Make Arch Diag

Make-Arch-Diag: Architecture Diagram Generation

Creates comprehensive architecture diagrams for selected components or systems using mermaid syntax.

When to Use

• Documenting a new feature or component
• Updating architecture documentation after changes
• Onboarding new team members
• Explaining complex system interactions
• Before making significant architectural changes

Critical Constraints

ALWAYS:

• Ask user which component/system to diagram
• Use the /mermaid skill for diagram creation
• Include multiple views (data flow, component structure, sequence diagrams)
• Save diagrams to temp/make-arch-diag/{component-name}/
• Use consistent color coding across all diagrams

NEVER:

• Create diagrams without understanding the code
• Skip reading the actual implementation
• Use generic placeholder names
• Create diagrams that contradict the code

---

Workflow

Step 1: Component Selection

Ask the user which area they want diagrammed:

Which component or system would you like to diagram?

Examples:
- Authentication system
- Database layer
- API endpoints
- Message queue processing
- State management
- Specific feature (e.g., "user registration flow")

Please specify the component/system:

Step 2: Scope Definition

Based on user input, determine:

• Boundaries: What's in scope vs out of scope
• Level of Detail: High-level architecture vs detailed implementation
• Audience: Developers, architects, stakeholders

Step 3: Code Exploration

Investigate the codebase:

• Find entry points (main, CLI, API routes)
• Trace execution flows
• Identify components and their relationships
• Map data flows
• Document external dependencies

Step 4: Diagram Types Selection

Choose appropriate diagram types:

Component Diagram (Always include)

• Shows major components and their relationships
• Good for: Understanding system structure

Data Flow Diagram (Include if data transformation is central)

• Shows how data moves through the system
• Good for: Understanding pipelines, ETL, processing

Sequence Diagram (Include if interactions are complex)

• Shows step-by-step execution flow
• Good for: Understanding request/response, async operations

State Diagram (Include if state management is central)

• Shows states and transitions
• Good for: Understanding lifecycle, workflows

Deployment Diagram (Include for infrastructure docs)

• Shows how system is deployed
• Good for: Understanding runtime environment

Step 5: Create Diagrams

Use /mermaid skill to create each diagram:

• Follow standard color palette
• Include legends
• Add clear labels and descriptions
• Group related components in subgraphs

Step 6: Write Architecture Description

Create temp/make-arch-diag/{component}/architecture.md:

# {Component} Architecture

## Overview
[2-3 paragraph overview of the component]

## Diagrams

### Component Structure
[Embed component diagram]

### Data Flow
[Embed data flow diagram]

### Sequence Diagrams
[Embed sequence diagrams for key operations]

## Components

### Component 1: {Name}
- **Purpose**: [What it does]
- **Responsibilities**: [What it's responsible for]
- **Dependencies**: [What it depends on]
- **Interface**: [How others interact with it]

### Component 2: {Name}
[Repeat for each component]

## Key Flows

### Flow 1: {Operation}
1. [Step 1]
2. [Step 2]
3. [Step 3]

### Flow 2: {Operation}
[Repeat for each key operation]

## Design Decisions

### Decision 1: {Topic}
- **Context**: [Why this decision was needed]
- **Options Considered**: [Alternatives]
- **Chosen**: [What was chosen]
- **Rationale**: [Why]
- **Tradeoffs**: [Costs and benefits]

## Constraints and Invariants

- [Constraint 1]
- [Constraint 2]
- [Invariant 1]
- [Invariant 2]

## Extension Points

- [Where/how to extend functionality]

## Related Documentation

- [Links to other architecture docs]
- [Links to API documentation]
- [Links to design documents]

---

Example: Authentication System

Component Diagram

%%{init: {'flowchart': {'nodeSpacing': 50, 'rankSpacing': 60}}}%%
graph TB
    classDef handler fill:#e65100,stroke:#ffb74d,stroke-width:2px,color:#fff;
    classDef stateNode fill:#004d40,stroke:#4db6ac,stroke-width:2px,color:#fff;
    classDef integration fill:#c62828,stroke:#ef9a9a,stroke-width:2px,color:#fff;
    classDef output fill:#00695c,stroke:#4db6ac,stroke-width:2px,color:#fff;

    subgraph API ["API Layer"]
        Login["/login endpoint━━━━━━━━━━POST credentials"]
        Refresh["/refresh endpoint━━━━━━━━━━POST refresh token"]
        Logout["/logout endpoint━━━━━━━━━━POST token"]
    end

    subgraph Auth ["Authentication Service"]
        AuthService["AuthService━━━━━━━━━━authenticate()generate_token()verify_token()"]
        TokenManager["TokenManager━━━━━━━━━━create_access_token()create_refresh_token()validate_token()"]
    end

    subgraph Storage ["Data Layer"]
        UserDB[(User Database)]
        TokenCache[(Token CacheRedis)]
    end

    Login --> AuthService
    Refresh --> TokenManager
    Logout --> TokenManager

    AuthService --> UserDB
    AuthService --> TokenManager
    TokenManager --> TokenCache

    class Login,Refresh,Logout handler;
    class UserDB,TokenCache stateNode;
    class AuthService,TokenManager integration;

Color Legend: | Color | Category | Description | |-------|----------|-------------| | Orange | Handler | API endpoints | | Teal | State | Data storage | | Red | Integration | Service components |

Sequence Diagram: Login Flow

sequenceDiagram
    participant Client
    participant API as /login endpoint
    participant Auth as AuthService
    participant DB as User Database
    participant TM as TokenManager
    participant Cache as Redis

    Client->>API: POST /login {username, password}
    API->>Auth: authenticate(username, password)
    Auth->>DB: query user by username
    DB-->>Auth: User record
    Auth->>Auth: verify password hash

    alt Valid credentials
        Auth->>TM: generate_tokens(user_id)
        TM->>Cache: store refresh token
        Cache-->>TM: OK
        TM-->>Auth: {access_token, refresh_token}
        Auth-->>API: Success + tokens
        API-->>Client: 200 OK + tokens
    else Invalid credentials
        Auth-->>API: AuthenticationError
        API-->>Client: 401 Unauthorized
    end

Data Flow Diagram

%%{init: {'flowchart': {'nodeSpacing': 40, 'rankSpacing': 50}}}%%
flowchart LR
    classDef phase fill:#6a1b9a,stroke:#ba68c8,stroke-width:2px,color:#fff;
    classDef handler fill:#e65100,stroke:#ffb74d,stroke-width:2px,color:#fff;
    classDef output fill:#00695c,stroke:#4db6ac,stroke-width:2px,color:#fff;

    Input["Credentials━━━━━━━━━━usernamepassword"]

    subgraph Processing
        Hash["Hash Password━━━━━━━━━━bcrypt"]
        Compare["Compare━━━━━━━━━━stored vs provided"]
        Generate["Generate Tokens━━━━━━━━━━JWT + Refresh"]
    end

    Output["Response━━━━━━━━━━access_tokenrefresh_tokenexpires_in"]

    Input --> Hash --> Compare --> Generate --> Output

    class Input phase;
    class Hash,Compare,Generate handler;
    class Output output;

Color Legend: | Color | Category | Description | |-------|----------|-------------| | Purple | Phase | Input/stages | | Orange | Handler | Processing steps | | Dark Teal | Output | Final output |

---

Diagram Best Practices

1. Component Diagrams

• Group related components in subgraphs
• Show only direct dependencies (avoid clutter)
• Use consistent colors for component types
• Label interfaces/contracts

2. Data Flow Diagrams

• Flow left-to-right or top-to-bottom
• Show transformations clearly
• Indicate data format at each stage
• Highlight validation points

3. Sequence Diagrams

• Include all actors/systems
• Show both success and error paths
• Annotate with actual function/method names
• Include timing constraints if relevant

4. State Diagrams

• Show all valid states
• Show all valid transitions
• Annotate transitions with trigger conditions
• Highlight error/terminal states

---

Common Patterns to Diagram

Layered Architecture

Presentation Layer → Business Logic Layer → Data Access Layer

Use component diagram with horizontal layers.

Pipeline Architecture

Input → Stage 1 → Stage 2 → Stage 3 → Output

Use data flow diagram showing transformations.

Event-Driven Architecture

Event Source → Event Bus → Handlers → Side Effects

Use sequence diagram showing event flow.

Microservices Architecture

Service A ↔ API Gateway ↔ Service B ↔ Database

Use deployment diagram showing runtime structure.

---

Tips

Understand Before Diagramming

• Read the code, don't guess
• Trace actual execution paths
• Verify assumptions with code inspection

Choose Right Level of Detail

• Executive overview: High-level components only
• Developer docs: Show classes/modules
• Implementation guide: Show methods/functions

Keep It Current

• Update diagrams when code changes
• Include diagram generation date
• Link diagrams to specific code versions/commits

Make It Useful

• Diagrams should answer questions
• Diagrams should reveal structure
• Diagrams should not just be pretty pictures

Source & license

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

• Author: Trecek
• Source: Trecek/useful-claude-skills
• License: MIT

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