System Design

This is an opinionated architecture guide that pushes you toward Clean Architecture and DDD principles with some practical guardrails. The interesting bit is how strongly it emphasizes library-first development, telling you to search npm and existing SaaS before writing custom code, with specific examples like using cockatiel for retries instead of rolling your own. It enforces early returns, bans generic file names like utils.js and helpers.js in favor of domain-specific naming, and keeps functions under 50 lines and files under 200. The anti-patterns section is refreshingly direct about NIH syndrome. If you want Claude to be more pragmatic about leveraging existing solutions and less likely to reinvent wheels, this adds useful constraints to system design conversations.

skills.sh installs: 217
GitHub stars: 48
last updated: Aug 21, 2026

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Install

$ npx -y skills add qodex-ai/ai-agent-skills --skill system-design --agent claude-code

Installs into .claude/skills of the current project.

Files

Software Architecture Development Skill

This skill provides guidence for quality focused software development and architecture. It is based on Clean Architecture and Domain Driven Design principles.

Code Style Rules

General Principles

Early return pattern: Always use early returns when possible, over nested conditions for better readability
Avoid code duplication through creation of reusable functions and modules
Decompose long (more than 80 lines of code) components and functions into multiple smaller components and functions. If they cannot be used anywhere else, keep it in the same file. But if file longer than 200 lines of code, it should be split into multiple files.
Use arrow functions instead of function declarations when possible

System Design

Install

Files

Software Architecture Development Skill

Code Style Rules

General Principles

Best Practices

Library-First Approach

Details

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