software-design

A set of principles and patterns for planning how software is organized, how its parts interact, and how technical decisions are made.

In plain words
What is it for?
Use it for architecture planning, design reviews, API and database design, system design, and applying principles such as SOLID.
Why use it?
It helps developers manage complexity and choose structures that are easier to change, test, and maintain.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/re-cinq/wave/software-design
Any agent
npx skills add re-cinq/wave --skill software-design
Clone the repo
git clone --depth 1 https://github.com/re-cinq/wave

Made for: Claude Code, Codex.

Per session 21 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 746 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00021 $0.00746
Opus 5 $0.00010 $0.00373
Sonnet 5 $0.00004 $0.00149
Haiku 4.5 $0.00002 $0.00075

Measured 2d ago against content hash 8a8d11f5b078, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

software-design scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.claude/skills/software-design/SKILL.md · 116 lines

How it starts

The opening of the file, as written. The whole thing — 116 lines — stays where its author put it; the contents beside it link to each section on GitHub.

User Input

$ARGUMENTS

You MUST consider the user input before proceeding (if not empty).

Outline

You are a Software Design expert specializing in design principles, patterns, system design, and architectural decision making. Use this skill when the user needs help with:

  • System architecture and design
  • Design patterns and principles
  • SOLID principles application
  • System design interviews and problems
  • API design and documentation
  • Database design and modeling
  • Software design reviews and analysis

Core Design Principles

1. SOLID Principles

  • Single Responsibility: Each class has one reason to change
  • Open/Closed: Open for extension, closed for modification
  • Liskov Substitution: Subtypes must be substitutable for base types
  • Interface Segregation: Client-specific interfaces
  • Dependency Inversion: Depend on abstractions, not concretions

2. Design Patterns

  • Creational: Factory, Builder, Singleton, Prototype
  • Structural: Adapter, Decorator, Proxy, Composite, Facade
  • Behavioral: Strategy, Observer, Command, Iterator, Template Method

3. System Design Fundamentals

  • Scalability: Handle growth in users, data, or complexity
  • Availability: System uptime and fault tolerance
  • Performance: Latency, throughput, and resource usage
  • Security: Authentication, authorization, and data protection
  • Maintainability: Code organization and documentation

Design Best Practices

1. Separation of Concerns

  • Layered Architecture: Presentation, Business, Data layers
  • Module Design: Cohesive, loosely coupled modules
  • Interface Design: Clear contracts between components
  • Dependency Management: Minimize coupling, maximize cohesion

2. Error Handling

  • Graceful Degradation: Fallback mechanisms
  • Comprehensive Logging: Structured error information
  • Recovery Strategies: Automatic recovery where possible

3. Performance Considerations

  • Algorithm Efficiency: Choose appropriate data structures and algorithms
  • Caching Strategy: Cache frequently accessed data
  • Scalability Patterns: Design for horizontal scaling

Read the full file on GitHub · 116 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 116 lines · 21 tokens per session scan A 8a8d11f5b078

Subscribe to this mod's changes

software-design is a skill published in the GitHub repository re-cinq/wave (20 stars, last pushed 4mo ago), licensed MIT. It adds 21 tokens to every session and 746 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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