tsdown

tsdown is a skill for Claude Code, Codex from sanity-io/next-sanity. It costs 41 tokens per session (3,319 once invoked), scanned A, a copy of tsdown, MIT.

A bundler for TypeScript and JavaScript libraries. It packages source code for formats such as ESM and CommonJS and can also produce TypeScript declaration files for consumers.

In plain words
What is it for?
Use it when building npm libraries or React, Vue, Solid, and Svelte component libraries, creating declaration files, or moving a project from tsup.
Why use it?
It handles the build steps needed to publish a library, including packaging different module formats, reducing unused code, and generating type information.

Skill for Claude CodeCodex

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

Good fit Use it when building npm libraries or React, Vue, Solid, and Svelte component libraries, creating declaration files, or moving a project from tsup.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/sanity-io/next-sanity/tsdown
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.

Any agent
npx skills add sanity-io/next-sanity --skill tsdown
Clone the repo
git clone --depth 1 https://github.com/sanity-io/next-sanity

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/sanity-io/next-sanity/tsdown/github.svg)](https://agentmods.dev/skills/sanity-io/next-sanity/tsdown)
Your own site
<a href="https://agentmods.dev/skills/sanity-io/next-sanity/tsdown"><img src="https://agentmods.dev/badge/skills/sanity-io/next-sanity/tsdown/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for tsdown

Your own site · 80×15
<a href="https://agentmods.dev/skills/sanity-io/next-sanity/tsdown"><img src="https://agentmods.dev/badge/skills/sanity-io/next-sanity/tsdown.svg" alt="Reviewed on agentmods" width="80" 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 3,319 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 $0.03319
Opus 5 $0.00020 $0.01659
Sonnet 5 $0.00008 $0.00664
Haiku 4.5 $0.00004 $0.00332

Measured 9d ago against content hash 0e9348c1699d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, 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 9d 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 — 166 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 · 429 lines

How it starts

The opening of the file, as written. The whole thing — 429 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

Read the full file on GitHub · 429 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. 9d ago First seen · 429 lines · 41 tokens per session scan A 0e9348c1699d

Subscribe to this mod's changes

tsdown is a skill published in the GitHub repository sanity-io/next-sanity (949 stars, last pushed today), licensed MIT. It adds 41 tokens to every session and 3,319 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 166 lines, and is treated as a copy.

Related

Other skills, from other repositories

client-setup

Create a vanilla tRPC client with createTRPCClient (), configure link chain with httpBatchLink/httpLink, dynamic headers for auth, transformer on links (not client constructor). Infer types with inferRouterInputs and inferRouterOutputs. AbortController signal support. TRPCClientError typing.

trpc/trpc · 63 tokens

adapter-express

Mount tRPC as Express middleware with createExpressMiddleware() from @trpc/server/adapters/express. Access Express req/res in createContext via CreateExpressContextOptions. Mount at a path prefix like app.use('/trpc', ...). Avoid global express.json() conflicting with tRPC body parsing for FormData.

trpc/trpc · 67 tokens

trpc-router

Entry point for all tRPC skills. Decision tree routing by task: initTRPC.create(), t.router(), t.procedure, createTRPCClient, adapters, subscriptions, React Query, Next.js, links, middleware, validators, error handling, caching, FormData.

trpc/trpc · 59 tokens

fast-typescript-check

Keep www-sacred's TypeScript fast to type-check and fast to run. Use when touching the ASCII/canvas animation components (the only real per-frame code here), tightening type-check wall-clock, or auditing a change for runtime or compiler regressions. Scoped to this repo — a React 19 / Next.js 16 component library plus…

internet-development/www-sacred · 84 tokens

port-sacred-terminal-ui-to-typescript-cli

Take a React Window.tsx (or any sacred component) and produce a terminal CLI screen written in TypeScript that uses Simulacrum — the sacred CLI framework in scripts/cli/lib/.

internet-development/www-sacred · 0 tokens

typescript-language

Apply modern TypeScript standards for type safety and maintainability. Use when working with types, interfaces, generics, enums, unions, or tsconfig settings.

HoangNguyen0403/agent-skills-standard · 35 tokens