fix: keep visible workbench duration monotonic

web/hwlab-cloud-web/src/components/workbench/ConversationPanel.vue

@@ -26,6 +26,7 @@ const clipboard = useClipboard();
 const panelRef = ref<HTMLElement | null>(null);
 const { following, keepBottomAfterUpdate, onScroll: onPanelScroll, scrollToBottom } = useBottomFollowScroll(panelRef, { threshold: 56 });
 const detailMessageId = ref<string | null>(null);
+const displayedDurationFloorMs = new Map<string, number>();
 const visibleMessages = computed(() => workbench.sessionDetailLoading ? [] : workbench.activeMessages);
 const hasRunningAgentMessages = computed(() => visibleMessages.value.some(isRunningMessage));
 const { nowMs } = useWorkbenchNowTicker(hasRunningAgentMessages);
@@ -56,6 +57,13 @@ watch(() => workbench.sessionDetailLoading, async () => {
   acknowledgeVisibleMessages();
 });
 
+watch(visibleMessages, (messages) => {
+  const visibleKeys = new Set(messages.map(messageDurationFloorKey));
+  for (const key of Array.from(displayedDurationFloorMs.keys())) {
+    if (!visibleKeys.has(key)) displayedDurationFloorMs.delete(key);
+  }
+}, { immediate: true });
+
 function openDetails(message: ChatMessage): void {
   detailMessageId.value = message.id;
 }
@@ -234,12 +242,25 @@ function traceForDisplay(message: ChatMessage): ChatMessage["runnerTrace"] {
 function messageDurationMeta(message: ChatMessage): { text: string; label: string } | null {
   if (message.role !== "agent") return null;
   const timing = messageTimingForDisplay(message);
-  const durationMs = isRunningMessage(message) ? durationSince(timing?.startedAt) : finiteDurationMs(timing?.durationMs);
-  if (durationMs === null) return null;
+  const rawDurationMs = isRunningMessage(message) ? durationSince(timing?.startedAt) : finiteDurationMs(timing?.durationMs);
+  if (rawDurationMs === null) return null;
+  const durationMs = monotonicDisplayDurationMs(message, rawDurationMs);
   const value = formatDuration(durationMs);
   return { text: `耗时 ${value}`, label: `总耗时：${value}` };
 }
 
+function monotonicDisplayDurationMs(message: ChatMessage, durationMs: number): number {
+  const key = messageDurationFloorKey(message);
+  const previous = displayedDurationFloorMs.get(key);
+  const next = previous === undefined ? durationMs : Math.max(previous, durationMs);
+  if (next !== previous) displayedDurationFloorMs.set(key, next);
+  return next;
+}
+
+function messageDurationFloorKey(message: ChatMessage): string {
+  return firstNonEmptyString(message.id, message.runnerTrace?.traceId, message.traceId) ?? "unknown-agent-message";
+}
+
 function messageActivityMeta(message: ChatMessage): { text: string; label: string } | null {
   if (!isRunningMessage(message)) return null;
   const timing = messageTimingForDisplay(message);