fix(chat): preserve latest reply through layout changes

apps/presentation/dashboard/src/features/personal-workspace/personal-workspace-page.tsx

@@ -1079,6 +1079,7 @@ export function PersonalWorkspacePage({
   const composerRef = useRef<HTMLTextAreaElement>(null);
   const channelScrollRef = useRef<HTMLDivElement>(null);
   const followConversationRef = useRef(true);
+  const conversationScrollTopRef = useRef(0);
   const [showLatestMessage, setShowLatestMessage] = useState(false);
   const settingsReturnFocusRef = useRef<HTMLElement | null>(null);
   const settingsFromModelMenuRef = useRef(false);
@@ -1403,16 +1404,36 @@ export function PersonalWorkspacePage({
     followConversationRef.current = true;
     setShowLatestMessage(false);
     const scroller = channelScrollRef.current;
-    if (scroller) scroller.scrollTop = scroller.scrollHeight;
+    if (scroller) {
+      scroller.scrollTop = scroller.scrollHeight;
+      conversationScrollTopRef.current = scroller.scrollTop;
+    }
   }
   useEffect(() => {
     followConversationRef.current = true;
+    conversationScrollTopRef.current = channelScrollRef.current?.scrollTop ?? 0;
     setShowLatestMessage(false);
   }, [conversationKey, selectedAgentId, conversationOpen]);
   useEffect(() => {
-    if (!conversationOpen || !followConversationRef.current) return;
-    const frame = window.requestAnimationFrame(scrollToLatestMessage);
-    return () => window.cancelAnimationFrame(frame);
+    if (!conversationOpen) return;
+    let frame = 0;
+    const follow = () => {
+      if (!followConversationRef.current) return;
+      window.cancelAnimationFrame(frame);
+      frame = window.requestAnimationFrame(() => {
+        if (followConversationRef.current) scrollToLatestMessage();
+      });
+    };
+    follow();
+    // Images, expanded replies and a resized window can change the viewport
+    // without a new message. Keep following only while the reader is at the end.
+    const observer = new ResizeObserver(follow);
+    const scroller = channelScrollRef.current;
+    if (scroller) {
+      observer.observe(scroller);
+      scroller.querySelectorAll(".personal-channel-timeline").forEach(element => observer.observe(element));
+    }
+    return () => {observer.disconnect(); window.cancelAnimationFrame(frame);};
   }, [conversationOpen, conversationKey, selectedAgentId, conversationMessages.length,
     latestMessageTextLength, latestMessage?.pending, latestMessage?.activity?.length, latestMessage?.steps]);
   useEffect(() => {
@@ -2855,7 +2876,10 @@ export function PersonalWorkspacePage({
               if (!conversationOpen) return;
               const { scrollHeight, scrollTop, clientHeight } = event.currentTarget;
               const nearBottom = scrollHeight - scrollTop - clientHeight < 64;
-              followConversationRef.current = nearBottom;
+              // Growing content or a shorter viewport is not a reader moving up.
+              if (nearBottom) followConversationRef.current = true;
+              else if (scrollTop < conversationScrollTopRef.current) followConversationRef.current = false;
+              conversationScrollTopRef.current = scrollTop;
               setShowLatestMessage(!nearBottom);
             }}>
             {!rootUnavailable && !runtimeSourceUnavailable ? <>

docs/architecture/rfcs/app-conversation-and-async-inbox-v0.md

@@ -1288,6 +1288,14 @@ unreadable current Session blocks ordinary send until its exact record recovers;
 never infer an empty conversation or create a replacement driver from a read
 failure. A recovered read does not prove receiver adoption or native GQ02/GQ09.
 
+Following the newest reply also survives a resized viewport or timeline, including
+image layout and expanded replies, without waiting for another message. Scrolling
+up keeps the reader in history across layout changes; the existing latest-message
+button resumes following. This stays in the shared conversation view, without a
+new session or execution owner. The [synthetic desktop and narrow captures](../../assets/personal-workspace/conversation-layout-follow/README.md)
+qualify this layout boundary; they do not establish installed native input,
+complete history pagination, provider delivery or bidirectional Lark media.
+
 App 历史恢复由管家与 Goal 对话共用的 TS 读取边界负责。旧 Session 读取失败不应
 隐藏可用消息、丢失原结果位置或重启当前流；应明确展示历史不完整，退避重读缺失
 快照，并保留实时文本与草稿。当前 Session 无法读取时，普通发送等待原记录恢复，

docs/architecture/rfcs/app-conversation-and-async-inbox-v0.zh-CN.md

@@ -960,6 +960,10 @@ App 历史与重连读取同一条消息；managed 和 attached 完成存储均
 [公开模型评测](../../../examples/evaluations/chat-intake.py) 仅在 release 候选版本验收时显式启用付费调用，默认及新增宣传的模型配置分别至少重复两次。平时 PR、每次提交和 heartbeat 只跑离线回归及受影响的浏览器场景，不运行付费评测。记录候选版本，保留失败；凭证不可用记为跳过，不视为通过。评测使用生产 prompt/parser 和固定公开上下文，覆盖新建、已有负责人、多候选、停止/无授权、纠偏、当前 Goal 追问、引用、否定、普通问答与中英文表达。冲突操作、协议缺失、生成截断均记录为失败。记录模型、prompt/用例哈希、请求参数、token 用量和重复次数，不泄露凭证。该层只验证模型解释已提供证据，不证明真实发现、派发、停止执行或完整 GQ01/GQ02；打包浏览器和实际委派传输测试分别覆盖其边界。
 
 同一对话界面在用户停留底部时跟随输出，上翻阅读后保持位置，并提供回到最新消息的入口。
+窗口或时间线尺寸变化（包括图片布局与展开回复）后仍应跟随最新回复，不必等待下一条消息。
+用户上翻阅读时，布局变化保留当前位置；既有回到最新消息按钮恢复跟随。该行为留在共享
+对话界面，不新增 Session 或执行者。[合成桌面与窄屏截图](../../assets/personal-workspace/conversation-layout-follow/README.md)
+只验收布局边界，不代表已安装原生输入、完整历史分页、provider 投递或飞书媒体双向同步已通过。
 多行草稿在有界输入框中展开；快捷提问留在总览或空对话入口，避免挤占当前对话。
 
 ### 图片准入与当前对话位置

docs/assets/personal-workspace/conversation-layout-follow/README.md

@@ -0,0 +1,27 @@
+# Conversation layout following / 对话布局跟随
+
+These unedited captures use the existing `conversation-image-request` browser
+fixture. All messages, operation cards, images and provider responses are synthetic.
+No private conversation or real financial operation appears here. The delegation
+read failure in the fixture header is intentional and unrelated to this change.
+
+The desktop viewport is 1512 × 600 and the narrow viewport is 390 × 600. Before
+uses the production view from `c56f55307e87110e54d9a82c868d3649280f22fb` with the
+new regression: after shrinking the window, the newest reply falls below the
+visible area. After uses this change: the newest reply remains visible. The
+scenario separately verifies that resizing while reading older history preserves
+the reader’s position, and the existing latest-message button resumes following.
+
+这些原始截图来自既有合成浏览器场景，展示同一共享对话界面的窗口缩放行为。
+源码及打包后的场景验收、已安装原生输入、真实 provider 投递与完整 App/飞书同步分别核验；
+截图不证明后三项通过。测试修订及实际通过范围以 PR 验证记录为准。
+
+## Before / 修改前
+
+![Desktop before shrinking follow repair](before-desktop.png)
+
+## After / 修改后
+
+![Desktop after follow repair](after-desktop.png)
+
+![Narrow viewport after follow repair](after-narrow.png)

examples/personal-workspace-browser/conversation-image-request.mjs

@@ -76,6 +76,28 @@ export const conversationImageRequestScenario = {
         assert.ok(box && box.y >= 0 && box.y + box.height <= 982, "Sending keeps the current reply in view");
         assert.equal(api.durableWriteCount, 0, "Reading operations and sending a chat message cannot execute an operation");
         await page.screenshot({path: resolve(outputDir, `conversation-image-${width}.png`), animations: "disabled"});
+        // A shorter window must keep the current reply readable without a new
+        // message/stream event. Layout changes are not a request to read history.
+        await page.setViewportSize({width, height: 600});
+        try {
+          await page.waitForFunction(() => {
+            const scroll = document.querySelector(".personal-channel-scroll");
+            return scroll && scroll.scrollHeight - scroll.scrollTop - scroll.clientHeight < 2;
+          }, undefined, {timeout: 3000});
+        } finally {
+          await page.screenshot({path: resolve(outputDir, `conversation-image-resized-${width}.png`), animations: "disabled"});
+        }
+        const transcript = page.locator(".personal-channel-scroll");
+        assert.ok(await transcript.evaluate(element => element.scrollHeight > element.clientHeight + 100),
+          "The fixture must have older history outside the viewport");
+        await transcript.evaluate(element => {element.scrollTop = 0;});
+        await page.getByRole("button", {name: "回到最新消息 ↓", exact: true}).waitFor();
+        await page.setViewportSize({width, height: 720});
+        await page.evaluate(() => new Promise(resolveFrame => requestAnimationFrame(() => requestAnimationFrame(resolveFrame))));
+        assert.equal(await transcript.evaluate(element => element.scrollTop), 0,
+          "Resizing while reading older history must not pull the reader to the newest reply");
+        await page.getByRole("button", {name: "回到最新消息 ↓", exact: true}).click();
+        await page.setViewportSize({width, height: 982});
         // A confirmed pre-admission rejection retains the exact draft/image.
         await page.route("**/api/chat/sessions/*/turns", route => route.fulfill({status: 400, json: {
           ok: false, error: "Synthetic invalid attachment", turn_replay_safe: true, delivery_state: "not_delivered",