Fix removing a room from a Space and interaction with `m.space.parent` (#6944)

src/components/structures/SpaceHierarchy.tsx

@@ -545,9 +545,19 @@ const ManageButtons = ({ hierarchy, selected, setSelected, setError }: IManageBu
             onClick={async () => {
                 setRemoving(true);
                 try {
+                    const userId = cli.getUserId();
                     for (const [parentId, childId] of selectedRelations) {
                         await cli.sendStateEvent(parentId, EventType.SpaceChild, {}, childId);
 
+                        // remove the child->parent relation too, if we have permission to.
+                        const childRoom = cli.getRoom(childId);
+                        const parentRelation = childRoom?.currentState.getStateEvents(EventType.SpaceParent, parentId);
+                        if (childRoom?.currentState.maySendStateEvent(EventType.SpaceParent, userId) &&
+                            Array.isArray(parentRelation?.getContent().via)
+                        ) {
+                            await cli.sendStateEvent(childId, EventType.SpaceParent, {}, parentId);
+                        }
+
                         hierarchy.removeRelation(parentId, childId);
                     }
                 } catch (e) {

src/stores/SpaceStore.ts

@@ -307,16 +307,23 @@ export class SpaceStoreClass extends AsyncStoreWithClient<IState> {
         return room?.currentState.getStateEvents(EventType.SpaceParent)
             .map(ev => {
                 const content = ev.getContent();
-                if (Array.isArray(content?.via) && (!canonicalOnly || content?.canonical)) {
-                    const parent = this.matrixClient.getRoom(ev.getStateKey());
-                    // only respect the relationship if the sender has sufficient permissions in the parent to set
-                    // child relations, as per MSC1772.
-                    // https://github.com/matrix-org/matrix-doc/blob/main/proposals/1772-groups-as-rooms.md#relationship-between-rooms-and-spaces
-                    if (parent?.currentState.maySendStateEvent(EventType.SpaceChild, userId)) {
-                        return parent;
-                    }
+                if (!Array.isArray(content.via) || (canonicalOnly && !content.canonical)) {
+                    return; // skip
                 }
-                // else implicit undefined which causes this element to be filtered out
+
+                // only respect the relationship if the sender has sufficient permissions in the parent to set
+                // child relations, as per MSC1772.
+                // https://github.com/matrix-org/matrix-doc/blob/main/proposals/1772-groups-as-rooms.md#relationship-between-rooms-and-spaces
+                const parent = this.matrixClient.getRoom(ev.getStateKey());
+                const relation = parent.currentState.getStateEvents(EventType.SpaceChild, roomId);
+                if (!parent?.currentState.maySendStateEvent(EventType.SpaceChild, userId) ||
+                    // also skip this relation if the parent had this child added but then since removed it
+                    (relation && !Array.isArray(relation.getContent().via))
+                ) {
+                    return; // skip
+                }
+
+                return parent;
             })
             .filter(Boolean) || [];
     }

test/stores/SpaceStore-test.ts

@@ -281,7 +281,7 @@ describe("SpaceStore", () => {
                 mkSpace(space1, [fav1, room1]);
                 mkSpace(space2, [fav1, fav2, fav3, room1]);
                 mkSpace(space3, [invite2]);
-                // client.getRoom.mockImplementation(roomId => rooms.find(room => room.roomId === roomId));
+                client.getRoom.mockImplementation(roomId => rooms.find(room => room.roomId === roomId));
 
                 [fav1, fav2, fav3].forEach(roomId => {
                     client.getRoom(roomId).tags = {