Prevent sliding sync from showing a room under multiple sublists (#9266)

* Prevent sliding sync from showing a room under multiple sublists

* Add tests

(cherry picked from commit 96656e4)

cypress/e2e/sliding-sync/sliding-sync.ts

@@ -319,4 +319,16 @@ describe("Sliding Sync", () => {
             "Join", "Test Room",
         ]);
     });
+
+    it("should show a favourite DM only in the favourite sublist", () => {
+        cy.createRoom({
+            name: "Favourite DM",
+            is_direct: true,
+        }).as("room").then(roomId => {
+            cy.getClient().then(cli => cli.setRoomTag(roomId, "m.favourite", { order: 0.5 }));
+        });
+
+        cy.get('.mx_RoomSublist[aria-label="Favourites"]').contains(".mx_RoomTile", "Favourite DM").should("exist");
+        cy.get('.mx_RoomSublist[aria-label="People"]').contains(".mx_RoomTile", "Favourite DM").should("not.exist");
+    });
 });

src/stores/room-list/SlidingRoomListStore.ts

@@ -55,6 +55,8 @@ const filterConditions: Record<TagID, MSC3575Filter> = {
         is_dm: true,
         is_invite: false,
         is_tombstoned: false,
+        // If a DM has a Favourite & Low Prio tag then it'll be shown in those lists instead
+        not_tags: ["m.favourite", "m.lowpriority"],
     },
     [DefaultTagID.Untagged]: {
         is_dm: false,
@@ -66,6 +68,8 @@ const filterConditions: Record<TagID, MSC3575Filter> = {
     },
     [DefaultTagID.LowPriority]: {
         tags: ["m.lowpriority"],
+        // If a room has both Favourite & Low Prio tags then it'll be shown under Favourites
+        not_tags: ["m.favourite"],
         is_tombstoned: false,
     },
     // TODO https://github.com/vector-im/element-web/issues/23207