# Docker Sandboxes Kits

Use this skill when authoring, validating, packaging, signing, or composing a Docker...

- Repository: https://github.com/docker/skills (609 stars)
- Category: AI and agents
- License: Apache-2.0
- Last updated: 2026-10-30
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add docker/skills --skill docker-sandboxes-kits -g -a claude-code -y`
Codex: `npx skills add docker/skills --skill docker-sandboxes-kits -g -a codex -y`
Cursor: `npx skills add docker/skills --skill docker-sandboxes-kits -g -a cursor -y`
Gemini CLI: `npx skills add docker/skills --skill docker-sandboxes-kits -g -a gemini-cli -y`
Claude Code plugin marketplace: `/plugin marketplace add docker/skills`

## Description

Use this skill when authoring, validating, packaging, signing, or composing a Docker Sandboxes kit `spec.yaml` (`sbx kit add/inspect/pack/pull/push/sign/validate/verify`), even if the user just says they want to "add a tool to a sandbox agent", "build a reusable sandbox extension", "publish a kit to a registry", or "give a mixin its own credentials and network access". Covers the kit-spec v2 grammar (`kind: sandbox` vs `kind: mixin`, the `sandbox:` block, `permissions.network`, `ports`, `credentials` apiKey/oauth, `environment`, `setup` install/startup/files, `volumes`, `args`, `extends`, `mixins`, `requires.agent`), composition via `--kit`/`sbx kit add`, and distribution (pack/push/pull/sign/verify/provenance).

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# Docker Sandboxes: Kits (spec.yaml)

## Overview

A **kit** is a directory (or ZIP/OCI/git artifact) containing a `spec.yaml`
plus an optional `files/` tree. `sbx` composes a kit into a running or
about-to-be-created sandbox at `sbx create`/`sbx run --kit`/`sbx env` time or
at `sbx kit add` time. This skill owns kit-spec v2 authoring, validation, and
distribution, everything under `spec.yaml`'s own grammar, and defers what a
kit's declarations *mean at runtime* (credential injection, network
enforcement) to `docker-sandboxes-network-credentials`, and the sandboxes a
kit is composed into to `docker-sandboxes-lifecycle`.

## When to use this skill

Activate this skill when:
- The user wants to write, validate, or pack a `spec.yaml` for a `kind:
  sandbox` (complete agent) or `kind: mixin` (extension) kit.
- The user wants a mixin to add a tool, credential, network allowance, or
  files to an existing built-in agent.
- The user wants to publish a kit to (or pull one from) an OCI registry,
  sign it, or verify a signature/provenance attestation.
- The user is debugging a kit-validation error, an argument-substitution
  error, or `sbx kit add`'s recreate-aware requirement.

## Do not use this skill when

Do not use this skill when:
- The task is creating/running/removing the sandbox a kit is composed into,
  independent of the kit's own content, use `docker-sandboxes-lifecycle`.
- The task is what a credential or network rule a kit declares actually
  does at runtime (proxy injection, allow/deny precedence, or what the
  CURRENT network/global policy already permits), or is about secrets/
  policy that have nothing to do with a kit, use
  `docker-sandboxes-network-credentials`.
- The task is the `sbxenv.yaml` file format that references kits via its
  own `kits:` block, use `docker-sandboxes-env` for that file's schema
  (this skill still owns what goes inside the referenced kit itself).

## Core guidance

### `kind: sandbox` vs `kind: mixin`, pick the right one

The rest: https://github.com/docker/skills/blob/HEAD/skills/docker-sandboxes-kits/SKILL.md