fix no room selected after leave / init

lib/controllers/room_chat.dart

@@ -25,6 +25,7 @@ class RoomChatController(final ChatParams info)
   @override
   Future<RoomChat?> build() async {
     final client = ref.read(ClientController.provider.notifier);
+
     final room = ref.read(
       RoomsController.provider.select((rooms) => rooms[info.roomId]),
     );

lib/controllers/selected_room.dart

@@ -0,0 +1,31 @@
+import "package:fast_immutable_collections/fast_immutable_collections.dart";
+import "package:flutter_riverpod/flutter_riverpod.dart";
+import "package:nexus/controllers/key.dart";
+import "package:nexus/controllers/selected_space.dart";
+import "package:nexus/helpers/extensions/get_all_child_rooms.dart";
+
+class SelectedRoomController extends Notifier<String?> {
+  @override
+  String? build() {
+    final roomId = ref.watch(
+      KeyController.provider(KeyController.roomKey)
+          .select((async) => async.value),
+    );
+
+    final roomIds = ref.watch(
+      SelectedSpaceController.provider.select(
+        (space) => space?.allChildRooms
+            .map((room) => room.metadata?.id)
+            .nonNulls
+            .toIList(),
+      ),
+    );
+    if (roomIds == null) return roomId;
+
+    return roomIds.contains(roomId) ? roomId : roomIds.firstOrNull;
+  }
+
+  static final provider = NotifierProvider<SelectedRoomController, String?>(
+    SelectedRoomController.new,
+  );
+}

lib/controllers/selected_space.dart

@@ -0,0 +1,25 @@
+import "package:collection/collection.dart";
+import "package:flutter_riverpod/flutter_riverpod.dart";
+import "package:nexus/controllers/key.dart";
+import "package:nexus/controllers/spaces.dart";
+import "package:nexus/models/space.dart";
+
+class SelectedSpaceController extends Notifier<Space?> {
+  @override
+  Space? build() {
+    final spaces = ref.watch(SpacesController.provider).value;
+    if (spaces == null) return null;
+
+    final spaceId = ref.watch(
+      KeyController.provider(KeyController.spaceKey)
+          .select((async) => async.value),
+    );
+
+    return spaces.firstWhereOrNull((space) => space.id == spaceId) ??
+        spaces.firstOrNull;
+  }
+
+  static final provider = NotifierProvider<SelectedSpaceController, Space?>(
+    SelectedSpaceController.new,
+  );
+}

lib/controllers/unified_push.dart

@@ -5,7 +5,7 @@ import "dart:io";
 import "package:flutter/foundation.dart";
 import "package:flutter_riverpod/flutter_riverpod.dart";
 import "package:intl/intl.dart";
-import "package:nexus/controllers/key.dart";
+import "package:nexus/controllers/selected_room.dart";
 import "package:nexus/controllers/notification.dart";
 import "package:nexus/controllers/push_key.dart";
 import "package:nexus/main.dart";
@@ -90,10 +90,7 @@ class UnifiedPushController extends AsyncNotifier<String?> {
         if (event.unreadType?.has(.notify) != true ||
             (!isInBackground &&
                 await windowManager.isFocused().onError((_, _) => true) &&
-                await ref.read(
-                      KeyController.provider(KeyController.roomKey).future,
-                    ) ==
-                    event.roomId)) {
+                ref.read(SelectedRoomController.provider) == event.roomId)) {
           if (isInBackground) exit(0);
           return;
         }

lib/widgets/pages/chat.dart

@@ -2,7 +2,7 @@ import "package:flutter_hooks/flutter_hooks.dart";
 import "package:material_ui/material_ui.dart";
 import "package:hooks_riverpod/hooks_riverpod.dart";
 import "package:nexus/controllers/init_complete.dart";
-import "package:nexus/controllers/key.dart";
+import "package:nexus/controllers/selected_room.dart";
 import "package:nexus/controllers/notification_request.dart";
 import "package:nexus/helpers/extensions/is_desktop.dart";
 import "package:nexus/widgets/appbar.dart";
@@ -37,9 +37,7 @@ class const ChatPage({super.key}) extends HookConsumerWidget {
       builder: (context, constraints) {
         final isDesktop = context.isDesktop;
         final showMembersByDefault = constraints.maxWidth > 1000;
-        final roomId = ref
-            .watch(KeyController.provider(KeyController.roomKey))
-            .requireValue;
+        final roomId = ref.watch(SelectedRoomController.provider);
 
         return SafeArea(
           child: Scaffold(

lib/widgets/room_list.dart

@@ -22,9 +22,10 @@ import "package:nexus/widgets/room_summary_sheet.dart";
 import "package:nexus/widgets/room_menu_button.dart";
 import "package:nexus/widgets/space_hierarchy_sheet.dart";
 import "package:nexus/controllers/key.dart";
+import "package:nexus/controllers/selected_room.dart";
+import "package:nexus/controllers/selected_space.dart";
 import "package:nexus/controllers/rooms.dart";
 import "package:nexus/controllers/spaces.dart";
-import "package:collection/collection.dart";
 
 // Needed for navigation_rail_m3e (#65).
 import "package:flutter/material.dart" as old_mat;
@@ -217,23 +218,8 @@ class const SpacesRail({super.key}) extends ConsumerWidget {
 class const RoomsPane({super.key}) extends ConsumerWidget {
   @override
   Widget build(BuildContext context, WidgetRef ref) {
-    final selectedSpaceId = ref.watch(
-      KeyController.provider(KeyController.spaceKey)
-          .select((async) => async.requireValue),
-    );
-    final selectedRoomId = ref.watch(
-      KeyController.provider(KeyController.roomKey)
-          .select((async) => async.requireValue),
-    );
-    final selectedSpace = ref.watch(
-      SpacesController.provider.select((async) {
-        final spaces = async.requireValue;
-        return spaces.firstWhereOrNull(
-              (space) => space.id == selectedSpaceId,
-            ) ??
-            spaces.first;
-      }),
-    );
+    final selectedRoomId = ref.watch(SelectedRoomController.provider);
+    final selectedSpace = ref.watch(SelectedSpaceController.provider)!;
     final isDm = selectedSpace.id == "dms";
     final spaceMetadata = selectedSpace.room?.metadata;