fix(mobile): avoid bottom-edge scroll bounce

mobile/lib/features/channels/agent_activity/agent_activity_sheet.dart

@@ -39,23 +39,34 @@ class AgentActivitySheet extends HookConsumerWidget {
     );
     final botName = profile?.label ?? shortPubkey(agentPubkey);
 
-    // Auto-scroll to bottom on new items.
+    // Follow live activity only while the user is already reading its tail.
+    // New bot items are passive updates, so correcting with an animation at
+    // max extent makes iOS repeatedly rubber-band at the bottom.
     final sheetControllerRef = useRef<ScrollController?>(null);
     final previousLength = useRef(0);
+    final autoScrollQueued = useRef(false);
 
     useEffect(() {
       final sc = sheetControllerRef.value;
       if (transcript.length > previousLength.value &&
           sc != null &&
-          sc.hasClients) {
+          sc.hasClients &&
+          !autoScrollQueued.value) {
+        final position = sc.position;
+        final wasAtTail =
+            position.maxScrollExtent - position.pixels <= 1;
+        if (!wasAtTail) {
+          previousLength.value = transcript.length;
+          return null;
+        }
+        final previousPixels = position.pixels;
+        autoScrollQueued.value = true;
         WidgetsBinding.instance.addPostFrameCallback((_) {
-          if (sc.hasClients) {
-            sc.animateTo(
-              sc.position.maxScrollExtent,
-              duration: const Duration(milliseconds: 150),
-              curve: Curves.easeOut,
-            );
-          }
+          autoScrollQueued.value = false;
+          if (!sc.hasClients || sc.position.pixels + 1 < previousPixels) return;
+          final maxScrollExtent = sc.position.maxScrollExtent;
+          if (maxScrollExtent - sc.position.pixels <= 1) return;
+          sc.jumpTo(maxScrollExtent);
         });
       }
       previousLength.value = transcript.length;

mobile/lib/features/channels/channel_detail_page/message_list.dart

@@ -350,7 +350,16 @@ class _MessageList extends HookConsumerWidget {
         return null;
       }
       WidgetsBinding.instance.addPostFrameCallback((_) {
-        if (context.mounted) scrollToLatest();
+        // Incoming messages are passive layout updates, not user navigation.
+        // In a reversed list an already-pinned tail normally stays put; if it
+        // needs correction, realign with an instant jump rather than restarting
+        // a 220ms bottom-edge animation for every agent event on iOS.
+        if (!context.mounted ||
+            !followsLatest.value ||
+            hasUserScrolled.value) {
+          return;
+        }
+        realignLatestAfterLayoutChange();
       });
       return null;
     }, [latestEntryId]);

mobile/lib/features/channels/thread_detail_page.dart

@@ -213,6 +213,11 @@ class ThreadDetailPage extends HookConsumerWidget {
             userOptedOutOfTailFollow.value = false;
             followsThreadTail.value = true;
           }
+          // Rapid agent replies can arrive while the newly laid-out tail is
+          // already visible. There is nothing to navigate to in that case;
+          // restarting a bottom-edge animation for every reply produces iOS
+          // rubber-banding.
+          if (threadTailIsVisible()) return;
           if (animate) {
             itemScrollController.scrollTo(
               index: lastIndex,

mobile/test/features/channels/channel_detail_page_test.dart

@@ -2491,6 +2491,62 @@ void main() {
       );
     });
 
+    testWidgets('does not animate an already pinned tail for rapid live updates', (
+      tester,
+    ) async {
+      final initialMessages = [
+        for (var i = 0; i < 20; i++)
+          _textMsg(
+            id: 'msg$i',
+            pubkey: 'alice',
+            content: 'Message $i',
+            createdAt: 1000 + i,
+          ),
+      ];
+      final messagesNotifier = _FakeMessagesNotifier(initialMessages);
+
+      await tester.pumpWidget(
+        _buildTestable(
+          messages: const [],
+          messagesNotifier: messagesNotifier,
+          users: const {
+            'alice': UserProfile(pubkey: 'alice', displayName: 'Alice'),
+          },
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      final composerDock = find.byKey(const ValueKey('channel-composer-dock'));
+      for (var i = 0; i < 5; i++) {
+        final latestId = 'agent-update-$i';
+        messagesNotifier.setMessages([
+          ...initialMessages,
+          for (var previous = 0; previous <= i; previous++)
+            _textMsg(
+              id: 'agent-update-$previous',
+              pubkey: 'agent',
+              content: 'Agent update $previous',
+              createdAt: 2000 + previous,
+            ),
+        ]);
+        await tester.pump();
+        await tester.pump();
+
+        final latestMessage = find.byKey(
+          ValueKey('channel-message-group-$latestId'),
+        );
+        expect(
+          tester.getBottomLeft(latestMessage).dy,
+          closeTo(tester.getTopLeft(composerDock).dy, 1),
+        );
+        expect(
+          find.byKey(const ValueKey('channel-jump-to-latest')),
+          findsNothing,
+        );
+      }
+      await tester.pumpAndSettle();
+    });
+
     testWidgets(
       'keeps follow mode off while a tall newest message stays visible',
       (tester) async {