fix(chat): 问答回答时间戳不再漂移到当前电脑时间

AI 回答无自身时间戳,原先在首次渲染时用 new Date() 兜底,导致
未在原会话完成、或从历史重新加载的回答显示加载时刻而非真实时间。
改为让 AI 回答继承同轮提问的可靠 client_ts(turnTime),并停止给
AI 消息打 now 戳;显示层优先用提问时间,可自愈历史错误时间。

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend-web/src/components/workspace/messages/message-list-item.tsx

@@ -138,6 +138,7 @@ export function MessageListItem({
   extraRehypePlugins,
   onEditResubmit,
   onMessageDeleted,
+  turnTime,
 }: {
   className?: string;
   fitRowToContent?: boolean;
@@ -154,6 +155,13 @@ export function MessageListItem({
   extraRehypePlugins?: ReturnType<typeof useRehypeSplitWordsIntoSpans>;
   onEditResubmit?: (text: string) => void;
   onMessageDeleted?: (deletedIds: string[]) => void;
+  /**
+   * Durable ask time of the turn this message belongs to (the preceding
+   * question's `client_ts`). Used to time-stamp the AI answer, which carries no
+   * timestamp of its own — without it the answer would fall back to the current
+   * wall clock at render time and appear to "drift" to now on every reload.
+   */
+  turnTime?: string;
 }) {
   const isHuman = message.type === 'human';
   const messageMarkdown =
@@ -182,6 +190,7 @@ export function MessageListItem({
         extraRehypePlugins={extraRehypePlugins}
         onEditResubmit={onEditResubmit}
         onMessageDeleted={onMessageDeleted}
+        turnTime={turnTime}
       />
       {/*
         Human messages carry their own inline copy/edit toolbar inside
@@ -390,6 +399,7 @@ function MessageContent_({
   extraRehypePlugins,
   onEditResubmit,
   onMessageDeleted,
+  turnTime,
 }: {
   className?: string;
   message: Message;
@@ -400,6 +410,7 @@ function MessageContent_({
   extraRehypePlugins?: ReturnType<typeof useRehypeSplitWordsIntoSpans>;
   onEditResubmit?: (text: string) => void;
   onMessageDeleted?: (deletedIds: string[]) => void;
+  turnTime?: string;
 }) {
   const baseRehypePlugins = useRehypeSplitWordsIntoSpans(isLoading);
 
@@ -456,9 +467,15 @@ function MessageContent_({
     [threadId, resolveArtifact],
   );
 
+  // Question carries its own `client_ts` (round-trips through the checkpoint).
+  // The AI answer has no timestamp of its own, so it inherits the turn's ask
+  // time (its question's `client_ts`, threaded down as `turnTime`). This is
+  // durable and turn-accurate, and — unlike the old per-id `now` fallback —
+  // never drifts to the current clock when an unfinished answer is reloaded.
+  const ownAskTime = message.id ? askTimes[message.id] : undefined;
   const messageTime = formatAskedTime(
     message.additional_kwargs?.client_ts ??
-      (message.id ? askTimes[message.id] : undefined),
+      (isHuman ? ownAskTime : (turnTime ?? ownAskTime)),
   );
 
   const rawContent = extractContentFromMessage(message);

frontend-web/src/components/workspace/messages/message-list.tsx

@@ -11,7 +11,7 @@ import {
 } from "@/components/ai-elements/conversation";
 import { Button } from "@/components/ui/button";
 import { Textarea } from "@/components/ui/textarea";
-import { rememberAskTimes } from "@/core/chat-timestamps";
+import { rememberAskTimes, useChatAskTimes } from "@/core/chat-timestamps";
 import { useI18n } from "@/core/i18n/hooks";
 import {
   extractContentFromMessage,
@@ -167,15 +167,24 @@ export function MessageList({
     [allMessages, hiddenMessageIds],
   );
 
-  // Stamp a wall-clock time onto every question/answer the first time it is
-  // seen, in a single batched commit. Questions sent this session already carry
-  // an accurate time (see useThreadStream); this also covers assistant answers
-  // and messages loaded from history. First-write-wins keeps the earliest time.
+  const askTimes = useChatAskTimes();
+
+  // Stamp a wall-clock time onto every *question* the first time it is seen, in
+  // a single batched commit. Questions sent this session already carry an
+  // accurate `client_ts` (see useThreadStream) and are skipped; this only backs
+  // up legacy questions loaded from history that predate `client_ts`.
+  // First-write-wins keeps the earliest time.
+  //
+  // AI answers are deliberately NOT stamped here: they carry no timestamp of
+  // their own, so a `now` stamp would be the *load* time, not the answer time —
+  // and for an unfinished/interrupted turn that re-stamps to the current clock
+  // on every reload. Instead the answer inherits its question's durable time
+  // via `turnTimes` below.
   useEffect(() => {
     const now = new Date().toISOString();
     const entries: Record<string, string> = {};
     for (const message of messages) {
-      if (message.type !== "human" && message.type !== "ai") continue;
+      if (message.type !== "human") continue;
       if (!message.id || message.id.startsWith("opt-")) continue;
       if (typeof message.additional_kwargs?.client_ts === "string") continue;
       entries[message.id] = now;
@@ -183,6 +192,24 @@ export function MessageList({
     if (Object.keys(entries).length > 0) rememberAskTimes(entries);
   }, [messages]);
 
+  // Durable ask time per message id, used to time-stamp the AI answer (which has
+  // no timestamp of its own) with the time of the question that triggered it.
+  const turnTimes = useMemo(() => {
+    const map = new Map<string, string>();
+    let lastQuestionTime: string | undefined;
+    for (const message of messages) {
+      if (message.type === "human") {
+        const ts = message.additional_kwargs?.client_ts;
+        const fromAskTimes = message.id ? askTimes[message.id] : undefined;
+        lastQuestionTime =
+          typeof ts === "string" && ts ? ts : fromAskTimes;
+      } else if (message.type === "ai" && message.id && lastQuestionTime) {
+        map.set(message.id, lastQuestionTime);
+      }
+    }
+    return map;
+  }, [messages, askTimes]);
+
   const [settings] = useLocalSettings();
   const ragModeEnabled =
     settings.display.ragModeEnabled || isThreadRagModeLocked(threadId);
@@ -358,6 +385,7 @@ export function MessageList({
                   onMessageDeleted={
                     allowDelete ? handleMessageDeleted : undefined
                   }
+                  turnTime={msg.id ? turnTimes.get(msg.id) : undefined}
                 />
               );
             });