feat: 添加分页功能和缓存管理，优化问答记录展示

server/utils/runtimeState.ts

@@ -1,5 +1,4 @@
 // server/utils/runtimeState.ts - 服务启动时间内存状态 + 问答记录 DB 读写
-import { answerCache } from "~~/server/utils/cache";
 import { prisma } from "~~/server/utils/db";
 import { serverEnv } from "~~/server/utils/env";
 
@@ -29,6 +28,7 @@ export const addQaRecord = async (record: {
   type: string;
   options: string;
   answer: string;
+  hash: string;
 }) => {
   await prisma.qaRecord.create({
     data: {
@@ -36,11 +36,34 @@ export const addQaRecord = async (record: {
       question: record.question,
       type: record.type,
       options: record.options || null,
-      answer: record.answer || null
+      answer: record.answer || null,
+      hash: record.hash
     }
   });
 };
 
+/**
+ * 按用户 + hash 查找 DB 缓存答案
+ *
+ * 只返回 cacheClearedAt 之后写入的记录；未存入时间或 hash 为 null 的老记录不会命中
+ */
+export const lookupCachedAnswer = async (
+  userId: string,
+  hash: string,
+  cacheClearedAt: Date | null
+): Promise<string | null> => {
+  const record = await prisma.qaRecord.findFirst({
+    where: {
+      userId,
+      hash,
+      ...(cacheClearedAt ? { createdAt: { gt: cacheClearedAt } } : {})
+    },
+    orderBy: { createdAt: "desc" },
+    select: { answer: true }
+  });
+  return record?.answer ?? null;
+};
+
 /**
  * 从数据库分页读取指定用户的问答记录，按创建时间倒序
  */
@@ -76,13 +99,11 @@ export const getQaRecords = async (
   }));
   return { records, total };
 };
-/** 生成 `/api/stats` 响应，实时计算 uptime 和有效缓存数量 */
+/** 生成 `/api/stats` 的基础运行时信息，不包含用户相关数据 */
 export const getRuntimeStats = () => {
   return {
     version: SERVICE_VERSION,
     uptime: (Date.now() - startTime) / 1000,
-    model: serverEnv.openAiModel,
-    cache_enabled: serverEnv.enableCache,
-    cache_size: answerCache?.size() ?? 0
+    model: serverEnv.openAiModel
   };
 };