bun-1-4

bun-1-4 is a skill for Claude Code, Codex from code-yeongyu/senpi. It costs 159 tokens per session (1,447 once invoked), scanned A, original, MIT.

A set of instructions for using built-in features in Bun 1.4, a JavaScript runtime and package tool, before adding outside packages.

In plain words
What is it for?
Checking how to handle images, browsers, Markdown, scheduled jobs, terminal sessions, and concurrent scripts with Bun’s built-in tools.
Why use it?
It helps avoid unnecessary dependencies and workarounds when Bun already provides the needed function.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Checking how to handle images, browsers, Markdown, scheduled jobs, terminal sessions, and concurrent scripts with Bun’s built-in tools.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/code-yeongyu/senpi/bun-1-4
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 code-yeongyu/senpi --skill bun-1-4
Clone the repo
git clone --depth 1 https://github.com/code-yeongyu/senpi

Made for: Claude Code, Codex.

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-1-4

README.md
[![agentmods](https://agentmods.dev/badge/skills/code-yeongyu/senpi/bun-1-4.svg)](https://agentmods.dev/skills/code-yeongyu/senpi/bun-1-4)
Your own site
<a href="https://agentmods.dev/skills/code-yeongyu/senpi/bun-1-4"><img src="https://agentmods.dev/badge/skills/code-yeongyu/senpi/bun-1-4.svg" alt="Measured on agentmods" height="20"></a>
Per session 159 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,447 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00159 $0.01447
Opus 5 $0.00079 $0.00724
Sonnet 5 $0.00032 $0.00289
Haiku 4.5 $0.00016 $0.00145

Measured 4d ago against content hash c62d01920c6a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

bun-1-4 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 4d 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.

Makes network callslowCapability

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

| HTTP/3 server; `fetch` protocol/compress/proxy | `http3: true`, `fetch(url, { protocol, compress, proxy })` | — | http-networking |
packages/senpi-codemode/src/skill/bun-1-4/SKILL.md · 45 lines

How it starts

The opening of the file, as written. The whole thing — 45 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Bun 1.4 — Use the Builtins First

Bun 1.4 (2026) ships builtins that replace most utility npm packages. Before adding a dependency or writing a workaround, check the capability map below — if Bun ships it, use the builtin. This skill is loaded because this session's eval js kernel runs Bun >= 1.4; on other machines or pinned projects, confirm with bun --version ([v1.3.x]/[v1.4.0] tags in the references give exact minimums). Release post: https://bun.com/blog/bun-v1.4

Capability map — what you can do now

You want to... Use Replaces Ref = references/<name>.md
Resize/convert/rotate images Bun.file(p).image().resize().webp().write() sharp runtime-apis
Headless browser: navigate, click, screenshot, evaluate, CDP new Bun.WebView() puppeteer, playwright (scraping) runtime-apis
Markdown → HTML / React / ANSI Bun.markdown.html() / .react() / .render() marked, react-markdown runtime-apis
Schedule cron jobs Bun.cron() node-cron runtime-apis
Drive a PTY (bash, vim, TUIs) from JS Bun.spawn([...], { terminal }) node-pty runtime-apis
Run package scripts concurrently, glob-matched bun run --parallel "build:*" concurrently, npm-run-all runtime-apis
Parse JSON5 / JSONL / JSONC / XML / TOML; tarballs Bun.JSON5/.JSONL/.JSONC/.XML/.TOML, Bun.Archive json5, ndjson, jsonc-parser, fast-xml-parser, @iarna/toml, tar runtime-apis
ANSI-aware terminal text: width, slice, wrap Bun.stringWidth(), Bun.sliceAnsi(), Bun.wrapAnsi() string-width, slice-ansi, wrap-ansi runtime-apis
Call C libraries 3x faster, plain strings back bun:ffi (buffer_length, cstring) runtime-apis
Serve a static dir (ETag/Range/304 handled) Bun.serve({ routes: { "/x/*": { dir } } }) express.static, serve-static, sirv http-networking
HTTP/3 server; fetch protocol/compress/proxy http3: true, fetch(url, { protocol, compress, proxy }) http-networking
Tests across CPU workers / CI shards / changed files / flaky retry bun test --parallel --shard=1/3 --changed=main --retry jest/vitest infra test
Kill "passes alone, fails in suite" bugs bun test --isolate vitest default behavior test
React Compiler auto-memoization bun build --react-compiler babel-plugin-react-compiler build
Embed assets/dirs into a single-file executable bun build --compile --asset ./public pkg hacks build
Compile-time feature flags, in-memory bundling, metafile bun:bundle feature(), files:{}, metafile: true esbuild define/plugins build
Diff package versions, fix vulns, dedupe/prune, license audit bun pm diff, bun audit fix, bun dedupe, bun prune, bun pm licenses npm-diff, npm audit fix install
7x faster CI installs (global virtual store) linker = "isolated" in bunfig.toml pnpm store install
Profile CPU/heap/bundle as grep-able Markdown bun --cpu-prof-md, --heap-prof-md, bun build --metafile-md Chrome DevTools round-trip dev-tooling
Native REPL; render Markdown in terminal bun repl, bun ./README.md node repl, glow runtime-apis
Run Playwright, vitest, Next.js 16, OpenTelemetry, dd-trace they now just work Node.js node-compat-platforms

Read the full file on GitHub · 45 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.

  1. 4d ago First seen · 45 lines · 159 tokens per session scan A c62d01920c6a

Subscribe to this mod's changes

bun-1-4 is a skill published in the GitHub repository code-yeongyu/senpi (420 stars, last pushed today), licensed MIT. It adds 159 tokens to every session and 1,447 once invoked, about $0.0008 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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