Style Enforcement

Style Enforcement

Validate code files against configured style rules from project configuration files.

Triggers

• check style compliance
• validate editorconfig rules
• run style enforcement
• check naming conventions
• validate line endings

Quick Start

# Check all files in current directory
python3 scripts/check_style.py --target .

# Check only changed files (CI mode)
python3 scripts/check_style.py --git-staged

# Check specific files
python3 scripts/check_style.py src/models/user.cs src/services/auth.cs

# JSON output for automation
python3 scripts/check_style.py --target . --format json --output violations.json

Evidence

Created based on analysis of moq.analyzers closed PR reviewer patterns:

• 9.8% of human reviewer feedback (11 of 112 comments) addressed naming/style conventions
• Common patterns: line endings (CRLF vs LF), naming conventions (FooAsync), style guide violations
• Examples: "Use lf not crlf", "Should be named FooAsync", "Conflicting style rules"

Source: .agents/analysis/moq-analyzers-reviewer-patterns-2026-02-08.md

Configuration Sources

The skill reads style configuration from these files (in priority order):

.editorconfig Properties Checked

.editorconfig Naming Conventions (C#)

# Example naming rules
dotnet_naming_rule.async_methods_should_end_with_async.symbols = async_methods
dotnet_naming_rule.async_methods_should_end_with_async.style = async_suffix_style
dotnet_naming_rule.async_methods_should_end_with_async.severity = warning

dotnet_naming_style.async_suffix_style.required_suffix = Async

Detection Capabilities

Line Ending Violations

Detects when file line endings differ from .editorconfig end_of_line setting.

Rule: STYLE-001
Severity: warning
Example: "File uses CRLF but editorconfig requires LF"

Indentation Violations

Detects tabs vs spaces mismatches and incorrect indent sizes.

Rule: STYLE-002
Severity: warning
Example: "Line uses tabs but editorconfig requires spaces (indent_size=4)"

Charset Violations

Detects incorrect file encoding (BOM presence/absence).

Rule: STYLE-003
Severity: warning
Example: "File has UTF-8 BOM but editorconfig requires utf-8 (no BOM)"

Trailing Whitespace

Detects trailing whitespace when trim_trailing_whitespace = true.

Rule: STYLE-004
Severity: info
Example: "Line 42 has trailing whitespace"

Final Newline

Detects missing final newline when insert_final_newline = true.

Rule: STYLE-005
Severity: info
Example: "File does not end with newline"

Naming Convention Violations (C#)

Detects async method naming when dotnet_naming_rule configured.

Rule: STYLE-010
Severity: warning
Example: "Async method 'GetUser' should end with 'Async' suffix"

Process

┌─────────────────────────────────────────┐
│ 1. Configuration Discovery              │
│    - Walk up from target to find root   │
│    - Parse .editorconfig hierarchy      │
│    - Parse .stylecop.json if present    │
│    - Parse Directory.Build.props        │
├─────────────────────────────────────────┤
│ 2. Rule Compilation                     │
│    - Match globs to file extensions     │
│    - Build per-file rule set            │
│    - Merge inherited properties         │
├─────────────────────────────────────────┤
│ 3. File Scanning                        │
│    - Check each file against its rules  │
│    - Detect violations with line info   │
│    - Apply suppression comments         │
├─────────────────────────────────────────┤
│ 4. Report Generation                    │
│    - Format: markdown, JSON, or SARIF   │
│    - Include violation counts           │
│    - Exit code based on findings        │
└─────────────────────────────────────────┘

Command Reference

Basic Usage

python3 scripts/check_style.py [options] [files...]

Parameters

Exit Codes

Scripts

Integration

Pre-commit Hook

# .pre-commit-config.yaml
repos:
  - repo: local
    hooks:
      - id: style-enforcement
        name: Style Enforcement
        entry: python3 .claude/skills/style-enforcement/scripts/check_style.py
        args: [--git-staged]
        language: python
        pass_filenames: false

GitHub Actions

# .github/workflows/style.yml
jobs:
  style:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Check style
        run: |
          python3 .claude/skills/style-enforcement/scripts/check_style.py \
            --target . \
            --format sarif \
            --output style-results.sarif
      - uses: github/codeql-action/upload-sarif@v3
        with:
          sarif_file: style-results.sarif

Agent Pre-Submission

Before creating a PR, run style enforcement:

python3 .claude/skills/style-enforcement/scripts/check_style.py --git-staged

If exit code is 10, fix violations before proceeding.

Examples

Example 1: Check Single File

python3 scripts/check_style.py src/models/User.cs

Output:

Style Enforcement Report
========================

Violations: 2

src/models/User.cs
  Line 1: [STYLE-001] File uses CRLF but editorconfig requires LF
  Line 45: [STYLE-010] Async method 'GetUser' should end with 'Async' suffix

Exit code: 10 (violations detected)

Example 2: JSON Output for CI

python3 scripts/check_style.py --target . --format json

{
  "scan_timestamp": "2026-02-08T10:30:00Z",
  "files_scanned": 42,
  "violations": [
    {
      "file": "src/models/User.cs",
      "line": 1,
      "column": 1,
      "rule": "STYLE-001",
      "message": "File uses CRLF but editorconfig requires LF",
      "severity": "warning"
    }
  ],
  "summary": {
    "total": 1,
    "by_severity": {"warning": 1}
  }
}

Example 3: SARIF for GitHub Code Scanning

python3 scripts/check_style.py --target . --format sarif --output results.sarif

Suppression

Suppress specific violations with inline comments:

// style-enforcement: ignore STYLE-001
var data = GetData();  // CRLF line ending allowed here

# style-enforcement: ignore STYLE-002
 pass  # Tab indentation allowed here

When to Use

Use this skill when:

• Checking style compliance before commits
• Enforcing consistent code formatting in CI
• Validating editorconfig rules are applied correctly
• Detecting naming convention violations

Use existing linters instead when:

• Full ESLint/Prettier rules needed (JavaScript)
• Full StyleCop Analyzer output needed (C#, use dotnet build)
• Auto-formatting is desired (use dotnet format, black, prettier)

Language Support

Fully Supported

Basic Support (line endings, indentation, charset)

• Go (.go)
• Rust (.rs)
• Java (.java)
• Ruby (.rb)
• Markdown (.md)
• YAML (.yml, .yaml)
• JSON (.json)

Anti-Patterns

Verification

After running style check, the gate is check_style.py's exit code, not a self-check:

python3 .claude/skills/style-enforcement/scripts/check_style.py "$TARGET_PATH"
echo "exit=$?"   # 0 = clean, 10 = violations found, 1 = tool error

• Exit 0 to pass; exit 10 means violations exist and must be reported with file:line:rule
• Exit 1 (tool error) is a BLOCKED result, not a pass
• Suppression comments honored
• SARIF output validates (if used)

Related Skills

References

Timelessness: 8/10

EditorConfig is an industry standard (2012+) supported by all major editors and IDEs. Style conventions (naming, indentation, line endings) are fundamental to code quality. The skill delegates language-specific rules to external analyzers when available.