diff --git a/client/src/dom.ts b/client/src/dom.ts
index 0ae5860..5132366 100644
--- a/client/src/dom.ts
+++ b/client/src/dom.ts
@@ -8,7 +8,7 @@
  * - 输入区采用圆角容器包裹文本框与发送按钮
  */
 import { ResolvedConfig, RagSource } from './types';
-import { debounce, formatTime } from './utils';
+import { debounce, formatTime, formatHistoryTime } from './utils';
 import { t } from './i18n';
 import { DialogPlugin } from 'tdesign-web-components/lib/dialog/index.js';
 // omi 的 render/h 用于创建带 on* 函数回调的组件（见 createEventful 说明）
@@ -915,8 +915,11 @@ function createChatAction(wrapper: HTMLElement, text: string, msgId?: string, fe
   const el = actionEl as unknown as {
     actionBar: string[];
     handleAction: (action: string, data: { event?: Event; active?: boolean }) => void;
+    tooltipProps: Record<string, unknown>;
   };
   el.actionBar = ['replay', 'copy', 'good', 'bad'];
+  // 浮层 portal 到 body：zIndex 越过弹窗(9999)防遮挡，overlayClassName 加 SDK 私有类用于补样式
+  el.tooltipProps = { overlayClassName: 'csk-tooltip', zIndex: 10000 };
   // copyText/comment 为 String 简单类型，须用 setAttribute（property 赋值在 omi 下静默失效）
   actionEl.setAttribute('copyText', text);
   actionEl.setAttribute('comment', feedback === 'up' ? 'good' : feedback === 'down' ? 'bad' : '');
@@ -1160,8 +1163,9 @@ export function renderHistoryList(
     const metaParts: string[] = [];
     if (item.roleName) metaParts.push(item.roleName);
     if (item.messageCount !== undefined) metaParts.push(`${item.messageCount} 条消息`);
-    if (item.lastMessageTime) metaParts.push(item.lastMessageTime);
-    else if (item.createdAt) metaParts.push(item.createdAt);
+    const timeStr = item.lastMessageTime || item.createdAt;
+    const timeText = formatHistoryTime(timeStr);
+    if (timeText) metaParts.push(timeText);
     metaEl.textContent = metaParts.join(' · ');
 
     info.appendChild(idEl);
diff --git a/client/src/styles.ts b/client/src/styles.ts
index 051451a..38a30cc 100644
--- a/client/src/styles.ts
+++ b/client/src/styles.ts
@@ -624,6 +624,26 @@ function getStyles(config: ResolvedConfig): string {
 .csk-launcher, .csk-teaser { box-sizing: border-box; }
 .csk-launcher *, .csk-teaser * { box-sizing: border-box; }
 
+/* ===== tooltip 浮层（t-popup portal 到 body，light DOM）样式补注入 =====
+ * .t-tooltip 样式在 globalCSS（constructable stylesheet）里只对 shadow DOM 生效，
+ * 但浮层 portal 到 document.body 是 light DOM，故补注入；用 csk-tooltip 私有类避免污染宿主。
+ * 来源：tdesign-web-components v1.2.10 的 _chunks/dep-a3fbe4be.js（css_248z）。 */
+.csk-tooltip .t-popup__content {
+  display: inline-block;
+  border: 0;
+  z-index: 5600;
+  margin-bottom: 1px;
+  max-width: 480px;
+  word-break: break-word;
+  box-sizing: border-box;
+  border-radius: var(--td-radius-medium);
+  color: var(--td-text-color-anti);
+  background: var(--td-gray-color-13);
+  box-shadow: inset 0 0.5px 0 var(--td-gray-color-9), inset 0.5px 0 0 var(--td-gray-color-9), inset 0 -0.5px 0 var(--td-gray-color-9), inset -0.5px 0 0 var(--td-gray-color-9);
+}
+.csk-tooltip .t-popup__arrow { background: inherit; height: auto; }
+.csk-tooltip .t-popup__arrow::before { background: inherit; }
+
 /* ===== t-tag（light DOM 组件）样式补注入 =====
  * t-tag 是 tdesign-web-components 的 light DOM 组件（isLightDOM: true），其 .t-tag
  * 样式定义在 globalCSS 的 constructable stylesheet 里，但 globalCSS 只对 shadow DOM
diff --git a/client/src/utils.ts b/client/src/utils.ts
index 3d0d3d0..fb712a2 100644
--- a/client/src/utils.ts
+++ b/client/src/utils.ts
@@ -40,6 +40,27 @@ export function formatTime(timestamp: number): string {
   return `${hh}:${mm}`;
 }
 
+/** 格式化历史会话时间：今天/昨天显示 HH:mm，同年显示 MM-DD HH:mm，跨年显示 YYYY-MM-DD HH:mm */
+export function formatHistoryTime(timeStr: string | undefined): string {
+  if (!timeStr) return '';
+  const d = new Date(timeStr);
+  if (isNaN(d.getTime())) return timeStr; // 解析失败原样返回，避免破坏展示
+  const pad = (n: number) => String(n).padStart(2, '0');
+  const hh = pad(d.getHours());
+  const mm = pad(d.getMinutes());
+  const now = new Date();
+  const todayStart = new Date(now.getFullYear(), now.getMonth(), now.getDate()).getTime();
+  const yesterdayStart = todayStart - 86400000;
+  const ts = d.getTime();
+  // 今天或昨天：只显示时分
+  if (ts >= yesterdayStart) return `${hh}:${mm}`;
+  const md = `${pad(d.getMonth() + 1)}-${pad(d.getDate())}`;
+  // 今年内：月-日 时分
+  if (d.getFullYear() === now.getFullYear()) return `${md} ${hh}:${mm}`;
+  // 跨年：完整年月日 时分
+  return `${d.getFullYear()}-${md} ${hh}:${mm}`;
+}
+
 /** 获取当前时间戳（毫秒） */
 export function now(): number {
   return Date.now();