Analyze code

Refactoring Analyzer

Overview

Systematically analyze code for refactoring opportunities by checking against comprehensive checklists and architectural principles. This skill identifies code smells, architectural violations, design pattern misuse, and improvement opportunities in any language or framework.

When to Use This Skill

Use this skill when the user requests:

• "Analyze code smells in [module/file]"
• "Find refactoring opportunities in [module/file]"
• "Check [module/file] for architecture violations"
• "Review code quality in [module/file]"
• "What can be improved in [module/file]?"
• "Look for code duplication in [module/file]"

Important: This skill analyzes specific modules or files, NOT the entire codebase. The user should specify the scope.

Analysis Workflow

Step 1: Determine Scope

Identify what needs to be analyzed from the user's request:

Module-Level Analysis (directory with related files):

• A feature module, package, or namespace
• A domain/service layer
• A shared/utility library

File-Level Analysis:

• A specific source file
• A specific test file
• A configuration file

If the scope is unclear, ask the user to specify the module or file path.

Step 2: Detect Language & Context

Before analyzing, identify the project's technology stack:

1. Language: Look at file extensions (.swift, .ts, .py, .go, .rs, .java, .kt, etc.)
2. Framework: Check imports/dependencies (React, SwiftUI, Django, Spring, etc.)
3. Architecture: Check for CLAUDE.md, .claude/rules/, .github/instructions/, or other project docs describing the architecture
4. Conventions: Check for linter configs (.eslintrc, .swiftlint.yml, pyproject.toml, etc.)

This context shapes which checklist items are most relevant and what patterns to validate against.

Step 3: Read the Target Code

Use appropriate tools to read the code being analyzed:

For Module Analysis:

1. Use Glob to find all source files in the module directory
2. Use Read to load each file in the module
3. Note the module's purpose and dependencies

For File Analysis:

1. Use Read to load the specific file
2. Check related files (e.g., if analyzing a view, also read its controller/model/service)

Context Gathering:

• Understand the code's purpose and responsibility
• Identify dependencies and relationships
• Note patterns and conventions used
• Check .claude/rules/ and .github/instructions/ for project-specific knowledge

Step 4: Apply Refactoring Checklist

Load and apply the comprehensive refactoring checklist from references/refactoring-checklist.md.

How to use the checklist:

1. Read the checklist: Use the Read tool to load references/refactoring-checklist.md into context

2. Scan systematically: Go through each category relevant to the code type:

   • For UI/View code: Focus on Presentation Layer, State Management, Component Reuse
   • For Business Logic: Focus on Architecture, Code Organization, Error Handling
   • For Data/API code: Focus on API Integration, Error Handling, Async Patterns
   • For Tests: Focus on Testing & Testability, Code Clarity
   • For All code: Always check Architecture, Duplication, Security, Performance

3. Document findings: For each issue found, note:

   • Issue category and specific checklist item
   • File and line number (if applicable)
   • Code snippet demonstrating the issue
   • Severity (Critical, High, Medium, Low)

Severity Guidelines:

• Critical: Security vulnerabilities, data loss risks, crashes, resource leaks
• High: Architectural violations, major pattern violations, significant maintainability issues
• Medium: Code duplication, missing best practices, moderate complexity
• Low: Naming inconsistencies, minor style issues, documentation gaps

False Positive Avoidance: Only flag issues you are CERTAIN about from the visible code. If you cannot see the full context (e.g., an extension method defined in another file, the reason behind a keyword like nonisolated), do NOT flag it as a problem. When flagging potential issues in code you cannot fully verify (e.g., unused enum cases that may be used elsewhere), explicitly qualify with "verify before acting" language. Speculative future advice ("you could migrate to X someday") is NOT an issue — omit it. When assessing lifecycle/memory issues, consider whether the runtime already handles the scenario (e.g., a Task holding self strongly is not a "leak" if the task completes or is cancelled — it just extends lifetime). Do not flag working dependency imports as potential risks ("what if this dependency is removed someday").

Step 5: Validate Against Architecture

Load and validate against architectural principles from references/architecture-patterns.md.

How to validate:

1. Read architecture guide: Use the Read tool to load references/architecture-patterns.md into context

2. Discover the project's architecture: Check CLAUDE.md, .claude/rules/, .github/instructions/, and project docs for declared boundaries, dependency rules, and conventions. Do NOT assume a specific architecture style — use whatever the project declares.

3. Identify the code's role: Determine what role this code plays within the project's own architecture. What module does it belong to? What is that module responsible for? What should it depend on?

4. Validate against universal principles:

   • Single Responsibility: Does each unit have one clear purpose?
   • Dependency Direction: Do dependencies flow in the direction the project declares?
   • Boundary Compliance: Does the code respect the boundaries between modules?
   • Separation of Concerns: Are distinct concerns in distinct modules?

5. Document violations: For each architectural violation, note:

   • What boundary or principle was violated
   • File and location
   • What the project's architecture expects instead
   • Suggested refactoring approach

Step 6: Identify Refactoring Opportunities

Beyond checklist items, look for higher-level refactoring opportunities:

Extract and Consolidate:

• Duplicate code that should be extracted to shared utilities
• Custom implementations where framework/library solutions exist
• Repeated logic that should be helper functions or shared modules
• Similar structures that could share a base component or abstraction

Architectural Improvements:

• Code in wrong layer that should be moved
• Missing abstractions (interfaces, protocols, base classes)
• Tight coupling that should be loosened
• Missing error handling or edge case handling

Modern Language Adoption:

• Old patterns that have modern replacements in the language
• Manual implementations of things the standard library provides
• Imperative code that could be declarative/functional
• Callback/promise chains that could use async/await

Performance Optimizations:

• Unnecessary re-computation or re-rendering
• Missing lazy evaluation or caching
• Inefficient algorithms or data structures
• Blocking operations that should be async

Step 6.5: Virtue Scorecard

Score the analyzed code against the 7 Code Virtues (see skills/_references/virtues/code-virtues.md). This provides a positive quality assessment alongside the issue-based findings.

For each virtue, assign 1-5 stars based on evidence:

Virtue	What to Measure	Evidence Sources
Working	Test coverage, CI status, known bugs	Test files, coverage reports, issue trackers
Unique	Duplication level, copy-paste patterns	Duplication analysis from Step 4
Simple	Cyclomatic complexity, entity count, nesting depth	Complexity metrics from Step 4
Clear	Naming quality, self-documenting structure, magic values	Code Clarity checks from Step 4
Easy	How many files/layers a typical change touches	Grain analysis, coupling assessment
Developed	Type maturity, abstraction quality, API design	Architecture validation from Step 5
Brief	Verbosity, boilerplate ratio, unnecessary code	Code Organization checks from Step 4

Scoring guide:

• ★☆☆☆☆ — Significant problems, this virtue is actively violated
• ★★☆☆☆ — Below expectations, notable issues
• ★★★☆☆ — Adequate, some room for improvement
• ★★★★☆ — Good, minor issues only
• ★★★★★ — Excellent, this virtue is well-served

Evidence MUST be concrete: Each virtue's evidence cell must cite specific line numbers, metrics, or issue references — not vague prose. Bad: "Some complexity issues." Good: "save() at line 127 is 44 lines with 3 nesting levels; setupPlayerPerformances at line 207 uses imperative loop where filter() would suffice."

The scorecard highlights what to protect (high scores) as well as what to improve (low scores). This is especially valuable when prioritizing refactoring work — fix the lowest-scoring virtue that has the highest priority number first (Working before Unique before Simple, etc.).

Step 7: Generate Report

Create a comprehensive, actionable report with the following structure.

Non-Negotiable Output Rules (the report MUST satisfy all of these):

1. The Virtue Scorecard must use exactly these 7 virtue names in this order: Working, Unique, Simple, Clear, Easy, Developed, Brief. Use ★ star ratings (1-5). Do NOT substitute other dimensions.
2. Every issue must include a Location with file_path:line_number — never use step names or vague references instead of line numbers.
3. Every Critical and High severity issue must include a Suggested Fix section with a concrete code snippet — not just a prose description of what to change.
4. The Architecture Validation section is MANDATORY — never skip it. You MUST discover the project's declared architecture (from CLAUDE.md, .claude/rules/, .github/instructions/, or project docs) and validate the code against those specific boundaries. If no project architecture docs exist, state that explicitly and validate against universal principles only.

Report Template

# Refactoring Analysis: [Module/File Name]

## Summary
- **Language/Framework**: [detected stack]
- **Total Issues Found**: [count]
- **Critical**: [count]
- **High**: [count]
- **Medium**: [count]
- **Low**: [count]

## Virtue Scorecard
| Virtue      | Score | Evidence |
|-------------|-------|----------|
| Working     | [★☆☆☆☆ - ★★★★★] | [brief evidence] |
| Unique      | [★☆☆☆☆ - ★★★★★] | [brief evidence] |
| Simple      | [★☆☆☆☆ - ★★★★★] | [brief evidence] |
| Clear       | [★☆☆☆☆ - ★★★★★] | [brief evidence] |
| Easy        | [★☆☆☆☆ - ★★★★★] | [brief evidence] |
| Developed   | [★☆☆☆☆ - ★★★★★] | [brief evidence] |
| Brief       | [★☆☆☆☆ - ★★★★★] | [brief evidence] |

**Lowest-priority virtue to fix first:** [virtue name — why]

## Critical Issues

### 1. [Issue Title]
**Category**: [Category from checklist]
**Severity**: Critical
**Location**: `[File]:[Line]`

**Description**: [What's wrong and why it's critical]

**Current Code**:

[Code snippet showing the issue]

**Suggested Fix**:

[Code snippet showing the solution]

**Impact**: [Why this matters]

---

## High Priority Issues

[Same format as Critical]

---

## Medium Priority Issues

[Same format as Critical]

---

## Low Priority Issues

[Same format as Critical]

---

## Architecture Validation

### Principle Compliance
- [ ] Single Responsibility: each unit has one clear purpose
- [ ] Dependency Direction: dependencies flow in the direction the project declares
- [ ] Boundary Compliance: module boundaries are respected
- [ ] Separation of Concerns: distinct concerns live in distinct modules
- [ ] Naming Conventions: consistent naming throughout

### Violations Found
[List any architectural violations with references]

---

## Refactoring Opportunities

### Extract to Shared Code
[List code that should be extracted with suggestions]

### Existing Solutions to Adopt
[List framework/library features that could replace custom code]

### Modernization Opportunities
[List areas where modern language/framework features could be adopted]

---

## Positive Observations

[List things done well - proper patterns, good practices, etc.]

---

## Recommended Action Plan

1. **Immediate** (Critical/High issues):
   - [Action item]
   - [Action item]

2. **Short-term** (Medium issues):
   - [Action item]
   - [Action item]

3. **Long-term** (Low issues + optimizations):
   - [Action item]
   - [Action item]

Report Guidelines

Be Specific:

• Always include file paths and line numbers
• Show actual code snippets, not descriptions
• Provide concrete fix suggestions in the project's language

Be Actionable:

• Prioritize issues clearly
• Explain why each issue matters
• Provide working code examples for fixes

Be Balanced:

• Include positive observations
• Don't overwhelm with minor issues
• Focus on impactful improvements

Be Contextual:

• Consider the code's purpose and constraints
• Acknowledge tradeoffs
• Respect the project's existing conventions and style
• Adapt recommendations to the language/framework idioms

Tips for Effective Analysis

Focus on Impact

Prioritize issues that:

• Affect security or stability
• Violate core architectural principles
• Create maintenance burden
• Impact performance noticeably

Provide Context

For each finding:

• Explain why it's an issue
• Show how to fix it
• Describe the impact of fixing it

Be Constructive

• Frame issues as opportunities
• Acknowledge good practices when present
• Suggest incremental improvements
• Consider team coding style and constraints

Use References

• Point to specific checklist items in refactoring-checklist.md
• Reference principles in architecture-patterns.md
• Check .claude/rules/ and .github/instructions/ for project-specific knowledge
• Link to relevant language/framework documentation when helpful

Common Analysis Patterns

For Any Module With a Clear Responsibility

1. Check that the module only does what its declared responsibility says
2. Validate that dependencies flow in the direction the project expects
3. Review error handling completeness for the module's operations
4. Check for proper abstractions at the module's boundaries
5. Verify no concerns from other modules leak in

For Code That Coordinates Other Modules

1. Check it delegates rather than implements (orchestration, not business logic)
2. Validate it doesn't depend on implementation details of the modules it coordinates
3. Review that state management is appropriate for the coordination scope
4. Check for proper separation between coordination logic and the work being coordinated

For Code That Provides a Public API (library, SDK, shared module)

1. Verify the API surface is intentional (no accidental exposure of internals)
2. Check reusability and API design consistency
3. Review for unnecessary dependencies that consumers would inherit
4. Check for proper error handling and documentation
5. Validate that internal implementation details don't leak through the API

Limitations

• This skill analyzes code structure and patterns, not runtime behavior
• Cannot detect all performance issues without profiling
• Cannot validate business logic correctness
• Cannot verify against proprietary external APIs
• Recommendations are based on universal best practices but may need adjustment for specific project contexts
• Language-specific deep analysis may require additional domain knowledge

References

This skill uses three reference documents:

1. refactoring-checklist.md: 15 categories covering universal refactoring opportunities

   • Architecture & Design Patterns
   • Code Organization & Structure
   • Presentation / UI Layer
   • State Management
   • Asynchronous Programming
   • API & External Integration
   • Code Duplication
   • Error Handling & Edge Cases
   • Performance & Efficiency
   • Testing & Testability
   • Documentation & Code Clarity
   • Security & Privacy
   • Language Idioms & Modern Features
   • Observability & Monitoring
   • Build, Configuration & Dependencies

2. architecture-patterns.md: Universal architectural principles and validation methodology

   • Universal design principles (SOLID, DRY, YAGNI, etc.)
   • Project-specific architecture validation methodology (discover, identify role, validate boundaries)
   • Dependency management principles
   • Universal refactoring strategies (Extract, Move, Replace, Simplify, Introduce)
   • Architecture smell summary

3. skills/_references/virtues/code-virtues.md: The 7 Code Virtues positive quality framework

   • Priority-ordered virtues: Working, Unique, Simple, Clear, Easy, Developed, Brief
   • Virtue Scorecard methodology for balanced code assessment
   • Trade-off resolution when virtues conflict

These references are loaded into context during analysis to ensure comprehensive and accurate findings.