Guide · Agent skill
How to use the Bun runtime agent skill (bun-runtime guide)
Updated · written with AI from the project's own documentation and checked against our catalogue data
The bun-runtime skill is a reference guide that gives an AI agent working knowledge of Bun, a fast all-in-one JavaScript and TypeScript toolkit that includes a runtime, package manager, bundler and test runner. This guide is for people who have never installed an agent skill before. By the end you will know how to install the skill, how to ask for help with it in plain language, and what it needs and how to use it safely.
Bun runtime guideaffaan-m/ECC · MIT Download the skill Quick start
- 1Download and unzip. Download the bun-runtime ZIP file from this page and unzip it. You should end up with a folder containing SKILL.md.
- 2Place the skill folder. Move the folder into ~/.claude/skills/ for personal use, or into your project's .claude/skills/ folder. Alternatively, upload it under Settings → Capabilities → Skills in the Claude apps.
- 3Confirm Bun is installed. Run bun --version in a terminal. If Bun is missing, install it first, then continue.
- 4Ask a Bun question in plain language. Describe your task and mention Bun, for example asking whether Bun or Node suits a new project. The agent loads the skill when the request matches.
- 5Apply and verify the changes. Run the commands the agent suggests, such as bun install and bun test. Check the results yourself before relying on them.
What the bun-runtime skill makes the agent do
An agent skill is a folder of instructions that an AI agent can load when a task matches it. The bun-runtime skill is contained in a single file, SKILL.md, and is text guidance only. It does not run any code itself.
Once loaded, the agent can explain when Bun or Node.js is the better choice, suggest Bun commands such as bun install, bun run and bun test, help move a Node project to Bun, and advise on configuring Bun on Vercel. It also points to Bun's built-in APIs before you add extra dependencies.
- Choosing between Bun and Node.js for a project
- Migrating scripts and installs from Node.js to Bun
- Writing and debugging Bun tests
- Configuring Bun for Vercel or other platforms
- Reviewing dependency commands such as bun outdated and bun audit
How to install the bun-runtime skill
Download the ZIP file for the bun-runtime skill from this page and unzip it. You can install the skill in one of three ways, depending on how you use your agent.
For a personal setup, place the unzipped skill folder inside ~/.claude/skills/. For a single project, place it inside that project's .claude/skills/ folder. In the Claude apps, you can instead upload the skill under Settings, then Capabilities, then Skills.
- Personal: unzip into ~/.claude/skills/
- Project only: unzip into the project's .claude/skills/ folder
- Claude apps: upload under Settings → Capabilities → Skills
Check that Bun is installed
The skill expects Bun to be installed on your machine and a Node.js-compatible project to work on. The skill itself needs no API keys or accounts.
Run bun --version in a terminal to see which Bun version you have. The skill notes that command-line flags can change between releases, so the agent should check your actual version before relying on a specific flag.
bun --versionHow to trigger the skill with natural requests
You do not need special syntax. Describe your task in plain language that mentions Bun, and the agent will load the skill when it matches. Name the goal, such as installing, migrating, testing or deploying, and say which project you are working on.
The skill's guidance is shaped by the kinds of work it covers, so requests that match those tasks work best.
- Should I use Bun or Node for this new TypeScript API?
- Move this Node project to Bun and tell me what might break.
- Write a bun test file for this utility function.
- Set up Bun on Vercel for this app and make the deploy reproducible.
- Which built-in Bun API can replace this extra dependency?
Common Bun commands the skill covers
The skill covers installing and running code, managing dependencies, and testing. Use bun install to install dependencies and create or update bun.lock. Use bun run to run scripts or files, and bun x for one-off npx-style runs. Under Node.js, npm install becomes bun install and node script.js becomes bun run script.js.
For CI, the skill lists test options available in Bun 1.4. --changed runs only affected tests, --isolate gives each file a fresh global environment within the same process, --parallel runs tests in worker processes, and --shard splits a run across CI jobs. --isolate is not a process or security sandbox.
- bun add, bun remove and bun update manage dependencies
- bun outdated lists outdated dependencies
- bun pm ls shows resolved versions, and --all includes transitive dependencies
- bun dedupe removes duplicate installs and bun prune removes unreferenced packages
- bun run --filter <pkg-name> <script> runs a script in one workspace
bun install
bun run dev
bun test
bun test --watch
bun run --env-file=.env devWhat people use it for
- Starting a new TypeScript project with one toolchain for running, installing, testing and building
- Checking whether a Node.js project is likely to work under Bun and listing the parts to test
- Setting up a Vercel deployment with a reproducible bun install --frozen-lockfile step
- Adding bun test to a CI pipeline with --changed, --parallel or --shard options
- Replacing an extra dependency with a built-in Bun API such as Bun.file or Bun.serve
Frequently asked questions
Is the bun-runtime skill free?
The skill is released under the MIT licence, as stated on its source page. The skill is a text file of guidance and requires no API keys or accounts of its own.
What do I need before using the bun-runtime skill?
You need Bun installed, which you can check with bun --version, and a Node.js-compatible project to work on. The skill itself does not run scripts or require credentials, but it does use the network for certain Bun features such as dependency audits.
Where do I put the bun-runtime skill folder?
Place it in ~/.claude/skills/ for personal use, or in a project's .claude/skills/ folder to use it only in that project. In the Claude apps you can upload it under Settings → Capabilities → Skills.
Will my Node.js project work with Bun?
Most packages work, but Bun is not 100% Node.js compatible. Some native addons, uncommon node: internal APIs and packages that rely on Node-specific internals may fail, so test before you depend on them in production.
Does the skill run commands like bun audit fix for me?
No. The skill is text guidance only and does not run code. bun audit fix changes your lockfile and installed packages, so review it before running it. bun audit itself does not modify package.json, bun.lock or node_modules.
How does this skill compare with just asking an agent about Bun?
The skill gives the agent a focused, Bun-specific reference to work from, covering runtime, package manager, bundler, test runner and Vercel settings. Without it, the agent relies on general knowledge, which may be less specific to Bun's current commands and options.
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Our verdict
Use the bun-runtime skill if you are starting a JavaScript or TypeScript project and want one toolchain, if you are migrating a Node.js project to Bun, or if you are configuring Bun on Vercel or CI. Pick something else, or stay on Node.js, if your project depends on native Node addons or obscure Node internals, and review any dependency audit or fix commands carefully before running them.
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