better loading indicators for timetables, talk and files

lib/state/app/infrastructure/loadableState/view/loadable_state_consumer.dart

@@ -17,7 +17,21 @@ class LoadableStateConsumer<TController extends Bloc<LoadableHydratedBlocEvent<T
   final Widget Function(TState state, bool loading) child;
   final void Function(TState state)? onLoad;
   final bool wrapWithScrollView;
-  const LoadableStateConsumer({required this.child, this.onLoad, this.wrapWithScrollView = false, super.key});
+
+  /// Optional predicate for callers whose [TState] always contains a non-null
+  /// envelope but where actual content (e.g. a nested response) is loaded
+  /// lazily. When provided, this overrides the default `data != null` check
+  /// so primary loading / error screens / content visibility correctly reflect
+  /// whether the inner content is ready.
+  final bool Function(TState state)? isReady;
+
+  const LoadableStateConsumer({
+    required this.child,
+    this.onLoad,
+    this.wrapWithScrollView = false,
+    this.isReady,
+    super.key,
+  });
 
   static Duration animationDuration = const Duration(milliseconds: 200);
 
@@ -30,6 +44,16 @@ class LoadableStateConsumer<TController extends Bloc<LoadableHydratedBlocEvent<T
       WidgetsBinding.instance.addPostFrameCallback((timeStamp) => onLoad!(loadedData));
     }
 
+    final typedData = loadedData is TState ? loadedData : null;
+    final hasContent = typedData != null && (isReady?.call(typedData) ?? loadableState.showContent());
+    final hasError = loadableState.error != null;
+    final isLoading = loadableState.isLoading;
+
+    final showPrimaryLoading = isLoading && !hasContent;
+    final showBackgroundLoading = isLoading && hasContent;
+    final showError = hasError && !hasContent;
+    final showErrorBar = hasError && hasContent;
+
     var childWidget = ConditionalWrapper(
       condition: loadableState.reFetch != null,
       wrapper: (child) => RefreshIndicator(
@@ -48,8 +72,8 @@ class LoadableStateConsumer<TController extends Bloc<LoadableHydratedBlocEvent<T
       ),
       child: SizedBox(
         height: MediaQuery.of(context).size.height,
-        child: loadableState.showContent() && loadedData is TState
-          ? child(loadedData, loadableState.isLoading)
+        child: hasContent
+          ? child(typedData as TState, isLoading)
           : const SizedBox.shrink(),
       ),
     );
@@ -60,16 +84,21 @@ class LoadableStateConsumer<TController extends Bloc<LoadableHydratedBlocEvent<T
         bloc.reFetch = loadableState.reFetch;
         return Column(
           children: [
-            LoadableStateErrorBar(visible: loadableState.showErrorBar(), message: loadableState.error?.message, lastUpdated: loadableState.lastFetch),
+            LoadableStateErrorBar(
+              visible: showErrorBar,
+              hasContent: hasContent,
+              message: loadableState.error?.message,
+              lastUpdated: loadableState.lastFetch,
+            ),
             Expanded(
               child: Stack(
                 children: [
-                  LoadableStatePrimaryLoading(visible: loadableState.showPrimaryLoading()),
-                  LoadableStateBackgroundLoading(visible: loadableState.showBackgroundLoading()),
-                  LoadableStateErrorScreen(visible: loadableState.showError(), message: loadableState.error?.message),
+                  LoadableStatePrimaryLoading(visible: showPrimaryLoading),
+                  LoadableStateBackgroundLoading(visible: showBackgroundLoading),
+                  LoadableStateErrorScreen(visible: showError, message: loadableState.error?.message),
 
                   AnimatedOpacity(
-                    opacity: loadableState.showContent() ? 1.0 : 0.0,
+                    opacity: hasContent ? 1.0 : 0.0,
                     duration: animationDuration,
                     curve: Curves.easeInOut,
                     child: childWidget,

lib/state/app/infrastructure/loadableState/view/loadable_state_error_bar.dart

@@ -8,49 +8,62 @@ import '../bloc/loadable_state_bloc.dart';
 
 class LoadableStateErrorBar extends StatelessWidget {
   final bool visible;
+  final bool hasContent;
   final String? message;
   final int? lastUpdated;
-  const LoadableStateErrorBar({required this.visible, this.message, this.lastUpdated, super.key});
+  const LoadableStateErrorBar({
+    required this.visible,
+    this.hasContent = false,
+    this.message,
+    this.lastUpdated,
+    super.key,
+  });
 
   final Duration animationDuration = const Duration(milliseconds: 200);
 
   @override
-  Widget build(BuildContext context) => AnimatedSize(
-    duration: animationDuration,
-    child: AnimatedSwitcher(
-        duration: animationDuration,
-        transitionBuilder: (Widget child, Animation<double> animation) => SlideTransition(
-          position: Tween<Offset>(
-            begin: const Offset(0.0, -1.0),
-            end: Offset.zero,
-          ).animate(animation),
-          child: child,
-        ),
-        child: Visibility(
-            key: Key(visible.hashCode.toString()),
-            visible: visible,
-            replacement: const SizedBox(width: double.infinity),
-            child: Builder(
-              builder: (context) {
-                var bloc = context.watch<LoadableStateBloc>();
-                return InkWell(
-                  onTap: () {
-                    if(!bloc.isConnected()) return;
-                    InfoDialog.show(context, 'Exception: ${message.toString()}');
-                  },
-                  child: Container(
-                    height: 20,
-                    decoration: BoxDecoration(
-                      color: bloc.connectionColor(context),
+  Widget build(BuildContext context) {
+    final bloc = context.watch<LoadableStateBloc>();
+    final isOfflineWithCache = hasContent && bloc.connectivityStatusKnown() && !bloc.isConnected();
+    final shouldShow = visible || isOfflineWithCache;
+
+    return AnimatedSize(
+      duration: animationDuration,
+      child: AnimatedSwitcher(
+          duration: animationDuration,
+          transitionBuilder: (Widget child, Animation<double> animation) => SlideTransition(
+            position: Tween<Offset>(
+              begin: const Offset(0.0, -1.0),
+              end: Offset.zero,
+            ).animate(animation),
+            child: child,
+          ),
+          child: Visibility(
+              key: Key(shouldShow.hashCode.toString()),
+              visible: shouldShow,
+              replacement: const SizedBox(width: double.infinity),
+              child: Builder(
+                builder: (context) {
+                  var bloc = context.watch<LoadableStateBloc>();
+                  return InkWell(
+                    onTap: () {
+                      if(!bloc.isConnected()) return;
+                      InfoDialog.show(context, 'Exception: ${message.toString()}');
+                    },
+                    child: Container(
+                      height: 20,
+                      decoration: BoxDecoration(
+                        color: bloc.connectionColor(context),
+                      ),
+                      child: LoadableStateErrorBarText(lastUpdated: lastUpdated),
                     ),
-                    child: LoadableStateErrorBarText(lastUpdated: lastUpdated),
-                  ),
-                );
-              },
-            )
-        )
-    ),
-  );
+                  );
+                },
+              )
+          )
+      ),
+    );
+  }
 }
 
 class LoadableStateErrorBarText extends StatefulWidget {