alepha@docs:~/docs/reference/primitives$
cat $topic.md
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#$topic

#Import

typescript 
1import { $topic } from "alepha/topic";

#Overview

Creates a topic primitive for publish/subscribe messaging and event-driven architecture.

Enables decoupled communication through a pub/sub pattern where publishers send messages and multiple subscribers receive them. Supports type-safe messages, real-time delivery, event filtering, and pluggable backends (memory, Redis, custom providers).

Use Cases: User notifications, real-time chat, event broadcasting, microservice communication

#Options

Option Type Required Description
name string No Unique name identifier for the topic
description string No Human-readable description of the topic's purpose and usage
provider "memory" | Service<TopicProvider> No Topic provider configuration for message storage and delivery
schema T Yes TypeBox schema defining the structure of messages published to this topic
handler TopicHandler<T> No Default subscriber handler function that processes messages published to this topic

#Examples

ts 
 1class NotificationService { 2  userActivity = $topic({ 3    name: "user-activity", 4    schema: { 5      payload: t.object({ 6        userId: t.text(), 7        action: t.enum(["login", "logout", "purchase"]), 8        timestamp: t.number() 9      })10    },11    handler: async (message) => {12      console.log(`User ${message.payload.userId}: ${message.payload.action}`);13    }14  });15 16  async trackLogin(userId: string) {17    await this.userActivity.publish({ userId, action: "login", timestamp: Date.now() });18  }19 20  async subscribeToEvents() {21    await this.userActivity.subscribe(async (message) => {22      // Additional subscriber logic23    });24  }25}