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.
npx agentmods add skills/secondsky/claude-skills/bun-runtimenpx skills add secondsky/claude-skills --skill bun-runtimegit clone --depth 1 https://github.com/secondsky/claude-skillsWrote 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.
[](https://agentmods.dev/skills/secondsky/claude-skills/bun-runtime)<a href="https://agentmods.dev/skills/secondsky/claude-skills/bun-runtime"><img src="https://agentmods.dev/badge/skills/secondsky/claude-skills/bun-runtime.svg" alt="Measured on agentmods" height="20"></a>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 | $0.00028 | $0.01097 |
| Opus 5 | $0.00014 | $0.00549 |
| Sonnet 5 | $0.00006 | $0.00219 |
| Haiku 4.5 | $0.00003 | $0.00110 |
Grade A, and why
bun-runtime scanned grade A with 0 findings 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 2d 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.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 201 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Bun Runtime
Bun is a fast all-in-one JavaScript runtime built on JavaScriptCore (Safari's engine). It provides 4x faster startup than Node.js on Linux.
Quick Start
# Run a file
bun run index.ts
bun index.ts # shorthand
# Run with watch mode
bun --watch run index.ts
# Run package.json script
bun run dev
# Run with hot reloading
bun --hot run server.ts
Core CLI Flags
| Flag | Purpose |
|---|---|
--watch |
Restart on file changes |
--hot |
Hot module replacement (preserves state) |
--smol |
Reduce memory usage (slower GC) |
--inspect |
Enable debugger |
--preload |
Load modules before execution |
--env-file |
Load specific .env file |
-e, --eval |
Evaluate code string |
Running Files
Bun transpiles TypeScript and JSX on-the-fly:
bun run index.js
bun run index.ts
bun run index.jsx
bun run index.tsx
Important: Put Bun flags immediately after bun:
bun --watch run dev # Correct
bun run dev --watch # Wrong - flag passed to script
Package.json Scripts
# Run script
bun run dev
bun dev # shorthand (if no Bun command conflicts)
# List available scripts
bun run
# Run with Bun instead of Node
bun run --bun vite
Bun respects lifecycle hooks (preclean, postclean, etc.).
Watch Mode vs Hot Reloading
| Mode | Flag | Behavior |
|---|---|---|
| Watch | --watch |
Full process restart on changes |
| Hot | --hot |
Replace modules, preserve state |
# Watch mode - full restart
bun --watch run server.ts
# Hot reloading - preserves connections/state
bun --hot run server.ts
Environment Variables
Bun automatically loads .env files:
# Loads automatically: .env, .env.local, .env.development
bun run index.ts
# Specify env file
bun --env-file .env.production run index.ts
# Disable auto-loading
# In bunfig.toml: env = false
Access in code:
const apiKey = process.env.API_KEY;
const bunEnv = Bun.env.NODE_ENV;
What ships with it
3 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.
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.
- 2d ago First seen · 201 lines · 28 tokens per session scan A 7bbdb5037e6f
bun-runtime is a skill published in the GitHub repository secondsky/claude-skills (214 stars, last pushed 2d ago), licensed MIT. It adds 28 tokens to every session and 1,097 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.
Other skills, from other repositories
remember
Record why something is the way it is — a decision and its reasoning, a lesson that cost time, or a standing constraint. Use when the reasoning behind a choice would be expensive to reconstruct later.
resume
Write down where this stretch of work stopped, so the next session continues instead of restarting. Use at the end of a working session, or when handing the repository to someone else.
bootstrap
Set up chamnan in this repository for the first time — build the architecture index, measure how well the code describes itself, fill in missing file comments, and record a baseline. Run once per repo.
milestone
Record a change that reshaped the repository — what moved, why it was worth doing, and which areas it touched. Use after a migration, a rewrite, or a decision that changed how part of the system works.
capture
Write down a procedure worth keeping — a multi-step process, a trap that cost real time, or something that has now come up three times. Use it the moment you finish such a task, while the details are still exact.
promote
Turn a scratch script into a permanent tool this repo keeps. Use when a check, report, or analysis has proved worth running more than once.