A React state-management library where shared application data is stored in small stores that components can read through hooks.

Use it for application-wide values such as user preferences, counters, editing state, or other data shared across React components.

It keeps shared state and its update functions in one place without requiring provider components or much setup code.

zustand — Skill for Claude Code and Codex by fellipeutaka/leon

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.

Any agent

npx skills add fellipeutaka/leon --skill zustand

Clone the repo

git clone --depth 1 https://github.com/fellipeutaka/leon

Made for: Claude Code, Codex.

Or install frontend, the plugin that ships this one along with the rest of its 35 skills.

Wrote 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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/fellipeutaka/leon/zustand/github.svg)](https://agentmods.dev/skills/fellipeutaka/leon/zustand)

Your own site

<a href="https://agentmods.dev/skills/fellipeutaka/leon/zustand"><img src="https://agentmods.dev/badge/skills/fellipeutaka/leon/zustand/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/fellipeutaka/leon/zustand"><img src="https://agentmods.dev/badge/skills/fellipeutaka/leon/zustand.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 75 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 670 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

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.

Model	Per session	Once invoked
Fable 5.1	$0.00075	$0.00670
Opus 5.5	$0.00030	$0.00268
Sonnet 5.5	$0.00015	$0.00134
Haiku 4.5	$0.00007	$0.00067

Measured 2mo ago against content hash 6297bc73d32c, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

zustand 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 2mo 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.

skills/zustand/SKILL.md · 61 lines

How it starts

The opening of the file, as written. The whole thing — 61 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Zustand

Lightweight state management for React. No providers, no boilerplate. Stores are hooks.

Quick start

import { create } from "zustand"

interface BearState {
  bears: number
  increase: (by: number) => void
}

const useBearStore = create<BearState>()((set) => ({
  bears: 0,
  increase: (by) => set((state) => ({ bears: state.bears + by })),
}))

// In components — select only what you need
const bears = useBearStore((state) => state.bears)

Critical rules

TypeScript: Use curried form create<T>()(...) — required for type inference
Immutability: Treat state as immutable. set shallow-merges at one level only
Selectors: Always select specific fields, not the whole store. Use useShallow for multi-field selectors returning new references
Middleware order: devtools must be outermost: devtools(persist(immer(...)))
Next.js: Create stores per-request via createStore + Context, NOT global create
Nested updates: Use Immer for deep nesting, spread operator for shallow

When to use what

Need	Solution
Basic React store	`create<T>()(...)`
Vanilla (non-React) store	`createStore` from `zustand/vanilla`
Use vanilla store in React	`useStore(store, selector)`
Auto-infer types (no interface)	`combine` middleware
Persist to localStorage	`persist` middleware
Redux DevTools	`devtools` middleware
Mutable-style updates	`immer` middleware
Subscribe to slices externally	`subscribeWithSelector` middleware
Multiple fields without rerender	`useShallow` wrapper
Large store modularization	Slices pattern with `StateCreator`
Next.js App Router	`createStore` + Context + Provider
Reset store	`set(initialState)` or `store.getInitialState()`

References

API reference (create, createStore, hooks, shallow): See references/apis.md
TypeScript patterns (curried create, slices, middleware typing, custom middleware): See references/typescript.md
Middlewares (persist, devtools, immer, redux, combine, subscribeWithSelector): See references/middlewares.md
Patterns & best practices (Next.js, testing, reset, auto-selectors, SSR, deep updates): See references/patterns.md

Read the full file on GitHub · 61 lines

Files

What ships with it

5 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.

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.

2mo ago First seen · 61 lines · 75 tokens per session scan A 6297bc73d32c

Subscribe to this mod's changes

zustand is a skill published in the GitHub repository fellipeutaka/leon (5 stars, last pushed yesterday), licensed MIT. It adds 75 tokens to every session and 670 once invoked, about $0.0003 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 2026-09-03.

Frontend React

zustand next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
zustandfellipeutaka/leon	Skill	5	yesterday	MIT	A	75	Claude Code, Codex
build-ghost-appTryGhost/Ghost	Skill	56k	yesterday	MIT	A	44	Claude Code, Codex
chakra-ui-builderchakra-ui/chakra-ui	Skill	41k	yesterday	MIT	A	214	Claude Code, Codex
material-ui-tailwindmui/material-ui	Skill	99k	yesterday	MIT	A	67	Claude Code, Codex
fuzzy-rankingTanStack/table	Skill	29k	4d ago	MIT	A	62	Claude Code, Codex
r3f-best-practiceszebbern/claude-code-guide	Skill	4.7k	3d ago	MIT	A	74	Claude Code, Codex
git-safetytamagui/tamagui	Skill	14k	today	MIT	A	0	Claude Code