Code Style Validator

Installation

No separate download: the skill runs the in-repo tool .claude/tools/cli/security-lint.cjs.

• Ensure Node.js (v18+) is installed: nodejs.org or winget install OpenJS.NodeJS.LTS (Windows), brew install node (macOS).
• From the project root, the script is invoked automatically; no extra install steps.

Cheat Sheet & Best Practices

AST-based validation: Use ESLint (or equivalent) with selectors/patterns; rules listen for specific node types. Prefer existing community rules before writing custom ones; custom rules need meta (type, fixable, schema) and create.

Process: Check naming (camelCase/PascalCase/snake_case), indentation, import order, function/class structure, comment style. Run in pre-commit and CI; provide auto-fix where possible.

Hacks: Use --fix for auto-fixable rules; combine with security-lint for policy. Define rule metadata clearly for docs and tooling. Use AST selectors for precise pattern matching (node type, attributes, child/sibling).

Certifications & Training

ESLint: Use in project, custom rules, selectors. No cert; skill data: AST-based validation, pre-commit/CI, auto-fix, naming/indent/imports.

Hooks & Workflows

Suggested hooks: Pre-commit: run security-lint (skill script) or ESLint; block commit on failure. Use with developer (secondary), code-reviewer (secondary), qa (CI).

Workflows: Use with code-reviewer (secondary), developer (secondary). Flow: before commit or in CI → run validator → fix or block. See code-review-workflow.md, validation hooks.

Step 1: Identify Code Style Patterns

Analyze the codebase to identify style patterns:

• Naming conventions (camelCase, PascalCase, snake_case)
• Indentation style (spaces vs tabs, width)
• Import organization
• Function/class structure
• Comment style

Step 2: AST-Based Validation

Use language-specific AST parsers:

TypeScript/JavaScript:

const ts = require('typescript');
const fs = require('fs');

function validateTypeScriptFile(filePath) {
  const sourceCode = fs.readFileSync(filePath, 'utf8');
  const sourceFile = ts.createSourceFile(filePath, sourceCode, ts.ScriptTarget.Latest, true);

  const issues = [];

  // Validate naming conventions
  ts.forEachChild(sourceFile, node => {
    if (ts.isFunctionDeclaration(node) && node.name) {
      if (!/^[a-z][a-zA-Z0-9]*$/.test(node.name.text)) {
        issues.push({
          line: sourceFile.getLineAndCharacterOfPosition(node.name.getStart()).line + 1,
          message: `Function name "${node.name.text}" should be camelCase`,
        });
      }
    }
  });

  return issues;
}

import ast
import re

def validate_python_file(file_path):
    with open(file_path, 'r') as f:
        source_code = f.read()

    tree = ast.parse(source_code)
    issues = []

    for node in ast.walk(tree):
        if isinstance(node, ast.FunctionDef):
            if not re.match(r'^[a-z][a-z0-9_]*$', node.name):
                issues.append({
                    'line': node.lineno,
                    'message': f'Function name "{node.name}" should be snake_case'
                })

    return issues

Naming Conventions:

• Variables: camelCase (JS/TS) or snake_case (Python)
• Functions: camelCase (JS/TS) or snake_case (Python)
• Classes: PascalCase
• Constants: UPPER_CASE
• Private: prefix with underscore

Formatting:

• Indentation: 2 spaces (JS/TS) or 4 spaces (Python)
• Line length: 88-100 characters
• Trailing commas: Yes (JS/TS)
• Semicolons: Consistent usage

Structure:

• Import order: external, internal, relative
• Function length: < 50 lines
• File organization: exports, helpers, types

Validate Single File:

# After implementing your validator:
node validate-code-style.js src/components/Button.tsx

Validate Directory:

# After implementing your validator:
node validate-code-style.js src/components/

Output Format:

{
  "file": "src/components/Button.tsx",
  "valid": false,
  "issues": [
    {
      "line": 15,
      "column": 10,
      "rule": "naming-convention",
      "message": "Variable 'UserData' should be camelCase: 'userData'",
      "severity": "error"
    },
    {
      "line": 23,
      "column": 5,
      "rule": "indentation",
      "message": "Expected 2 spaces, found 4",
      "severity": "warning"
    }
  ],
  "summary": {
    "total": 2,
    "errors": 1,
    "warnings": 1
  }
}

#!/bin/bash
# .git/hooks/pre-commit
changed_files=$(git diff --cached --name-only --diff-filter=ACM | grep -E '\.(ts|tsx|js|jsx|py)$')

for file in $changed_files; do
  # Replace with your actual validator path
  if ! node validate-code-style.js "$file"; then
    echo "Code style validation failed for $file"
    exit 1
  fi
done

# .github/workflows/code-style.yml
- name: Validate code style
  run: |
    # Replace with your actual validator path
    node validate-code-style.js src/
    if [ $? -ne 0 ]; then
      echo "Code style validation failed"
      exit 1
    fi

Iron Laws

1. ALWAYS use AST-based validation over regex — regex-based style checking breaks on multi-line constructs, comments, and strings; AST-based tools (ESLint, Prettier) are format-independent and semantically accurate.
2. ALWAYS check for existing ESLint/Prettier rules before writing custom ones — custom rules are expensive to maintain; 95% of style needs are covered by existing rules with configuration.
3. NEVER block commits for style warnings, only errors — warnings are informational; blocking CI on warnings creates friction that leads teams to disable style checks entirely.
4. ALWAYS provide auto-fix suggestions alongside findings — reports without auto-fix require manual intervention for each issue; auto-fixable violations have near-100% resolution rates vs 30% for manual.
5. ALWAYS run style validation in both pre-commit hooks and CI — pre-commit catches issues locally before they reach the repository; CI catches cases where hooks were bypassed or aren't installed.

Anti-Patterns

Memory Protocol (MANDATORY)

Before starting: Read .claude/context/memory/learnings.md

After completing:

• New pattern -> .claude/context/memory/learnings.md
• Issue found -> .claude/context/memory/issues.md
• Decision made -> .claude/context/memory/decisions.md

ASSUME INTERRUPTION: If it's not in memory, it didn't happen.