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name: Code Quality description: This skill should be used when the user asks to "check code quality", "analyze code metrics", "find dead code", "check style compliance", "measure complexity", "find unused imports", "check type hints", "run linting", "PEP8 compliance", or mentions code quality analysis. version: 1.0.0

Code Quality Analysis

Comprehensive code quality analysis skill covering style, complexity, dead code detection, and type checking.

Core Capabilities

Style Compliance

Check adherence to language-specific style guides:

Python (PEP8/Black):

• Line length (88 chars for Black, 79 for PEP8)
• Indentation (4 spaces)
• Import ordering (standard, third-party, local)
• Naming conventions (snake_case for functions/variables, PascalCase for classes)
• Whitespace usage

Style check commands:

Copy# Black formatting check
black --check --diff .

# Flake8 linting
flake8 --max-line-length=88 .

# isort import sorting
isort --check-only --diff .

Complexity Metrics

Measure and report code complexity:

Cyclomatic Complexity:

• Number of independent paths through code
• Target: < 10 per function
• Warning: 10-20
• Critical: > 20

Cognitive Complexity:

• Mental effort to understand code
• Accounts for nesting depth and control flow

Function Length:

• Target: < 50 lines
• Warning: 50-100 lines
• Critical: > 100 lines

Nesting Depth:

• Target: < 4 levels
• Warning: 4-6 levels
• Critical: > 6 levels

Complexity analysis:

Copy# Using radon for Python
radon cc . -a -s  # Cyclomatic complexity
radon mi .        # Maintainability index
radon hal .       # Halstead metrics

Dead Code Detection

Identify unused code elements:

Unused Imports:

Copy# Python - using autoflake
autoflake --check --remove-all-unused-imports .

# Using flake8 with F401
flake8 --select=F401 .

Unused Variables:

• Local variables assigned but never read
• Function parameters ignored
• Class attributes never accessed

Unused Functions/Classes:

• Defined but never called
• Private methods not used internally
• Dead code branches (always false conditions)

Unreachable Code:

• Code after return/raise/break/continue
• Branches with impossible conditions
• Deprecated code still in codebase

Type Hint Analysis

Validate type annotations:

Missing Type Hints:

Copy# Using mypy
mypy --strict .

# Check specific strictness levels
mypy --disallow-untyped-defs .
mypy --disallow-incomplete-defs .

Type Errors:

• Incompatible types in assignments
• Wrong argument types
• Missing return types
• Generic type issues

Type Coverage:

• Percentage of code with type annotations
• Target: > 80% coverage

Quality Metrics Dashboard

When analyzing a codebase, report:

Analysis Workflow

Full Quality Analysis

To perform comprehensive quality check:

1. Style check: Run linters and formatters
2. Complexity analysis: Calculate metrics
3. Dead code scan: Find unused elements
4. Type check: Validate annotations
5. Report generation: Summarize findings

Quick Quality Check

For rapid assessment of changes:

1. Get changed files from git diff
2. Run focused linting on changed files
3. Check complexity of modified functions
4. Validate types in touched code

Language-Specific Guidance

Python

Recommended tooling:

• Black (formatting)
• isort (import sorting)
• flake8 (linting)
• mypy (type checking)
• radon (complexity)
• vulture (dead code)

Configuration (pyproject.toml):

Copy[tool.black]
line-length = 88
target-version = ['py311']

[tool.isort]
profile = "black"
line_length = 88

[tool.mypy]
python_version = "3.11"
strict = true

JavaScript/TypeScript

Recommended tooling:

• ESLint (linting)
• Prettier (formatting)
• TypeScript compiler (type checking)

Configuration (.eslintrc.json):

Copy{
  "extends": ["eslint:recommended"],
  "rules": {
    "complexity": ["warn", 10],
    "max-depth": ["warn", 4],
    "max-lines-per-function": ["warn", 50]
  }
}

Common Quality Issues

High Priority Fixes

1. Unused imports: Remove immediately
2. Type errors: Fix type mismatches
3. High complexity: Refactor into smaller functions
4. Long functions: Extract logical blocks

Medium Priority

1. Style violations: Apply formatter
2. Missing type hints: Add annotations
3. Moderate complexity: Consider refactoring
4. Unused variables: Remove or use

Low Priority

1. Minor style preferences: Team decision
2. Optional type hints: Add gradually
3. Documentation gaps: Address incrementally

Output Format

Present findings organized by severity:

Errors (must fix):

• Type errors
• Syntax issues
• Critical complexity

Warnings (should fix):

• Unused code
• High complexity
• Missing types in public APIs

Info (consider):

• Style suggestions
• Optimization opportunities
• Best practice recommendations

Integration

Coordinate with other skills:

• refactoring skill: For complexity reduction
• documentation skill: For missing docstrings
• security-scanning skill: For security-related quality issues