refactor(stores): tighten chat and payment boundaries

src/stores/chat/chat-unlock-helpers.ts

@@ -0,0 +1,56 @@
+import type { UiMessage, UnlockPrivateResponse } from "@/data/dto/chat";
+
+export interface UnlockMessageOutput {
+  messageId: string;
+  response: UnlockPrivateResponse;
+}
+
+export function countLockedHistoryMessages(messages: readonly UiMessage[]): number {
+  return messages.filter(isUnlockableLockedMessage).length;
+}
+
+export function applySingleUnlockOutput(
+  messages: readonly UiMessage[],
+  output: UnlockMessageOutput,
+): UiMessage[] {
+  if (!output.response.unlocked) return [...messages];
+
+  return messages.map((message) => {
+    if (message.id !== output.messageId) return message;
+
+    const nextContent =
+      output.response.content.length > 0
+        ? output.response.content
+        : message.content;
+
+    return {
+      ...message,
+      content: nextContent,
+      locked: output.response.lockDetail.locked,
+      lockReason: output.response.lockDetail.reason,
+      imagePaywalled: message.imageUrl
+        ? output.response.lockDetail.locked &&
+          output.response.lockDetail.showUpgrade
+        : undefined,
+      lockedPrivate: false,
+      privateMessageHint: null,
+    };
+  });
+}
+
+export function shouldAutoUnlockHistory(messages: readonly UiMessage[]): boolean {
+  return countLockedHistoryMessages(messages) === 1;
+}
+
+export function shouldPromptUnlockHistory(messages: readonly UiMessage[]): boolean {
+  return countLockedHistoryMessages(messages) > 1;
+}
+
+function isUnlockableLockedMessage(message: UiMessage): boolean {
+  if (!message.isFromAI || message.locked !== true) return false;
+  if (message.imagePaywalled === true) return true;
+  return (
+    message.lockReason === "private_message" ||
+    message.lockReason === "voice_message"
+  );
+}