feat: add new events to broadcast section state

Author: florianduros

apps/web/src/dispatcher/actions.ts

@@ -403,4 +403,16 @@ export enum Action {
      * or keyboard event).
      */
     UserActivity = "user_activity",
+
+    /**
+     * Fired to request collapsing or expanding all room list sections.
+     * Payload: {@link RoomListCollapseAllSectionsPayload}
+     */
+    RoomListCollapseAllSections = "room_list_collapse_all_sections",
+
+    /**
+     * Fired to report the collapse state of a given room list section.
+     * Payload: {@link RoomListSectionsCollapseStateChangedPayload}
+     */
+    RoomListSectionsCollapseStateChanged = "room_list_sections_collapse_state_changed",
 }

apps/web/src/dispatcher/payloads/RoomListCollapseAllSectionsPayload.ts

@@ -0,0 +1,15 @@
+/*
+ * Copyright 2026 New Vector 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 ActionPayload } from "../payloads";
+import { type Action } from "../actions";
+
+export interface RoomListCollapseAllSectionsPayload extends ActionPayload {
+    action: Action.RoomListCollapseAllSections;
+    /** true = expand all, false = collapse all */
+    expand: boolean;
+}

apps/web/src/dispatcher/payloads/RoomListSectionsCollapseStateChangedPayload.ts

@@ -0,0 +1,19 @@
+/*
+ * Copyright 2026 New Vector 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 ActionPayload } from "../payloads";
+import { type Action } from "../actions";
+
+export interface RoomListSectionsCollapseStateChangedPayload extends ActionPayload {
+    action: Action.RoomListSectionsCollapseStateChanged;
+    /**
+     * true = all collapsed (header shows "expand all")
+     * false = some/all expanded (header shows "collapse all")
+     * null = hide button (flat list or sections disabled)
+     */
+    allCollapsed: boolean | null;
+}