diff --git a/packages/core-realtime/src/realtime-handler.interface.ts b/packages/core-realtime/src/realtime-handler.interface.ts
new file mode 100644
index 0000000..d0fb09e
--- /dev/null
+++ b/packages/core-realtime/src/realtime-handler.interface.ts
@@ -0,0 +1,14 @@
+import type { z } from "zod";
+import type { RealtimeChannelDescriptor } from "./realtime-channel";
+
+export type RealtimeContext = {
+  userId: string | null;
+  roles: string[];
+};
+
+export type IRealtimeHandler<T> = (input: T, ctx: RealtimeContext) => Promise<void>;
+
+export type IInboundDescriptor<TName extends string, TSchema extends z.ZodType> = {
+  readonly descriptor: RealtimeChannelDescriptor<TName, TSchema>;
+  readonly handler: IRealtimeHandler<z.infer<TSchema>>;
+};