Mark the threads icon as unread due to activity.

src/Unread.ts

@@ -70,7 +70,7 @@ export function doesRoomHaveUnreadMessages(room: Room): boolean {
     return false;
 }
 
-function doesRoomOrThreadHaveUnreadMessages(room: Room | Thread): boolean {
+export function doesRoomOrThreadHaveUnreadMessages(room: Room | Thread): boolean {
     const myUserId = MatrixClientPeg.get().getUserId();
 
     // as we don't send RRs for our own messages, make sure we special case that

src/components/views/right_panel/RoomHeaderButtons.tsx

@@ -44,6 +44,7 @@ import { NotificationStateEvents } from "../../../stores/notifications/Notificat
 import PosthogTrackers from "../../../PosthogTrackers";
 import { ButtonEvent } from "../elements/AccessibleButton";
 import { MatrixClientPeg } from "../../../MatrixClientPeg";
+import { doesRoomOrThreadHaveUnreadMessages } from "../../../Unread";
 
 const ROOM_INFO_PHASES = [
     RightPanelPhases.RoomSummary,
@@ -191,9 +192,17 @@ export default class RoomHeaderButtons extends HeaderButtons<IProps> {
                 return NotificationColor.Red;
             case NotificationCountType.Total:
                 return NotificationColor.Grey;
-            default:
-                return NotificationColor.None;
         }
+        // We don't have any notified messages, but we might have unread messages. Let's
+        // find out.
+        for (const thread of this.props.room!.getThreads()) {
+            // If the current thread has unread messages, we're done.
+            if (doesRoomOrThreadHaveUnreadMessages(thread)) {
+                return NotificationColor.Bold;
+            }
+        }
+        // Otherwise, no notification color.
+        return NotificationColor.None;
     }
 
     private onUpdateStatus = (notificationState: SummarizedNotificationState): void => {

src/hooks/useUnreadNotifications.ts

@@ -15,12 +15,13 @@ limitations under the License.
 */
 
 import { NotificationCount, NotificationCountType, Room, RoomEvent } from "matrix-js-sdk/src/models/room";
+import { Thread } from "matrix-js-sdk/src/models/thread";
 import { useCallback, useEffect, useState } from "react";
 
 import { getUnsentMessages } from "../components/structures/RoomStatusBar";
 import { getRoomNotifsState, getUnreadNotificationCount, RoomNotifState } from "../RoomNotifs";
 import { NotificationColor } from "../stores/notifications/NotificationColor";
-import { doesRoomHaveUnreadMessages } from "../Unread";
+import { doesRoomOrThreadHaveUnreadMessages } from "../Unread";
 import { EffectiveMembership, getEffectiveMembership } from "../utils/membership";
 import { useEventEmitter } from "./useEventEmitter";
 
@@ -75,12 +76,14 @@ export const useUnreadNotifications = (
                 setColor(NotificationColor.Red);
             } else if (greyNotifs > 0) {
                 setColor(NotificationColor.Grey);
-            } else if (!threadId) {
-                // TODO: No support for `Bold` on threads at the moment
-
+            } else {
                 // We don't have any notified messages, but we might have unread messages. Let's
                 // find out.
-                const hasUnread = doesRoomHaveUnreadMessages(room);
+                let roomOrThread: Room | Thread = room;
+                if (threadId) {
+                    roomOrThread = room.getThread(threadId)!;
+                }
+                const hasUnread = doesRoomOrThreadHaveUnreadMessages(roomOrThread);
                 setColor(hasUnread ? NotificationColor.Bold : NotificationColor.None);
             }
         }

test/components/views/right_panel/RoomHeaderButtons-test.tsx

@@ -24,6 +24,7 @@ import RoomHeaderButtons from "../../../../src/components/views/right_panel/Room
 import { MatrixClientPeg } from "../../../../src/MatrixClientPeg";
 import SettingsStore from "../../../../src/settings/SettingsStore";
 import { stubClient } from "../../../test-utils";
+import { mkThread } from "../../../test-utils/threads";
 
 describe("RoomHeaderButtons-test.tsx", function () {
     const ROOM_ID = "!roomId:example.org";
@@ -52,7 +53,7 @@ describe("RoomHeaderButtons-test.tsx", function () {
         return container.querySelector(".mx_RightPanel_threadsButton");
     }
 
-    function isIndicatorOfType(container, type: "red" | "gray") {
+    function isIndicatorOfType(container, type: "red" | "gray" | "bold") {
         return container.querySelector(".mx_RightPanel_threadsButton .mx_Indicator").className.includes(type);
     }
 
@@ -76,7 +77,7 @@ describe("RoomHeaderButtons-test.tsx", function () {
         expect(container.querySelector(".mx_RightPanel_threadsButton .mx_Indicator")).toBeNull();
     });
 
-    it("room wide notification does not change the thread button", () => {
+    it.only("thread notification does change the thread button", () => {
         const { container } = getComponent(room);
 
         room.setThreadUnreadNotificationCount("$123", NotificationCountType.Total, 1);
@@ -89,6 +90,10 @@ describe("RoomHeaderButtons-test.tsx", function () {
         room.setThreadUnreadNotificationCount("$123", NotificationCountType.Highlight, 0);
 
         expect(container.querySelector(".mx_RightPanel_threadsButton .mx_Indicator")).toBeNull();
+
+        // Thread activity should appear on the icon.
+        mkThread({ room, client, authorId: client.getUserId()!, participantUserIds: ["@alice:example.org"] });
+        expect(isIndicatorOfType(getComponent(room), "bold")).toBe(true);
     });
 
     it("does not explode without a room", () => {

test/components/views/rooms/EventTile-test.tsx

@@ -137,7 +137,8 @@ describe("EventTile", () => {
         it("shows an unread notification bage", () => {
             const { container } = getComponent({}, TimelineRenderingType.ThreadsList);
 
-            expect(container.getElementsByClassName("mx_NotificationBadge")).toHaveLength(0);
+            // By default, the thread will assume there's unread activity in it.
+            expect(container.getElementsByClassName("mx_NotificationBadge")).toHaveLength(1);
 
             act(() => {
                 room.setThreadUnreadNotificationCount(mxEvent.getId(), NotificationCountType.Total, 3);

test/components/views/rooms/NotificationBadge/UnreadNotificationBadge-test.tsx

@@ -17,13 +17,14 @@ limitations under the License.
 import React from "react";
 import "jest-mock";
 import { screen, act, render } from "@testing-library/react";
-import { MatrixClient, PendingEventOrdering } from "matrix-js-sdk/src/client";
+import { MsgType } from "matrix-js-sdk/src/matrix";
+import { PendingEventOrdering } from "matrix-js-sdk/src/client";
 import { NotificationCountType, Room } from "matrix-js-sdk/src/models/room";
-import { mocked } from "jest-mock";
 import { EventStatus } from "matrix-js-sdk/src/models/event-status";
 
+import { mkThread } from "../../../../test-utils/threads";
 import { UnreadNotificationBadge } from "../../../../../src/components/views/rooms/NotificationBadge/UnreadNotificationBadge";
-import { mkMessage, stubClient } from "../../../../test-utils/test-utils";
+import { mkEvent, mkMessage, stubClient } from "../../../../test-utils/test-utils";
 import { MatrixClientPeg } from "../../../../../src/MatrixClientPeg";
 import * as RoomNotifs from "../../../../../src/RoomNotifs";
 
@@ -34,28 +35,38 @@ jest.mock("../../../../../src/RoomNotifs", () => ({
 }));
 
 const ROOM_ID = "!roomId:example.org";
-let THREAD_ID;
+let THREAD_ID: string;
 
 describe("UnreadNotificationBadge", () => {
-    let mockClient: MatrixClient;
+    stubClient();
+    const client = MatrixClientPeg.get();
     let room: Room;
 
     function getComponent(threadId?: string) {
         return <UnreadNotificationBadge room={room} threadId={threadId} />;
     }
 
+    beforeAll(() => {
+        client.supportsExperimentalThreads = () => true;
+    });
+
     beforeEach(() => {
         jest.clearAllMocks();
 
-        stubClient();
-        mockClient = mocked(MatrixClientPeg.get());
-
-        room = new Room(ROOM_ID, mockClient, mockClient.getUserId() ?? "", {
+        room = new Room(ROOM_ID, client, client.getUserId()!, {
             pendingEventOrdering: PendingEventOrdering.Detached,
         });
         room.setUnreadNotificationCount(NotificationCountType.Total, 1);
         room.setUnreadNotificationCount(NotificationCountType.Highlight, 0);
 
+        const { rootEvent } = mkThread({
+            room,
+            client,
+            authorId: client.getUserId()!,
+            participantUserIds: [client.getUserId()!],
+        });
+        THREAD_ID = rootEvent.getId()!;
+
         room.setThreadUnreadNotificationCount(THREAD_ID, NotificationCountType.Total, 1);
         room.setThreadUnreadNotificationCount(THREAD_ID, NotificationCountType.Highlight, 0);
 
@@ -125,4 +136,33 @@ describe("UnreadNotificationBadge", () => {
         const { container } = render(getComponent());
         expect(container.querySelector(".mx_NotificationBadge")).toBeNull();
     });
+
+    it("activity renders unread notification badge", () => {
+        act(() => {
+            room.setThreadUnreadNotificationCount(THREAD_ID, NotificationCountType.Total, 0);
+            room.setThreadUnreadNotificationCount(THREAD_ID, NotificationCountType.Highlight, 0);
+
+            // Add another event on the thread which is not sent by us.
+            const event = mkEvent({
+                event: true,
+                type: "m.room.message",
+                user: "@alice:server.org",
+                room: room.roomId,
+                content: {
+                    "msgtype": MsgType.Text,
+                    "body": "Hello from Bob",
+                    "m.relates_to": {
+                        event_id: THREAD_ID,
+                        rel_type: "m.thread",
+                    },
+                },
+            });
+            room.addLiveEvents([event]);
+        });
+
+        const { container } = render(getComponent(THREAD_ID));
+        expect(container.querySelector(".mx_NotificationBadge_dot")).toBeTruthy();
+        expect(container.querySelector(".mx_NotificationBadge_visible")).toBeTruthy();
+        expect(container.querySelector(".mx_NotificationBadge_highlighted")).toBeFalsy();
+    });
 });