Prettier Config Skill

Purpose

Generate Prettier configuration file for code formatting.

🚨 MANDATORY FILE COUNT

This skill MUST create exactly 1 file:

• .prettierrc (preferred format - JSON without extension)

🔍 BEFORE GENERATING - CRITICAL RESEARCH REQUIRED

⚠️ HIGH PRIORITY: Verify current Prettier configuration options to prevent outdated settings

Required Research Steps:

1. Prettier Version: Check current Prettier version and configuration format
   • Verify .prettierrc format is still recommended
   • Check if any configuration options have been deprecated
2. Configuration Options: Verify the following options are still valid:
   • singleQuote - Still accepts boolean values
   • semi - Still accepts boolean values
   • trailingComma - Still accepts "es5" / "all" / "none" values
3. Default Values: Check if Prettier defaults have changed
   • Verify current default for printWidth (usually 80)
   • Verify current default for tabWidth (usually 2)
   • Check if endOfLine default is still "lf"
4. Optional Settings: Research if new recommended options have been added:
   • printWidth - Line length (default 80)
   • tabWidth - Spaces per indentation (default 2)
   • endOfLine - Line ending style (lf/crlf/auto)
   • arrowParens - Arrow function parentheses
5. File Format Alternatives: Check if format is deprecated
   • Verify .prettierrc (JSON) is still preferred
   • Check .prettierrc.json, .prettierrc.js, package.json field

Output

Create the file: .prettierrc

Supported Formats (in order of preference):

1. .prettierrc (preferred - JSON without extension)
2. .prettierrc.json (explicit JSON format)
3. .prettierrc.js (JavaScript with dynamic logic)
4. prettier field in package.json

Template

See: examples.md in this directory for complete template and detailed examples.

⚠️ IMPORTANT: The examples.md file contains December 2025 configurations. Always verify current Prettier options before using.

Execution Checklist

• [ ] Research current Prettier version and recommended config format
• [ ] Verify singleQuote, semi, trailingComma options are still valid
• [ ] Check if option syntax or values have changed
• [ ] Verify default values haven't changed (printWidth, tabWidth, endOfLine)
• [ ] Check for new recommended options
• [ ] Create .prettierrc with minimal, verified configuration
• [ ] Verify file format is still recommended (not deprecated)

🛑 BLOCKING VALIDATION CHECKPOINT

STOP! Before proceeding to the next skill, verify:

Automated Verification

Run this command to verify the file exists:

if [ -f ".prettierrc" ] || [ -f ".prettierrc.json" ] || [ -f ".prettierrc.js" ] || grep -q "prettier" package.json 2>/dev/null; then
  echo "✓ Prettier configuration found"
  if [ -f ".prettierrc" ]; then
    echo "✓ Using .prettierrc (preferred format)"
    # Validate JSON syntax
    if command -v jq >/dev/null 2>&1; then
      jq empty .prettierrc && echo "✓ Valid JSON syntax" || echo "✗ Invalid JSON syntax"
    elif command -v node >/dev/null 2>&1; then
      node -e "JSON.parse(require('fs').readFileSync('.prettierrc', 'utf8'))" && echo "✓ Valid JSON" || echo "✗ Invalid JSON"
    fi
  fi
else
  echo "✗ Prettier configuration missing"
  exit 1
fi

Manual Verification

1. ✓ .prettierrc exists at project root (or alternative format)
2. ✓ File contains valid JSON syntax
3. ✓ File includes singleQuote option (verify current syntax)
4. ✓ File includes semi option (verify current syntax)
5. ✓ File includes trailingComma option (verify current values)
6. ✓ Configuration options use current Prettier syntax
7. ✓ All option values are valid for current Prettier version

If Validation Fails

DO NOT PROCEED to the next skill. Create or fix the missing/incorrect file immediately.

Notes

• Minimal Configuration: Uses only 3 essential options (singleQuote, semi, trailingComma)
• Prettier Defaults: Relies on Prettier's sensible defaults for other options
• Single Quotes: "singleQuote": true - Uses single quotes for strings
• Semicolons: "semi": true - Requires semicolons at end of statements
• Trailing Commas: "trailingComma": "es5" - ES5 compatible trailing commas (objects, arrays)
• Works with ESLint: Compatible with eslint-plugin-prettier integration
• Git-Friendly: Minimal diffs when configuration changes
• Optional Settings: Can add printWidth, tabWidth, endOfLine if needed
• Format Flexibility: Supports .prettierrc, .json, .js, package.json field
• Always verify current options - Prettier may change configuration schema
• JSON Preferred: Simple, declarative, no build step required
• Team Consistency: Ensures all developers use same formatting rules