Archive code-to-diagram

Generate architecture diagrams, ER diagrams, sequence diagrams, flowcharts, and class diagrams from codebases using Mermaid.js. Use when users ask to visualize code structure, draw architecture diagrams, create ER diagrams from database models, generate sequence diagrams from API flows, or produce any diagram from source code. Triggers on: 'draw architecture', 'generate diagram', 'visualize code', 'ER diagram', 'sequence diagram', 'class diagram', 'flowchart from code', 'module dependency graph'.

install

source · Clone the upstream repo

git clone https://github.com/dp-archive/archive

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/dp-archive/archive "$T" && mkdir -p ~/.claude/skills && cp -r "$T/seed_skills/code-to-diagram" ~/.claude/skills/dp-archive-archive-code-to-diagram && rm -rf "$T"

manifest: seed_skills/code-to-diagram/SKILL.md

source content

Code to Diagram

Generate production-quality diagrams from source code via Mermaid.js, rendered to SVG/PNG with

mmdc

Environment

Executor required: This skill needs the

diagram

executor (Chromium + Node.js + mmdc pre-installed). If

mmdc

is not available, install first:

npm install -g @mermaid-js/mermaid-cli

Puppeteer config for headless environments — create at

/tmp/puppeteer-config.json

if missing:

{"args": ["--no-sandbox", "--disable-setuid-sandbox"]}

Workflow

Analyze — Read the codebase to understand structure (
```
glob
```
,
```
grep
```
,
```
read
```
)
Plan — Decide diagram type(s) based on user request and code patterns
Generate — Write
```
.mmd
```
file with Mermaid syntax
Render — Run
```
mmdc
```
to produce SVG and PNG
Verify — Read the output image and check correctness

Diagram Type Selection

User Intent	Diagram Type	Mermaid Keyword
System overview, module layout	Architecture	`graph TD` + `subgraph`
Database tables, ORM models	ER Diagram	`erDiagram`
API flow, request lifecycle	Sequence Diagram	`sequenceDiagram`
Inheritance, interfaces	Class Diagram	`classDiagram`
Business logic, conditionals	Flowchart	`flowchart TD`
Task states, lifecycle	State Diagram	`stateDiagram-v2`
Import/dependency tree	Dependency Graph	`graph LR`
Timeline, project phases	Gantt Chart	`gantt`

Analysis Strategy

Do NOT read every file. Use progressive analysis:

Step 1 — Directory scan:

glob("**/*.py")

glob("**/*.ts")

to understand module structure.

Step 2 — Entry points:

Python:
```
main.py
```
,
```
app.py
```
,
```
__init__.py
```
,
```
pyproject.toml
```
Node.js:
```
package.json
```
,
```
index.ts
```
,
```
app.ts
```
Java:
```
pom.xml
```
,
```
Application.java
```

Step 3 — Targeted reads by diagram type:

ER → ORM models (
```
models.py
```
,
```
schema.prisma
```
,
```
*.entity.ts
```
)
Architecture → Router registrations, dependency injection, config
Sequence → Specific endpoint handler + service call chain
Class → Class definitions via
```
grep("class ")
```

Step 4 — GitHub repos:

git clone --depth 1 <url> /tmp/repo-name

Then apply the same progressive scan.

Rendering

# SVG (transparent background, good for docs)
mmdc -i diagram.mmd -o diagram.svg -b transparent -p /tmp/puppeteer-config.json

# PNG (white background, 2x scale for sharpness)
mmdc -i diagram.mmd -o diagram.png -b white -s 2 -p /tmp/puppeteer-config.json

Always generate both formats. Use

-s 2

for PNG (sharp at any zoom level).

Mermaid Syntax Reference

For detailed patterns and examples per diagram type, see references/mermaid-patterns.md.

Key rules:

Short IDs, descriptive labels:
```
DB[("PostgreSQL 16")]
```
Use
```
subgraph
```
for logical grouping in architecture diagrams
Limit ER diagrams to ~10 entities — split by domain if larger
```
participant
```
aliases in sequence diagrams for short names
Quote labels with special chars:
```
A["Node (v1)"]
```
Max ~20 nodes per diagram — split into multiple if larger

Output Conventions

Write
```
.mmd
```
source + rendered files to workspace

Descriptive names:

architecture.mmd

er-diagram.png

api-sequence.svg

Multiple diagrams → create
```
diagrams/
```
folder with index

Quality Checklist

All entities/modules from the code are represented
Relationships and data flow directions are correct
Labels readable, not truncated or overlapping
No Mermaid syntax errors
Output image visually verified