bun: Instructions file for Claude Code

CLAUDE.md

bun CLAUDE.md is an instructions file for Claude Code from oven-sh/bun. It costs 4,496 tokens per session, scanned B, original, no licence file.

A set of Claude Code instructions for the Bun project, a JavaScript runtime and toolkit. It covers how to build, run, test, and decide when a build is unnecessary.

In plain words
What is it for?
Use it while working in the oven-sh/bun repository. It helps with builds, test runs, and changes that can be checked without rebuilding.
Why use it?
It gives the coding agent project-specific commands and expectations, reducing mistakes when changing or testing Bun.

Instructions file for Claude Code

Written for Claude Code: the file is CLAUDE.md.

This is oven-sh/bun's own configuration. It tells Claude Code how to work on bun 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 bun configures →

Reuse

Borrowing it

Nothing to install: this file belongs to oven-sh/bun. 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/oven-sh/bun/main/CLAUDE.md
Clone the repo
git clone --depth 1 https://github.com/oven-sh/bun

Made for: Claude Code.

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 bun CLAUDE.md

README.md
[![agentmods](https://agentmods.dev/badge/instructions/oven-sh/bun/claude-md/github.svg)](https://agentmods.dev/instructions/oven-sh/bun/claude-md)
Your own site
<a href="https://agentmods.dev/instructions/oven-sh/bun/claude-md"><img src="https://agentmods.dev/badge/instructions/oven-sh/bun/claude-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 bun CLAUDE.md

Your own site · 80×15
<a href="https://agentmods.dev/instructions/oven-sh/bun/claude-md"><img src="https://agentmods.dev/badge/instructions/oven-sh/bun/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 4,496 This file is loaded in full into every session.
When invoked 4,496 The same file — it is already loaded in full.
Security scan B 1 finding. A grade says what 26 rules found in the file — not that it is safe.
Origin unknown 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 $0.04496 $0.04496
Opus 5.5 $0.01798 $0.01798
Sonnet 5.5 $0.00899 $0.00899
Haiku 4.5 $0.00450 $0.00450

Measured yesterday against content hash bf1782672873, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade B, and why

bun CLAUDE.md scanned grade B with 1 finding 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 yesterday.

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.

Unrestricted tool accessmediumExcessive agency

A wildcard tool grant or "run any command" leaves no least-privilege boundary at all.

- **Run any command with debug build**: `bun bd <command>`
CLAUDE.md · 240 lines

The source is not reproduced here

A licence we could not identify

The repository carries a LICENSE file, but it is custom or dual enough that GitHub cannot name it and neither can this catalogue. Unknown terms are not permission, so the body is not copied here. Read the licence at the source and decide for yourself.

Read it on GitHub

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. yesterday Changed · -11 tokens per session bf1782672873
  2. 4d ago Changed · -1 lines · -18 tokens per session 84d2cbf2aa40
  3. 6d ago Changed · -1 lines · -26 tokens per session 9353d0d05912
  4. 12d ago Changed · +1 lines · +36 tokens per session ec5ed6b18090
  5. 15d ago Changed · +4 tokens per session 9ae03a5c1a03
  6. 1mo ago Changed · -9 tokens per session 23aaeec4bec9
  7. 1mo ago Changed · +12 tokens per session 67ca793882ba
  8. 2mo ago First seen · 241 lines · 4,508 tokens per session scan B 51bfba7963b0

Subscribe to this mod's changes

bun CLAUDE.md is an instructions file published in the GitHub repository oven-sh/bun (96,454 stars, last pushed today), with no licence file. It adds 4,496 tokens to every session, about $0.0180 per session on Opus 5.5. A static security scan graded it B with 1 finding (unrestricted tool access). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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