fix: LeafViewerHero gates heroes to the settled page (keep-alive neighbours flew too); video controls bar bottom-anchored with natural height (was stretched full-screen, blocking gestures)

lib/src/video/leaf_video_controls.dart

@@ -109,17 +109,24 @@ class _LeafVideoControlsState extends State<LeafVideoControls> {
               onDoubleTap: _handleDoubleTap,
             ),
           ),
-          // Bottom bar — fades with the viewer's chrome state.
+          // Bottom bar — fades with the viewer's chrome state. Bottom-anchored
+          // with its natural height: inside a StackFit.expand stack a bare
+          // child stretches full-screen and eats every gesture meant for the
+          // tap detector above it.
           if (chrome != null)
             ValueListenableBuilder<bool>(
               valueListenable: chrome.visibleListenable,
               builder: (context, visible, _) => IgnorePointer(
                 ignoring: !visible,
-                child: AnimatedOpacity(duration: const Duration(milliseconds: 200), opacity: visible ? 1.0 : 0.0, child: _buildBar(context)),
+                child: AnimatedOpacity(
+                  duration: const Duration(milliseconds: 200),
+                  opacity: visible ? 1.0 : 0.0,
+                  child: Align(alignment: Alignment.bottomCenter, child: SafeArea(child: _buildBar(context))),
+                ),
               ),
             )
           else
-            _buildBar(context),
+            Align(alignment: Alignment.bottomCenter, child: SafeArea(child: _buildBar(context))),
           // Center play badge while paused.
           Center(
             child: IgnorePointer(
@@ -175,6 +182,7 @@ class _LeafVideoControlsState extends State<LeafVideoControls> {
       ),
       padding: const EdgeInsets.all(10),
       child: Column(
+        mainAxisSize: MainAxisSize.min,
         children: [
           const SizedBox(height: 50),
           Row(

lib/src/viewer/leaf_viewer.dart

@@ -94,6 +94,11 @@ class LeafViewer extends StatefulWidget {
     return LeafViewerScope.maybeOf(context)?.registry.activeController;
   }
 
+  /// The index of the page this context belongs to, if inside a viewer.
+  static int? pageIndexOf(BuildContext context) {
+    return LeafPageIndexScope.maybeOf(context);
+  }
+
   /// Reactive index of the currently settled page, if inside a viewer.
   static ValueListenable<int>? currentIndexListOf(BuildContext context) {
     return LeafViewerScope.maybeOf(context)?.currentIndex;
@@ -393,6 +398,33 @@ class _LeafViewerState extends State<LeafViewer> with TickerProviderStateMixin i
   }
 }
 
+/// A [Hero] that only participates on the viewer's currently active page.
+///
+/// LeafViewer keeps neighbour pages alive, so an unconditional hero on every
+/// page registers several per route — popping the viewer then flies the
+/// active page AND its neighbours back to the grid. This gates the hero on
+/// "this page is the settled one", so exactly one flight happens. The child
+/// instance is passed through untouched, so providers stay stable across
+/// page changes. Outside a viewer it behaves like a plain [Hero].
+class LeafViewerHero extends StatelessWidget {
+  const LeafViewerHero({super.key, required this.tag, required this.child});
+
+  final Object tag;
+  final Widget child;
+
+  @override
+  Widget build(BuildContext context) {
+    final index = LeafViewer.pageIndexOf(context);
+    final currentIndex = LeafViewer.currentIndexListOf(context);
+    if (index == null || currentIndex == null) return Hero(tag: tag, child: child);
+    return ValueListenableBuilder<int>(
+      valueListenable: currentIndex,
+      child: child,
+      builder: (context, current, child) => current == index ? Hero(tag: tag, child: child!) : child!,
+    );
+  }
+}
+
 class _LeafViewerDefaultControls extends StatelessWidget {
   const _LeafViewerDefaultControls({required this.controls, this.showPageCounter = true});
 

test/viewer/leaf_chrome_test.dart

@@ -141,6 +141,42 @@ void main() {
       debugDefaultTargetPlatformOverride = null;
     });
   });
+
+  group('LeafViewerHero', () {
+    testWidgets('only the settled page registers a hero', (tester) async {
+      final controller = PageController();
+      addTearDown(controller.dispose);
+      await tester.pumpWidget(MaterialApp(
+        home: Scaffold(
+          body: LeafViewer(
+            pageCount: 3,
+            pageController: controller,
+            pageBuilder: (context, i) =>
+                LeafViewerHero(tag: 'post_$i', child: SizedBox.expand(key: ValueKey('page-$i'))),
+          ),
+        ),
+      ));
+      await tester.pumpAndSettle();
+      // Neighbours are alive but must not carry heroes.
+      expect(find.byType(Hero), findsOneWidget);
+      expect(find.byKey(const ValueKey('page-0')), findsOneWidget);
+
+      controller.jumpToPage(1);
+      await tester.pumpAndSettle();
+      expect(find.byType(Hero), findsOneWidget);
+      expect(tester.widget<Hero>(find.byType(Hero)).tag, 'post_1');
+    });
+
+    testWidgets('behaves like a plain hero outside a viewer', (tester) async {
+      await tester.pumpWidget(MaterialApp(
+        home: Scaffold(
+          body: LeafViewerHero(tag: 'x', child: const SizedBox.expand()),
+        ),
+      ));
+      await tester.pumpAndSettle();
+      expect(find.byType(Hero), findsOneWidget);
+    });
+  });
 }
 
 String chromeState(BuildContext context) {