优化会话标题生成逻辑，增加消息限制与格式处理

src/routes/chatSession.ts

@@ -4,7 +4,10 @@ import { type OpencodeRuntimeAdapter } from "../runtime/opencode.js";
 
 import { collectTextContent } from "./chatStream.js";
 
-const TITLE_PROMPT_TIMEOUT_MS = 2500;
+const TITLE_PROMPT_TIMEOUT_MS = 5000;
+const TITLE_CONTEXT_MESSAGE_LIMIT = 40;
+const TITLE_CONTEXT_CHAR_LIMIT = 2400;
+const TITLE_CONTEXT_MESSAGE_CHAR_LIMIT = 240;
 
 const buildSessionTitle = (message: string) => {
   const normalized = message.replace(/\s+/g, " ").trim();
@@ -18,7 +21,7 @@ const buildTitleConversationContext = async (
   runtime: OpencodeRuntimeAdapter,
   sessionId: string,
 ) => {
-  const messages = await runtime.messages(sessionId, 12);
+  const messages = await runtime.messages(sessionId, TITLE_CONTEXT_MESSAGE_LIMIT);
   const recentMessages = messages
     .filter(
       (message) =>
@@ -26,19 +29,35 @@ const buildTitleConversationContext = async (
     )
     .map((message) => ({
       role: message.info.role,
-      content: collectTextContent(message.parts).replace(/\s+/g, " ").trim(),
+      content: collectTextContent(message.parts)
+        .replace(/\s+/g, " ")
+        .trim()
+        .slice(0, TITLE_CONTEXT_MESSAGE_CHAR_LIMIT),
     }))
-    .filter((message) => message.content.length > 0)
-    .slice(-6);
+    .filter((message) => message.content.length > 0);
 
   if (recentMessages.length === 0) {
     return "";
   }
 
-  return recentMessages
-    .map((message) => `${message.role === "user" ? "用户" : "助手"}：${message.content}`)
-    .join("\n")
-    .slice(0, 2400);
+  const formattedMessages = recentMessages.map(
+    (message) => `${message.role === "user" ? "用户" : "助手"}：${message.content}`,
+  );
+  const fullConversation = formattedMessages.join("\n");
+  if (fullConversation.length <= TITLE_CONTEXT_CHAR_LIMIT) {
+    return fullConversation;
+  }
+
+  const headCount = Math.min(4, formattedMessages.length);
+  const tailCount = Math.min(8, Math.max(0, formattedMessages.length - headCount));
+  const middleOmitted = formattedMessages.length > headCount + tailCount;
+  const summary = [
+    ...formattedMessages.slice(0, headCount),
+    ...(middleOmitted ? ["……（中间省略若干轮对话）"] : []),
+    ...formattedMessages.slice(-tailCount),
+  ].join("\n");
+
+  return summary.slice(0, TITLE_CONTEXT_CHAR_LIMIT);
 };
 
 const normalizeGeneratedTitle = (rawTitle: string, fallback: string) => {
@@ -75,15 +94,17 @@ export const generateSessionTitle = async (
         titleSession.id,
         [
           "你是会话标题生成器。",
-          "请根据用户问题生成一个 8-16 字中文标题。",
+          "请根据下面整段多轮对话生成一个 8-16 字中文标题。",
           "要求：简洁、可读、避免标点、不要引号、不要解释。",
-          "请优先概括最近这轮对话的核心任务或结论。",
+          "先理解完整对话，再概括核心任务或结论。",
+          "不要直接照抄用户任一条消息原文。",
           "只输出标题本身。",
           "",
           conversation,
         ].join("\n"),
       )
       .then(async () => {
+        await runtime.waitForSessionIdle(titleSession.id, TITLE_PROMPT_TIMEOUT_MS);
         const messages = await runtime.messages(titleSession.id, 20);
         const assistantMessage = [...messages]
           .reverse()