重构会话管理，简化上下文存储逻辑

src/routes/chatSession.ts

@@ -192,15 +192,22 @@ export const buildPromptWithLearningContext = async (
   memoryStore: MemoryStore,
   actorKey: string,
   projectKey: string,
-  recentTurns: SessionTurnRecord[],
-  message: string,
+  options: {
+    recentTurns: SessionTurnRecord[];
+    persistedMessages?: unknown[];
+    message: string;
+    restoreConversation?: boolean;
+  },
 ) => {
   const snapshot = await memoryStore.buildPromptSnapshot({ actorKey, projectKey });
-  const restoredConversation = buildRestoredConversationContext(recentTurns);
+  const restoredConversation = options.restoreConversation === false
+    ? ""
+    : buildRestoredConversationFromMessages(options.persistedMessages) ||
+      buildRestoredConversationContext(options.recentTurns);
   if (!snapshot && !restoredConversation) {
-    return message;
+    return options.message;
   }
-  return [snapshot, restoredConversation, `[Current user request]\n${message}`]
+  return [snapshot, restoredConversation, `[Current user request]\n${options.message}`]
     .filter(Boolean)
     .join("\n\n");
 };
@@ -239,4 +246,57 @@ const compactMessage = (value: string) => {
   return normalized.length > RESTORE_MESSAGE_CHAR_LIMIT
     ? `${normalized.slice(0, RESTORE_MESSAGE_CHAR_LIMIT - 3)}...`
     : normalized;
+};
+
+const isObjectRecord = (value: unknown): value is Record<string, unknown> =>
+  typeof value === "object" && value !== null && !Array.isArray(value);
+
+const isSyntheticAssistantError = (content: string) =>
+  /^⚠️\s*\*\*(请求已中断|错误[:：]?)/.test(content);
+
+const buildRestoredConversationFromMessages = (messages: unknown[] | undefined) => {
+  if (!Array.isArray(messages) || messages.length === 0) {
+    return "";
+  }
+
+  const formattedMessages = messages
+    .slice(-(RESTORE_TURN_LIMIT * 2 + 2))
+    .flatMap((message) => {
+      if (!isObjectRecord(message)) {
+        return [];
+      }
+
+      const role = message.role;
+      const content = message.content;
+      if ((role !== "user" && role !== "assistant") || typeof content !== "string") {
+        return [];
+      }
+
+      const normalizedContent = compactMessage(content);
+      if (!normalizedContent) {
+        return [];
+      }
+
+      if (role === "assistant" && isSyntheticAssistantError(normalizedContent)) {
+        return [];
+      }
+
+      return [`${role === "user" ? "用户" : "助手"}：${normalizedContent}`];
+    });
+
+  if (formattedMessages.length === 0) {
+    return "";
+  }
+
+  const conversation = formattedMessages.join("\n");
+  const trimmedConversation =
+    conversation.length > RESTORE_CONTEXT_CHAR_LIMIT
+      ? `${conversation.slice(0, RESTORE_CONTEXT_CHAR_LIMIT - 3)}...`
+      : conversation;
+
+  return [
+    "[Previous conversation context]",
+    "以下为当前前端对话线程中最近的历史对话，请延续其中已确认的目标、约束、结论与引用结果。",
+    trimmedConversation,
+  ].join("\n");
 };