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/app/src/views/ai/agent-chat/agentChatRuntimeManager.test.ts

@@ -1,7 +1,7 @@
 // @vitest-environment happy-dom
 
 import { createPinia, setActivePinia } from 'pinia';
-import { beforeEach, describe, expect, it, vi } from 'vitest';
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 
 import { useUserStore } from '@easyflow/stores';
 
@@ -23,6 +23,10 @@ describe('agentChatRuntimeManager', () => {
     vi.clearAllMocks();
   });
 
+  afterEach(() => {
+    vi.useRealTimers();
+  });
+
   it('replaces draft image URLs and isolates snapshots by account', async () => {
     let callbacks: any;
     vi.mocked(sendAgentChat).mockImplementation((_data, options) => {
@@ -95,4 +99,76 @@ describe('agentChatRuntimeManager', () => {
     userStore.setUserInfo(firstAccount);
     expect(agentChatRuntimeManager.getSnapshot('101')).toBeUndefined();
   });
+
+  it('coalesces streaming notifications and persists terminal state immediately', async () => {
+    vi.useFakeTimers();
+    let callbacks: any;
+    vi.mocked(sendAgentChat).mockImplementation((_data, options) => {
+      callbacks = options;
+      return Promise.resolve() as any;
+    });
+    const account = {
+      avatar: '',
+      id: 'stream-user',
+      loginName: 'stream-user',
+      nickname: '流式用户',
+      tenantId: 'tenant-1',
+    };
+    useUserStore().setUserInfo(account);
+
+    await agentChatRuntimeManager.start({
+      agentId: 'agent-1',
+      prompt: '流式测试',
+      sessionId: 'stream-session',
+    });
+    const listener = vi.fn();
+    const unsubscribe = agentChatRuntimeManager.subscribe(listener);
+    const storageSpy = vi.spyOn(sessionStorage, 'setItem');
+
+    for (const delta of ['A', 'B', 'C']) {
+      callbacks.onMessage({
+        data: JSON.stringify({
+          domain: 'LLM',
+          payload: { delta },
+          type: 'MESSAGE',
+        }),
+      });
+    }
+
+    expect(listener).not.toHaveBeenCalled();
+    expect(storageSpy).not.toHaveBeenCalled();
+    expect(
+      JSON.stringify(
+        agentChatRuntimeManager.getSnapshot('stream-session')?.items,
+      ),
+    ).toContain('ABC');
+
+    await vi.advanceTimersByTimeAsync(50);
+    expect(listener).toHaveBeenCalledTimes(1);
+    expect(storageSpy).not.toHaveBeenCalled();
+
+    await vi.advanceTimersByTimeAsync(250);
+    expect(storageSpy).toHaveBeenCalledTimes(2);
+
+    callbacks.onMessage({
+      data: JSON.stringify({
+        domain: 'LLM',
+        payload: { delta: 'D' },
+        type: 'MESSAGE',
+      }),
+    });
+    listener.mockClear();
+    storageSpy.mockClear();
+    callbacks.onFinished();
+
+    expect(listener).toHaveBeenCalledTimes(1);
+    expect(storageSpy).toHaveBeenCalledTimes(2);
+    expect(agentChatRuntimeManager.getSnapshot('stream-session')).toEqual(
+      expect.objectContaining({ completed: true, sending: false }),
+    );
+
+    unsubscribe();
+    storageSpy.mockRestore();
+    clearAgentChatBrowserCache(account);
+  });
 });