State Management

The website keeps its shared state in one Zustand store, web/lib/store.ts. Zustand does the job NgRx does in Angular, with much less code: state plus the functions that change it.

What lives where

State	Where	Why
Sign-in, open page, drawer, last failed save	The store	Several parts of the site use them
Data from the database	Each page loads its own	Supabase is the master copy
One component's own state	React `useState`	Nothing else needs it
Small preferences (panel widths)	`localStorage`	They belong to this browser

The store

Field	Meaning
`auth`	`{session}` when signed in, `{message}` when not, `null` while checking
`section`	`"sources"` or `"math"`
`menuOpen`	Whether the ☰ drawer is open
`saveError`	The last save to the account that failed

Action	When
`setAuth`	Sign-in is checked, the token refreshes, or you sign out
`setSection`	You move between Sources and Maths
`toggleMenu`	You press ☰
`closeMenu`	The drawer closes (Escape, or a link on a phone)
`setSaveError`	A save fails, or a page clears the last error

Sessions

Supabase keeps the sign-in session in the browser and refreshes its token (persistSession: true in web/lib/auth.js). There is no server, so no cookies or middleware. watchSession() keeps the store's auth current: signing out in one tab signs out the others.

Seeing the store

On dev and locally only, never on the live site:

Install the Redux DevTools browser extension.
Open abhyas.dev.nishko.co, open developer tools, go to the Redux tab.
Pick abhyas. Each action appears by name as it happens.

Or type abhyas.getState() in the Console.

Using it in code

// React: the component redraws only when the picked value changes
const menuOpen = useSite((s) => s.menuOpen);

// Plain JavaScript (lib/sources.js, lib/math/app.js)
site.getState().setSaveError("");
const stop = site.subscribe((s, before) => { /* ... */ });  // call stop() when the page closes

Add state to the store only when more than one part of the site needs it. Give it a default, a comment and a setter in web/lib/store.ts. Keep database data out of it.