Imported from sahit-sai/saviaa (.agents/skills/zustand-store-ts/SKILL.md). Install upstream with npx skills add sahit-sai/saviaa --skill zustand-store-ts. Copyright stays with the author (MIT).

Zustand Store

Create Zustand stores following established patterns with proper TypeScript types and middleware.

Quick Start

Copy the template from assets/template.ts and replace placeholders:

• {{StoreName}} → PascalCase store name (e.g., Project)
• {{description}} → Brief description for JSDoc

Always Use subscribeWithSelector

import { create } from 'zustand';
import { subscribeWithSelector } from 'zustand/middleware';

export const useMyStore = create<MyStore>()(
  subscribeWithSelector((set, get) => ({
    // state and actions
  }))
);

Separate State and Actions

export interface MyState {
  items: Item[];
  isLoading: boolean;
}

export interface MyActions {
  addItem: (item: Item) => void;
  loadItems: () => Promise<void>;
}

export type MyStore = MyState & MyActions;

Use Individual Selectors

// Good - only re-renders when `items` changes
const items = useMyStore((state) => state.items);

// Avoid - re-renders on any state change
const { items, isLoading } = useMyStore();

Subscribe Outside React

useMyStore.subscribe(
  (state) => state.selectedId,
  (selectedId) => console.log('Selected:', selectedId)
);

Integration Steps

1. Create store in src/frontend/src/store/
2. Export from src/frontend/src/store/index.ts
3. Add tests in src/frontend/src/store/*.test.ts