Coupling Analysis Skill

Analyze code coupling across three dimensions and generate actionable HTML reports.

Framework: Balanced Coupling (Vlad Khononov)

Three key dimensions determine coupling risk:

1. Integration Strength (How tightly modules connect)

Level	Score	Detection Pattern
Intrusive	1.00	Direct property access, internal state manipulation
Functional	0.75	Function/component usage, hooks, methods
Model	0.50	Data type imports, interfaces used as data
Contract	0.25	Pure interface/type imports

2. Distance (Where dependencies live)

Level	Score	Detection Pattern
Same Module	0.25	Same directory (./Component)
Sibling Module	0.50	Sibling directory (../utils)
Distant Module	0.75	Different top-level (@/contexts, ~/lib)
External	1.00	External packages (react, lodash)

3. Volatility (Change frequency from Git history)

Level	Score	Changes (6 months)
Low	0.00	0-2 changes
Medium	0.50	3-10 changes
High	1.00	11+ changes

Balance Score Formula

balance = (strength × volatility) × 0.6 + |strength - (1 - distance)| × 0.4

Interpretation:

• 0.0 - 0.2: Well balanced (ideal)
• 0.2 - 0.4: Acceptable
• 0.4 - 0.6: Needs attention
• 0.6+: Risky, consider refactoring

Execution Steps

Step 1: Identify Target Directory and Language

Determine the primary language by checking for:

• tsconfig.json or *.ts/*.tsx → TypeScript
• pyproject.toml or *.py → Python
• go.mod or *.go → Go
• Cargo.toml or *.rs → Rust
• package.json with *.js/*.jsx → JavaScript

Step 2: Gather File List

# TypeScript/JavaScript
find . -type f \( -name "*.ts" -o -name "*.tsx" -o -name "*.js" -o -name "*.jsx" \) \
  -not -path "*/node_modules/*" \
  -not -path "*/.git/*" \
  -not -name "*.d.ts" \
  -not -name "*.stories.*" \
  -not -name "*.test.*" \
  -not -name "*.spec.*"

# Python
find . -type f -name "*.py" \
  -not -path "*/.venv/*" \
  -not -path "*/venv/*" \
  -not -path "*/__pycache__/*" \
  -not -name "*_test.py" \
  -not -name "test_*.py"

# Go
find . -type f -name "*.go" \
  -not -path "*/vendor/*" \
  -not -name "*_test.go"

Step 3: Extract Import Dependencies

For each source file, extract imports using language-specific patterns:

TypeScript/JavaScript:

import\s+(?:(?:\{[^}]+\}|\*\s+as\s+\w+|\w+)\s+from\s+)?['"]([^'"]+)['"]

Python:

(?:from\s+(\S+)\s+import|import\s+(\S+))

Go:

import\s+(?:\w+\s+)?["']([^"']+)["']

Step 4: Calculate Git Volatility

# Get change count for each file (last 6 months)
git log --since="6 months ago" --name-only --pretty=format: -- "*.ts" "*.tsx" | \
  grep -v '^$' | sort | uniq -c | sort -rn

Step 5: Analyze Each Coupling

For each import relationship:

1. Determine strength from import pattern
2. Calculate distance from file paths
3. Look up volatility from git history
4. Compute balance score

Step 6: Generate HTML Report

The report MUST include these sections:

Summary Statistics Card

• Total files analyzed
• Total couplings found
• Average strength, distance, volatility
• Overall balance score with color indicator

Most Frequently Changed Files

• Top 10 files by change count
• Badge indicating volatility level (High/Medium/Low)

Two-Column Layout

Left Column:

• Risky Couplings (score ≥ 0.4) with:

  • Score badge
  • Volatility indicator
  • Strength type
  • File path → dependency path
  • Warning box explaining WHY it's risky
  • Action box with specific refactoring suggestions

• Well-Balanced Couplings (score < 0.2) with:

  • Score badge
  • Pattern explanation

Right Column:

• D3.js Force-Directed Dependency Graph:
  • Nodes colored by volatility (red=high, yellow=medium, green=low)
  • Node size by dependency count
  • Edges showing coupling relationships
  • Filters for strength and volatility
  • Zoom and pan support

Legend Section

• Strength levels with scores
• Distance levels with scores
• Balance score interpretation guide

Step 7: Provide "So What?" Context

Every metric MUST include explanatory text:

BAD (raw numbers only):

Average Strength: 0.74

GOOD (with context):

Average Strength: 0.74
→ Component usage is central (Functional level)
→ Most dependencies are function/hook calls, not loose contracts

Output Location

Save the HTML report to:

<project-root>/coupling-analysis.html

Or if analyzing a specific package:

<package-dir>/coupling-analysis.html

Example Insights to Include

For AuthContext-like patterns (high volatility + many dependents):

⚠️ Warning: AuthContextは16回変更されており、12以上のファイルから依存されています。
変更のたびに広範囲に影響が及ぶリスクがあります。

💡 Action:
- 認証状態（isAuthenticated）と認証操作（signIn/signOut）を分離検討
- 状態のみのuseAuthStateと操作のみのuseAuthActionsに分割
- カスタムフックで必要な部分だけを公開

Anti-Patterns to Detect

1. God Module: Single file with 10+ dependents AND high volatility
2. Shotgun Surgery: One change requires modifying many files
3. Distant Intrusive: High strength (0.75+) combined with high distance (0.75+)
4. Volatile Core: Core utilities with 10+ changes in 6 months

Report Quality Checklist

• Two-column responsive layout
• D3.js interactive graph with filters
• Every metric has "So What?" explanation
• Risky couplings have Warning + Action boxes
• Color-coded badges (red/yellow/green)
• Dark theme (GitHub-style)
• Japanese explanations for Japanese codebases
• Mobile-responsive design