feat: localized unread count (#3679)

## 🎯 Goal

SDK followup to this PR:
GetStream/stream-chat-js#1787.

All details can be read there.

## 🛠 Implementation details

<!-- Provide a description of the implementation -->

## 🎨 UI Changes

<!-- Add relevant screenshots -->

<details>
<summary>iOS</summary>


<table>
    <thead>
        <tr>
            <td>Before</td>
            <td>After</td>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td>
                <!--<img src="" /> -->
            </td>
            <td>
                <!--<img src="" /> -->
            </td>
        </tr>
    </tbody>
</table>
</details>


<details>
<summary>Android</summary>

<table>
    <thead>
        <tr>
            <td>Before</td>
            <td>After</td>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td>
                <!--<img src="" /> -->
            </td>
            <td>
                <!--<img src="" /> -->
            </td>
        </tr>
    </tbody>
</table>
</details>

## 🧪 Testing

<!-- Explain how this change can be tested (or why it can't be tested)
-->

## ☑️ Checklist

- [ ] I have signed the [Stream
CLA](https://docs.google.com/forms/d/e/1FAIpQLScFKsKkAJI7mhCr7K9rEIOpqIDThrWxuvxnwUq2XkHyG154vQ/viewform)
(required)
- [ ] PR targets the `develop` branch
- [ ] Documentation is updated
- [ ] New code is tested in main example apps, including all possible
scenarios
  - [ ] SampleApp iOS and Android
  - [ ] Expo iOS and Android

Author: isekovanic

examples/ExpoMessaging/package.json

@@ -51,7 +51,7 @@
     "react-native-teleport": "^1.0.2",
     "react-native-web": "^0.21.0",
     "react-native-worklets": "0.8.3",
-    "stream-chat": "^9.48.0",
+    "stream-chat": "^9.50.0",
     "stream-chat-expo": "workspace:^",
     "stream-chat-react-native-core": "workspace:^"
   },

examples/SampleApp/package.json

@@ -64,7 +64,7 @@
     "react-native-teleport": "^1.1.7",
     "react-native-video": "^6.19.2",
     "react-native-worklets": "^0.8.3",
-    "stream-chat": "^9.48.0",
+    "stream-chat": "^9.50.0",
     "stream-chat-react-native": "workspace:^",
     "stream-chat-react-native-core": "workspace:^"
   },

examples/TypeScriptMessaging/package.json

@@ -33,7 +33,7 @@
     "react-native-svg": "^15.12.0",
     "react-native-video": "^6.16.1",
     "react-native-worklets": "^0.4.1",
-    "stream-chat": "^9.48.0",
+    "stream-chat": "^9.50.0",
     "stream-chat-react-native": "workspace:^",
     "stream-chat-react-native-core": "workspace:^"
   },

package/package.json

@@ -78,7 +78,7 @@
     "path": "0.12.7",
     "react-native-markdown-package": "1.8.2",
     "react-native-url-polyfill": "^2.0.0",
-    "stream-chat": "^9.48.0",
+    "stream-chat": "^9.50.0",
     "use-sync-external-store": "^1.5.0"
   },
   "peerDependencies": {

package/src/components/Channel/Channel.tsx

@@ -511,12 +511,12 @@ const ChannelWithContext = (props: PropsWithChildren<ChannelPropsWithContext>) =
   const styles = useStyles();
   const [deleted, setDeleted] = useState<boolean>(false);
   const [error, setError] = useState<Error | boolean>(false);
-  const [lastRead, setLastRead] = useState<Date | undefined>();
+  const lastReadRef = useRef<Date | undefined>(undefined);
   const [thread, setThread] = useState<LocalMessage | null>(threadProps || null);
   const [threadHasMore, setThreadHasMore] = useState(true);
   const [threadLoadingMore, setThreadLoadingMore] = useState(false);
-  const [channelUnreadStateStore] = useState(new ChannelUnreadStateStore());
-  const [messageInputHeightStore] = useState(new MessageInputHeightStore());
+  const [channelUnreadStateStore] = useState(() => new ChannelUnreadStateStore());
+  const [messageInputHeightStore] = useState(() => new MessageInputHeightStore());
   // TODO: Think if we can remove this and just rely on the channelUnreadStateStore everywhere.
   const setChannelUnreadState = useCallback(
     (data: ChannelUnreadStateStoreType['channelUnreadState']) => {
@@ -690,6 +690,13 @@ const ChannelWithContext = (props: PropsWithChildren<ChannelPropsWithContext>) =
           return;
         }
 
+        if (event.type === 'message.read_locally') {
+          // When local unread reset happens, the count is already updated in the client state,
+          // and the preview badge / unread divider are handled elsewhere, so there is nothing
+          // to copy into channel state here. Thus, we skip it.
+          return;
+        }
+
         if (event.type === 'message.read' || event.type === 'notification.mark_read') {
           setReadThrottled();
           return;
@@ -703,7 +710,7 @@ const ChannelWithContext = (props: PropsWithChildren<ChannelPropsWithContext>) =
   useEffect(() => {
     let listener: ReturnType<typeof channel.on>;
     const initChannel = async () => {
-      setLastRead(new Date());
+      lastReadRef.current = new Date();
       const unreadCount = channel.countUnread();
       const shouldLoadAtFirstUnread = shouldLoadInitialChannelAtFirstUnreadMessage(unreadCount);
       if (!channel || !shouldSyncChannel) {
@@ -812,7 +819,25 @@ const ChannelWithContext = (props: PropsWithChildren<ChannelPropsWithContext>) =
   const markReadInternal: ChannelContextValue['markRead'] = throttle(
     async (options?: MarkReadFunctionOptions) => {
       const { updateChannelUnreadState = true } = options ?? {};
-      if (!channel || channel?.disconnected || !clientChannelConfig?.read_events) {
+      if (!channel || channel?.disconnected) {
+        return;
+      }
+
+      // When read events are disabled (e.g. livestreams) we cannot mark read on the backend. If the
+      // client opted into a local unread count, reset it locally instead so the user's "caught up"
+      // state is reflected without a server round trip.
+      if (!clientChannelConfig?.read_events) {
+        if (client.options.isLocalUnreadCountEnabled) {
+          const event = channel.markReadLocally();
+          if (updateChannelUnreadState && event && lastReadRef.current) {
+            setChannelUnreadState({
+              last_read: lastReadRef.current,
+              last_read_message_id: event.last_read_message_id,
+              unread_messages: 0,
+            });
+            lastReadRef.current = new Date();
+          }
+        }
         return;
       }
 
@@ -821,13 +846,13 @@ const ChannelWithContext = (props: PropsWithChildren<ChannelPropsWithContext>) =
       } else {
         try {
           const response = await channel.markRead();
-          if (updateChannelUnreadState && response && lastRead) {
+          if (updateChannelUnreadState && response && lastReadRef.current) {
             setChannelUnreadState({
-              last_read: lastRead,
+              last_read: lastReadRef.current,
               last_read_message_id: response?.event.last_read_message_id,
               unread_messages: 0,
             });
-            setLastRead(new Date());
+            lastReadRef.current = new Date();
           }
         } catch (err) {
           console.log('Error marking channel as read:', err);
@@ -1578,7 +1603,6 @@ const ChannelWithContext = (props: PropsWithChildren<ChannelPropsWithContext>) =
     hideStickyDateHeader,
     highlightedMessageId,
     isChannelActive: shouldSyncChannel,
-    lastRead,
     loadChannelAroundMessage,
     loadChannelAtFirstUnreadMessage,
     loading: channelMessagesState.loading,
@@ -1590,7 +1614,6 @@ const ChannelWithContext = (props: PropsWithChildren<ChannelPropsWithContext>) =
     reloadChannel,
     scrollToFirstUnreadThreshold,
     setChannelUnreadState,
-    setLastRead,
     setTargetedMessage,
     hasPendingInitialTargetLoad,
     targetedMessage,

package/src/components/Channel/hooks/useCreateChannelContext.ts

@@ -13,7 +13,6 @@ export const useCreateChannelContext = ({
   hideStickyDateHeader,
   highlightedMessageId,
   isChannelActive,
-  lastRead,
   loadChannelAroundMessage,
   loadChannelAtFirstUnreadMessage,
   loading,
@@ -25,7 +24,6 @@ export const useCreateChannelContext = ({
   reloadChannel,
   scrollToFirstUnreadThreshold,
   setChannelUnreadState,
-  setLastRead,
   setTargetedMessage,
   hasPendingInitialTargetLoad,
   targetedMessage,
@@ -35,7 +33,6 @@ export const useCreateChannelContext = ({
   watchers,
 }: ChannelContextValue) => {
   const channelId = channel?.id;
-  const lastReadTime = lastRead?.getTime();
   const membersLength = Object.keys(members).length;
 
   const readUsers = Object.values(read);
@@ -56,7 +53,6 @@ export const useCreateChannelContext = ({
       hideStickyDateHeader,
       highlightedMessageId,
       isChannelActive,
-      lastRead,
       loadChannelAroundMessage,
       loadChannelAtFirstUnreadMessage,
       loading,
@@ -68,7 +64,6 @@ export const useCreateChannelContext = ({
       reloadChannel,
       scrollToFirstUnreadThreshold,
       setChannelUnreadState,
-      setLastRead,
       setTargetedMessage,
       hasPendingInitialTargetLoad,
       targetedMessage,
@@ -84,7 +79,6 @@ export const useCreateChannelContext = ({
       error,
       isChannelActive,
       highlightedMessageId,
-      lastReadTime,
       loading,
       membersLength,
       readUsersLength,

package/src/components/ChannelPreview/hooks/useChannelPreviewData.ts

@@ -109,8 +109,14 @@ export const useChannelPreviewData = (
         setForceUpdate((prev) => prev + 1);
       }
     };
-    const { unsubscribe } = client.on('message.read', handleReadEvent);
-    return unsubscribe;
+    const readSubscription = client.on('message.read', handleReadEvent);
+    // `message.read_locally` is the client-only equivalent emitted by `channel.markReadLocally()` when
+    // read events are disabled (e.g. livestreams with `isLocalUnreadCountEnabled`).
+    const localReadSubscription = client.on('message.read_locally', handleReadEvent);
+    return () => {
+      readSubscription.unsubscribe();
+      localReadSubscription.unsubscribe();
+    };
   }, [client, channel]);
 
   /**

package/src/components/MessageList/MessageFlashList.tsx

@@ -718,9 +718,14 @@ const MessageFlashListWithContext = (props: MessageFlashListPropsWithContext) =>
     const lastReadMessageId = channelUnreadState?.last_read_message_id;
     const lastReadMessageVisible = viewableItems.some((item) => item.item.id === lastReadMessageId);
 
+    // Channels with disabled `read-events` (i.e livestreams) still surface the unread
+    // notification when the client opted into a local unread count, so the gate accepts
+    // either source.
+    const unreadNotificationSupported = readEvents || client.options.isLocalUnreadCountEnabled;
+
     if (
       !viewableItems.length ||
-      !readEvents ||
+      !unreadNotificationSupported ||
       lastReadMessageVisible ||
       attachmentPickerStore.state.getLatestValue().selectedPicker === 'images'
     ) {

package/src/components/MessageList/MessageList.tsx

@@ -555,9 +555,14 @@ const MessageListWithContext = (props: MessageListPropsWithContext) => {
       (item) => item.item.message.id === lastReadMessageId,
     );
 
+    // Channels with disabled `read-events` (i.e livestreams) still surface the unread
+    // notification when the client opted into a local unread count, so the gate accepts
+    // either source.
+    const unreadNotificationSupported = readEvents || client.options.isLocalUnreadCountEnabled;
+
     if (
       !viewableItems.length ||
-      !readEvents ||
+      !unreadNotificationSupported ||
       lastReadMessageVisible ||
       attachmentPickerStore.state.getLatestValue().selectedPicker === 'images'
     ) {

package/src/components/Thread/__tests__/Thread.test.tsx

@@ -142,7 +142,9 @@ describe('Thread', () => {
       threadResponses as unknown as Parameters<typeof channel.state.addMessagesSorted>[0],
     );
 
-    let setLastRead: ((date?: Date) => void) | undefined;
+    let setChannelUnreadState:
+      | React.ContextType<typeof ChannelContext>['setChannelUnreadState']
+      | undefined;
 
     const { getByText, toJSON } = render(
       <ChannelsStateProvider>
@@ -161,7 +163,7 @@ describe('Thread', () => {
               <Channel channel={channel} thread={thread} threadList>
                 <ChannelContext.Consumer>
                   {(c) => {
-                    setLastRead = c.setLastRead;
+                    setChannelUnreadState = c.setChannelUnreadState;
                     return <Thread />;
                   }}
                 </ChannelContext.Consumer>
@@ -178,7 +180,7 @@ describe('Thread', () => {
       expect(getByText('Message6')).toBeTruthy();
     });
 
-    act(() => setLastRead!(new Date('2020-08-17T18:08:03.196Z')));
+    act(() => setChannelUnreadState!(undefined));
 
     const snapshot = toJSON() as unknown as {
       children: Array<{