Ts packaging

Skill fusengine/agents/plugins/typescript-expert/skills/ts-packaging

Use when publishing a TypeScript library — exports map, JSR vs npm, dual ESM/CJS, type validation, provenance. Covers modern package.json, jsr.json, and release CI. Do NOT use for application deployment (not a library) or framework build pipelines (use the framework expert's skills).From its SKILL.md

Install

npx -y skills add fusengine/agents --skill ts-packaging

Assembled from the repository path, not quoted from the project. Check it against their README if it does not work.

One thing to look at

22 stars22 stars. Stars are a popularity signal and not a quality one, but at this level it is likely that nobody has read this closely except its author, and you would be relying on your own review.

SKILL.md

3.8 KB, 851 tokens by cl100k_base, as published. Nobody here has run it

TypeScript Packaging

Ship a TypeScript library with a correct exports map, on the right registry.

Agent Workflow (MANDATORY)

Before ANY implementation, use TeamCreate to spawn 3 agents:

fuse-ai-pilot:explore-codebase - Inspect package.json, build output, targets
fuse-ai-pilot:research-expert - Verify latest JSR / npm / Node exports docs via Context7/Exa
mcp__context7__query-docs - Check conditions ordering, attw usage

After implementation, run fuse-ai-pilot:sniper for validation.

Overview

Registry	Format	Publishes	Best for
JSR	ESM only	TS source directly	Deno/Node/Bun libs, doc-rich APIs
npm	ESM (or dual ESM/CJS)	Built `.js` + `.d.ts`	Broadest public reach, CJS consumers

Rule of thumb: internal or Bun/Deno/ESM-only consumer → ESM-pure; broad public library still serving CommonJS → dual ESM/CJS.

Critical Rules

"types" first, "default" last - Conditions match in object order
Match import↔ESM and require↔CJS - Never point require at ESM
One subpath per module - Consistent specifier; set "type": "module" explicitly
Validate with attw - arethetypeswrong before every publish
Provenance on public releases - Publish from CI with id-token: write

Decision Guide

Publishing a TS library?
├── Consumers on Deno/Bun/Node ESM, want source + docs → JSR (ESM only)
│   └── Fix "slow types" (explicit return/prop/const types)
└── Public npm audience
    ├── ESM-only consumers → ESM-pure package.json
    └── Some consumers still on CJS → dual ESM/CJS exports

→ See references/exports-map.md for the conditions model

Reference Guide

Concepts

Topic	Reference	Load when
Exports map & conditions	`references/exports-map.md`	Writing the `exports` field
JSR publishing	`references/jsr-publishing.md`	Publishing TS source to JSR
npm publishing	`references/npm-publishing.md`	Publishing to npm (dual/ESM)
Type validation	`references/validation.md`	Checking types resolve correctly

Templates

Template	Use Case
`references/templates/package-json-dual.md`	Dual ESM/CJS + ESM-pure package.json
`references/templates/jsr-json.md`	jsr.json with multi-entry exports
`references/templates/publish-workflow.md`	GitHub Actions release with provenance

Quick Start

Modern exports (ESM-pure)

{
  "type": "module",
  "exports": {
    ".": { "types": "./dist/index.d.ts", "default": "./dist/index.js" }
  }
}

Validate before publish

npx @arethetypeswrong/cli --pack

→ See references/validation.md

Best Practices

DO

Set "type" explicitly, even for CJS packages
Provide types in every conditional branch
Publish from CI so provenance is automatic

DON'T

Ship dual CJS when every consumer is ESM (dead weight)
Order "default" before "types" (breaks type resolution)
Use --allow-slow-types on JSR as a habit (degrades docs + npm compat)

What ships with it: 8 files

15.3 KB alongside SKILL.md

references/

.gitkeep0 B

Gives 0 of the 12 instructions most ship operate skills give in 851 tokens

Counted across 779 of the 1,178 authors here whose files we hold, read 2026-08-07

Document a rollback plan before deploymentin 41 of 779, across 22 files
Update the changelogin 21 of 779, across 19 files
Run the test suitein 20 of 779
Create an annotated git tagin 20 of 779
Clean up feature flags after full rolloutin 18 of 779, across 10 files
Verify deployment health after launchin 18 of 779, across 10 files
Test both feature flag statesin 17 of 779, across 9 files
Verify the working tree is cleanin 17 of 779
Make database migrations backward-compatiblein 16 of 779, across 8 files
Set up error monitoring before launchin 15 of 779, across 7 files
Monitor metrics at each rollout stagein 14 of 779, across 5 files
Create a GitHub releasein 14 of 779

Said here and by no other author read

spawn 3 agents before implementation
place types condition before default condition
match import to ESM and require to CJS
set type field explicitly
use one subpath per module
fix slow types in JSR packages

Grouped from the skills themselves: near-identical wordings counted once, and counted by distinct author, so one author publishing three of these counts once. Length counted with cl100k_base; the agent that loads this file may tokenize it differently.