Move domain stuff to sub directory, clean up base classes

packages/domain/src/kinds/RoomLeave.ts

@@ -0,0 +1,30 @@
+import {ROOM_LEAVE} from "@welshman/util"
+import {EventReader} from "../EventReader.js"
+import {EventBuilder} from "../EventBuilder.js"
+
+// NIP-29 kind-9022 room leave op, the counterpart to RoomJoin. A regular event
+// carrying the target group id ("h") tag, which resets the membership state
+// machine (ROOM_LEAVE -> Initial). The only represented tag is the group ("h"),
+// which the base owns as a behavior tag, so buildTags is empty. Tags-only content.
+export class RoomLeave extends EventReader {
+  readonly kind = ROOM_LEAVE
+
+  // The group id ("h") is read via the base group() accessor.
+  h() {
+    return this.group()
+  }
+
+  builder() {
+    return new RoomLeaveBuilder(this)
+  }
+}
+
+export class RoomLeaveBuilder extends EventBuilder<RoomLeave> {
+  readonly kind = ROOM_LEAVE
+
+  protected validate() {
+    if (!this.groupTag) {
+      throw new Error("RoomLeave requires an h identifier")
+    }
+  }
+}