Coming from Firebase Realtime Database

Concept mapping

Firebase	svelte-realtime
`ref.on('value', cb)`	`live.stream()` with `merge: 'set'`
`ref.on('child_added', cb)`	`live.stream()` with `merge: 'crud'`, `created` events
`ref.on('child_changed', cb)`	Same stream, `updated` events
`ref.on('child_removed', cb)`	Same stream, `deleted` events
`ref.set(data)`	`live()` RPC call
`ref.push()`	RPC + `ctx.publish(topic, 'created', data)`
`ref.update(data)`	RPC + `ctx.publish(topic, 'updated', data)`
`ref.remove()`	RPC + `ctx.publish(topic, 'deleted', data)`
Security rules	`upgrade()` + `guard()`
`.orderByChild().limitToLast()`	Cursor pagination with `loadMore()`
`onDisconnect()`	`onUnsubscribe` lifecycle hook

Side-by-side: Real-time list

Firebase

import { getDatabase, ref, onChildAdded, onChildRemoved, push, set } from 'firebase/database';

const db = getDatabase();
const todosRef = ref(db, 'todos');

onChildAdded(todosRef, (snapshot) => {
  todos = [...todos, { id: snapshot.key, ...snapshot.val() }];
});

onChildRemoved(todosRef, (snapshot) => {
  todos = todos.filter(t => t.id !== snapshot.key);
});

function addTodo(text) {
  const newRef = push(todosRef);
  set(newRef, { text, done: false });
}

svelte-realtime

// src/live/todos.js
export const addTodo = live(async (ctx, text) => {
  const todo = { id: crypto.randomUUID(), text, done: false };
  ctx.publish('todos', 'created', todo);
  return todo;
});

export const todos = live.stream('todos', () => [], {
  merge: 'crud', key: 'id'
});

<script>
  import { todos, addTodo } from '$live/todos';
</script>

{#each $todos as todo (todo.id)}
  <p>{todo.text}</p>
{/each}

Key differences

No Firebase SDK. No Google dependency, no vendor lock-in. Runs on your own server.
Server-side logic. Firebase security rules are JSON-based and limited. svelte-realtime uses real code - guard() with full access to your database, auth system, and business logic.
No listener management. Firebase requires on()/off() cleanup. svelte-realtime stores auto-subscribe and auto-cleanup on component destroy.
WebSocket, not long polling. Firebase falls back to long polling in some environments. svelte-realtime is always WebSocket.

Migration steps

Replace ref.on('value', cb) with live.stream() subscriptions
Replace ref.set()/push()/update() with live() RPC handlers
Add ctx.publish() after each write to broadcast changes
Replace Firebase security rules with upgrade() + guard()
Replace onDisconnect() with onUnsubscribe lifecycle hooks

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