arch-from-code

Architecture from Code

Overview

Read the actual codebase. Generate accurate architecture diagrams. No guessing, no outdated docs — diagrams that reflect what the code ACTUALLY does right now.

When to Use

• "Document this project's architecture"
• "Show me the dependency graph"
• "Generate a C4 diagram of this system"
• "What services talk to each other?"
• "Map out the data flow"
• Onboarding onto an unfamiliar codebase
• Architecture review before major refactoring
• Generating ADRs (Architecture Decision Records)

Quick Start

# Step 1: Identify the codebase structure
find . -name "*.ts" -o -name "*.py" -o -name "*.go" | head -50
# Or: list top-level directories
ls -la src/ app/ lib/ services/ packages/

# Step 2: Run this skill's analysis process (below)
# Step 3: Output Mermaid diagram

Process

Step 1: Discover Project Shape

# Package manager = tech stack signal
ls package.json pyproject.toml go.mod Cargo.toml pom.xml *.csproj 2>/dev/null

# Entry points
ls src/index.* src/main.* app/main.* cmd/main.* 2>/dev/null

# Service boundaries (microservices)
ls -d services/* apps/* packages/* 2>/dev/null

# Configuration reveals integrations
cat .env.example docker-compose.yml 2>/dev/null | grep -i "host\|url\|port\|database\|redis\|queue"

Step 2: Trace Dependencies

For TypeScript/JavaScript:

# External dependencies = integration points
cat package.json | jq '.dependencies' 
# Internal imports = module relationships
grep -r "from ['\"]\.\./" src/ --include="*.ts" | sed 's/.*from ['\''\"]\(.*\)['\''\"]/\1/' | sort | uniq -c | sort -rn

For Python:

cat requirements.txt pyproject.toml | grep -v "^#"
grep -r "^from\|^import" src/ --include="*.py" | grep -v __pycache__ | sort | uniq -c | sort -rn

For Go:

cat go.mod | grep -v "^//"
grep -r "import" . --include="*.go" | grep -v vendor | sort | uniq -c | sort -rn

Step 3: Identify Layers & Boundaries

Read top-level directories and classify: