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 event4u-app/agent-config --skill js-library-packaginggit clone --depth 1 https://github.com/event4u-app/agent-configWrote 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/event4u-app/agent-config/js-library-packaging)<a href="https://agentmods.dev/skills/event4u-app/agent-config/js-library-packaging"><img src="https://agentmods.dev/badge/skills/event4u-app/agent-config/js-library-packaging.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 | $0.00042 | $0.02182 |
| Opus 5 | $0.00021 | $0.01091 |
| Sonnet 5 | $0.00008 | $0.00436 |
| Haiku 4.5 | $0.00004 | $0.00218 |
Grade A, and why
js-library-packaging 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 3d 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 — 174 lines — stays where its author put it; the contents beside it link to each section on GitHub.
js-library-packaging
Pack placement.
engineering-base. The step asked for it to be suggested by thereactandtypescriptpacks, and the skill schema carries nosuggested_bykey — so the intent is recorded here rather than expressed in frontmatter that would fail validation. A React or TypeScript consumer receives this skill throughengineering-base, which both of those packs require.
The JavaScript twin of composer-packages. A component is
a file; a library is a package with a public surface, and that surface is declared in
package.json rather than inferred. Most of the failures below are silent at author time
and loud at the consumer's — which is why the surface is read, not assumed.
The Iron Law
`react` AND `react-dom` ARE peerDependencies. NEVER dependencies.
`types` IS THE FIRST KEY OF EVERY CONDITIONS OBJECT.
DECIDE buildable-VS-source-consumed BEFORE WRITING THE EXPORTS MAP.
NEVER HAND-BUMP A VERSION.
When to use
A package in the repository is imported by another package, or is about to be published:
an exports map is being written or changed, a hook fails at runtime with "invalid hook
call", an install fails on a workspace: range, a release needs cutting, or the
buildable-vs-source question has not been answered yet.
Procedure
- Answer buildable-vs-source-consumed FIRST. It determines the exports map, the
fileslist, and whether a build step exists at all — deciding it after writing the map means rewriting the map.- Source of truth: is the package published to a registry, or only consumed inside this workspace?
- Verify: the exports targets all point into one of the two worlds (
src/or the build directory), never a mix.
- Read the surface rather than asserting it. Run the check below over the package root.
- Source of truth:
package.json—exports,dependencies,peerDependencies,files,private,publishConfig. - Verify: zero
error-severity findings.
- Source of truth:
- Fix peer placement before anything else. A library carrying
reactindependenciesgives the consumer a second copy of React.- Verify:
reactandreact-domappear underpeerDependenciesonly.
- Verify:
- Order the conditions.
typesfirst, thenimport/require.- Verify: the check reports no
types-not-first.
- Verify: the check reports no
- Cut the release through the repository's own mechanism — never by editing a version
field. See § Release.
- Verify: the version change is produced by the tool the repository already carries.
What ships with it
2 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.
- 3d ago First seen · 174 lines · 42 tokens per session scan A be62ed5a8aea
js-library-packaging is a skill published in the GitHub repository event4u-app/agent-config (10 stars, last pushed today), licensed MIT. It adds 42 tokens to every session and 2,182 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 2026-09-03.
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