/create-code-diagram

Generate a comprehensive Mermaid class diagram of the entire project codebase. Shows every class, interface, entity, handler, service — and how they relate to each other (inheritance, implementation, dependency, composition).

This is for humans — when you want to see the full picture, understand the system, or debug your mental model of the architecture.

Ships as a global skill in core.

Usage

/create-code-diagram                       # writes .claude/docs/code-diagram.md
/create-code-diagram path/to/output.md     # writes to the path you specify

Re-runnable. Each run overwrites the previous diagram. Always fresh.

What gets discovered

Discovered	How
Classes, records, interfaces, enums, abstract classes	Codebase scan via codebase-memory-mcp if available, otherwise direct file scanning
Inheritance	class extends base
Interface implementations	class implements interface
Dependencies	Constructor injection, method parameters
Composition	Class has property of another class type
Mediator handlers	Which command/query each handler covers

What gets organized

Discovered types are grouped by architectural layer:

%% Domain Layer
%% Application Layer — Interfaces
%% Application Layer — Features
%% Infrastructure Layer
%% API Layer — Endpoints

For each layer, the skill lists every type with its key members — properties for entities, methods for services and handlers.

Relationship arrows

Relationship	Mermaid syntax	When
Inheritance	`Child --	> Parent`
Implementation	Impl ..|> Interface	class implements interface
Dependency	ClassA --> ClassB	constructor injection, method call
Composition	ClassA *-- ClassB	has property of type ClassB
Association	ClassA o-- ClassB	collection of ClassB

Output format

Default location: .claude/docs/code-diagram.md

# Code Diagram

> Auto-generated by /create-code-diagram on {date}
> Re-run `/create-code-diagram` to update after code changes.

## Full Project Diagram

{mermaid classDiagram block}

## Legend
{relationship-arrow table}

## Statistics
- Total types: {count}
- Classes: {count}
- Interfaces: {count}
- Records: {count}
- Relationships: {count}
- Generated: {timestamp}

The output is pure Mermaid markdown — viewable in GitHub, VS Code Mermaid preview, or any markdown renderer that supports Mermaid (no external tools needed).

Sample diagram fragment

classDiagram
    %% ═══════════════════════════════════════
    %% DOMAIN LAYER
    %% ═══════════════════════════════════════

    class BaseEntity {
        +Guid Id
        +DateTime CreatedAt
        +DateTime? UpdatedAt
        +uint RowVersion
    }

    class IAuditableEntity {
        <<interface>>
        +string? CreatedBy
        +DateTime? ModifiedAt
        +string? ModifiedBy
    }

    class User {
        +string Email
        +string PasswordHash
        +string? FirstName
        +string? LastName
    }
    User --|> BaseEntity
    User ..|> IAuditableEntity

    %% ═══════════════════════════════════════
    %% APPLICATION LAYER — FEATURES
    %% ═══════════════════════════════════════

    class PingHandler {
        +Handle(PingQuery)
    }
    PingHandler --> IApplicationDbContext

Important rules

1. Include EVERYTHING. Don't skip small classes or "obvious" relationships. The user wants the full picture.
2. Group by layer. Domain → Application Interfaces → Application Features → Infrastructure → API/Socket/Worker.
3. Show key members. Properties for entities, methods for services and handlers. Don't list every private field.
4. Correct arrow types. Inheritance vs implementation vs dependency — use the right Mermaid syntax.
5. Re-runnable. Running again overwrites the previous diagram.
6. No external tools. Pure Mermaid markdown.

Related

• Concepts: Skill — where this fits in the skill ecosystem

Source

• Spec: core/skills/create-code-diagram/skill.md