修复消息发送失败/排队中时长按菜单仍提供"撤回"

判断只查 params.seq > 0，未排除 tinode-sdk 本地占位 seq（LOCAL_SEQID，
268435455，同样是正数）——发送失败/仍在排队的消息会被误判成"已持久化
的真实消息"，点击撤回后端正确拒绝（无此消息），却给用户一个答非所问
的"请求内容有误"提示。

第十一轮最小粒度测试 Ch3-4 发现。

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

src/views/messages-view.jsx

@@ -3,7 +3,7 @@
 import React, { Suspense } from 'react';
 import { FormattedMessage, defineMessages, injectIntl } from 'react-intl';
 
-import { Drafty, Tinode, TheCard } from 'tinode-sdk';
+import { Drafty, Tinode, TheCard, LOCAL_SEQID } from 'tinode-sdk';
 
 const CallPanel = React.lazy(_ => import('../widgets/call-panel.jsx'));
 import ChatMessage from '../widgets/chat-message.jsx';
@@ -1088,10 +1088,22 @@ class MessagesView extends React.Component {
       // allowAdmin=true, so the backend has always accepted this; the reference screenshot
       // (消息页面—长按弹出.png) lists "群撤回" as its own, always-shown menu item alongside "撤回" --
       // this was previously never offered at all since the only condition checked was authorship.
+      //
+      // `params.seq > 0` alone is not enough to mean "a real, server-persisted message": Tinode
+      // SDK gives every message that hasn't been confirmed by the server yet (still sending, or
+      // failed outright) a local placeholder seq of LOCAL_SEQID (0xFFFFFFF = 268435455) -- a large
+      // *positive* number, so it passed this check. Round 11 live testing reproduced this: sending
+      // a message into a since-blocked P2P topic left a bubble stuck in "发送失败" with seq
+      // 268435455, and this menu still offered "撤回" for it -- clicking it fired
+      // POST /topics/.../messages/268435455/recall, which the server correctly rejects (no such
+      // message), surfacing a confusing "请求内容有误，请稍后重试" toast for an action that should
+      // never have been offered. `seq < LOCAL_SEQID` excludes exactly that placeholder range,
+      // matching the same bound the SDK itself uses internally to distinguish a confirmed seq from
+      // a queued one.
       const recallWindow = this.state.messagePolicy ? this.state.messagePolicy.recall_window_seconds : 0;
       const canRecallAsAdmin = topic.isGroupType() && topic.getAccessMode() && topic.getAccessMode().isAdmin();
-      if ((params.userFrom == this.props.myUserId || canRecallAsAdmin) && params.seq > 0 && recallWindow > 0 &&
+      if ((params.userFrom == this.props.myUserId || canRecallAsAdmin) && params.seq > 0 && params.seq < LOCAL_SEQID &&
-          params.timestamp && params.timestamp.getTime() > (new Date().getTime() - recallWindow * 1000)) {
+          recallWindow > 0 && params.timestamp && params.timestamp.getTime() > (new Date().getTime() - recallWindow * 1000)) {
         menuItems.push('menu_item_recall');
       }
       // Self -> (1) always hard-delete with [Delete] title.