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code-clone-assistant

@terrylica/cc-skills
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Detects and refactors code duplication using PMD CPD. Use when identifying code clones, addressing DRY violations, or refactoring duplicate code across repositories.

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SKILL.md

name code-clone-assistant
description Detects and refactors code duplication using PMD CPD. Use when identifying code clones, addressing DRY violations, or refactoring duplicate code across repositories.
allowed-tools Read, Grep, Bash, Edit, Write

Code Clone Assistant

Detect code clones and guide refactoring using PMD CPD (exact duplicates) + Semgrep (patterns).

Tools

  • PMD CPD v7.17.0+: Exact duplicate detection
  • Semgrep v1.140.0+: Pattern-based detection

Tested: October 2025 - 30 violations detected across 3 sample files Coverage: ~3x more violations than using either tool alone

When to Use

Triggers: "find duplicate code", "DRY violations", "refactor similar code", "detect code duplication", "similar validation logic", "repeated patterns", "copy-paste code", "exact duplicates"

Why Two Tools?

PMD CPD and Semgrep detect different clone types:

Aspect PMD CPD Semgrep
Detects Exact copy-paste duplicates Similar patterns with variations
Scope Across files ✅ Within/across files (Pro only)
Matching Token-based (ignores formatting) Pattern-based (AST matching)
Rules ❌ No custom rules ✅ Custom rules

Result: Using both finds ~3x more DRY violations.

Clone Types

Type Description PMD CPD Semgrep
Type-1 Exact copies ✅ Default ✅
Type-2 Renamed identifiers ✅ --ignore-* ✅
Type-3 Near-miss with variations ⚠️ Partial ✅ Patterns
Type-4 Semantic clones (same behavior) ❌ ❌

Quick Start Workflow

# Step 1: Detect exact duplicates (PMD CPD)
pmd cpd -d . -l python --minimum-tokens 20 -f markdown > pmd-results.md

# Step 2: Detect pattern violations (Semgrep)
semgrep --config=clone-rules.yaml --sarif --quiet > semgrep-results.sarif

# Step 3: Analyze combined results (Claude Code)
# Parse both outputs, prioritize by severity

# Step 4: Refactor (Claude Code with user approval)
# Extract shared functions, consolidate patterns, verify tests

Reference Documentation

For detailed information, see: