修改缓存命中逻辑

server/ai/client.js

@@ -39,6 +39,17 @@ async function callDeepSeek(messages, userId, temperature = 0.1, jsonMode = true
     console.error('DeepSeek 返回异常:', JSON.stringify(data));
     throw new Error('AI 返回数据异常');
   }
+  // 缓存命中日志
+  if (data.usage) {
+    var hit = data.usage.prompt_cache_hit_tokens || 0;
+    var miss = data.usage.prompt_cache_miss_tokens || 0;
+    var total = data.usage.prompt_tokens || 0;
+    var rate = total > 0 ? (hit / total * 100).toFixed(1) : 0;
+    console.log('缓存: hit=' + hit + ' miss=' + miss + ' total=' + total + ' 命中率=' + rate + '%');
+  }
+  // 输入消息大小日志
+  var inputChars = JSON.stringify(messages).length;
+  console.log('输入大小: ' + inputChars + ' 字符, ' + messages.length + ' 条消息');
   return data.choices[0].message.content;
 }
 

server/ai/prompt.js

@@ -2,7 +2,8 @@
 function buildSystemPrompt(username, isAdmin) {
   const now = new Date().toLocaleString('zh-CN', { timeZone: 'Asia/Shanghai', hour12: false });
 
-  const role = '你是智能财务助手"小财"。当前服务器时间：' + now + '。结合对话历史理解用户意图，只返回JSON。';
+  // 稳定前缀放前面（提升缓存命中率）
+  const role = '你是智能财务助手"小财"。结合对话历史理解用户意图，只返回JSON。';
 
   const intent = [
     '意图分类：',
@@ -68,7 +69,10 @@ function buildSystemPrompt(username, isAdmin) {
     '- 无法确定物品名 → action="ask" 追问'
   ].join('\n');
 
-  return [role, intent, permission, deleteRules, attachmentRules, prohibitionRules, modifyGuide, purchaseRules].join('\n');
+  // 变动的放最后
+  const timeInfo = '当前服务器时间：' + now;
+
+  return [role, intent, permission, deleteRules, attachmentRules, prohibitionRules, modifyGuide, purchaseRules, timeInfo].join('\n');
 }
 
 module.exports = { buildSystemPrompt };