stabilize conversation list scroll

docs/reference/cloud-workbench.md

@@ -112,8 +112,10 @@ Code Agent trace 在消息卡片内使用独立滚动容器展示。SSE、轮询
 更新只能刷新内容，不得重置用户已展开/折叠状态，也不得把 `#conversation-list`
 或 `.message-trace-events` 的滚动位置跳回顶部；渲染前后必须保存并恢复外层
 conversation list 和按 `messageId/traceId` 记录的 trace list
-`scrollTop/scrollLeft`。完整 trace 可通过复制/下载获取，页面内默认保持“显示全部
-+ 内部滚动”的单一模式。
+`scrollTop/scrollLeft`。`#conversation-list` 需要绑定 scroll listener 持续记录用户
+位置，并在 DOM 替换后立即恢复一次、下一帧再恢复一次，避免布局重算或 scroll
+anchoring 把列表拉回顶部。完整 trace 可通过复制/下载获取，页面内默认保持“显示全部 +
+内部滚动”的单一模式。
 
 ## Lightweight Checks
 

web/hwlab-cloud-web/app.mjs

@@ -219,6 +219,7 @@ initSideTabs();
 initHardwareTabs();
 initQuickActions();
 initCodeAgentTimeoutControl();
+initConversationScrollMemory();
 initCommandBar();
 initLiveBuildOverlay();
 initWorkbenchLogout(el.logoutButton);
@@ -2022,6 +2023,16 @@ function renderConversation() {
   replaceChildren(el.conversationList, ...[...introMessages, ...state.chatMessages].map(messageCard));
   restoreConversationScrollPosition();
   restoreTraceScrollPositions();
+  window.requestAnimationFrame(() => {
+    restoreConversationScrollPosition();
+    restoreTraceScrollPositions();
+  });
+}
+
+function initConversationScrollMemory() {
+  el.conversationList.addEventListener("scroll", () => {
+    captureConversationScrollPosition();
+  }, { passive: true });
 }
 
 function captureConversationScrollPosition() {

web/hwlab-cloud-web/scripts/check.mjs

@@ -816,6 +816,8 @@ assert.match(app, /state\.conversationScrollPosition\s*=\s*\{\s*top:\s*0,\s*left
 assert.match(app, /state\.traceScrollPositions\.clear\(\)/);
 assert.match(app, /function messageTraceUiKey/);
 assert.match(app, /function defaultTraceDetailsOpen/);
+assert.match(app, /initConversationScrollMemory\(\)/);
+assert.match(app, /function initConversationScrollMemory/);
 assert.match(app, /function captureConversationScrollPosition/);
 assert.match(app, /function restoreConversationScrollPosition/);
 assert.match(app, /function captureTraceScrollPositions/);
@@ -825,6 +827,7 @@ assert.match(functionBody(app, "renderConversation"), /captureConversationScroll
 assert.match(functionBody(app, "renderConversation"), /restoreConversationScrollPosition\(\)/);
 assert.match(functionBody(app, "renderConversation"), /captureTraceScrollPositions\(\)/);
 assert.match(functionBody(app, "renderConversation"), /restoreTraceScrollPositions\(\)/);
+assert.match(functionBody(app, "renderConversation"), /requestAnimationFrame/);
 assert.match(functionBody(app, "messageTracePanel"), /state\.traceDetailsOpen\.get\(traceUiKey\)/);
 assert.match(functionBody(app, "messageTracePanel"), /defaultTraceDetailsOpen\(message\)/);
 assert.match(functionBody(app, "messageTracePanel"), /state\.traceDetailsOpen\.set\(traceUiKey,\s*details\.open\)/);