# Class Diagram

> Generates a Mermaid class diagram showing types, inheritance, and composition. Use when visualizing class hierarchies or documenting a module public API.

- **Type:** Skill
- **Install:** `agentstack add skill-athola-claude-night-market-class-diagram`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [athola](https://agentstack.voostack.com/s/athola)
- **Installs:** 0
- **Category:** [Agent Skills](https://agentstack.voostack.com/c/agent-skills)
- **Latest version:** 0.1.0
- **License:** MIT
- **Upstream author:** [athola](https://github.com/athola)
- **Source:** https://github.com/athola/claude-night-market/tree/master/plugins/cartograph/skills/class-diagram
- **Website:** https://athola.github.io/claude-night-market

## Install

```sh
agentstack add skill-athola-claude-night-market-class-diagram
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# Class Diagram

Generate a Mermaid class diagram showing types, their
relationships, and public interfaces from a codebase.

## When To Use

- Understanding class hierarchies and inheritance
- Documenting public APIs of a module
- Analyzing composition vs. inheritance patterns
- Answering "what types exist and how do they relate?"

## Workflow

### Step 1: Explore the Codebase

Dispatch the codebase explorer agent:

```
Agent(cartograph:codebase-explorer)
Prompt: Explore [scope] and return a structural model.
Focus on classes, dataclasses, protocols, type aliases,
inheritance, and composition for a class diagram.
Extract: class names, methods (public only), attributes,
parent classes, and composed types.
```

### Step 2: Generate Mermaid Syntax

Transform the structural model into a Mermaid class
diagram.

**Rules for class diagrams**:

- Use `classDiagram` diagram type
- Show only public methods and key attributes
- Use Mermaid relationship notation:
  - `` for dependency/usage
- Add stereotypes for special types:
  - `>` for Python protocols/interfaces
  - `>` for dataclasses
  - `>` for enums
  - `>` for abstract classes
- Limit to 12-15 classes maximum
- Group related classes with `namespace`
- Omit private methods and dunder methods
- Show return types for methods

**Example output**:

```mermaid
classDiagram
    class ResumeSession {
        +Path config_path
        +dict data
        +load() ResumeSession
        +to_pdf(Path) Path
        +to_html(Path) Path
    }

    class ResumeError {
        >
        +str message
        +str context
    }

    class ValidationError {
        +list~str~ fields
    }

    class RenderError {
        +str template
    }

    ResumeError  ResumeError
```

### Step 3: Render via MCP

Call the Mermaid Chart MCP to render:

```
mcp__claude_ai_Mermaid_Chart__validate_and_render_mermaid_diagram
  prompt: "Class diagram of [scope]"
  mermaidCode: [generated syntax]
  diagramType: "classDiagram"
  clientName: "claude-code"
```

If rendering fails, fix syntax and retry (max 2 retries).

### Step 4: Present Results

Show the rendered diagram with analysis notes:

- Total classes and relationship count
- Key inheritance hierarchies identified
- Composition patterns noted

## Exit Criteria

- [ ] Mermaid `classDiagram` syntax generated with at least one class
      definition including public methods or attributes
- [ ] `mcp__claude_ai_Mermaid_Chart__validate_and_render_mermaid_diagram`
      called with `diagramType: "classDiagram"` and returns without error
- [ ] Analysis notes include total class count, identified inheritance
      hierarchies, and composition patterns
- [ ] Private methods and dunder methods (`__init__`, `__repr__`, etc.)
      are absent from the generated diagram
- [ ] Diagram contains at most 15 classes; if more exist in scope,
      aggregation is applied and noted

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [athola](https://github.com/athola)
- **Source:** [athola/claude-night-market](https://github.com/athola/claude-night-market)
- **License:** MIT
- **Homepage:** https://athola.github.io/claude-night-market

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-athola-claude-night-market-class-diagram
- Seller: https://agentstack.voostack.com/s/athola
- Browse the marketplace: https://agentstack.voostack.com/browse

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