diff --git a/mobile/lib/features/activity/activity_page.dart b/mobile/lib/features/activity/activity_page.dart
index 9c85d9a45b..afbea12ab7 100644
--- a/mobile/lib/features/activity/activity_page.dart
+++ b/mobile/lib/features/activity/activity_page.dart
@@ -186,8 +186,6 @@ class ActivityPage extends HookConsumerWidget {
           (channelById[id]?.isDm ?? false) ||
           ref.read(channelsProvider.notifier).hiddenDmIds.contains(id),
     );
-    // A filtered DM row holds only part of its conversation, so the DM
-    // channel marker would also read events this view hides.
     final rowsArePartial =
         filter.value == InboxFilter.thread ||
         filter.value == InboxFilter.mention ||
@@ -220,8 +218,10 @@ class ActivityPage extends HookConsumerWidget {
       ref
           .read(inboxLocalStateProvider.notifier)
           .clearUnread(groupedInboxItemIds(item));
+      // A filtered row holds only part of its conversation, so channel and
+      // thread markers would also read events this view hides.
       final isDmRow = item.conversationId.startsWith('dm:');
-      if (isDmRow && rowsArePartial) {
+      if (rowsArePartial && item.item.channelId != null) {
         for (final e in {item.item, ...item.groupItems}) {
           notifier.markContextRead(msgContextKey(e.id), e.createdAt);
         }
diff --git a/mobile/test/features/activity/activity_page_test.dart b/mobile/test/features/activity/activity_page_test.dart
index d3b42abce2..eb4711f912 100644
--- a/mobile/test/features/activity/activity_page_test.dart
+++ b/mobile/test/features/activity/activity_page_test.dart
@@ -879,6 +879,60 @@ void main() {
     },
   );
 
+  testWidgets(
+    'reading a thread row under People leaves hidden agent replies unread',
+    (tester) async {
+      FeedItem threadEvent(String id, String pubkey, int age) => FeedItem(
+        id: id,
+        kind: 9,
+        pubkey: pubkey,
+        content: 'body $id',
+        createdAt: now - age,
+        channelId: 'ch1',
+        channelName: 'general',
+        tags: const [
+          ['e', threadIdRoot1, '', 'root'],
+          ['e', threadIdRoot1, '', 'reply'],
+        ],
+        category: 'mention',
+      );
+
+      await tester.pumpWidget(
+        await buildTestable(
+          knownAgentPubkeys: const {'agent_pk'},
+          feed: HomeFeedResponse(
+            mentions: [
+              threadEvent('g1', 'agent_pk', 300),
+              threadEvent('p1', 'bob_pk', 200),
+            ],
+            needsAction: const [],
+            activity: const [],
+            agentActivity: const [],
+          ),
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      Future<void> chooseSender(String label) async {
+        await tester.tap(find.byKey(const ValueKey('activity-sender-menu')));
+        await tester.pumpAndSettle();
+        await tester.tap(find.text(label).last);
+        await tester.pumpAndSettle();
+      }
+
+      await chooseSender('People');
+      await tester.drag(
+        find.byKey(const ValueKey('inbox-row-p1')),
+        const Offset(-500, 0),
+      );
+      await tester.pumpAndSettle();
+      expect(find.byKey(const ValueKey('inbox-unread-dot-p1')), findsNothing);
+
+      await chooseSender('Anyone');
+      expect(find.byKey(const ValueKey('inbox-unread-dot-p1')), findsOneWidget);
+    },
+  );
+
   testWidgets('sender filter preloads authors hidden under newer rows', (
     tester,
   ) async {