feat(chat): handle daily message paywall

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

@@ -13,7 +13,7 @@
  * 设计目标：
  *   - helpers 无 XState 依赖（可独立 import / 测试）
  *   - actors 依赖 helpers（import）
- *   - machine 依赖 actors（import）—— 不直接依赖 helpers
+ *   - machine 依赖 actors，并复用 helpers 里的纯状态转换函数
  *
  * 历史：
  *   - `readInitData` + `InitResult` 已删（被 2 个独立 helper 替换）
@@ -27,6 +27,8 @@ import { ChatStorage } from "@/data/storage/chat/chat_storage";
 import { ChatSendResponse } from "@/data/dto/chat/chat_send_response";
 import { formatDate, Result, Logger } from "@/utils";
 
+import type { ChatState } from "./chat-state";
+
 const log = new Logger("StoresChatChatMachineHelpers");
 
 // ============================================================
@@ -76,6 +78,51 @@ export function sendResponseToUiMessage(response: ChatSendResponse): UiMessage {
   };
 }
 
+export type HttpSendOutput = {
+  response: ChatSendResponse;
+  reply: UiMessage | null;
+};
+
+export function applyHttpSendOutput(
+  context: ChatState,
+  output: HttpSendOutput,
+): Partial<ChatState> {
+  const { response, reply } = output;
+
+  if (response.blocked === true && response.blockReason === "daily_limit") {
+    const detail = response.blockDetail;
+    const lastMessage = context.messages[context.messages.length - 1];
+    const messages =
+      lastMessage && !lastMessage.isFromAI
+        ? context.messages.slice(0, -1)
+        : context.messages;
+
+    return {
+      messages,
+      isReplyingAI: false,
+      paywallTriggered: true,
+      paywallReason: "daily_limit",
+      paywallDetail: detail
+        ? { usedToday: detail.usedToday, limit: detail.limit }
+        : null,
+    };
+  }
+
+  if (!reply) {
+    return {
+      isReplyingAI: false,
+    };
+  }
+
+  return {
+    messages: [...context.messages, reply],
+    isReplyingAI: false,
+    paywallTriggered: false,
+    paywallReason: null,
+    paywallDetail: null,
+  };
+}
+
 // ============================================================
 // Result → number 映射
 // ============================================================