perf: 优化 Agent 流式会话处理

- 合并流式通知与持久化写入，限制浏览器会话缓存

- 增量投影轮次事件并稳定关联异步工具任务

easyflow-ui-admin/packages/effects/common-ui/src/components/chat-timeline/ChatTimeline.vue

@@ -6,7 +6,7 @@ import type {
   ChatTimelineToolApprovalPayload,
 } from './types';
 
-import { nextTick, onBeforeUnmount, ref, watch } from 'vue';
+import { computed, nextTick, onBeforeUnmount, ref, watch } from 'vue';
 
 import ChatTimelineItem from './ChatTimelineItem.vue';
 
@@ -38,6 +38,15 @@ let preservedScrollTop: number | undefined;
 
 const bottomThreshold = 24;
 let scrollFrame = 0;
+const assistantActionAnchorIds = computed(() => {
+  const latestAssistantByRound = new Map<string, string>();
+  for (const item of props.items) {
+    if (item.type === 'message' && item.role === 'assistant' && item.roundId) {
+      latestAssistantByRound.set(item.roundId, item.id);
+    }
+  }
+  return new Set(latestAssistantByRound.values());
+});
 
 function isNearBottom(container: HTMLElement) {
   return (
@@ -85,26 +94,13 @@ function canRegenerateMessage(item: ChatTimelineItemType) {
   return item.type === 'message' && (props.regenerable?.(item) ?? false);
 }
 
-function isAssistantActionAnchor(
-  item: ChatTimelineItemType,
-  index: number,
-  items: ChatTimelineItemType[],
-) {
-  if (item.type !== 'message' || item.role !== 'assistant' || !item.roundId) {
-    return false;
-  }
-  for (let cursor = items.length - 1; cursor >= 0; cursor -= 1) {
-    const current = items[cursor];
-    if (
-      current &&
-      current.type === 'message' &&
-      current.role === 'assistant' &&
-      current.roundId === item.roundId
-    ) {
-      return cursor === index;
-    }
-  }
-  return false;
+function isAssistantActionAnchor(item: ChatTimelineItemType) {
+  return (
+    item.type === 'message' &&
+    item.role === 'assistant' &&
+    Boolean(item.roundId) &&
+    assistantActionAnchorIds.value.has(item.id)
+  );
 }
 
 function isVariantLoading(item: ChatTimelineItemType) {
@@ -152,9 +148,9 @@ watch(
     </div>
     <template v-else>
       <ChatTimelineItem
-        v-for="(item, index) in items"
+        v-for="item in items"
         :key="item.id"
-        :assistant-actions-visible="isAssistantActionAnchor(item, index, items)"
+        :assistant-actions-visible="isAssistantActionAnchor(item)"
         :item="item"
         :image-loader="imageLoader"
         :approval-loading="approvalLoading"