fix(ui): refine app update dialog layout and scrolling (#1503)

ui/flutter/lib/features/settings/presentation/widgets/app_update_dialog.dart

@@ -10,6 +10,7 @@ import '../../../../util/package_info.dart';
 import '../../../../util/updater.dart';
 import '../../../../util/util.dart';
 import '../../../../l10n/l10n.dart';
+import 'app_update_notes_viewport.dart';
 
 typedef StartAppUpdate = Future<void> Function(VersionInfo versionInfo, UpdateProgressCallback onProgress);
 
@@ -74,11 +75,18 @@ Future<void> showAppUpdateDialog(
                     key: const ValueKey('app-update-heading'),
                     textAlign: TextAlign.center,
                   ),
-                  const SizedBox(height: 3),
+                  const SizedBox(height: 8),
                   Text(
                     '$appVersion  →  ${versionInfo.version}',
                     textAlign: TextAlign.center,
-                    style: TextStyle(color: palette.textSecondary, fontSize: 12, fontWeight: FontWeight.w400),
+                    style: DefaultTextStyle.of(dialogContext).style.copyWith(
+                      inherit: false,
+                      color: palette.textSecondary,
+                      fontSize: 12,
+                      fontWeight: FontWeight.w400,
+                      height: 1.4,
+                      decoration: TextDecoration.none,
+                    ),
                   ),
                 ],
               ),
@@ -90,18 +98,9 @@ Future<void> showAppUpdateDialog(
                 mainAxisSize: MainAxisSize.min,
                 crossAxisAlignment: CrossAxisAlignment.stretch,
                 children: [
-                  Text(
-                    dialogContext.l10n.releaseNotes,
-                    style: TextStyle(color: palette.textPrimary, fontSize: 12, fontWeight: FontWeight.w700),
-                  ),
-                  const SizedBox(height: 10),
-                  ConstrainedBox(
-                    constraints: const BoxConstraints(maxHeight: 210),
-                    child: SingleChildScrollView(
-                      padding: const EdgeInsets.symmetric(horizontal: 4),
-                      child: _ReleaseNotes(
-                        notes: releaseNotes.isEmpty ? dialogContext.l10n.noReleaseNotes : releaseNotes,
-                      ),
+                  AppUpdateNotesViewport(
+                    child: _ReleaseNotes(
+                      notes: releaseNotes.isEmpty ? dialogContext.l10n.noReleaseNotes : releaseNotes,
                     ),
                   ),
                   if (updating) ...[
@@ -157,7 +156,6 @@ Future<void> showAppUpdateDialog(
                         onPressed: () => unawaited(update()),
                         loading: updating,
                         variant: AppLoadingButtonVariant.primary,
-                        icon: const Icon(Icons.system_update_alt_outlined, size: 17),
                         child: Text(dialogContext.l10n.newVersionUpdate),
                       ),
                     ],

ui/flutter/lib/features/settings/presentation/widgets/app_update_notes_viewport.dart

@@ -0,0 +1,59 @@
+import 'package:flutter/widgets.dart';
+import 'package:shadcn_flutter/shadcn_flutter.dart' as shad;
+
+import '../../../../shared/theme/app_design_tokens.dart';
+
+class AppUpdateNotesViewport extends StatefulWidget {
+  const AppUpdateNotesViewport({super.key, required this.child});
+
+  final Widget child;
+
+  @override
+  State<AppUpdateNotesViewport> createState() => _AppUpdateNotesViewportState();
+}
+
+class _AppUpdateNotesViewportState extends State<AppUpdateNotesViewport> {
+  final _controller = ScrollController();
+
+  @override
+  void dispose() {
+    _controller.dispose();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    const fadeHeight = AppDesignTokens.space24;
+    return ConstrainedBox(
+      constraints: const BoxConstraints(maxHeight: 240),
+      child: shad.Scrollbar(
+        controller: _controller,
+        thumbVisibility: true,
+        child: ShaderMask(
+          blendMode: BlendMode.dstIn,
+          shaderCallback: (bounds) => LinearGradient(
+            begin: Alignment.topCenter,
+            end: Alignment.bottomCenter,
+            // Mask colors control opacity only; they do not tint the content.
+            colors: const [shad.Colors.white, shad.Colors.white, shad.Colors.transparent],
+            stops: [0, (1 - fadeHeight / bounds.height).clamp(0.0, 1.0), 1],
+          ).createShader(bounds),
+          child: ScrollConfiguration(
+            behavior: ScrollConfiguration.of(context).copyWith(scrollbars: false),
+            child: SingleChildScrollView(
+              controller: _controller,
+              padding: const EdgeInsetsDirectional.fromSTEB(
+                AppDesignTokens.space4,
+                0,
+                AppDesignTokens.space16,
+                // Keep the final line above the fade at the end of the scroll.
+                fadeHeight,
+              ),
+              child: widget.child,
+            ),
+          ),
+        ),
+      ),
+    );
+  }
+}

ui/flutter/test/updater_test.dart

@@ -1,7 +1,9 @@
+import 'package:flutter/material.dart' show Icons;
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:gopeed/api/model/downloader_config.dart';
 import 'package:gopeed/features/settings/presentation/widgets/app_update_dialog.dart';
+import 'package:gopeed/features/settings/presentation/widgets/app_update_notes_viewport.dart';
 import 'package:gopeed/shared/theme/app_theme.dart';
 import 'package:gopeed/util/arch/arch.dart';
 import 'package:gopeed/util/github_mirror.dart';
@@ -193,10 +195,47 @@ void main() {
     expect(find.text('下载更快'), findsNothing);
     expect(find.text('Later'), findsOneWidget);
     expect(find.text('Update Now'), findsOneWidget);
+    expect(find.text("What's New"), findsNothing);
+    final versionText = tester.widget<Text>(find.text('2.0.0-beta.1  →  2.0.0-beta.2'));
+    expect(versionText.style?.decoration, TextDecoration.none);
+    expect(versionText.style?.inherit, isFalse);
+    expect(find.byIcon(Icons.system_update_alt_outlined), findsNothing);
     final dialog = tester.getRect(find.byKey(const ValueKey('app-update-dialog')));
     expect(dialog.width, lessThan(320));
     expect(tester.getCenter(find.byKey(const ValueKey('app-update-heading'))).dx, closeTo(dialog.center.dx, 0.01));
     expect(tester.getCenter(find.byKey(const ValueKey('app-update-actions'))).dx, closeTo(dialog.center.dx, 0.01));
     expect(tester.takeException(), isNull);
   });
+
+  testWidgets('release notes keep the last line above the fade when scrolled to the end', (tester) async {
+    await tester.pumpWidget(
+      shad.ShadcnApp(
+        theme: AppTheme.dark(),
+        materialTheme: AppTheme.materialDark(),
+        home: Center(
+          child: SizedBox(
+            width: 280,
+            child: AppUpdateNotesViewport(
+              child: Column(children: [for (var i = 0; i < 30; i++) Text('Release note $i')]),
+            ),
+          ),
+        ),
+      ),
+    );
+    await tester.pumpAndSettle();
+    final scrollbar = tester.widget<shad.Scrollbar>(find.byType(shad.Scrollbar));
+    expect(scrollbar.thumbVisibility, isTrue);
+    final controller = scrollbar.controller!;
+    expect(controller.position.maxScrollExtent, greaterThan(0));
+    controller.jumpTo(controller.position.maxScrollExtent);
+    await tester.pumpAndSettle();
+    final viewport = tester.getRect(find.byType(AppUpdateNotesViewport));
+    final lastLine = tester.getRect(find.text('Release note 29'));
+    expect(lastLine.bottom, lessThanOrEqualTo(viewport.bottom - 24));
+    expect(lastLine.top, greaterThan(viewport.top));
+    expect(tester.takeException(), isNull);
+    await tester.pumpWidget(const SizedBox.shrink());
+    await tester.pumpAndSettle();
+    expect(tester.takeException(), isNull);
+  });
 }