product-starter: Skill for Claude Code

.claude/skills/add-feature/SKILL.md

add-feature is a skill for Claude Code from jujunjun110/product-starter. It costs 38 tokens per session (748 once invoked), scanned A, original, MIT.

A feature-building workflow for a four-layer Domain-Driven Design structure, which separates business rules, application actions, technical integrations, and user-facing code.

In plain words
What is it for?
Use it to create the domain model, database repository, optional external-service adapter, use case, data loader, and page action needed for a feature.
Why use it?
It reduces the chance that a new feature will mix unrelated responsibilities or bypass the project's architecture rules.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

This is jujunjun110/product-starter's own configuration. It tells Claude Code how to work on product-starter itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything product-starter configures →

Reuse

Borrowing it

Nothing to install: this file belongs to jujunjun110/product-starter. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/jujunjun110/product-starter/main/.claude/skills/add-feature/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/jujunjun110/product-starter

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 add-feature

README.md
[![agentmods](https://agentmods.dev/badge/skills/jujunjun110/product-starter/add-feature/github.svg)](https://agentmods.dev/skills/jujunjun110/product-starter/add-feature)
Your own site
<a href="https://agentmods.dev/skills/jujunjun110/product-starter/add-feature"><img src="https://agentmods.dev/badge/skills/jujunjun110/product-starter/add-feature/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 add-feature

Your own site · 80×15
<a href="https://agentmods.dev/skills/jujunjun110/product-starter/add-feature"><img src="https://agentmods.dev/badge/skills/jujunjun110/product-starter/add-feature.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 38 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 748 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 $0.00038 $0.00748
Opus 5.5 $0.00015 $0.00299
Sonnet 5.5 $0.00008 $0.00150
Haiku 4.5 $0.00004 $0.00075

Measured 1mo ago against content hash 9ae16e26d5bb, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

add-feature 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 1mo 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/add-feature/SKILL.md · 66 lines

What it actually says

機能追加スキル

ユーザーが「〇〇な機能を作って」と指示したときに適用する。 DDD 4層アーキテクチャに従い、以下のファイルを一括生成する。

生成するファイル

  1. Domain Model (src/backend/domain/models/{name}.model.ts)

    • Rich Domain Model として設計(ファクトリメソッド create() + reconstruct())
    • バリデーションはモデル自身で行う
    • エラーは Result<T, E> 型で返す
  2. Repository Interface (src/backend/domain/repositories/{name}.repository.ts)

    • ドメインモデル型のみ使用(ORM型を出さない)
  3. Gateway Interface(必要な場合: src/backend/domain/gateways/{name}.gateway.ts)

    • 外部API連携がある場合のみ
  4. UseCase (src/backend/application/usecases/{action}-{name}.usecase.ts)

    • クラスベース + コンストラクタ DI
    • execute() メソッドで公開
  5. Repository 実装 (src/backend/infrastructure/repositories/prisma-{name}.repository.ts)

    • Prisma 経由。ORM型 ↔ ドメインモデル変換を担当
  6. Gateway 実装(必要な場合)

    • 本番: src/backend/infrastructure/adapters/{provider}-{name}.adapter.ts
    • Stub: src/backend/infrastructure/adapters/stub-{name}.adapter.ts
  7. Composition (src/backend/presentation/composition/{name}.composition.ts)

    • DI組み立て。環境変数でStub/本番を切り替え
  8. Loader (src/backend/presentation/loaders/{name}.loader.ts)

    • データ取得用
  9. Action (src/backend/presentation/actions/{name}.action.ts)

    • 'use server' 付き。副作用用
  10. ページ (src/app/{path}/page.tsx)

    • Server Component。loader を呼んでデータ表示
  11. Unit テスト

    • test/unit/domain/models/{name}.model.test.ts
    • test/unit/application/usecases/{action}-{name}.usecase.test.ts

Prisma スキーマ

必要に応じて prisma/schema.prisma にモデルを追加し、pnpm db:migrate でマイグレーションを作成する。

ルール

  • ファイル命名は kebab-case + レイヤーサフィックス
  • 依存方向: presentation → application → domain ← infrastructure
  • application から infrastructure を直接 import しない
  • presentation/loaders, actions から domain, infrastructure を直接 import しない
  • 関数エクスポートでサービスを実装しない(クラスベース必須)
  • 生成後に pnpm verify を実行して全パスすることを確認

サンプル(参考)

既存の Joke 機能(joke.model.ts, generate-joke.usecase.ts 等)を参考にする。

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. 1mo ago First seen · 66 lines · 38 tokens per session scan A 9ae16e26d5bb

Subscribe to this mod's changes

add-feature is a skill published in the GitHub repository jujunjun110/product-starter (17 stars, last pushed 4mo ago), licensed MIT. It adds 38 tokens to every session and 748 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-09-03.

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