tsdown is a tool that packages TypeScript libraries into distributable builds using the Rolldown bundler. Library authors use it to bundle code and generate declaration files while supporting plugins from related JavaScript tooling.
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 skills add rolldown/tsdown --skill tsdown-migrategit clone --depth 1 https://github.com/rolldown/tsdownWrote 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/rolldown/tsdown/tsdown-migrate)<a href="https://agentmods.dev/skills/rolldown/tsdown/tsdown-migrate"><img src="https://agentmods.dev/badge/skills/rolldown/tsdown/tsdown-migrate/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.
<a href="https://agentmods.dev/skills/rolldown/tsdown/tsdown-migrate"><img src="https://agentmods.dev/badge/skills/rolldown/tsdown/tsdown-migrate.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket pass
- Snyk pass
- NVIDIA SkillSpector warn
SkillSpector: 1 finding, up to high
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- high Anti-Refusal · line 90 Skill instructs the agent to omit warnings, disclaimers, or ethical commentary. Stripping safety caveats hides risk from the user and is a common jailbreak preamble.Fix: Remove instructions that suppress warnings, disclaimers, or ethical commentary. Let the agent surface safety-relevant caveats to the user.
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 | $0.00043 | $0.03304 |
| Opus 5.5 | $0.00017 | $0.01322 |
| Sonnet 5.5 | $0.00009 | $0.00661 |
| Haiku 4.5 | $0.00004 | $0.00330 |
Grade A, and why
tsdown-migrate 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 1mo 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 — 270 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Migrating from tsup to tsdown
Knowledge base for AI agents to migrate tsup projects to tsdown — the Rolldown-powered library bundler.
Target Version: Two-Stage Migration
tsdown v0.23 removed all previously-deprecated tsup compatibility options — bundle, outExtension, publicDir, removeNodeProtocol, injectStyle, and skipNodeModulesBundle are no longer recognized. They fail TypeScript type checking and are silently ignored at runtime, so a missed mapping on v0.23+ produces wrong output without any error. Migrating directly to v0.23+ is therefore unsafe. tsdown v0.22.14 is the last version that still accepts these options and flags each one with a deprecation warning, making it the safe migration checkpoint. Migrate in two stages:
- Stage 1 — migrate on
[email protected]: Install[email protected], migrate the config per the tables below, run a build, and resolve every deprecation warning by mapping each flagged tsup option to its real tsdown equivalent. The warnings are the completeness check — the migration is not done until the build produces zero warnings. - Stage 2 — upgrade to the latest tsdown (
^0.23.0or newer): Only after a warning-free build on 0.22.14. Since the config no longer uses any removed compat options, the silent-ignore behavior of v0.23+ is no longer a risk.
Runtime Requirement
tsdown requires Node.js ^22.18.0 || ^24.11.0 || >=26.0.0 to run (build-time only) — that is, Node.js 22.18+, 24.11+, or 26+. Odd-numbered and EOL release lines (e.g. Node.js 23, 25) are not supported. The bundled output can still target lower Node.js versions via the target option, so a library that previously supported Node.js 18 / 20 with tsup can continue to do so after migrating.
Recommended workflow when supporting Node.js 18 / 20:
- Build with Node.js 22+ in CI, setting an explicit
targetsuch as'node18'or'node20'. - Test the built output (or the packed tarball) on the lower Node.js versions you need to support.
What ships with it
4 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.
- 1mo ago First seen · 270 lines · 43 tokens per session scan A 444ba2ab9b7d
tsdown-migrate is a skill published in the GitHub repository rolldown/tsdown (4,309 stars, last pushed 3d ago), licensed MIT. It adds 43 tokens to every session and 3,304 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-08-30.
Other skills, from other repositories
rolldown-docs
Rolldown 1.x — Rust-based JS bundler with Rollup-compatible API. Treeshaking, plugins, code splitting, minification.
vite-docs
Use this skill whenever the user asks about Vite, build tools, dev servers, HMR, production builds, or frontend tooling. Covers Vite 8.x with Rolldown and Oxc, including plugins, SSR, Environment API, library mode, deployment, and configuration. Use it for code generation, architecture decisions, debugging, migration…
bun
Bun all-in-one JavaScript runtime and toolkit reference. Covers runtime APIs (file I/O, HTTP server, SQLite, shell), ultra-fast package manager, built-in bundler with plugins, test runner with mocking, TypeScript support, and Node.js compatibility.
no-bare-casts
Writing as in TypeScript or TSX production code, modifying a file that contains a bare as cast, silencing a type error with a cast, encountering as unknown as, or reviewing a cast site.
league-akari-shard-development
Use when creating, extending, refactoring, splitting, or reviewing League Akari main or renderer shards, including shard file organization, controller/loader/executor/handler boundaries, naming conventions, renderer TSX usage, platform guards, and public contract compatibility.
dd-code-generation
Use pup CLI for immediate Datadog operations or generate code for integration into applications.