implement BrandApi and it's titleRenderer

apps/web/src/components/structures/MatrixChat.tsx

@@ -248,6 +248,9 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
     // What to focus on next component update, if anything
     private focusNext: FocusNextType;
     private subTitleStatus: string;
+    private notificationCount = 0;
+    private hasActivity = false;
+    private errorDidOccur = false;
     private prevWindowWidth: number;
 
     private readonly loggedInView = createRef<LoggedInViewType>();
@@ -2081,17 +2084,36 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
     }
 
     private setPageSubtitle(subtitle = ""): void {
-        if (this.state.currentRoomId) {
-            const client = MatrixClientPeg.get();
-            const room = client?.getRoom(this.state.currentRoomId);
-            if (room) {
-                subtitle = `${this.subTitleStatus} | ${room.name} ${subtitle}`;
+        const brand = SdkConfig.get().brand;
+        const room = this.state.currentRoomId
+            ? MatrixClientPeg.get()?.getRoom(this.state.currentRoomId)
+            : undefined;
+
+        const customTitle = ModuleApi.instance.brand.renderTitle({
+            brand,
+            notificationCount: this.notificationCount || undefined,
+            hasActivity: this.hasActivity || undefined,
+            statusText: this.errorDidOccur ? _t("common|offline") : undefined,
+            roomId: this.state.currentRoomId ?? undefined,
+            roomName: room?.name,
+        });
+
+        if (customTitle !== undefined) {
+            if (document.title !== customTitle) {
+                document.title = customTitle;
             }
+            return;
+        }
+
+        const elementSuffix = brand !== "Element" ? " | Element" : "";
+
+        if (room) {
+            subtitle = `${this.subTitleStatus} | ${room.name} ${subtitle}`;
         } else {
             subtitle = `${this.subTitleStatus} ${subtitle}`;
         }
 
-        const title = `${SdkConfig.get().brand} ${subtitle}`;
+        const title = `${brand}${elementSuffix} ${subtitle}`;
 
         if (document.title !== title) {
             document.title = title;
@@ -2107,12 +2129,15 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
         }
 
         this.subTitleStatus = "";
-        if (state === SyncState.Error) {
+        this.errorDidOccur = state === SyncState.Error;
+        if (this.errorDidOccur) {
             this.subTitleStatus += `[${_t("common|offline")}] `;
         }
+        this.notificationCount = numUnreadRooms;
+        this.hasActivity = notificationState.level >= NotificationLevel.Activity;
         if (numUnreadRooms > 0) {
             this.subTitleStatus += `[${numUnreadRooms}]`;
-        } else if (notificationState.level >= NotificationLevel.Activity) {
+        } else if (this.hasActivity) {
             this.subTitleStatus += `*`;
         }
 

apps/web/src/modules/Api.ts

@@ -33,6 +33,7 @@ import { StoresApi } from "./StoresApi.ts";
 import { WidgetLifecycleApi } from "./WidgetLifecycleApi.ts";
 import { WidgetApi } from "./WidgetApi.ts";
 import { CustomisationsApi } from "./customisationsApi.ts";
+import { ElementWebBrandApi } from "./BrandApi.ts";
 
 const legacyCustomisationsFactory = <T extends object>(baseCustomisations: T) => {
     let used = false;
@@ -87,6 +88,7 @@ export class ModuleApi implements Api {
     public readonly i18n = new I18nApi();
     public readonly customComponents = new CustomComponentsApi();
     public readonly customisations = new CustomisationsApi();
+    public readonly brand = new ElementWebBrandApi();
     public readonly extras = new ElementWebExtrasApi();
     public readonly builtins = new ElementWebBuiltinsApi();
     public readonly widgetLifecycle = new WidgetLifecycleApi();

apps/web/src/modules/BrandApi.ts

@@ -0,0 +1,27 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE files in the repository root for full details.
+*/
+
+import { type BrandApi, type TitleRenderFunction, type TitleRenderOptions } from "@element-hq/element-web-module-api";
+
+export class ElementWebBrandApi implements BrandApi {
+    private titleRenderer: TitleRenderFunction | undefined;
+
+    public registerTitleRenderer(renderFunction: TitleRenderFunction): void {
+        if (this.titleRenderer) {
+            throw new Error("A title renderer has already been registered by another module");
+        }
+        this.titleRenderer = renderFunction;
+    }
+
+    /**
+     * Render the window title using the registered renderer, or return undefined
+     * to fall back to the default title logic.
+     */
+    public renderTitle(opts: TitleRenderOptions): string | undefined {
+        return this.titleRenderer?.(opts);
+    }
+}