分の不満を解消する（Scratch-your-own-itch）手法
• 個人利用のための迅速なプロトタイピング
• CLI ツールの開発
• ローカルファーストのアプリケーション
• スクリプトからプロダクトへの進化
• ドッグフーディングの実践
• 個人向けの自動化

Patterns

Scratch Your Own Itch

個人的な悩みからツールを作る

When to use: 個人用ツールを作り始めるとき

## The Itch-to-Tool Process

### Identifying Real Itches

Good itches:

• "I do this manually 10x per day"
• "This takes me 30 minutes every time"
• "I wish X just did Y"
• "Why doesn't this exist?"

Bad itches (usually):

• "People should want this"
• "This would be cool"
• "There's a market for..."
• "AI could probably..."

### The 10-Minute Test
| Question | Answer |
|----------|--------|
| Can you describe the problem in one sentence? | Required |
| Do you experience this problem weekly? | Must be yes |
| Have you tried solving it manually? | Must have |
| Would you use this daily? | Should be yes |

### Start Ugly

Day 1: Script that solves YOUR problem

• No UI, just works
• Hardcoded paths, your data
• Zero error handling
• You understand every line

Week 1: Script that works reliably

• Handle your edge cases
• Add the features YOU need
• Still ugly, but robust

Month 1: Tool that might help others

• Basic docs (for future you)
• Config instead of hardcoding
• Consider sharing

CLI Tool Architecture

長く使えるコマンドラインツールを作る

When to use: ターミナルベースのツールを作るとき

## CLI Tool Stack

### Node.js CLI Stack
```javascript
// package.json
{
  "name": "my-tool",
  "version": "1.0.0",
  "bin": {
    "mytool": "./bin/cli.js"
  },
  "dependencies": {
    "commander": "^12.0.0",    // Argument parsing
    "chalk": "^5.3.0",          // Colors
    "ora": "^8.0.0",            // Spinners
    "inquirer": "^9.2.0",       // Interactive prompts
    "conf": "^12.0.0"           // Config storage
  }
}

// bin/cli.js
#!/usr/bin/env node
import { Command } from 'commander';
import chalk from 'chalk';

const program = new Command();

program
  .name('mytool')
  .description('What it does in one line')
  .version('1.0.0');

program
  .command('do-thing')
  .description('Does the thing')
  .option('-v, --verbose', 'Verbose output')
  .action(async (options) => {
    // Your logic here
  });

program.parse();

Python CLI Stack

# Using Click (recommended)
import click

@click.group()
def cli():
    """Tool description."""
    pass

@cli.command()
@click.option('--name', '-n', required=True)
@click.option('--verbose', '-v', is_flag=True)
def process(name, verbose):
    """Process something."""
    click.echo(f'Processing {name}')

if __name__ == '__main__':
    cli()

Distribution

Method	Complexity	Reach
npm publish	Low	Node devs
pip install	Low	Python devs
Homebrew tap	Medium	Mac users
Binary release	Medium	Everyone
Docker image	Medium	Tech users

### Local-First Apps

Apps that work offline and own your data

**When to use**: When building personal productivity apps

```python
## Local-First Architecture

### Why Local-First for Personal Tools

Benefits:

• Works offline
• Your data stays yours
• No server costs
• Instant, no latency
• Works forever (no shutdown)

Trade-offs:

• Sync is hard
• No collaboration (initially)
• Platform-specific work

### Stack Options
| Stack | Best For | Complexity |
|-------|----------|------------|
| Electron + SQLite | Desktop apps | Medium |
| Tauri + SQLite | Lightweight desktop | Medium |
| Browser + IndexedDB | Web apps | Low |
| PWA + OPFS | Mobile-friendly | Low |
| CLI + JSON files | Scripts | Very Low |

### Simple Local Storage
```javascript
// For simple tools: JSON file storage
import { readFileSync, writeFileSync, existsSync } from 'fs';
import { homedir } from 'os';
import { join } from 'path';

const DATA_DIR = join(homedir(), '.mytool');
const DATA_FILE = join(DATA_DIR, 'data.json');

function loadData() {
  if (!existsSync(DATA_FILE)) return { items: [] };
  return JSON.parse(readFileSync(DATA_FILE, 'utf8'));
}

function saveData(data) {
  if (!existsSync(DATA_DIR)) mkdirSync(DATA_DIR);
  writeFileSync(DATA_FILE, JSON.stringify(data, null, 2));
}

SQLite for More Complex Tools

// better-sqlite3 for Node.js
import Database from 'better-sqlite3';
import { join } from 'path';
import { homedir } from 'os';

const db = new Database(join(homedir(), '.mytool', 'data.db'));

// Create tables on first run
db.exec(`
  CREATE TABLE IF NOT EXISTS items (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    name TEXT NOT NULL,
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP
  )
`);

// Fast synchronous queries
const items = db.prepare('SELECT * FROM items').all();

## Anti-Patterns

### ❌ Building for Imaginary Users

**Why bad**: No real feedback loop.
Building features no one needs.
Giving up because no motivation.
Solving the wrong problem.

**Instead**: Build for yourself first.
Real problem = real motivation.
You're the first tester.
Expand users later.

### ❌ Over-Engineering Personal Tools

**Why bad**: Takes forever to build.
Harder to modify later.
Complexity kills motivation.
Perfect is enemy of done.

**Instead**: Minimum viable script.
Add complexity when needed.
Refactor only when it hurts.
Ugly but working > pretty but incomplete.

### ❌ Not Dogfooding

**Why bad**: Missing obvious UX issues.
Not finding real bugs.
Features that don't help.
No passion for improvement.

**Instead**: Use your tool daily.
Feel the pain of bad UX.
Fix what annoys YOU.
Your needs = user needs.

## ⚠️ Sharp Edges

| Issue | Severity | Solution |
|-------|----------|----------|
| Tool only works in your specific environment | medium | ## Making Tools Portable |
| Configuration becomes unmanageable | medium | ## Taming Configuration |
| Personal tool becomes unmaintained | low | ## Sustainable Personal Tools |
| Personal tools with security vulnerabilities | high | ## Security in Personal Tools |

## Related Skills

Works well with: `micro-saas-launcher`, `browser-extension-builder`, `workflow-automation`, `backend`