sandbox: Instructions file for Codex

AGENTS.md

sandbox AGENTS.md is an instructions file for Codex, OpenCode from vercel/sandbox. It costs 116 tokens per session, scanned A, original, Apache-2.0.

A short contribution guide for Vercel Sandbox, covering its agent instructions and use of Changesets. Changesets are small files that record package changes so releases can choose the right version number.

In plain words
What is it for?
Use it when changing a package and deciding whether the release should be a patch, minor, or major update.
Why use it?
It makes sure package changes include the release information needed by the project’s versioning workflow.

Instructions file for CodexOpenCode ✓ vendor

Written for Codex and OpenCode: the file is AGENTS.md.

This is vercel/sandbox's own configuration. It tells Codex and OpenCode how to work on sandbox 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 sandbox configures →

About the project

Vercel Sandbox provides temporary, isolated Linux virtual machines for running arbitrary or untrusted code. Developers use its SDK or CLI to create sandboxes, run projects, start development servers, and stream execution logs.

vercel/sandbox · 213 stars · on GitHub · vercel.com

Reuse

Borrowing it

Nothing to install: this file belongs to vercel/sandbox. 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/vercel/sandbox/main/AGENTS.md
Clone the repo
git clone --depth 1 https://github.com/vercel/sandbox

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.

agentmods badge for sandbox AGENTS.md

README.md
[![agentmods](https://agentmods.dev/badge/instructions/vercel/sandbox/agents-md/github.svg)](https://agentmods.dev/instructions/vercel/sandbox/agents-md)
Your own site
<a href="https://agentmods.dev/instructions/vercel/sandbox/agents-md"><img src="https://agentmods.dev/badge/instructions/vercel/sandbox/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.

agentmods 80×15 button for sandbox AGENTS.md

Your own site · 80×15
<a href="https://agentmods.dev/instructions/vercel/sandbox/agents-md"><img src="https://agentmods.dev/badge/instructions/vercel/sandbox/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 116 This file is loaded in full into every session.
When invoked 116 The same file — it is already loaded in full.
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 $0.00116 $0.00116
Opus 5.5 $0.00046 $0.00046
Sonnet 5.5 $0.00023 $0.00023
Haiku 4.5 $0.00012 $0.00012

Measured 1mo ago against content hash 8df5d402404e, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

sandbox AGENTS.md 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.

AGENTS.md · 16 lines

What it actually says

Agents

Changesets

This repo uses changesets for versioning. When making changes to any package, add a changeset by running pnpm changeset or by creating a markdown file in .changeset/ with the following format:

---
"package-name": patch
---

A short description of the change.

Use patch for bug fixes, cosmetic changes, and DX improvements. Use minor for new features. Use major for breaking changes.

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 · 16 lines · 116 tokens per session scan A 8df5d402404e

Subscribe to this mod's changes

sandbox AGENTS.md is an instructions file published in the GitHub repository vercel/sandbox (213 stars, last pushed today), licensed Apache-2.0. It adds 116 tokens to every session, about $0.0005 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 2026-08-30.

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