@rubriclab/state

A lightweight, real-time state management library for Next.js applications with WebSocket support.

Get started

Installation

bun add @rubriclab/state

@rubriclab scope packages are not built, they are all raw TypeScript. If using in a Next.js app, make sure to transpile.

import type { NextConfig } from  'next'

export default {
	transpilePackages: ['@rubriclab/state']
} satisfies  NextConfig

If using inside the monorepo (@rubric), simply add {"@rubriclab/state": "*"} to dependencies and then run bun i

Define shape

To get started, define a few objects.

import { z } from 'zod/v4'

export const schema = z.object({
  todos: z.record(z.string(), z.object({
    title: z.string(),
    completed: z.boolean()
  })).default({})
})

Wrap your app in the provider

The provider handles fetching initial data for first-paint (SSR)

import { RealtimeProvider } from '@rubriclab/state'

export default function Layout({ children }) {
  return (
    <RealtimeProvider websocketUrl="ws://localhost:3001">
      {children}
    </RealtimeProvider>
  )
}

Create a hook

Pass your schema into the hook creator to get typesafe states.

import { createLiveState } from '@rubriclab/state/client'

const { useLiveState } = createLiveState(schema)

export function MyComponent() {
  const [todos, setTodos] = useLiveState('todos')
  
  const addTodo = () => {
    setTodos(prev => ({
      ...prev,
      [crypto.randomUUID()]: { title: 'New todo', completed: false }
    }))
  }

  return (
    <div>
      <button onClick={addTodo} type="button">
        Add Todo
      </button>
      <ul>
        {Object.entries(todos).map(([id, todo]) => (
          <li key={id}>
            <input
              type="checkbox"
              checked={todo.completed}
              onChange={() => 
                setTodos(prev => ({
                  ...prev,
                  [id]: { ...todo, completed: !todo.completed }
                }))
              }
            />
            {todo.title}
          </li>
        ))}
      </ul>
    </div>
  )
}

Use it as you would useState.

Start the server

Run bun run rubriclab-state-start to start the server.

The server can be deployed eg. on Railway by setting this as the custom start command.

Redis Persistence (Optional)

To enable state persistence across server restarts, set the REDIS_URL environment variable:

REDIS_URL=redis://localhost:6379 bun run rubriclab-state-start

When Redis is configured:

• State is automatically persisted to Redis on every update
• State is loaded from Redis when a channel is accessed
• State persists across server restarts and deployments
• Each channel's state is stored with the key pattern state:{channelId}

This is particularly useful for production deployments where you want state to survive server restarts.

Test it

Open your Next.js app in two browser windows. Values should be synced between the two.

Try disabling JS in one browser:

⌘+⇧+i > ⌘+⇧+p > disable j... > ⏎

then refreshing - the page should still reflect fresh data.

Features

• 🔄 Real-time state synchronization
• 🔒 Type-safe with Zod schemas
• 🚀 Built with Bun.js for performance
• ⚡️ Minimal API surface
• 🔌 WebSocket-based communication
• 💾 Optional Redis persistence for production deployments

Development

Start the WebSocket server:

bun dev

License

MIT