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Use when editing files in a Bun project (bun.lock or bun.lockb at the root, a packageManager field set to bun in package.json, or imports from the bun namespace) or running bun/bunx commands. Covers Bun-native APIs, the bun test runner, bun build --compile, and the Bun-optimized tsconfig.
Codex または Claude でインストール この Prompt をコピーして Codex、Claude、または他のアシスタントに貼り付けると、Skill ページを確認してインストールできます。
SOC 職業分類に基づく
Browser automation CLI wrapping Playwright for one-shot tasks like navigation, page interaction, screenshots, and scraping. Use when driving a live browser from the terminal. Skip for repeat automations that warrant a full Playwright script.
Author and maintain agent context markdown — AGENTS.md, rules, skills, memory files. Use when creating, editing, or refactoring any agent-focused doc, or after major codebase exploration to capture learning.
Author and audit Agent Skills. Use when creating a new skill, refactoring an existing one, or rewriting skill metadata (name, description, allowed-tools).
Build ASCII/Unicode animations such as loading spinners, logo reveals, particle effects, and terminal art. Covers character grids, frame loops, per-character state machines, ordering, and performance. Use when designing any character-based visual animation.
Run tests, builds, migrations, or any command needing real CI secrets/services on Blacksmith. Use when testing or validating code, or before any commit or push that should be verified against CI.
End-of-session capture of state changes, novel learnings, and durable preferences into project context files. Use when the user runs `/capture-context`, says "capture context" / "update the docs", or when wrapping a session that introduced non-trivial deps, architecture changes, or explicit "remember this" callouts.
| name | bun-development |
| description | Use when editing files in a Bun project (bun.lock or bun.lockb at the root, a packageManager field set to bun in package.json, or imports from the bun namespace) or running bun/bunx commands. Covers Bun-native APIs, the bun test runner, bun build --compile, and the Bun-optimized tsconfig. |
[!IMPORTANT] In Claude Code's sandbox,
bunandbunxbypass$TMPDIRand hit a blocked darwin temp path (see~/.claude/tmpdirs.md). For one-off package execution useaubx(orpnpxifaubeisn't available); for a JS runner preferaube, withpnpmas a backup (only use plainnpmif it's the only option on the system). Reach forbunonly when the project mandates it, and expectbun install/bun testto need user-side execution outside the sandbox.
Bun ≥ 1.1.45 writes text bun.lock by default; older projects have binary bun.lockb. Either at the repo root signals a Bun project. CI/reproducible installs: bun install --frozen-lockfile.
| Need | Use | Not |
|---|---|---|
| Read/write files | Bun.file(p).text() / Bun.write(p, data) | fs.readFile/writeFile |
| HTTP server | Bun.serve({ fetch }) (or Elysia, Hono) | Express, Fastify |
| SQLite | import { Database } from "bun:sqlite" | better-sqlite3 |
| Password hash | Bun.password.hash / .verify | bcrypt, argon2 |
| Hi-res time | Bun.nanoseconds() | process.hrtime() |
| Resolve module | Bun.resolveSync(spec, dir) | require.resolve |
| Env vars | Bun.env.X / process.env.X — .env auto-loaded | dotenv |
node:* modules work for compat — reach for them only when no Bun-native exists.
const server = Bun.serve({
port: 3000,
fetch(req, server) {
const url = new URL(req.url);
if (url.pathname === "/ws" && server.upgrade(req)) return;
return Response.json({ ok: true });
},
websocket: {
open(ws) { ws.send("hi"); },
message(ws, msg) { ws.send(`echo: ${msg}`); },
},
error(err) { return new Response(err.message, { status: 500 }); },
});
Returning undefined after server.upgrade(req) completes the WebSocket handshake.
Jest-compatible API, runs .ts natively with no transform:
import { describe, it, expect, mock, spyOn, beforeAll } from "bun:test";
const mockFn = mock((x: number) => x * 2);
mockFn(5);
expect(mockFn).toHaveBeenCalledWith(5);
const spy = spyOn(obj, "method").mockReturnValue("stub");
CLI: bun test, --watch, --coverage, --grep <pat>, --timeout <ms>.
# Bundle
bun build ./src/index.ts --outdir ./dist --target browser --minify --sourcemap
# Standalone binary (cross-compile)
bun build ./src/cli.ts --compile --outfile myapp
bun build ./src/cli.ts --compile --target=bun-linux-x64 --outfile myapp-linux
bun build ./src/cli.ts --compile --target=bun-darwin-arm64 --outfile myapp-mac
bun build ./src/cli.ts --compile --embed ./assets --outfile myapp
Programmatic:
const result = await Bun.build({
entrypoints: ["./src/index.ts"],
outdir: "./dist",
target: "browser", // "browser" | "bun" | "node"
minify: true,
sourcemap: "external",
splitting: true,
format: "esm",
external: ["react"],
define: { "process.env.NODE_ENV": JSON.stringify("production") },
});
if (!result.success) console.error(result.logs);
Bun ≥ 1.3.10 takes .html files as bundler entrypoints — it traces <script type="module" src="./x.ts">, <link rel="stylesheet">, CSS imported from JS/TS, and url() references inside CSS. Pair it with --compile --target=browser to emit one self-contained HTML with every asset inlined as a data: URI (woff2 fonts from @fontsource/* work out of the box). Replaces Vite + vite-plugin-singlefile for iframe widgets, MCP App resources, and other single-file SPAs.
bun build --compile --target=browser ./src/app.html --outfile ./dist/app.html
<!-- src/app.html — the entry; Bun walks the graph from here -->
<!DOCTYPE html>
<link rel="stylesheet" href="./app.css">
<script type="module" src="./app.ts"></script>
<div id="root"></div>
// src/app.ts — CSS imports fold into the same bundle
import "@fontsource/inter/400.css";
import "./component.css";
[!CAUTION] Plain
bun build --html(without--compile --target=browser) emits sibling JS/CSS chunks, not one file. The single-file behavior comes from--compile --target=browseragainst an HTML entry, added in Bun 1.3.10 (April 2026). No third-party inliner needed —vite-plugin-singlefile,inline-source,posthtml-inline-assetsare all obsolete for this case.
{
"compilerOptions": {
"lib": ["ESNext"],
"target": "ESNext",
"module": "Preserve",
"moduleResolution": "bundler",
"moduleDetection": "force",
"allowImportingTsExtensions": true,
"verbatimModuleSyntax": true,
"noEmit": true,
"strict": true,
"skipLibCheck": true,
"jsx": "react-jsx",
"types": ["bun"]
}
}
Pair "types": ["bun"] with @types/bun as a devDependency. The legacy bun-types package is superseded.
bun --watch <file> restarts the process on change — short scripts.bun --hot <file> keeps the process alive and hot-swaps modules — long-running servers.