被拉入新群时标题栏/桌面通知没有任何提示——扩展兜底同步机制覆盖这个场景

reconcileMeSubs()本来就能发现"此前完全不认识的话题"（今天早些时候为解决群聊
被动成员看不到新群加的兜底机制），但发现后只是原样信任服务端返回的read/unread
字段——服务端对一个刚加入的新成员，默认给的读游标经常是"视为已读"（read==seq），
如果这个群目前恰好一条消息都没有，unread就会是0，导致今天新加的标题栏滚动/
favicon角标（由同一个未读数驱动）完全没有反应，被拉群这件事本身悄无声息。

改成：对每一个新发现的话题，不管服务端给的read游标是什么，一律按"我自己完全
没确认过"处理（read清零，unread按当前seq计算）；如果是群，额外通过
subscribeNewGroupDiscovered（新增的发布-订阅，push.ts订阅它去弹真正的桌面
通知"你被拉入了这个群聊"，因为topics.ts不能反向依赖push.ts）触发一条独立的
桌面通知，不依赖未读数是否恰好大于0。

实机验证：systest04建一个只邀请systest05的全新群，systest05这边模拟切回
标签页触发兜底同步后，确认收到桌面通知（title/body/tag均正确）且标题栏
未读数正确增加。

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

web/src/lib/notifications/push.ts

@@ -6,7 +6,13 @@
 import type { StoredMessage } from 'tinode-sdk';
 
 import { formatMessagePreview } from '@/lib/messages/preview';
-import { getActiveConversationTopic, getChatListSnapshot, getMessagesSnapshot, subscribeAnyTopicChange } from '@/lib/tinode/topics';
+import {
+  getActiveConversationTopic,
+  getChatListSnapshot,
+  getMessagesSnapshot,
+  subscribeAnyTopicChange,
+  subscribeNewGroupDiscovered,
+} from '@/lib/tinode/topics';
 import { useNotificationNavStore } from '@/stores/notificationNav';
 import { useSessionStore } from '@/stores/session';
 
@@ -85,16 +91,12 @@ function shouldNotify(topicName: string, msg: StoredMessage): boolean {
   return true;
 }
 
-function fireNotification(topicName: string, msg: StoredMessage) {
+/** Shared by both real call sites below -- a new message, or being newly added to a group. `tag:
-  const contact = getChatListSnapshot().find((c) => c.topic === topicName);
+ *  topicName` makes a second notification from the same conversation REPLACE the first in the OS
-  const title = contact?.public?.fn || topicName;
+ *  notification tray instead of stacking, matching every mainstream IM web client. */
-  const myUserId = useSessionStore.getState().myUserId;
+function showNotification(topicName: string, title: string, body: string) {
-  const body = formatMessagePreview(msg, myUserId) || '发来一条新消息';
   let notif: Notification;
   try {
-    // `tag: topicName` -- a second notification from the same conversation REPLACES the first in the
-    // OS notification tray instead of stacking, matching every mainstream IM web client (you get one
-    // live-updating notification per conversation, not a pile of them from one chatty sender).
     notif = new Notification(title, { body, tag: topicName, icon: '/favicon.svg' });
   } catch {
     // Some browsers/contexts throw constructing Notification even with permission granted (e.g. an
@@ -109,13 +111,38 @@ function fireNotification(topicName: string, msg: StoredMessage) {
   };
 }
 
+function fireNotification(topicName: string, msg: StoredMessage) {
+  const contact = getChatListSnapshot().find((c) => c.topic === topicName);
+  const title = contact?.public?.fn || topicName;
+  const myUserId = useSessionStore.getState().myUserId;
+  const body = formatMessagePreview(msg, myUserId) || '发来一条新消息';
+  showNotification(topicName, title, body);
+}
+
+/** "被拉入群时title的消息没有提示" -- topics.ts's reconcileMeSubs() is the only thing that can even
+ *  detect this (nothing else observes a group appearing that this client never knew about), so it
+ *  fires this via subscribeNewGroupDiscovered rather than this module trying to infer "newly added"
+ *  from message/seq activity, which a group with zero messages so far wouldn't have at all. */
+function onNewGroupDiscovered(topicName: string) {
+  if (typeof Notification === 'undefined' || Notification.permission !== 'granted') return;
+  const contact = getChatListSnapshot().find((c) => c.topic === topicName);
+  if (contact?.private?.mute_notifications) return;
+  const title = contact?.public?.fn || topicName;
+  showNotification(topicName, title, '你被拉入了这个群聊');
+}
+
 let unsubscribe: (() => void) | null = null;
 
 /** Call once per authenticated session (RequireAuth.tsx, alongside startMeReconciliation) and invoke
  *  the returned function on logout/unmount. Safe to start/stop repeatedly. */
 export function initMessageNotifications(): () => void {
   if (unsubscribe) return unsubscribe;
-  unsubscribe = subscribeAnyTopicChange(scheduleScan);
+  const unsubScan = subscribeAnyTopicChange(scheduleScan);
+  const unsubNewGroup = subscribeNewGroupDiscovered(onNewGroupDiscovered);
+  unsubscribe = () => {
+    unsubScan();
+    unsubNewGroup();
+  };
   return () => {
     unsubscribe?.();
     unsubscribe = null;

web/src/lib/tinode/topics.ts

@@ -99,6 +99,18 @@ export function subscribeTopicInfo(callback: (topicName: string, info: RawTopicI
 
 const goneListeners = new Set<(topicName: string) => void>();
 
+const newGroupListeners = new Set<(topicName: string) => void>();
+
+/** Fires when reconcileMeSubs() (below) discovers a group topic this client has never seen before --
+ *  the "you were just added to a group" case (Zentao/user-reported: "被拉入群时title的消息没有提示").
+ *  Consumed by lib/notifications/push.ts to fire a desktop notification -- can't live there itself
+ *  since push.ts already depends on topics.ts and the reverse would be a cycle, same reasoning as
+ *  setActiveConversationTopic living here instead of in push.ts. */
+export function subscribeNewGroupDiscovered(callback: (topicName: string) => void): () => void {
+  newGroupListeners.add(callback);
+  return () => newGroupListeners.delete(callback);
+}
+
 /** Fires once a topic is confirmed gone (group dissolved by anyone, or removed from this account) --
  *  the SDK's own `Topic#_gone()` clears the topic's public/private/messages and calls
  *  `onDeleteTopic()` (confirmed reading tinode.dev.js). Without ConversationView reacting to this,
@@ -481,7 +493,21 @@ function reconcileMeSubs() {
       for (const c of getChatListSnapshot()) {
         if (!c.topic) continue;
         const prev = before.get(c.topic);
-        if (!prev) continue; // brand-new topic to this session -- exactly what this mitigation is for
+        if (!prev) {
+          // Brand-new topic to this session -- exactly what this mitigation is for. A fresh member's
+          // sub record can legitimately come back "already caught up" (read === seq) from the
+          // server's own default, which would otherwise leave being newly added to a group producing
+          // NO unread signal at all whenever it happens to have zero messages so far -- real,
+          // reported UX gap ("被拉入群时title的消息没有提示"): the tab-title/favicon-badge (see lib/
+          // notifications/tabIndicator.ts) are driven by this same unread count, so nothing tells the
+          // user anything happened. Force it to read as genuinely unread from this client's own
+          // perspective regardless of what the server defaulted it to.
+          c.read = 0;
+          c.unread = c.seq || 0;
+          notifyTopic(c.topic);
+          if (c.topic.startsWith('grp')) newGroupListeners.forEach((cb) => cb(c.topic!));
+          continue;
+        }
         const seq = c.seq || 0;
         const unread = c.unread || 0;
         if (seq <= prev.seq && unread > prev.unread) {