How do I install the Bun skill?

Run npx skillmds@latest add matthewharwood/bun in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

This skill has not completed SkillMD's automated safety review yet. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Bun?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Yes. Installing skills from SkillMD is free. This skill is licensed under MIT.

matthewharwood (@matthewharwood) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Bun by matthewharwood — Agent Skill

Name: Bun
Author: matthewharwood

Bun

Router skill for Bun 1.3.13 in dean-stack — pins the runtime via `packageManager` and dispatches to a sub-skill (runtime, test, package manager) based on the question. Triggers on: bun, bun 1.3.13, packageManager, which bun, bun overview.

File contents

Entry point for any Bun-shaped question in dean-stack. Bun 1.3.13 is the only allowed runtime/toolchain for this repo and is pinned via the root packageManager field.

When to invoke

The user types bun with no further specifier and you need to route them.
The user asks "which Bun skill," "Bun overview," or how Bun is installed/pinned for this repo.
A question mixes runtime + test + install concerns and the right sub-skill is ambiguous — pick after reading the patterns table below.

Owns

Entry point that routes Bun questions to the right sub-skill (runtime, test runner, package manager) and pins Bun 1.3.13 via packageManager.

Defers to

bun-runtime — anything about executing scripts (Bun.serve, Bun.file, Bun.$, bunx, runtime flags).
bun-test — anything about unit tests (bun test, bun:test matchers, mocks, coverage, watch).
bun-package-manager — anything about installing/adding/removing deps, the lockfile, workspaces, or overrides.
turborepo — for which task runs when (bun run check ordering, dependsOn); Bun is the executor, Turbo is the scheduler.

Dean-stack rules

Pillar 4 (CLI-gate-first) means: every script in package.json is invoked as bun run <name> and must be reachable through Turbo — no direct npx/pnpm/npm invocations slip in.
Pillar 3 (IDB-first state) is unaffected at the Bun layer (state lives in the browser), but Bun is what runs the migration unit tests in bun test.
The packageManager pin is load-bearing: a contributor on a different Bun version will get reproducible installs only if this field is honored by corepack/CI.

Patterns

Pin Bun via `packageManager`

// package.json (repo root)
{
  "packageManager": "bun@1.3.13",
  "engines": { "bun": ">=1.3.13" }
}

The pin is the single source of truth — no .bun-version, no Volta entry. CI reads packageManager and installs the matching Bun.

Routing table

Question shape	Sub-skill
"How do I write a unit test for an atom reducer?"	`bun-test`
"Add `idb` to the web app"	`bun-package-manager`
"Run a script that shells out to `git`"	`bun-runtime`
"Why is `bun install` slow in CI?"	`bun-package-manager`
"Cap test runner at 1 thread for IDB"	`bun-test`
"Read a JSON file in a build script"	`bun-runtime`

One Bun, three roles

bun install           # bun-package-manager
bun run check         # bun-runtime executes the script Turbo orchestrates
bun test app/state    # bun-test

Each command lives in a different sub-skill; pick the one whose surface owns the verb.

Anti-patterns

Don't suggest npm, pnpm, yarn, or npx — the repo is Bun-only; bunx replaces npx.
Don't unpin packageManager — a floating range (bun@*) defeats reproducibility.
Don't answer test/install/runtime questions inside this router — route to the sub-skill so the answer carries the right rules.
Don't introduce node as a runtime target — see node skill: Node 25 exists only for tools that refuse to run on Bun.

Triggers on

bun, bun 1.3.13, packageManager, which bun, bun overview

---name: bundescription: Router skill for Bun 1.3.13 in dean-stack — pins the runtime via `packageManager` and dispatches to a sub-skill (runtime, test, package manager) based on the question. Triggers on: bun, bun 1.3.13, packageManager, which bun, bun overview.license: MIT---Entry point for any Bun-shaped question in dean-stack. Bun 1.3.13 is the only allowed runtime/toolchain for this repo and is pinned via the root `packageManager` field.## When to invoke- The user types `bun` with no further specifier and you need to route them.- The user asks "which Bun skill," "Bun overview," or how Bun is installed/pinned for this repo.- A question mixes runtime + test + install concerns and the right sub-skill is ambiguous — pick after reading the patterns table below.## OwnsEntry point that routes Bun questions to the right sub-skill (runtime, test runner, package manager) and pins Bun 1.3.13 via `packageManager`.## Defers to- `bun-runtime` — anything about executing scripts (`Bun.serve`, `Bun.file`, `Bun.$`, `bunx`, runtime flags).- `bun-test` — anything about unit tests (`bun test`, `bun:test` matchers, mocks, coverage, watch).- `bun-package-manager` — anything about installing/adding/removing deps, the lockfile, workspaces, or overrides.- `turborepo` — for *which task runs when* (`bun run check` ordering, `dependsOn`); Bun is the executor, Turbo is the scheduler.## Dean-stack rules- Pillar 4 (CLI-gate-first) means: every script in `package.json` is invoked as `bun run <name>` and must be reachable through Turbo — no direct `npx`/`pnpm`/`npm` invocations slip in.- Pillar 3 (IDB-first state) is unaffected at the Bun layer (state lives in the browser), but Bun is what runs the migration unit tests in `bun test`.- The `packageManager` pin is load-bearing: a contributor on a different Bun version will get reproducible installs only if this field is honored by `corepack`/CI.## Patterns### Pin Bun via `packageManager````jsonc// package.json (repo root){ "packageManager": "bun@1.3.13", "engines": { "bun": ">=1.3.13" }}```The pin is the single source of truth — no `.bun-version`, no Volta entry. CI reads `packageManager` and installs the matching Bun.### Routing table| Question shape | Sub-skill ||---|---|| "How do I write a unit test for an atom reducer?" | `bun-test` || "Add `idb` to the web app" | `bun-package-manager` || "Run a script that shells out to `git`" | `bun-runtime` || "Why is `bun install` slow in CI?" | `bun-package-manager` || "Cap test runner at 1 thread for IDB" | `bun-test` || "Read a JSON file in a build script" | `bun-runtime` |### One Bun, three roles```bashbun install # bun-package-managerbun run check # bun-runtime executes the script Turbo orchestratesbun test app/state # bun-test```Each command lives in a different sub-skill; pick the one whose surface owns the verb.## Anti-patterns- **Don't suggest `npm`, `pnpm`, `yarn`, or `npx`** — the repo is Bun-only; `bunx` replaces `npx`.- **Don't unpin `packageManager`** — a floating range (`bun@*`) defeats reproducibility.- **Don't answer test/install/runtime questions inside this router** — route to the sub-skill so the answer carries the right rules.- **Don't introduce `node` as a runtime target** — see `node` skill: Node 25 exists only for tools that refuse to run on Bun.## Triggers onbun, bun 1.3.13, packageManager, which bun, bun overview

Frequently asked questions

Bun