sc-design

System & Component Design Skill

Architecture planning and interface design with industry best practices.

Quick Start

# Architecture design
/sc:design [target] --type architecture

# API specification
/sc:design payment-api --type api --format spec

# Database schema
/sc:design e-commerce --type database --format diagram

Behavioral Flow

1. Analyze - Examine requirements and existing system context
2. Plan - Define design approach based on type and format
3. Design - Create specifications with best practices
4. Validate - Ensure maintainability and scalability
5. Document - Generate diagrams and specifications

Flags

Flag	Type	Default	Description
--type	string	architecture	architecture, api, component, database
--format	string	spec	diagram, spec, code

Evidence Requirements

This skill does NOT require hard evidence. Deliverables are:

• Design specifications and diagrams
• Interface definitions
• Schema documentation

Design Types

Architecture (--type architecture)

• System structure and component relationships
• Scalability and reliability patterns
• Service boundaries and communication

API (--type api)

• RESTful/GraphQL endpoint design
• Request/response schemas
• Authentication and versioning

Component (--type component)

• Interface contracts and dependencies
• State management patterns
• Integration points

Database (--type database)

• Entity relationships and constraints
• Normalization and indexing
• Performance considerations

Output Formats

Diagram (--format diagram)

• ASCII or Mermaid diagrams
• Component relationship visualization
• Data flow representation

Specification (--format spec)

• OpenAPI/Swagger for APIs
• Detailed interface documentation
• Technical requirements

Code (--format code)

• Interface definitions
• Type declarations
• Skeleton implementations

Examples

System Architecture

/sc:design user-management --type architecture --format diagram
# Component relationships, data flow, scalability patterns

API Design

/sc:design payment-api --type api --format spec
# OpenAPI spec with endpoints, schemas, auth patterns

Component Interface

/sc:design notification-service --type component --format code
# TypeScript/Python interfaces with clear contracts

Database Schema

/sc:design inventory-db --type database --format diagram
# ER diagrams with relationships and constraints

MCP Integration

PAL MCP (Design Validation)

Tool	When to Use	Purpose
mcp__pal__planner	Architecture planning	Sequential planning with branching for design decisions
mcp__pal__consensus	Design decisions	Multi-model validation of architectural choices
mcp__pal__thinkdeep	Complex systems	Deep analysis of system requirements
mcp__pal__chat	Brainstorming	Collaborative design exploration
mcp__pal__apilookup	API standards	Get current API design best practices

PAL Usage Patterns

# Architecture planning
mcp__pal__planner(
    step="Designing microservices architecture for e-commerce platform",
    step_number=1,
    total_steps=4,
    more_steps_needed=True
)

# Validate design with consensus
mcp__pal__consensus(
    models=[
        {"model": "gpt-5.2", "stance": "for"},
        {"model": "gemini-3-pro", "stance": "against"},
        {"model": "deepseek", "stance": "neutral"}
    ],
    step="Evaluate: Should we use event sourcing for the order management system?"
)

# Deep system analysis
mcp__pal__thinkdeep(
    step="Analyzing scalability requirements for real-time notification system",
    hypothesis="WebSocket with Redis pub/sub will handle 100k concurrent users",
    confidence="medium",
    focus_areas=["scalability", "reliability", "performance"]
)

Rube MCP (Documentation & Collaboration)

Tool	When to Use	Purpose
mcp__rube__RUBE_SEARCH_TOOLS	External tools	Find diagramming, documentation tools
mcp__rube__RUBE_MULTI_EXECUTE_TOOL	Share designs	Post to Notion, Confluence, Slack
mcp__rube__RUBE_CREATE_UPDATE_RECIPE	Design workflows	Save reusable design processes

Rube Usage Patterns

# Create design document in Notion
mcp__rube__RUBE_SEARCH_TOOLS(queries=[
    {"use_case": "create notion page", "known_fields": "database:Architecture"}
])

mcp__rube__RUBE_MULTI_EXECUTE_TOOL(tools=[
    {"tool_slug": "NOTION_CREATE_PAGE", "arguments": {
        "title": "Payment API Design v2",
        "content": "## Overview\n..."
    }}
])

# Share design for review
mcp__rube__RUBE_MULTI_EXECUTE_TOOL(tools=[
    {"tool_slug": "SLACK_SEND_MESSAGE", "arguments": {
        "channel": "#architecture",
        "text": "New design ready for review: Payment API v2"
    }},
    {"tool_slug": "JIRA_CREATE_ISSUE", "arguments": {
        "project": "ARCH",
        "summary": "Review: Payment API Design",
        "issue_type": "Task"
    }}
])

Flags (Extended)

Flag	Type	Default	Description
--pal-plan	bool	false	Use PAL planner for systematic design
--consensus	bool	false	Validate design with multi-model consensus
--share	string	-	Share via Rube (notion, confluence, slack)
--create-ticket	bool	false	Create review ticket via Rube

Tool Coordination

• Read - Requirements analysis
• Grep/Glob - Pattern analysis
• Write - Design documentation
• Bash - External tool integration
• PAL MCP - Design planning, consensus validation, deep analysis
• Rube MCP - Documentation sharing, collaboration, review workflows