diff --git a/frontend/src/components/Sidebar.tsx b/frontend/src/components/Sidebar.tsx
index 4b0c7b2..a76ce69 100644
--- a/frontend/src/components/Sidebar.tsx
+++ b/frontend/src/components/Sidebar.tsx
@@ -373,11 +373,29 @@ export function Sidebar({
     </div>
   );
 
+  const getSectionUnreadCount = (rows: ConversationRow[]): number =>
+    rows.reduce((total, row) => total + row.unreadCount, 0);
+
+  const favoriteRows = favoriteItems.map((item) =>
+    item.type === 'channel'
+      ? buildChannelRow(item.channel, 'fav-chan')
+      : buildContactRow(item.contact, 'fav-contact')
+  );
+  const channelRows = nonFavoriteChannels.map((channel) => buildChannelRow(channel, 'chan'));
+  const contactRows = nonFavoriteContacts.map((contact) => buildContactRow(contact, 'contact'));
+  const repeaterRows = nonFavoriteRepeaters.map((contact) => buildContactRow(contact, 'repeater'));
+
+  const favoritesUnreadCount = getSectionUnreadCount(favoriteRows);
+  const channelsUnreadCount = getSectionUnreadCount(channelRows);
+  const contactsUnreadCount = getSectionUnreadCount(contactRows);
+  const repeatersUnreadCount = getSectionUnreadCount(repeaterRows);
+
   const renderSectionHeader = (
     title: string,
     collapsed: boolean,
     onToggle: () => void,
-    showSortToggle = false
+    showSortToggle = false,
+    unreadCount = 0
   ) => {
     const effectiveCollapsed = isSearching ? false : collapsed;
 
@@ -396,14 +414,23 @@ export function Sidebar({
           <span className="text-[10px]">{effectiveCollapsed ? '▸' : '▾'}</span>
           <span>{title}</span>
         </button>
-        {showSortToggle && (
-          <button
-            className="bg-transparent border border-border text-muted-foreground px-1.5 py-0.5 text-[10px] rounded hover:bg-accent hover:text-foreground"
-            onClick={handleSortToggle}
-            title={sortOrder === 'alpha' ? 'Sort by recent' : 'Sort alphabetically'}
-          >
-            {sortOrder === 'alpha' ? 'A-Z' : '⏱'}
-          </button>
+        {(showSortToggle || unreadCount > 0) && (
+          <div className="ml-auto flex items-center gap-1.5">
+            {showSortToggle && (
+              <button
+                className="bg-transparent border border-border text-muted-foreground px-1.5 py-0.5 text-[10px] rounded hover:bg-accent hover:text-foreground mr-0.5"
+                onClick={handleSortToggle}
+                title={sortOrder === 'alpha' ? 'Sort by recent' : 'Sort alphabetically'}
+              >
+                {sortOrder === 'alpha' ? 'A-Z' : '⏱'}
+              </button>
+            )}
+            {unreadCount > 0 && (
+              <span className="text-[10px] font-medium px-1.5 py-0.5 rounded-full bg-muted text-muted-foreground">
+                {unreadCount}
+              </span>
+            )}
+          </div>
         )}
       </div>
     );
@@ -549,14 +576,11 @@ export function Sidebar({
               'Favorites',
               favoritesCollapsed,
               () => setFavoritesCollapsed((prev) => !prev),
-              false
+              false,
+              favoritesUnreadCount
             )}
             {(isSearching || !favoritesCollapsed) &&
-              favoriteItems.map((item) =>
-                item.type === 'channel'
-                  ? renderConversationRow(buildChannelRow(item.channel, 'fav-chan'))
-                  : renderConversationRow(buildContactRow(item.contact, 'fav-contact'))
-              )}
+              favoriteRows.map((row) => renderConversationRow(row))}
           </>
         )}
 
@@ -567,12 +591,11 @@ export function Sidebar({
               'Channels',
               channelsCollapsed,
               () => setChannelsCollapsed((prev) => !prev),
-              true
+              true,
+              channelsUnreadCount
             )}
             {(isSearching || !channelsCollapsed) &&
-              nonFavoriteChannels.map((channel) =>
-                renderConversationRow(buildChannelRow(channel, 'chan'))
-              )}
+              channelRows.map((row) => renderConversationRow(row))}
           </>
         )}
 
@@ -583,12 +606,11 @@ export function Sidebar({
               'Contacts',
               contactsCollapsed,
               () => setContactsCollapsed((prev) => !prev),
-              true
+              true,
+              contactsUnreadCount
             )}
             {(isSearching || !contactsCollapsed) &&
-              nonFavoriteContacts.map((contact) =>
-                renderConversationRow(buildContactRow(contact, 'contact'))
-              )}
+              contactRows.map((row) => renderConversationRow(row))}
           </>
         )}
 
@@ -599,12 +621,11 @@ export function Sidebar({
               'Repeaters',
               repeatersCollapsed,
               () => setRepeatersCollapsed((prev) => !prev),
-              true
+              true,
+              repeatersUnreadCount
             )}
             {(isSearching || !repeatersCollapsed) &&
-              nonFavoriteRepeaters.map((contact) =>
-                renderConversationRow(buildContactRow(contact, 'repeater'))
-              )}
+              repeaterRows.map((row) => renderConversationRow(row))}
           </>
         )}
 
diff --git a/frontend/src/test/sidebar.test.tsx b/frontend/src/test/sidebar.test.tsx
new file mode 100644
index 0000000..c37c26c
--- /dev/null
+++ b/frontend/src/test/sidebar.test.tsx
@@ -0,0 +1,120 @@
+import { fireEvent, render, screen, waitFor, within } from '@testing-library/react';
+import { describe, expect, it, vi } from 'vitest';
+
+import { Sidebar } from '../components/Sidebar';
+import { CONTACT_TYPE_REPEATER, type Channel, type Contact, type Favorite } from '../types';
+import { getStateKey, type ConversationTimes } from '../utils/conversationState';
+
+function makeChannel(key: string, name: string): Channel {
+  return {
+    key,
+    name,
+    is_hashtag: false,
+    on_radio: false,
+    last_read_at: null,
+  };
+}
+
+function makeContact(public_key: string, name: string, type = 1): Contact {
+  return {
+    public_key,
+    name,
+    type,
+    flags: 0,
+    last_path: null,
+    last_path_len: -1,
+    last_advert: null,
+    lat: null,
+    lon: null,
+    last_seen: null,
+    on_radio: false,
+    last_contacted: null,
+    last_read_at: null,
+  };
+}
+
+function renderSidebar(overrides?: {
+  unreadCounts?: Record<string, number>;
+  favorites?: Favorite[];
+  lastMessageTimes?: ConversationTimes;
+}) {
+  const publicChannel = makeChannel('AA'.repeat(16), 'Public');
+  const flightChannel = makeChannel('BB'.repeat(16), '#flight');
+  const opsChannel = makeChannel('CC'.repeat(16), '#ops');
+  const alice = makeContact('11'.repeat(32), 'Alice');
+  const relay = makeContact('22'.repeat(32), 'Relay', CONTACT_TYPE_REPEATER);
+
+  const unreadCounts = overrides?.unreadCounts ?? {
+    [getStateKey('channel', flightChannel.key)]: 2,
+    [getStateKey('channel', opsChannel.key)]: 1,
+    [getStateKey('contact', alice.public_key)]: 3,
+    [getStateKey('contact', relay.public_key)]: 4,
+  };
+
+  const favorites = overrides?.favorites ?? [{ type: 'channel', id: flightChannel.key }];
+
+  render(
+    <Sidebar
+      contacts={[alice, relay]}
+      channels={[publicChannel, flightChannel, opsChannel]}
+      activeConversation={null}
+      onSelectConversation={vi.fn()}
+      onNewMessage={vi.fn()}
+      lastMessageTimes={overrides?.lastMessageTimes ?? {}}
+      unreadCounts={unreadCounts}
+      mentions={{}}
+      showCracker={false}
+      crackerRunning={false}
+      onToggleCracker={vi.fn()}
+      onMarkAllRead={vi.fn()}
+      favorites={favorites}
+      sortOrder="recent"
+      onSortOrderChange={vi.fn()}
+    />
+  );
+
+  return { flightChannel, opsChannel, alice };
+}
+
+function getSectionHeaderContainer(title: string): HTMLElement {
+  const btn = screen.getByRole('button', { name: new RegExp(title, 'i') });
+  const container = btn.closest('div');
+  if (!container) throw new Error(`Missing header container for section ${title}`);
+  return container;
+}
+
+describe('Sidebar section summaries', () => {
+  it('shows muted section unread totals in each visible section header', () => {
+    renderSidebar();
+
+    expect(within(getSectionHeaderContainer('Favorites')).getByText('2')).toBeInTheDocument();
+    expect(within(getSectionHeaderContainer('Channels')).getByText('1')).toBeInTheDocument();
+    expect(within(getSectionHeaderContainer('Contacts')).getByText('3')).toBeInTheDocument();
+    expect(within(getSectionHeaderContainer('Repeaters')).getByText('4')).toBeInTheDocument();
+  });
+
+  it('expands collapsed sections during search and restores collapse state after clearing search', async () => {
+    const { opsChannel, alice } = renderSidebar();
+
+    fireEvent.click(screen.getByRole('button', { name: /Channels/i }));
+    fireEvent.click(screen.getByRole('button', { name: /Contacts/i }));
+
+    expect(screen.queryByText(opsChannel.name)).not.toBeInTheDocument();
+    expect(screen.queryByText(alice.name)).not.toBeInTheDocument();
+
+    const search = screen.getByPlaceholderText('Search...');
+    fireEvent.change(search, { target: { value: 'alice' } });
+
+    await waitFor(() => {
+      expect(screen.getByText(alice.name)).toBeInTheDocument();
+    });
+
+    fireEvent.change(search, { target: { value: '' } });
+
+    await waitFor(() => {
+      expect(screen.queryByText(opsChannel.name)).not.toBeInTheDocument();
+      expect(screen.queryByText(alice.name)).not.toBeInTheDocument();
+    });
+  });
+});
+