feat(payment): add chat support discounts and gratitude

src/stores/chat/helper/commercial-message.ts

@@ -0,0 +1,30 @@
+import { createRemoteUiMessageIdentity, type UiMessage } from "../ui-message";
+import { todayString } from "@/utils/date";
+
+export interface IncomingCommercialMessage {
+  messageId: string;
+  message: string;
+  characterId: string;
+  createdAt: string;
+}
+
+export function appendCommercialMessage(
+  messages: readonly UiMessage[],
+  activeCharacterId: string,
+  incoming: IncomingCommercialMessage,
+): UiMessage[] {
+  if (incoming.characterId !== activeCharacterId) return [...messages];
+  if (messages.some((message) => message.remoteId === incoming.messageId)) {
+    return [...messages];
+  }
+  const createdAt = new Date(incoming.createdAt);
+  return [
+    ...messages,
+    {
+      ...createRemoteUiMessageIdentity(incoming.messageId, true),
+      content: incoming.message,
+      isFromAI: true,
+      date: todayString(Number.isNaN(createdAt.getTime()) ? new Date() : createdAt),
+    },
+  ];
+}