sbx/gstack-kit repository overview

⁠gstack

A standalone sandbox kit (kind: sandbox, the v2 spec naming) for gstack⁠ — Garry Tan's Claude Code skill pack: opinionated slash commands (/ship, /review, /qa, /browse, /office-hours, …) plus compiled Bun binaries including a headless-Chromium browse daemon.

The kit uses a pre-baked sandbox image on the claude-code template: Bun, the gstack checkout at a pinned commit with ./setup already run (all skills registered under ~/.claude/skills), and Chromium for the browse daemon. Attaching drops straight into a Claude Code session with every skill available — nothing installs at sandbox creation.

⁠Usage

$ sbx run --kit "docker.io/sbx/gstack-kit:latest" gstack

Or from a git URL targeting this repo:

$ sbx run --kit "git+https://github.com/docker/sbx-kits-contrib.git#dir=gstack" gstack

Then use the skills as usual: /review, /qa <url>, /browse, /ship, … The browse daemon self-starts on first use (loopback only, random port, per-project state in <workspace>/.gstack/).

⁠Ports

None published — the browse and design daemons bind loopback on random ports and are only used in-sandbox.

⁠How auth works

Standard Anthropic wiring for Claude Code: both apiKey and oauth are declared under the same anthropic credential — the API key wins when present, otherwise the OAuth flow against platform.claude.com (with proxy-managed sentinels) is used.

The browse security stack's prompt-injection classifier lazy-loads from huggingface.co on first /browse use (~112 MB, allowed in the network policy). gstack's Supabase telemetry endpoint is deliberately not allow-listed; its sync exits silently when unreachable.

⁠Base image

Unlike most kits here — which are kind: mixin or kind: agent and layer onto an existing docker/sandbox-templates image — a kind: sandbox kit is the whole environment, so it names the image the sandbox boots from. This kit builds and publishes its own, from the Dockerfile in this directory:

docker.io/sbx/gstack-image
└── FROM docker/sandbox-templates:claude-code
    ├── Bun 1.3.10 (/usr/local)
    ├── /opt/playwright-browsers        Chromium + xvfb/fonts for /browse
    └── ~/.claude/skills/gstack         checkout @ pinned SHA, ./setup run:
        ├── compiled binaries (browse, pdf, design, ...)
        ├── ~/.claude/skills/<name>/    all skills registered (symlinks)
        └── ~/.gstack/                  global state

The -image suffix distinguishes the base image from the kit itself: the kit is published separately as an OCI artifact at docker.io/sbx/gstack-kit (see Usage⁠ above).

gstack publishes no release tags — the image pins a commit SHA (GSTACK_REF in the Dockerfile). The checkout keeps .git so /gstack-upgrade and version checks work from inside the sandbox.

⁠Building and publishing

How the image is named, tagged, verified and pushed is the same for every kit in this repo that builds its own image — see PUBLISHING.md⁠ for the pipeline. There is no kit-specific build script or workflow; CI builds and publishes this image the same way it does for kiro/copilot.

To bump gstack: set GSTACK_REF to a new upstream commit SHA in the Dockerfile and rebuild.

⁠Building locally

$ docker build -t docker.io/sbx/gstack-image:latest gstack
$ ./scripts/test-kit.sh gstack

scripts/test-kit.sh builds the kit's own image before running the suite (SBX_KIT_SKIP_IMAGE_BUILD=1 to skip and reuse what's already built).

⁠Debugging

$ sbx exec <sandbox> -- ls /home/agent/.claude/skills/        # skills registered?
$ sbx exec <sandbox> -- /home/agent/.claude/skills/gstack/browse/dist/browse goto https://example.com
$ sbx exec <sandbox> -- cat <workspace>/.gstack/browse.json   # daemon port + token

See docs/recipe-prebaked-image-kit.md⁠ for the general pattern this kit follows.