feat(core-testing): RecordingRealtimeBroadcaster (local-type-alias pattern)

packages/core-testing/src/instrumentation/recording-realtime-broadcaster.ts

@@ -0,0 +1,29 @@
+// Local type aliases mirroring @repo/core-realtime's contracts. Kept inline to
+// avoid a build-graph cycle between core-testing (tooling) and core-realtime (core).
+// Same pattern recording-event-bus + recording-job-queue use.
+import type { z } from "zod";
+
+type RealtimeChannelDescriptor<TName extends string, TSchema extends z.ZodType> = {
+  readonly name: TName;
+  readonly schema: TSchema;
+  readonly scope?: string;
+};
+
+interface IRealtimeBroadcaster {
+  broadcast<T>(
+    descriptor: RealtimeChannelDescriptor<string, z.ZodType<T>>,
+    payload: T,
+  ): Promise<void>;
+}
+
+export class RecordingRealtimeBroadcaster implements IRealtimeBroadcaster {
+  readonly broadcasts: { channel: string; payload: unknown }[] = [];
+
+  async broadcast<T>(
+    descriptor: RealtimeChannelDescriptor<string, z.ZodType<T>>,
+    payload: T,
+  ): Promise<void> {
+    descriptor.schema.parse(payload);
+    this.broadcasts.push({ channel: descriptor.name, payload });
+  }
+}