Liveblocks Room Presence Requires Initial State on Room Entry

Liveblocks presence for new users shows as undefined or throws a type error when other users try to read their cursor or selection state immediately after they join a room.

Always provide an initialPresence object when entering a room. Define the full presence schema with sensible defaults so other users never encounter undefined fields.

import { createClient } from '@liveblocks/client';
import { createRoomContext } from '@liveblocks/react';

type Presence = {
  cursor: { x: number; y: number } | null;
  selectedId: string | null;
  name: string;
};

const client = createClient({ publicApiKey: 'pk_...' });
const { RoomProvider, useMyPresence, useOthers } = createRoomContext<Presence>(client);

function Editor() {
  return (
    <RoomProvider
      id="my-room"
      initialPresence={{
        cursor: null,
        selectedId: null,
        name: currentUser.name
      }}
    >
      <Canvas />
    </RoomProvider>
  );
}

Liveblocks broadcasts presence immediately on join. Without initialPresence the server has no state to broadcast and other clients receive null or partial objects, causing runtime errors in typed consumers.