tsdown

tsdown is a skill for Claude Code, Codex from christopher-buss/bedrock. It costs 41 tokens per session (3,168 once invoked), scanned A, a copy of tsdown, MIT.

A tool for bundling TypeScript and JavaScript libraries into distributable files, with support for type declaration files and several module formats.

In plain words
What is it for?
Use it to build npm libraries, generate .d.ts files, create ESM or CommonJS bundles, and migrate from tsup.
Why use it?
It turns library source code into packages that can be published or used by different JavaScript environments.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents).

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.

agentmods
npx agentmods add skills/christopher-buss/bedrock/tsdown
Any agent
npx skills add christopher-buss/bedrock --skill tsdown
Clone the repo
git clone --depth 1 https://github.com/christopher-buss/bedrock

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 tsdown

README.md
[![agentmods](https://agentmods.dev/badge/skills/christopher-buss/bedrock/tsdown.svg)](https://agentmods.dev/skills/christopher-buss/bedrock/tsdown)
Your own site
<a href="https://agentmods.dev/skills/christopher-buss/bedrock/tsdown"><img src="https://agentmods.dev/badge/skills/christopher-buss/bedrock/tsdown.svg" alt="Measured on agentmods" height="20"></a>
Per session 41 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,168 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 86% copy Near-identical to another mod 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 $0.00041 $0.03168
Opus 5 $0.00020 $0.01584
Sonnet 5 $0.00008 $0.00634
Haiku 4.5 $0.00004 $0.00317

Measured 4d ago against content hash 3c51a9bc3cc5, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

tsdown 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 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.

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.

Origin

This is a copy

86% identical to tsdown — 18 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.agents/skills/tsdown/SKILL.md · 405 lines

How it starts

The opening of the file, as written. The whole thing — 405 lines — stays where its author put it; the contents beside it link to each section on GitHub.

tsdown - The Elegant Library Bundler

Blazing-fast bundler for TypeScript/JavaScript libraries powered by Rolldown and Oxc.

When to Use

  • Building TypeScript/JavaScript libraries for npm
  • Generating TypeScript declaration files (.d.ts)
  • Bundling for multiple formats (ESM, CJS, IIFE, UMD)
  • Optimizing bundles with tree shaking and minification
  • Migrating from tsup with minimal changes
  • Building React, Vue, Solid, or Svelte component libraries

Quick Start

# Install
pnpm add -D tsdown

# Basic usage
npx tsdown

# With config file
npx tsdown --config tsdown.config.ts

# Watch mode
npx tsdown --watch

# Migrate from tsup
npx tsdown-migrate

Basic Configuration

import { defineConfig } from 'tsdown'

export default defineConfig({
  entry: ['./src/index.ts'],
  format: ['esm', 'cjs'],
  dts: true,
  clean: true,
})

Core References

Topic Description Reference
Getting Started Installation, first bundle, CLI basics guide-getting-started
Configuration File Config file formats, multiple configs, workspace option-config-file
CLI Reference All CLI commands and options reference-cli
Migrate from tsup Migration guide and compatibility notes guide-migrate-from-tsup
Plugins Rolldown, Rollup, Unplugin support advanced-plugins
Hooks Lifecycle hooks for custom logic advanced-hooks
Programmatic API Build from Node.js scripts advanced-programmatic
Rolldown Options Pass options directly to Rolldown advanced-rolldown-options
CI Environment CI detection, 'ci-only' / 'local-only' values advanced-ci

Build Options

Read the full file on GitHub · 405 lines

Files

What ships with it

41 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.

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 · 405 lines · 41 tokens per session scan A 3c51a9bc3cc5

Subscribe to this mod's changes

tsdown is a skill published in the GitHub repository christopher-buss/bedrock (14 stars, last pushed 2d ago), licensed MIT. It adds 41 tokens to every session and 3,168 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 86% identical to tsdown, differing in 18 lines, and is treated as a copy.

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