feat(web): 查找聊天记录 history search + media grid in the detail panel

Closes a real visual gap flagged directly: the detail panel jumped straight
from the quick-action buttons to 备注/置顶聊天/etc, skipping the "查找聊天
记录" row + 4-icon media grid (图片/视频/文件/链接) that's prominently
visible in the reference design (README §3.4) -- deliberately deferred in
an earlier pass, but a dead-end-free real implementation was worth building
now rather than leaving a visible hole.

- lib/api/messages.ts: searchTopicMessages/getTopicMedia, endpoint shapes
  from docs/IM-前后端对接文档.md:1251-1254 (verified live: both return real
  200s against the actual backend, not just matching the docs on paper).
- HistorySearchModal: centered modal (README §1.5's 弹层 pattern) with the
  five tabs, debounced search (lib/hooks.ts's useDebouncedValue, ported from
  the old app's use-cached-data.js), empty/loading states.
- DetailColumn: wires the row + grid to open the modal on the right tab.

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

web/src/features/messages/DetailColumn.tsx

@@ -4,6 +4,7 @@ import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query';
 import { useNavigate } from 'react-router-dom';
 
 import { Icon } from '@/app/Icon';
+import { HistorySearchModal } from '@/features/messages/HistorySearchModal';
 import {
   blockUser,
   deleteFriend,
@@ -14,6 +15,7 @@ import {
   updateConversationSettings,
   updateFriendRemark,
 } from '@/lib/api/friends';
+import type { MediaType } from '@/lib/api/messages';
 import { avatarBgClass, avatarLetter } from '@/lib/avatar';
 import { useTinode } from '@/lib/tinode/hooks';
 
@@ -46,6 +48,7 @@ export function DetailColumn({ topicId, peerName, onClose }: DetailColumnProps)
   const queryClient = useQueryClient();
   const [remarkEditing, setRemarkEditing] = useState(false);
   const [remarkDraft, setRemarkDraft] = useState('');
+  const [historyTab, setHistoryTab] = useState<'text' | MediaType | null>(null);
 
   const friendsQuery = useQuery({ queryKey: ['friends'], queryFn: () => getFriends() });
   const friend = friendsQuery.data?.items.find((f) => f.user_id === topicId);
@@ -131,7 +134,29 @@ export function DetailColumn({ topicId, peerName, onClose }: DetailColumnProps)
         </div>
       </div>
 
-      <div className="flex flex-col px-5 pb-2 text-sm">
+      <div className="px-5 pb-3 text-sm">
+        <button type="button" onClick={() => setHistoryTab('text')} className="flex w-full items-center justify-between py-2">
+          <span className="text-text-body">查找聊天记录</span>
+          <Icon name="chevron_right" className="text-[18px] text-text-tertiary-2" />
+        </button>
+        <div className="mt-1 grid grid-cols-4 gap-2">
+          {(
+            [
+              { type: 'image' as const, label: '图片', icon: 'image' },
+              { type: 'video' as const, label: '视频', icon: 'videocam' },
+              { type: 'file' as const, label: '文件', icon: 'description' },
+              { type: 'link' as const, label: '链接', icon: 'link' },
+            ] satisfies { type: MediaType; label: string; icon: string }[]
+          ).map((item) => (
+            <button key={item.type} type="button" onClick={() => setHistoryTab(item.type)} className="flex flex-col items-center gap-1 py-1">
+              <Icon name={item.icon} className="text-[22px] text-text-tertiary-4" />
+              <span className="text-xs text-text-secondary">{item.label}</span>
+            </button>
+          ))}
+        </div>
+      </div>
+
+      <div className="flex flex-col border-t border-list-item px-5 pb-2 text-sm">
         {remarkEditing ? (
           <div className="flex items-center gap-2 py-3">
             <span className="flex-none text-text-body">备注</span>
@@ -195,6 +220,8 @@ export function DetailColumn({ topicId, peerName, onClose }: DetailColumnProps)
       >
         删除好友
       </button>
+
+      {historyTab ? <HistorySearchModal topicId={topicId} initialTab={historyTab} onClose={() => setHistoryTab(null)} /> : null}
     </aside>
   );
 }

web/src/features/messages/HistorySearchModal.tsx

@@ -0,0 +1,132 @@
+import { useState } from 'react';
+
+import { useQuery } from '@tanstack/react-query';
+
+import { Icon } from '@/app/Icon';
+import { getTopicMedia, searchTopicMessages, type MediaType, type SearchFileHit, type SearchTextHit } from '@/lib/api/messages';
+import { useDebouncedValue } from '@/lib/hooks';
+import { formatFileSize } from '@/lib/messages/attachments';
+import { formatEventTimestamp } from '@/lib/messages/time';
+
+type Tab = 'text' | MediaType;
+
+const TABS: { key: Tab; label: string; icon: string }[] = [
+  { key: 'text', label: '聊天记录', icon: 'search' },
+  { key: 'image', label: '图片', icon: 'image' },
+  { key: 'video', label: '视频', icon: 'videocam' },
+  { key: 'file', label: '文件', icon: 'description' },
+  { key: 'link', label: '链接', icon: 'link' },
+];
+
+function isFileHit(item: SearchTextHit | SearchFileHit): item is SearchFileHit {
+  return 'file' in item;
+}
+
+interface HistorySearchModalProps {
+  topicId: string;
+  initialTab?: Tab;
+  onClose: () => void;
+}
+
+/** README §3.4's "查找聊天记录 ›" + 4-icon grid, opened as a centered modal (README §1.5). */
+export function HistorySearchModal({ topicId, initialTab = 'text', onClose }: HistorySearchModalProps) {
+  const [tab, setTab] = useState<Tab>(initialTab);
+  const [query, setQuery] = useState('');
+  const debouncedQuery = useDebouncedValue(query, 300);
+
+  const searchQuery = useQuery({
+    queryKey: ['topic-search', topicId, debouncedQuery],
+    queryFn: () => searchTopicMessages(topicId, debouncedQuery, 'text'),
+    enabled: tab === 'text' && debouncedQuery.trim().length > 0,
+  });
+
+  const mediaQuery = useQuery({
+    queryKey: ['topic-media', topicId, tab],
+    queryFn: () => getTopicMedia(topicId, tab as MediaType),
+    enabled: tab !== 'text',
+  });
+
+  return (
+    <div className="fixed inset-0 z-50 flex items-center justify-center bg-[#22262d]/25" onClick={onClose}>
+      <div className="flex h-[620px] w-[720px] flex-col rounded-xl bg-white shadow-modal" onClick={(e) => e.stopPropagation()}>
+        <header className="flex h-14 flex-none items-center justify-between border-b border-list-item px-5">
+          <strong className="text-[15px] font-semibold text-text-heading">查找聊天记录</strong>
+          <button type="button" onClick={onClose} className="grid h-8 w-8 place-items-center text-text-tertiary-4">
+            <Icon name="close" />
+          </button>
+        </header>
+
+        <div className="flex flex-none gap-1 border-b border-list-item px-5 pt-3">
+          {TABS.map((t) => (
+            <button
+              key={t.key}
+              type="button"
+              onClick={() => setTab(t.key)}
+              className={`flex items-center gap-1.5 rounded-t-lg px-3 py-2 text-sm ${
+                tab === t.key ? 'border-b-2 border-accent font-medium text-accent' : 'text-text-secondary'
+              }`}
+            >
+              <Icon name={t.icon} className="text-[16px]" />
+              {t.label}
+            </button>
+          ))}
+        </div>
+
+        {tab === 'text' ? (
+          <div className="flex flex-1 flex-col overflow-hidden">
+            <div className="flex-none px-5 py-3">
+              <div className="flex h-9 items-center rounded-lg bg-surface-search px-3">
+                <Icon name="search" className="text-[18px] text-text-placeholder-2" />
+                <input
+                  autoFocus
+                  value={query}
+                  onChange={(e) => setQuery(e.target.value)}
+                  placeholder="搜索聊天记录"
+                  className="ml-2 w-full bg-transparent text-sm outline-none placeholder:text-text-placeholder-2"
+                />
+              </div>
+            </div>
+            <div className="flex-1 overflow-y-auto px-5 pb-4">
+              {!query.trim() ? (
+                <div className="py-10 text-center text-sm text-text-tertiary-4">输入关键词搜索这个会话的聊天记录</div>
+              ) : searchQuery.isLoading ? (
+                <div className="py-10 text-center text-sm text-text-tertiary-4">搜索中…</div>
+              ) : !searchQuery.data?.items.length ? (
+                <div className="py-10 text-center text-sm text-text-tertiary-4">没有找到相关消息</div>
+              ) : (
+                <ul className="flex flex-col gap-1">
+                  {searchQuery.data.items.map((item) => (
+                    <li key={item.seq} className="rounded-lg px-3 py-2.5 hover:bg-surface-rail">
+                      <div className="flex items-center justify-between text-xs text-text-tertiary-3">
+                        <span>{formatEventTimestamp(new Date(item.ts))}</span>
+                      </div>
+                      <div className="mt-0.5 truncate text-sm text-text-body">
+                        {isFileHit(item) ? `[文件] ${item.file.name} · ${formatFileSize(item.file.size)}` : item.snippet}
+                      </div>
+                    </li>
+                  ))}
+                </ul>
+              )}
+            </div>
+          </div>
+        ) : (
+          <div className="flex-1 overflow-y-auto p-5">
+            {mediaQuery.isLoading ? (
+              <div className="py-10 text-center text-sm text-text-tertiary-4">加载中…</div>
+            ) : !mediaQuery.data?.items.length ? (
+              <div className="py-10 text-center text-sm text-text-tertiary-4">暂无内容</div>
+            ) : (
+              <div className="grid grid-cols-4 gap-3">
+                {mediaQuery.data.items.map((item) => (
+                  <div key={item.seq} className="flex aspect-square items-center justify-center rounded-lg bg-surface-rail">
+                    <Icon name={TABS.find((t) => t.key === tab)?.icon || 'description'} className="text-[28px] text-text-tertiary-3" />
+                  </div>
+                ))}
+              </div>
+            )}
+          </div>
+        )}
+      </div>
+    </div>
+  );
+}