Merge pull request #1322 from bentucker/fix/build-phase-ui-side-effects

fix(core): make UI side effects and provider reads safe during build

Author: rolandgeider

lib/core/build_safety.dart

@@ -0,0 +1,33 @@
+/*
+ * This file is part of wger Workout Manager <https://github.com/wger-project>.
+ * Copyright (c) 2026 wger Team
+ *
+ * wger Workout Manager is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+import 'package:flutter/widgets.dart';
+
+/// Runs [action] on the next frame: UI side effects (dialogs, snackbars,
+/// navigation) are illegal during build, but error handlers and provider
+/// listeners can fire there. Schedules a frame so idle-time requests run too.
+void runAfterFrame(VoidCallback action) {
+  WidgetsBinding.instance.addPostFrameCallback((_) => action());
+  WidgetsBinding.instance.scheduleFrame();
+}
+
+/// Yields past the synchronous phase of a provider create or widget
+/// life-cycle callback: reading a dirty provider there flushes it mid-build
+/// and crashes. A microtask, not a timer, since widget tests assert
+/// !timersPending at teardown.
+Future<void> yieldPastBuild() => Future<void>.microtask(() {});