Reference guidance for Bun, a JavaScript and TypeScript runtime and package manager. It covers commands, dependency lockfiles, shell execution, subprocesses, and file access.

Use it when running Bun commands, editing package files or bun.lock, writing TypeScript scripts for Bun, or developing Claude Code plugins.

It helps an agent use Bun’s command syntax and project conventions correctly instead of guessing or applying Node-specific patterns.

bun — Skill for Claude Code by bendrucker/claude

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent

npx skills add bendrucker/claude --skill bun

Clone the repo

git clone --depth 1 https://github.com/bendrucker/claude

Made for: Claude Code.

Or install bun, the plugin that ships this one along with the rest of its 1 skill.

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/skills/bendrucker/claude/bun/github.svg)](https://agentmods.dev/skills/bendrucker/claude/bun)

Your own site

<a href="https://agentmods.dev/skills/bendrucker/claude/bun"><img src="https://agentmods.dev/badge/skills/bendrucker/claude/bun/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/skills/bendrucker/claude/bun"><img src="https://agentmods.dev/badge/skills/bendrucker/claude/bun.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 34 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 461 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 1 finding. 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	$0.00034	$0.00461
Opus 5.5	$0.00014	$0.00184
Sonnet 5.5	$0.00007	$0.00092
Haiku 4.5	$0.00003	$0.00046

Measured 11d ago against content hash 59fa081b3cbc, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

bun scanned grade A 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 11d 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.

Runs shell commandslowCapability

Expected in a hook, worth knowing in a rule or an instructions file.

`Bun.spawn` spawns subprocesses with streaming I/O; `Bun.spawnSync` runs synchronously. Configure stdin/stdout/stderr, environment variables, and working directory. Check `exitCode` for errors.

plugins/bun/skills/bun/SKILL.md · 49 lines

What it actually says

Bun

bunx

Put --bun before the executable name to force the Bun runtime over Node shebangs. Use -p/--package when the binary name differs from the package name (e.g., bunx -p @angular/cli ng).

See references/bunx.md

Lockfile

bun.lock is a text-based lockfile. Resolve merge conflicts by regenerating it from origin/main with only the resolved manifests applied, never by hand.

See references/lockfile.md

Resolution

Runtime flags must precede the script path: bun --cwd ./packages/app run dev. Never use .js extensions in TypeScript imports — Bun resolves them natively.

See references/resolution.md

Shell

Bun.$ is a tagged template for shell execution. Use response methods (.text(), .json(), .lines()) to extract output, .nothrow() to handle failures without exceptions, and pipe/redirect syntax to compose commands.

See references/shell.md

Subprocess

Bun.spawn spawns subprocesses with streaming I/O; Bun.spawnSync runs synchronously. Configure stdin/stdout/stderr, environment variables, and working directory. Check exitCode for errors.

See references/spawn.md

File I/O

Bun.file() creates file handles with .text(), .json(), .arrayBuffer(), and .stream() methods. Bun.write() writes content to files or stdout/stderr. Both support streaming for large files.

See references/file-io.md

Testing

Bun runs tests in a single process, not worker-per-file like Vitest or Jest. Set AGENT=1 to suppress passing test output.

See references/testing.md

Files

What ships with it

7 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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.

11d ago Changed 59fa081b3cbc
2mo ago First seen · 49 lines · 34 tokens per session scan A 79f6a8874bfb

Subscribe to this mod's changes

bun is a skill published in the GitHub repository bendrucker/claude (18 stars, last pushed today), licensed MIT. It adds 34 tokens to every session and 461 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 1 finding (runs shell commands). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Claude Code Languages TypeScript claude-code-plugin

bun next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
bunbendrucker/claude	Skill	18	today	MIT	A	34	Claude Code
typescript-rulesshinpr/claude-code-workflows	Skill	713	4d ago	MIT	A	39	Claude Code
better-authsecondsky/claude-skills	Skill	248	9d ago	MIT	A	53	Claude Code
bun-bundlersecondsky/claude-skills	Skill	248	9d ago	MIT	A	90	Claude Code
bun-hot-reloadingsecondsky/claude-skills	Skill	248	9d ago	MIT	A	42	Claude Code
knip-cleanupsuxrobGM/jobpilot	Skill	111	today	MIT	A	79	Claude Code
pulumi-best-practicespulumi/agent-skills	Skill	79	7d ago	Apache-2.0	A	92	Claude Code, Codex

bun