bun: Skill for Claude Code

.claude/skills/rust-system-calls/SKILL.md

rust-system-calls is a skill for Claude Code from oven-sh/bun. It costs 42 tokens per session (1,111 once invoked), scanned A, original, no licence file.

A guide for using bunsys to make system calls and handle files in Rust. System calls are direct requests to operating-system services, such as opening a file.

In plain words
What is it for?
Use it when implementing file operations, opening file descriptors, or working on other system-call paths in Rust.
Why use it?
It helps code follow the required bunsys path instead of using Rust's standard file library or the libc library.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

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/skills/rust-system-calls/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/oven-sh/bun

Made for: Claude Code.

Wrote this? Show the measurements

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README.md
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Your own site
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agentmods 80×15 button for rust-system-calls

Your own site · 80×15
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Per session 42 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,111 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00042 $0.01111
Opus 5.5 $0.00017 $0.00444
Sonnet 5.5 $0.00008 $0.00222
Haiku 4.5 $0.00004 $0.00111

Measured 2mo ago against content hash 3f7ccb3f4c27, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

rust-system-calls 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 2mo 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.

.claude/skills/rust-system-calls/SKILL.md · 97 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. 2mo ago First seen · 97 lines · 42 tokens per session scan A 3f7ccb3f4c27

Subscribe to this mod's changes

rust-system-calls is a skill published in the GitHub repository oven-sh/bun (96,454 stars, last pushed today), with no licence file. It adds 42 tokens to every session and 1,111 once invoked, about $0.0002 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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