# Optional skills

> Five opt-in skills Devbook maintains because no vendor does - API design, database migrations, feature docs, licensing and LLM feature security.

Devbook writes skills only where no vendor maintains one. Each stands alone, with no links to other Devbook files, and loads only when a request matches its description. Install the ones a project needs; the bootstrap prompt counts them toward its cap of three.

| Skill | Use it for |
|---|---|
| [`api-design`](https://github.com/nitinraturi/devbook.raturi.in/blob/main/optional/plugins/api-design/skills/api-design/SKILL.md) | Adding or changing REST endpoints: OpenAPI first, RFC 9457 problem details, status codes, pagination, idempotency keys, ETags and Standard Webhooks |
| [`db-migration`](https://github.com/nitinraturi/devbook.raturi.in/blob/main/optional/plugins/db-migration/skills/db-migration/SKILL.md) | Relational schema changes: a plan you approve, constraints and indexes, and expand-migrate-contract for live tables |
| [`feature-doc`](https://github.com/nitinraturi/devbook.raturi.in/blob/main/optional/plugins/feature-doc/skills/feature-doc/SKILL.md) | `FEATURE.md` docs with EARS rules and stable IDs, only for features with business rules |
| [`licensing`](https://github.com/nitinraturi/devbook.raturi.in/blob/main/optional/plugins/licensing/skills/licensing/SKILL.md) | Licences of dependencies, assets and copied code, with SPDX identifiers and the notices they need |
| [`llm-security`](https://github.com/nitinraturi/devbook.raturi.in/blob/main/optional/plugins/llm-security/skills/llm-security/SKILL.md) | Features that call a language model: untrusted input and output, permissions in code, confirmation for actions, and cost caps |

## Install

In Claude Code, add Devbook's marketplace once, then install a skill as a plugin:

```sh
claude plugin marketplace add nitinraturi/devbook.raturi.in
claude plugin install api-design@devbook --scope project
```

In Codex, Cursor, GitHub Copilot or Gemini CLI, install the skill with the GitHub CLI:

```sh
gh skill install nitinraturi/devbook.raturi.in api-design --agent codex
```

Use `--agent cursor`, `github-copilot` or `gemini-cli` for the other agents. Skills installed by `gh skill` record their source, so `gh skill update` finds new versions.

The skills are licensed [CC BY 4.0](/license/). Each one has measured eval cases in its plugin folder, and the results are on the [evals page](/evals/).