What is sandboxd AGENTS.md?

Instructions for sandboxd, a service that uses Docker to create isolated Linux development containers with preview URLs for running dev servers.

Use it to install sandboxd, create and manage development sandboxes, expose previews, keep workspaces persistent, and troubleshoot basic setup.

It explains the setup, operation, and removal steps in one place, so users do not need to work out how the container service fits together.

How tastyeffectco/sandboxd configures Codex and OpenCode

Reuse

Borrowing it

Nothing to install: this file belongs to tastyeffectco/sandboxd. 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/tastyeffectco/sandboxd/main/AGENTS.md

Clone the repo

git clone --depth 1 https://github.com/tastyeffectco/sandboxd

Made for: Codex, OpenCode.

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.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/tastyeffectco/sandboxd/agents-md/github.svg)](https://agentmods.dev/instructions/tastyeffectco/sandboxd/agents-md)

Your own site

<a href="https://agentmods.dev/instructions/tastyeffectco/sandboxd/agents-md"><img src="https://agentmods.dev/badge/instructions/tastyeffectco/sandboxd/agents-md/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.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/tastyeffectco/sandboxd/agents-md"><img src="https://agentmods.dev/badge/instructions/tastyeffectco/sandboxd/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 2,315 This file is loaded in full into every session.

When invoked 2,315 The same file — it is already loaded in full.

Security scan B 2 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.

Model	Per session	Once invoked
Fable 5.1	$0.02315	$0.02315
Opus 5.5	$0.00926	$0.00926
Sonnet 5.5	$0.00463	$0.00463
Haiku 4.5	$0.00231	$0.00231

Measured 8d ago against content hash 6d57c11d28c5, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade B, and why

sandboxd AGENTS.md scanned grade B with 2 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 8d 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.

Sends data to an external URLmediumData exfiltration

A POST to an outside endpoint may be telemetry or may be exfiltration; either way the mod talks to somewhere, and you should know where.

curl -s -XPOST $API/v1/agents/claude-code/api-key -d '{"api_key":"sk-ant-..."}'

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

curl -s http://127.0.0.1:9090/healthz # -> ok

AGENTS.md · 165 lines

How it starts

The opening of the file, as written. The whole thing — 165 lines — stays where its author put it; the contents beside it link to each section on GitHub.

AGENTS.md — operating sandboxd

A complete, self-contained runbook for an AI agent (or a human) to install, run, use, and remove sandboxd with no outside knowledge. Commands are copy-pasteable. Human-readable docs: README.md, ARCHITECTURE.md.

What this is

A single-host service that creates isolated Linux dev containers ("sandboxes"), each with an HTTP/HTTPS preview URL for a dev server running inside it. It runs entirely on Docker: a Go control plane (sandboxd) + Traefik, both in containers; each sandbox is a sibling container. Sandboxes stop when idle and wake on the next request. Workspaces persist on disk.

Prerequisites

Linux host with Docker Engine + the Compose plugin (docker compose).
Ability to run Docker (either your user is in the docker group, or you have sudo; the scripts auto-detect and use sudo if needed).
Assumes a standard Docker daemon. (If the daemon uses userns-remap, the shipped --userns=host defaults keep it working — see ARCHITECTURE.md.)

Install

git clone https://github.com/tastyeffectco/sandboxd.git
cd sandboxd
./install.sh

install.sh is idempotent. It: checks Docker, copies .env.example→.env, builds the base image (sandboxd-base:0.3.0) and the control plane, creates the data dir, and runs docker compose up -d. The base-image build takes a few minutes the first time, then caches.

Configuration lives in .env (all keys documented in .env.example). The two you may change before installing:

HTTP_PORT (default 80) — set to e.g. 8088 if port 80 is taken; preview URLs then include it.
SANDBOXD_API_BIND (default 127.0.0.1:9090) — where the API is published.

Verify it's up:

curl -s http://127.0.0.1:9090/healthz   # -> ok
curl -s http://127.0.0.1:9090/readyz    # -> ready

Core API

Base URL = http://${SANDBOXD_API_BIND} (default http://127.0.0.1:9090). Auth is on by default. Use a console-issued API key or a configured SANDBOXD_API_TOKENS=name:secret token with -H "Authorization: Bearer secret".

Read the full file on GitHub · 165 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.

8d ago Changed · +3 lines · +78 tokens per session 6d57c11d28c5
17d ago Changed · +4 lines · +50 tokens per session f94103a09188
2mo ago First seen · 158 lines · 2,187 tokens per session scan B 703cbef8add8

Subscribe to this mod's changes

sandboxd AGENTS.md is an instructions file published in the GitHub repository tastyeffectco/sandboxd (978 stars, last pushed yesterday), licensed MIT. It adds 2,315 tokens to every session, about $0.0093 per session on Opus 5.5. A static security scan graded it B with 2 findings (sends data to an external url, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Containers DevOps and cloud agent-infrastructure ai developer-tools docker sandbox self-hosted

sandboxd AGENTS.md next to 6 instructions from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
sandboxd AGENTS.mdtastyeffectco/sandboxd	Instructions file	978	yesterday	MIT	B	2,315	Codex, OpenCode
vscode buildNext.instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	9,719	GitHub Copilot
next.js AGENTS.mdvercel/next.js	Instructions file	143k	today	MIT	A	7,461	Codex, OpenCode
langchain AGENTS.mdlangchain-ai/langchain	Instructions file	149k	yesterday	MIT	A	4,680	Codex, OpenCode
vscode oss-third-party-notices.instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	5,516	GitHub Copilot
vscode copilot-instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	3,093	GitHub Copilot
deepseek-harness AGENTS.mddeepseek-ai/deepseek-harness	Instructions file	274k	2d ago	MIT	A	4,313	Codex, OpenCode

sandboxd: Instructions file for Codex