alepha@docs:~/docs/reference/primitives$
cat $channel.md | pretty
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#$channel

#Import

typescript 
1import { $channel } from "alepha/websocket";

#Overview

Defines a WebSocket channel with specified client and server message schemas.

Channels must be defined as class properties to be registered in the Alepha context. They define the "vocabulary" for communication - the schema for messages flowing in both directions (server→client and client→server).

#Options

Option Type Required Description
path string Yes WebSocket endpoint path (e.g., "/ws/chat")
description string No Optional description for documentation
schema Object Yes Message schemas for bidirectional communication
roomId TString No Optional room ID schema validation Default: t.text() (any string) Can be enforced at application level: t.uuid(), t.regex(/^[a-f0-9-]{36}$/)
in TClient Yes Messages from server to client This is what clients will receive
out TServer Yes Messages from client to server This is what the server will receive

#Examples

Server-side with $websocket

typescript 
 1class ChatController { 2  // Channel must be defined inside a class 3  chatChannel = $channel({ 4    path: "/ws/chat", 5    description: "Real-time chat channel", 6    schema: { 7      // Server → Client messages 8      in: t.union([ 9        t.object({10          type: t.const("append"),11          content: t.text(),12          username: t.text()13        }),14        t.object({15          type: t.const("system"),16          message: t.text()17        })18      ]),19      // Client → Server messages20      out: t.object({21        content: t.text()22      })23    }24  });25 26  chat = $websocket({27    channel: this.chatChannel,28    handler: async ({ message, reply }) => {29      await reply({30        message: { type: "append", content: message.content, username: "user" }31      });32    }33  });34}

Browser-side with useRoom

typescript 
 1// Define channel in a class for browser context 2class ChatClient { 3  chatChannel = $channel({ 4    path: "/ws/chat", 5    schema: { in: inSchema, out: outSchema } 6  }); 7} 8  9// Use in React component10function Chat() {11  const client = useInject(ChatClient);12  const chat = useRoom({ roomId: "lobby", channel: client.chatChannel, handler: ... }, []);13}