unjs-citty

A reference guide for the citty JavaScript command-line library, including its current usage and version-specific behavior.

In plain words
What is it for?
Use it when writing, debugging, or modifying code that imports citty.
Why use it?
It helps avoid outdated examples and catches changes such as ESM-only imports and updated argument parsing.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/skilld-dev/skilld/unjs-citty
Any agent
npx skills add skilld-dev/skilld --skill unjs-citty
Clone the repo
git clone --depth 1 https://github.com/skilld-dev/skilld

Made for: Claude Code, Codex.

Per session 28 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,724 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found 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 $0.00028 $0.01724
Opus 5 $0.00014 $0.00862
Sonnet 5 $0.00006 $0.00345
Haiku 4.5 $0.00003 $0.00172

Measured 2d ago against content hash ab6167c25ee2, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

unjs-citty 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.

.claude/skills/unjs-citty/SKILL.md · 142 lines

How it starts

The opening of the file, as written. The whole thing — 142 lines — stays where its author put it; the contents beside it link to each section on GitHub.

unjs/citty citty

Version: 0.2.1 (yesterday) Tags: latest: 0.2.1 (yesterday)

References: package.jsonREADMEGitHub IssuesReleases

Use npx -y skilld search instead of grepping .skilld/ directories — hybrid semantic + keyword search across all indexed docs, issues, and releases.

npx -y skilld search "query" -p citty
npx -y skilld search "issues:error handling" -p citty
npx -y skilld search "releases:deprecated" -p citty

Filters: docs:, issues:, releases: prefix narrows by source type.

API Changes

⚠️ ESM-only — v0.2.0 ships ESM only, require('citty') no longer works source

⚠️ node:util.parseArgs internally — v0.2.0 replaced custom parser with Node.js native util.parseArgs, edge cases around arg parsing may differ from v0.1.x source

⚠️ Optional args type T | undefined — v0.2.0 improved type inference: args without required: true or default now correctly type as T | undefined instead of T source

⚠️ --no- negation conditionally printed — v0.2.0 only shows --no-<flag> in usage when negativeDescription is set; previously always shown source

type: "enum" — new arg type in v0.2.0, requires options: string[] array. Typed as union of options values source

args: {
  color: {
    type: "enum",
    options: ["red", "blue", "green"] as const,
    description: "Pick a color",
  },
}
// args.color typed as "red" | "blue" | "green" | undefined

meta.hidden — v0.2.0, hides a subcommand from usage/help output source

negativeDescription — v0.2.0, on boolean args, sets description for the --no-<flag> variant in usage source

cleanup hook — v0.1.4, runs after run() completes (mirror of setup) source

Read the full file on GitHub · 142 lines

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. 2d ago First seen · 142 lines · 28 tokens per session scan A ab6167c25ee2

Subscribe to this mod's changes

unjs-citty is a skill published in the GitHub repository skilld-dev/skilld (306 stars, last pushed 6d ago), licensed MIT. It adds 28 tokens to every session and 1,724 once invoked, about $0.0001 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.

Related

Other skills, from other repositories

systematic-debugging

Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes.

obra/superpowers · 21 tokens

next-cache-components-adoption

Turn on Cache Components in a Next.js app and resolve the blocking routes it surfaces. Use when the user wants to enable, adopt, or migrate to Cache Components, flip the cacheComponents flag, work through a flood of blocking-prerender / instant validation errors, run the cache-components-instant-false codemod, or…

vercel/next.js · 95 tokens

babysit-pr

Babysit a GitHub pull request after creation by continuously polling review comments, CI checks/workflow runs, and mergeability state until the PR is merged/closed or user help is required. Diagnose failures, retry likely flaky failures up to 3 times, auto-fix/push branch-related issues when appropriate, and keep…

openai/codex · 114 tokens

imagegen

Generate or edit raster images when the task benefits from AI-created bitmap visuals such as photos, illustrations, textures, sprites, mockups, or transparent-background cutouts. Use when Codex should create a brand-new image, transform an existing image, or derive visual variants from references, and the output…

openai/codex · 113 tokens

cpu-profile-analysis

Analyze V8/Chrome CPU profiles (.cpuprofile) and DevTools trace files (Trace-.json). Use when: profiling performance, investigating slow functions, comparing code paths, finding bottlenecks, analyzing timeToRequest, understanding call trees from sampling profiler data, analyzing layout/paint/rendering, investigating…

microsoft/vscode · 71 tokens

next-cache-components-optimizer

Drive a Next.js route to instant navigation by setting up an agentic loop, under Cache Components / PPR, on initial load (hard navigation) and client-side navigation (soft navigation). Encode the goal as a failing @next/playwright instant() e2e and work it to green, one verified route at a time; the shipped test then…

vercel/next.js · 170 tokens