feat(ui): add configurable StreamBackButton unread count

docs/docs_screenshots/test/localization/localization_rtl_test.dart

@@ -191,7 +191,7 @@ void main() {
           child: Scaffold(
             appBar: const StreamChannelHeader(
               automaticallyImplyLeading: false,
-              leading: StreamBackButton(showUnreadCount: false),
+              leading: StreamBackButton(),
             ),
             body: Column(
               children: [

migrations/redesign/headers_and_icons.md

@@ -185,6 +185,36 @@ The default leading is now [`StreamBackButton`] with a channel-aware
 unread badge; the default trailing is the channel avatar wrapped in a
 48×48 tap target wired to `onChannelAvatarPressed`.
 
+### `StreamBackButton`
+
+The unread badge is now supplied as a widget through a single `unreadIndicator`
+parameter (typically a `StreamUnreadIndicator`) instead of the `showUnreadCount`
+/ `channelId` flags, which are **deprecated** but still functional. The badge is
+overlaid on the button's top-end corner and hides itself when its count is zero.
+
+| Old                                     | New equivalent                                              |
+| --------------------------------------- | ----------------------------------------------------------- |
+| `showUnreadCount: false` (or omitted)   | `unreadIndicator:` omitted — no badge                       |
+| `showUnreadCount: true`                 | `unreadIndicator: StreamUnreadIndicator()`                  |
+| `showUnreadCount: true, channelId: cid` | `unreadIndicator: StreamUnreadIndicator.channels(cid: cid)` |
+
+`StreamUnreadIndicator` also takes an optional `excludeCid` to omit one channel
+from the total. The default `StreamChannelHeader` leading uses
+`StreamUnreadIndicator(excludeCid: channel.cid)` so its badge counts the unread
+messages in *other* channels.
+
+**Before:**
+
+```dart
+StreamBackButton(showUnreadCount: true)
+```
+
+**After:**
+
+```dart
+StreamBackButton(unreadIndicator: StreamUnreadIndicator())
+```
+
 ### `StreamChannelListHeader`
 
 | Old parameter                                                                                | New equivalent                                                                     |

packages/stream_chat_flutter/CHANGELOG.md

@@ -7,19 +7,22 @@
 - Added an `errorSubtitle` to `StreamScrollViewErrorWidget`, which now falls back to the design's generic error copy (title, description, and a "Try Again" retry label) when values aren't provided.
 - Added a `size` (`StreamLoadingSpinnerSize`) parameter to `StreamScrollViewLoadingWidget`.
 - Added `onReactionTap` to `StreamMessageItem` and `StreamMessageListView`, reporting the tapped message's `BuildContext` and a `ReactionTapDetails` with the tapped `message` and `reaction` (the reaction is `null` for a clustered or overflow chip that maps to no single reaction).
+- Added an `unreadIndicator` parameter to `StreamBackButton` that overlays a widget (typically a `StreamUnreadIndicator`) on the button's top-end corner. Pass `StreamUnreadIndicator(excludeCid: cid)` to show the total unread count of other channels, or `StreamUnreadIndicator.channels(cid: cid)` for a single channel's count.
 
 ⚠️ Deprecated
 
 - Deprecated `StreamMessageReactionPicker.onReactionPicked` in favor of `onReactionSelected`.
 - Deprecated `onReactionsTap` (and the `OnReactionsTap` typedef) on `StreamMessageItem` and `StreamMessageListView` in favor of `onReactionTap`.
 - Deprecated `height`/`width` of `StreamScrollViewLoadingWidget` in favor of `size`.
+- Deprecated `StreamBackButton.showUnreadCount` and `StreamBackButton.channelId` in favor of `unreadIndicator`.
 
 🐞 Fixed
 
 - Fixed the default `StreamChannel` loading and error states not being themed or localized; `StreamChat` now installs themed, connection-aware defaults, overridable per `StreamChannel` or via `DefaultStreamChannelBuilders`.
 - Fixed the default list/scroll-view error states (channel, message, member, user, thread, poll-vote, reaction, search, and photo) showing raw or fixed errors; they are now connection-aware (no internet / slow connection), falling back to each view's specific error text.
 - Fixed `StreamTypingIndicator` briefly showing typing users from a different context (main channel vs. thread) on its first frame.
 - Fixed the attachment picker throwing a `Tooltip` assertion error when a custom `TabbedAttachmentPickerOption` is added without a `title`; the tooltip is now only shown when a title is provided.
+- Fixed the `StreamBackButton` unread badge including the currently open channel in its total count.
 
 ## 10.2.0
 

packages/stream_chat_flutter/example/lib/main.dart

@@ -225,18 +225,21 @@ class _ChannelPageState extends State<ChannelPage> {
 
   @override
   Widget build(BuildContext context) {
+    // Show the unread count of the other channels on the back button,
+    // excluding the currently open one.
+    final unreadIndicator = switch (StreamChannel.of(context).channel.cid) {
+      final cid? => StreamUnreadIndicator(excludeCid: cid),
+      _ => const StreamUnreadIndicator(),
+    };
+
     return Scaffold(
       appBar: StreamChannelHeader(
         leading: switch ((widget.showBackButton, widget.onBackPressed)) {
           (true, final cb?) => StreamBackButton(
-            channelId: StreamChannel.of(context).channel.cid,
+            unreadIndicator: unreadIndicator,
             onPressed: () => cb(context),
-            showUnreadCount: true,
-          ),
-          (true, null) => StreamBackButton(
-            channelId: StreamChannel.of(context).channel.cid,
-            showUnreadCount: true,
           ),
+          (true, null) => StreamBackButton(unreadIndicator: unreadIndicator),
           _ => const SizedBox(),
         },
         trailing: GestureDetector(

packages/stream_chat_flutter/lib/src/channel/channel_header.dart

@@ -139,7 +139,9 @@ class StreamChannelHeader extends StatelessWidget implements PreferredSizeWidget
 
     var leading = this.leading;
     if (leading == null && automaticallyImplyLeading) {
-      leading = const StreamBackButton(showUnreadCount: true);
+      leading = StreamBackButton(
+        unreadIndicator: StreamUnreadIndicator(excludeCid: channel.cid),
+      );
     }
 
     var title = this.title;

packages/stream_chat_flutter/lib/src/indicators/unread_indicator.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import 'package:rxdart/rxdart.dart';
 import 'package:stream_chat_flutter/src/misc/empty_widget.dart';
 import 'package:stream_chat_flutter/stream_chat_flutter.dart';
 
@@ -17,12 +18,16 @@ import 'package:stream_chat_flutter/stream_chat_flutter.dart';
 /// {@endtemplate}
 class StreamUnreadIndicator extends StatelessWidget {
   /// Displays the total unread count.
+  ///
+  /// Optionally, provide [excludeCid] to omit a specific channel's unread
+  /// messages from the total — for example, the currently open channel.
   const StreamUnreadIndicator({
     super.key,
     this.child,
     this.alignment,
     this.offset,
     this.semanticLabel,
+    this.excludeCid,
   }) : _unreadType = const _TotalUnreadCount();
 
   /// Displays the unreadChannel count.
@@ -35,7 +40,8 @@ class StreamUnreadIndicator extends StatelessWidget {
     this.alignment,
     this.offset,
     this.semanticLabel,
-  }) : _unreadType = _UnreadChannels(cid: cid);
+  }) : _unreadType = _UnreadChannels(cid: cid),
+       excludeCid = null;
 
   /// Displays the unreadThreads count.
   ///
@@ -47,10 +53,18 @@ class StreamUnreadIndicator extends StatelessWidget {
     this.alignment,
     this.offset,
     this.semanticLabel,
-  }) : _unreadType = _UnreadThreads(id: id);
+  }) : _unreadType = _UnreadThreads(id: id),
+       excludeCid = null;
 
   final _UnreadTypes _unreadType;
 
+  /// The cid of a channel whose unread messages are excluded from the total
+  /// unread count.
+  ///
+  /// Only applies to the default (total) constructor; ignored by
+  /// [StreamUnreadIndicator.channels] and [StreamUnreadIndicator.threads].
+  final String? excludeCid;
+
   /// Optional child widget to overlay the badge on.
   ///
   /// When non-null, the badge is positioned on top of this widget.
@@ -85,7 +99,7 @@ class StreamUnreadIndicator extends StatelessWidget {
     final client = StreamChat.of(context).client;
 
     final stream = switch (_unreadType) {
-      _TotalUnreadCount() => client.state.totalUnreadCountStream,
+      _TotalUnreadCount() => _totalUnreadCountStream(client, excludeCid),
       _UnreadChannels(cid: final cid) => switch (cid) {
         final cid? => client.state.channels[cid]?.state?.unreadCountStream,
         _ => client.state.unreadChannelsStream,
@@ -97,7 +111,7 @@ class StreamUnreadIndicator extends StatelessWidget {
     };
 
     final initialData = switch (_unreadType) {
-      _TotalUnreadCount() => client.state.totalUnreadCount,
+      _TotalUnreadCount() => _totalUnreadCount(client, excludeCid),
       _UnreadChannels(cid: final cid) => switch (cid) {
         final cid? => client.state.channels[cid]?.state?.unreadCount,
         _ => client.state.unreadChannels,
@@ -135,6 +149,42 @@ class StreamUnreadIndicator extends StatelessWidget {
   }
 }
 
+/// Returns the client's total unread message count as a stream, optionally
+/// subtracting the unread messages of the channel identified by [excludeCid].
+Stream<int> _totalUnreadCountStream(
+  StreamChatClient client,
+  String? excludeCid,
+) {
+  final totalUnreadCount = client.state.totalUnreadCountStream;
+  if (excludeCid == null) return totalUnreadCount;
+
+  final excludedUnreadCount = client.state.channels[excludeCid]?.state?.unreadCountStream ?? Stream.value(0);
+
+  // The total and the excluded channel's unread count update through separate
+  // streams. Both settle within the same event-loop turn, so debouncing on a
+  // zero duration coalesces them into a single emission and avoids rendering a
+  // transient count before the two values agree.
+  return Rx.combineLatest2<int, int, int>(
+    totalUnreadCount,
+    excludedUnreadCount,
+    _subtractExcluded,
+  ).debounceTime(Duration.zero).distinct();
+}
+
+/// Returns the client's total unread message count, optionally subtracting the
+/// unread messages of the channel identified by [excludeCid].
+int _totalUnreadCount(StreamChatClient client, String? excludeCid) {
+  final totalUnreadCount = client.state.totalUnreadCount;
+  if (excludeCid == null) return totalUnreadCount;
+
+  final excludedUnreadCount = client.state.channels[excludeCid]?.state?.unreadCount ?? 0;
+
+  return _subtractExcluded(totalUnreadCount, excludedUnreadCount);
+}
+
+/// Subtracts [excluded] from [total], flooring the result at zero.
+int _subtractExcluded(int total, int excluded) => total > excluded ? total - excluded : 0;
+
 sealed class _UnreadTypes {
   const _UnreadTypes._();
 }

packages/stream_chat_flutter/lib/src/misc/back_button.dart

@@ -9,19 +9,44 @@ class StreamBackButton extends StatelessWidget {
   const StreamBackButton({
     super.key,
     this.onPressed,
+    @Deprecated(
+      "Use 'unreadIndicator: StreamUnreadIndicator()' instead. "
+      'This will be removed in a future version.',
+    )
     this.showUnreadCount = false,
+    @Deprecated(
+      "Use 'unreadIndicator: StreamUnreadIndicator.channels(cid: cid)' instead. "
+      'This will be removed in a future version.',
+    )
     this.channelId,
-  });
+    Widget? unreadIndicator = _unset,
+  }) : _unreadIndicator = unreadIndicator;
 
   /// Callback for when button is pressed
   final VoidCallback? onPressed;
 
   /// Show unread count
+  @Deprecated(
+    "Use 'unreadIndicator: StreamUnreadIndicator()' instead. "
+    'This will be removed in a future version.',
+  )
   final bool showUnreadCount;
 
   /// Channel ID used to retrieve unread count
+  @Deprecated(
+    "Use 'unreadIndicator: StreamUnreadIndicator.channels(cid: cid)' instead. "
+    'This will be removed in a future version.',
+  )
   final String? channelId;
 
+  /// The unread badge overlaid on the top-end corner of the button.
+  ///
+  /// Typically a [StreamUnreadIndicator]. The badge hides itself when its
+  /// count is zero. Null when not explicitly set.
+  Widget? get unreadIndicator => identical(_unreadIndicator, _unset) ? null : _unreadIndicator;
+
+  final Widget? _unreadIndicator;
+
   @override
   Widget build(BuildContext context) {
     final localizations = MaterialLocalizations.of(context);
@@ -47,13 +72,43 @@ class StreamBackButton extends StatelessWidget {
       },
     );
 
-    if (showUnreadCount) {
-      button = switch (channelId) {
-        final cid? => StreamUnreadIndicator.channels(offset: .zero, cid: cid, child: button),
-        _ => StreamUnreadIndicator(offset: .zero, child: button),
-      };
+    if (_effectiveUnreadIndicator case final indicator?) {
+      // The indicator is childless here, so it renders only the bare badge
+      // (or nothing when the count is zero). Overlay it on the top-end corner
+      // of the button.
+      button = Stack(
+        clipBehavior: Clip.none,
+        children: [
+          button,
+          Positioned.fill(
+            child: FittedBox(
+              fit: BoxFit.none,
+              alignment: AlignmentDirectional.topEnd,
+              child: indicator,
+            ),
+          ),
+        ],
+      );
     }
 
     return button;
   }
+
+  Widget? get _effectiveUnreadIndicator {
+    if (!identical(_unreadIndicator, _unset)) return _unreadIndicator;
+    if (!showUnreadCount) return null;
+    return switch (channelId) {
+      final cid? => StreamUnreadIndicator.channels(cid: cid),
+      _ => const StreamUnreadIndicator(),
+    };
+  }
 }
+
+class _WidgetSentinel extends Widget {
+  const _WidgetSentinel();
+
+  @override
+  Element createElement() => throw StateError('_WidgetSentinel must never be built.');
+}
+
+const _unset = _WidgetSentinel();

packages/stream_chat_flutter/lib/src/misc/thread_header.dart

@@ -71,7 +71,11 @@ class StreamThreadHeader extends StatelessWidget implements PreferredSizeWidget
 
     var leading = this.leading;
     if (leading == null && automaticallyImplyLeading) {
-      leading = StreamBackButton(channelId: channel?.cid, showUnreadCount: true);
+      final unreadIndicator = switch (channel?.cid) {
+        final cid? => StreamUnreadIndicator.channels(cid: cid),
+        null => const StreamUnreadIndicator(),
+      };
+      leading = StreamBackButton(unreadIndicator: unreadIndicator);
     }
 
     Widget? fallbackSubtitle;

packages/stream_chat_flutter/test/src/channel/channel_header_test.dart

@@ -42,6 +42,7 @@ void main() {
       when(() => channelState.unreadCountStream).thenAnswer((i) => Stream.value(1));
       when(() => clientState.totalUnreadCount).thenAnswer((i) => 1);
       when(() => clientState.totalUnreadCountStream).thenAnswer((i) => Stream.value(1));
+      when(() => clientState.channels).thenReturn({channel.cid!: channel});
       when(() => channelState.membersStream).thenAnswer(
         (i) => Stream.value([
           Member(
@@ -122,6 +123,7 @@ void main() {
       when(() => client.wsConnectionStatus).thenReturn(ConnectionStatus.disconnected);
       when(() => clientState.totalUnreadCount).thenAnswer((i) => 1);
       when(() => clientState.totalUnreadCountStream).thenAnswer((i) => Stream.value(1));
+      when(() => clientState.channels).thenReturn({channel.cid!: channel});
 
       await tester.pumpWidget(
         MaterialApp(
@@ -188,6 +190,7 @@ void main() {
       when(() => client.wsConnectionStatusStream).thenAnswer((_) => Stream.value(ConnectionStatus.connecting));
       when(() => clientState.totalUnreadCount).thenAnswer((i) => 1);
       when(() => clientState.totalUnreadCountStream).thenAnswer((i) => Stream.value(1));
+      when(() => clientState.channels).thenReturn({channel.cid!: channel});
 
       await tester.pumpWidget(
         MaterialApp(
@@ -399,6 +402,7 @@ void main() {
       when(() => client.wsConnectionStatusStream).thenAnswer((_) => Stream.value(ConnectionStatus.connecting));
       when(() => clientState.totalUnreadCount).thenAnswer((i) => 1);
       when(() => clientState.totalUnreadCountStream).thenAnswer((i) => Stream.value(1));
+      when(() => clientState.channels).thenReturn({channel.cid!: channel});
 
       var backPressed = false;
       var imageTapped = false;