From a5e09ebb53e7a9d1bcf8b421f13cb8432a1d9110 Mon Sep 17 00:00:00 2001
From: Florian Duros <florianduros@element.io>
Date: Thu, 9 Apr 2026 14:14:41 +0100
Subject: [PATCH] feat: expand sections when filter is toggled (#33077)

---
 .../viewmodels/room-list/RoomListViewModel.ts | 10 +++++++
 .../room-list/RoomListViewModel-test.tsx      | 27 +++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/apps/web/src/viewmodels/room-list/RoomListViewModel.ts b/apps/web/src/viewmodels/room-list/RoomListViewModel.ts
index 0dc476e09c..d2ff465db9 100644
--- a/apps/web/src/viewmodels/room-list/RoomListViewModel.ts
+++ b/apps/web/src/viewmodels/room-list/RoomListViewModel.ts
@@ -182,6 +182,16 @@ export class RoomListViewModel
         // Update roomsMap immediately before clearing VMs
         this.updateRoomsMap(this.roomsResult);
 
+        // When a filter is toggled on, expand sections that have results so they're visible
+        if (newFilter) {
+            for (const section of this.roomsResult.sections) {
+                if (section.rooms.length > 0) {
+                    const sectionHeaderVM = this.roomSectionHeaderViewModels.get(section.tag);
+                    if (sectionHeaderVM) sectionHeaderVM.isExpanded = true;
+                }
+            }
+        }
+
         this.updateRoomListData();
     };
 
diff --git a/apps/web/test/viewmodels/room-list/RoomListViewModel-test.tsx b/apps/web/test/viewmodels/room-list/RoomListViewModel-test.tsx
index b9172b680b..2207f08d19 100644
--- a/apps/web/test/viewmodels/room-list/RoomListViewModel-test.tsx
+++ b/apps/web/test/viewmodels/room-list/RoomListViewModel-test.tsx
@@ -885,6 +885,33 @@ describe("RoomListViewModel", () => {
                 expect(snapshot.sections[0].roomIds).toEqual(["!fav1:server"]);
             });
 
+            it("should expand collapsed sections that have results when a filter is toggled on", () => {
+                viewModel = new RoomListViewModel({ client: matrixClient });
+
+                // Collapse the favourite section
+                const favHeader = viewModel.getSectionHeaderViewModel(DefaultTagID.Favourite);
+                favHeader.onClick();
+                expect(favHeader.isExpanded).toBe(false);
+
+                // Toggle a filter that returns rooms in the favourite section
+                jest.spyOn(RoomListStoreV3.instance, "getSortedRoomsInActiveSpace").mockReturnValue({
+                    spaceId: "home",
+                    sections: [
+                        { tag: DefaultTagID.Favourite, rooms: [favRoom1] },
+                        { tag: CHATS_TAG, rooms: [] },
+                        { tag: DefaultTagID.LowPriority, rooms: [] },
+                    ],
+                    filterKeys: [FilterEnum.UnreadFilter],
+                });
+                viewModel.onToggleFilter("unread");
+
+                // The favourite section should be expanded and its rooms visible
+                expect(favHeader.isExpanded).toBe(true);
+                const snapshot = viewModel.getSnapshot();
+                const favSection = snapshot.sections.find((s) => s.id === DefaultTagID.Favourite);
+                expect(favSection!.roomIds).toEqual(["!fav1:server"]);
+            });
+
             it("should apply sticky room within the correct section", async () => {
                 stubClient();
                 viewModel = new RoomListViewModel({ client: matrixClient });