Complexity Skill

YOU MUST EXECUTE THIS WORKFLOW. Do not just describe it.

Analyze code complexity to identify refactoring targets.

Execution Steps

Given /complexity [path]:

Step 1: Determine Target

If path provided: Use it directly.

If no path: Use current directory or recent changes:

git diff --name-only HEAD~5 2>/dev/null | grep -E '\.(py|go)$' | head -10

Step 2: Detect Language

# Check for Python files
ls *.py **/*.py 2>/dev/null | head -1 && echo "Python detected"

# Check for Go files
ls *.go **/*.go 2>/dev/null | head -1 && echo "Go detected"

Step 3: Run Complexity Analysis

For Python (using radon):

# Check if radon is installed
which radon || pip install radon

# Run cyclomatic complexity
radon cc <path> -a -s

# Run maintainability index
radon mi <path> -s

For Go (using gocyclo):

# Check if gocyclo is installed
which gocyclo || go install github.com/fzipp/gocyclo/cmd/gocyclo@latest

# Run complexity analysis
gocyclo -over 10 <path>

Step 4: Interpret Results

Cyclomatic Complexity Grades:

Grade	CC Score	Meaning
A	1-5	Low risk, simple
B	6-10	Moderate, manageable
C	11-20	High risk, complex
D	21-30	Very high risk
F	31+	Untestable, refactor now

Step 5: Identify Refactor Targets

List functions/methods that need attention:

• CC > 10: Should refactor
• CC > 20: Must refactor
• CC > 30: Critical, immediate action

Step 6: Write Complexity Report

Write to: .agents/complexity/YYYY-MM-DD-<target>.md

# Complexity Report: <Target>

**Date:** YYYY-MM-DD
**Language:** <Python/Go>
**Files Analyzed:** <count>

## Summary
- Average CC: <score>
- Highest CC: <score> in <function>
- Functions over threshold: <count>

## Refactor Targets

### Critical (CC > 20)
| Function | File | CC | Recommendation |
|----------|------|-----|----------------|
| <name> | <file:line> | <score> | <how to simplify> |

### High (CC 11-20)
| Function | File | CC | Recommendation |
|----------|------|-----|----------------|
| <name> | <file:line> | <score> | <how to simplify> |

## Refactoring Recommendations

1. **<Function>**: <specific suggestion>
   - Extract: <what to extract>
   - Simplify: <how to simplify>

## Next Steps
- [ ] Address critical complexity first
- [ ] Create issues for high complexity
- [ ] Consider refactoring sprint

Step 7: Report to User

Tell the user:

1. Overall complexity summary
2. Number of functions over threshold
3. Top 3 refactoring targets
4. Location of full report
5. Run /refactor <function> to address critical complexity targets

Key Rules

• Use the right tool - radon for Python, gocyclo for Go
• Focus on high CC - prioritize 10+
• Provide specific fixes - not just "refactor this"
• Write the report - always produce artifact

Quick Reference

Simplifying High Complexity:

• Extract helper functions
• Replace conditionals with polymorphism
• Use early returns
• Break up long functions
• Simplify nested loops

Examples

Analyzing Python Project

User says: /complexity src/

What happens:

1. Agent detects Python files in src/ directory
2. Agent checks for radon installation, installs if missing
3. Agent runs radon cc src/ -a -s for cyclomatic complexity
4. Agent runs radon mi src/ -s for maintainability index
5. Agent identifies 3 functions with CC > 20, 7 functions with CC 11-20
6. Agent writes detailed report to .agents/complexity/2026-02-13-src.md
7. Agent recommends extracting nested conditionals in process_request() function

Result: Complexity report identifies process_request() (CC: 28) as critical refactor target with specific extraction recommendations.

Finding Refactor Targets in Go Module

User says: /complexity

What happens:

1. Agent checks recent changes with git diff --name-only HEAD~5
2. Agent detects Go files, verifies gocyclo installation
3. Agent runs gocyclo -over 10 ./... on project
4. Agent finds HandleWebhook() function with complexity 34
5. Agent writes report with recommendation to extract validation logic
6. Agent reports top 3 targets: HandleWebhook (34), ProcessBatch (22), ValidateInput (15)

Result: Critical function identified for immediate refactoring with actionable extraction plan.

See Also

• refactor — Safe, verified refactoring for complexity targets

Troubleshooting

Problem	Cause	Solution
Tool not installed (radon/gocyclo)	Missing dependency	Agent auto-installs: pip install radon for Python or go install github.com/fzipp/gocyclo/cmd/gocyclo@latest for Go. Verify install path in $PATH.
No complexity issues found	Threshold too high or genuinely simple code	Lower threshold: try gocyclo -over 5 or check if path includes actual implementation files vs tests.
Report shows functions without recommendations	Generic analysis without codebase context	Read the high-CC functions to understand structure, then provide specific refactoring suggestions based on actual code patterns.
Mixed language project	Multiple languages in target path	Run analysis separately per language: /complexity src/python/ then /complexity src/go/, combine reports manually.