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/rolldown/tsdown/tsdown-migratenpx skills add rolldown/tsdown --skill tsdown-migrategit clone --depth 1 https://github.com/rolldown/tsdownWhat 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 | $0.00043 | $0.03304 |
| Opus 5 | $0.00022 | $0.01652 |
| Sonnet 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 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 — 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.
- 2d ago First seen · 270 lines · 43 tokens per session scan A 444ba2ab9b7d
tsdown-migrate is a skill published in the GitHub repository rolldown/tsdown (4,238 stars, last pushed 4d ago), licensed MIT. It adds 43 tokens to every session and 3,304 once invoked, about $0.0002 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 2026-08-30.
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