agentmods.dev

musubix-c4-design

musubix-c4-design is a skill for Claude Code from nahisaho/katashiro. It costs 42 tokens per session (1,114 once invoked), scanned A, original, MIT.

A guide for writing software architecture documents with the C4 model, a way to describe systems from broad context down to deployable parts and code.

In plain words
What is it for?
Use it to create system-context, container, and component diagrams and document external users, services, technologies, responsibilities, and communication paths.
Why use it?
It gives architecture work a consistent structure and connects design decisions to project requirements and technical constraints.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

not rated 0repo 7mo ago A scan 42 tokens original MIT

Good fit Use it to create system-context, container, and component diagrams and document external users, services, technologies, responsibilities, and communication paths.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/nahisaho/katashiro/musubix-c4-design
View source ↗ nahisaho/katashiro
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.

Any agent
npx skills add nahisaho/katashiro --skill musubix-c4-design
Clone the repo
git clone --depth 1 https://github.com/nahisaho/katashiro

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for musubix-c4-design

README.md
[![agentmods](https://agentmods.dev/badge/skills/nahisaho/katashiro/musubix-c4-design/github.svg)](https://agentmods.dev/skills/nahisaho/katashiro/musubix-c4-design)
Your own site
<a href="https://agentmods.dev/skills/nahisaho/katashiro/musubix-c4-design"><img src="https://agentmods.dev/badge/skills/nahisaho/katashiro/musubix-c4-design/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for musubix-c4-design

Your own site · 80×15
<a href="https://agentmods.dev/skills/nahisaho/katashiro/musubix-c4-design"><img src="https://agentmods.dev/badge/skills/nahisaho/katashiro/musubix-c4-design.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 42 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,114 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00042 $0.01114
Opus 5 $0.00021 $0.00557
Sonnet 5 $0.00008 $0.00223
Haiku 4.5 $0.00004 $0.00111

Measured 11d ago against content hash 1be36e2dd831, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

musubix-c4-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 11d 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/musubix-c4-design/SKILL.md · 163 lines

How it starts

The opening of the file, as written. The whole thing — 163 lines — stays where its author put it; the contents beside it link to each section on GitHub.

MUSUBIX C4 Design Skill

This skill guides you through creating C4 model architecture designs for MUSUBIX projects.

Overview

The C4 model provides four levels of abstraction for describing software architecture:

  1. Context - System boundaries and external actors
  2. Container - Technology choices and deployable units
  3. Component - Internal structure of containers
  4. Code - Implementation details (optional)

Prerequisites

Before creating designs:

  1. Read requirements from storage/specs/ (REQ-* files)
  2. Check steering/structure.ja.md for architecture guidelines
  3. Review steering/tech.ja.md for technology constraints

Design Document Template

# DES-[CATEGORY]-[NUMBER]: [Design Title]

## メタデータ
- **作成日**: YYYY-MM-DD
- **トレーサビリティ**: REQ-XXX-NNN

## 1. Context Level

### システムコンテキスト図
[External actors and systems that interact with our system]

### 外部アクター
| アクター | 説明 | インタラクション |
|---------|------|-----------------|
| User | システム利用者 | Web UI経由でアクセス |

## 2. Container Level

### コンテナ構成
| コンテナ | 技術 | 責務 |
|---------|------|------|
| Web App | React/Next.js | UI提供 |
| API Server | Node.js/Express | ビジネスロジック |
| Database | PostgreSQL | データ永続化 |

### コンテナ間通信
[Describe how containers communicate]

## 3. Component Level

### [Container Name] コンポーネント

| コンポーネント | 種別 | 責務 | 依存先 |
|---------------|------|------|--------|
| XxxService | Service | ビジネスロジック | XxxRepository |
| XxxRepository | Repository | データアクセス | Database |
| XxxController | Controller | リクエスト処理 | XxxService |

## 4. 設計パターン

### 適用パターン
| パターン | 適用箇所 | 理由 |
|---------|---------|------|
| Repository | データアクセス層 | 永続化の抽象化 |
| Service | ビジネス層 | ロジックの集約 |
| Factory | オブジェクト生成 | 生成ロジックの分離 |

## 5. 非機能要件への対応

### セキュリティ
- 認証: [方式]
- 認可: [方式]
- データ保護: [方式]

### スケーラビリティ
- [スケーリング戦略]

### 可用性
- [可用性設計]

C4 Diagram Syntax (Mermaid)

Context Diagram

flowchart TB
    subgraph External["外部システム"]
        User[ユーザー]
        ExtAPI[外部API]
    end
    
    subgraph System["対象システム"]
        App[アプリケーション]
    end
    
    User --> App
    App --> ExtAPI

Read the full file on GitHub · 163 lines

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. 11d ago First seen · 163 lines · 42 tokens per session scan A 1be36e2dd831

Subscribe to this mod's changes

musubix-c4-design is a skill published in the GitHub repository nahisaho/katashiro (0 stars, last pushed 7mo ago), licensed MIT. It adds 42 tokens to every session and 1,114 once invoked, about $0.0002 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 2026-08-31.

PlanningWriting and docs
Related

Other skills, from other repositories

systematic-debugging

Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes.

obra/superpowers · 21 tokens

local-ai-agents

Build local-first AI agents that run entirely on a developer workstation with Microsoft Foundry Local and Qwen function-calling models. Covers Small Language Models (SLMs), the OpenAI-compatible local endpoint, sandboxed local tools, local RAG with Chroma, local MCP servers, hybrid cloud/local routing, and the…

microsoft/ai-agents-for-beginners · 200 tokens

next-cache-components-adoption

Turn on Cache Components in a Next.js app and resolve the blocking routes it surfaces. Use when the user wants to enable, adopt, or migrate to Cache Components, flip the cacheComponents flag, work through a flood of blocking-prerender / instant validation errors, run the cache-components-instant-false codemod, or…

vercel/next.js · 95 tokens

insight-error-page

Write or audit an insight-kind error page for the Next.js dev overlay. Use when creating a new errors/ .mdx page, auditing an existing one, or checking that a page matches the framework fix cards. Covers page structure, title alignment, FixCard cards with Copy prompt button, code snippets, terminology verification…

vercel/next.js · 83 tokens

next-cache-components-optimizer

Drive a Next.js route to instant navigation by setting up an agentic loop, under Cache Components / PPR, on initial load (hard navigation) and client-side navigation (soft navigation). Encode the goal as a failing @next/playwright instant() e2e and work it to green, one verified route at a time; the shipped test then…

vercel/next.js · 170 tokens

next-partial-prefetching-adoption

Turn on Partial Prefetching in a Next.js app and work through the insights it surfaces. Use when the user wants to enable or adopt Partial Prefetching, flip the partialPrefetching flag, opt routes in with export const prefetch = 'partial', audit Link prefetch={true} behavior, preserve existing prefetched UI with…

vercel/next.js · 103 tokens