feat(core-realtime): realtime-ping proof-of-life channel pair

packages/core-realtime/src/index.ts

@@ -13,3 +13,10 @@ export { SocketIORealtimeBroadcaster } from "./socket-io-realtime-broadcaster";
 export { SocketIORealtimeServer } from "./socket-io-realtime-server";
 export { authorize } from "./authorize";
 export { matchChannelTemplate } from "./channel-template";
+export {
+  realtimePingChannel,
+  realtimePongChannel,
+  realtimePingInboundDescriptor,
+  type PingPayload,
+  type PongPayload,
+} from "./realtime-ping";

packages/core-realtime/src/realtime-ping.ts

@@ -0,0 +1,36 @@
+import { z } from "zod";
+import { defineRealtimeChannel } from "./realtime-channel";
+import type { IRealtimeBroadcaster } from "./realtime-broadcaster.interface";
+import type { IInboundDescriptor, RealtimeContext } from "./realtime-handler.interface";
+
+const pingSchema = z.object({ at: z.string().datetime() }).strict();
+const pongSchema = z.object({ at: z.string().datetime(), echo: z.string() }).strict();
+
+export type PingPayload = z.infer<typeof pingSchema>;
+export type PongPayload = z.infer<typeof pongSchema>;
+
+export const realtimePingChannel = defineRealtimeChannel(
+  "realtime.ping",
+  pingSchema,
+  { scope: "authenticated" },
+);
+
+export const realtimePongChannel = defineRealtimeChannel(
+  "realtime.pong",
+  pongSchema,
+  { scope: "authenticated" },
+);
+
+export function realtimePingInboundDescriptor(
+  broadcaster: IRealtimeBroadcaster,
+): IInboundDescriptor<typeof realtimePingChannel.name, typeof pingSchema> {
+  return {
+    descriptor: realtimePingChannel,
+    handler: async (input: PingPayload, ctx: RealtimeContext): Promise<void> => {
+      await broadcaster.broadcast(realtimePongChannel, {
+        at: input.at,
+        echo: ctx.userId ?? "anonymous",
+      });
+    },
+  };
+}