feat(app): the bibliography at the foot of the side bar on the desktop

As on a phone's drawer: Bibliography at the end of the topics' foot,
across from New sub-studyset, instead of a button above the content. One
rail serves both now, the drawer and the side bar.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MMm7usAo6q9ZZRoPkWjoxi
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

halkyon_learn_flutter/lib/src/feature/studyset/widget/studyset_screen.dart

@@ -244,40 +244,28 @@ class _StudysetViewState() extends State<_StudysetView> {
     final all = widget.all;
     final theme = Theme.of(context);
     final wide = context.windowSize.isAtLeastExpanded;
+    // The topics, with the bibliography at their foot across from New
+    // sub-studyset: in the side bar from expanded windows on, below them in
+    // the drawer.
     final rail = StudysetRail(
       parent: studyset,
       all: all,
       onAddMaterial: _addMaterial.open,
+      footEnd: _BibliographyButton(studyset: studyset),
     );
     final content = _Content(studysetId: studyset.id);
     final description = studyset.content.description.isBlank
         ? null
         : _Description(studyset: studyset);
     final canGoBack = context.canPop();
-    final bibliography = Align(
-      alignment: AlignmentDirectional.centerEnd,
-      child: _BibliographyButton(studyset: studyset),
-    );
     return ScrollHidingFab(
       fab: wide
           ? null
           : _StudyBar(studyset: studyset, addMaterial: _addMaterial),
       builder: (context, fab) => Scaffold(
         backgroundColor: theme.colorScheme.surfaceContainerLow,
-        // The topics' home below expanded windows, the bibliography at its
+        // The topics' home below expanded windows.
-        // foot, across from New sub-studyset.
+        drawer: wide ? null : Drawer(child: SafeArea(child: rail)),
-        drawer: wide
-            ? null
-            : Drawer(
-                child: SafeArea(
-                  child: StudysetRail(
-                    parent: studyset,
-                    all: all,
-                    onAddMaterial: _addMaterial.open,
-                    footEnd: _BibliographyButton(studyset: studyset),
-                  ),
-                ),
-              ),
         appBar: AppBar(
           // A drawer would take the back button's place; the bar at the
           // bottom opens the topics instead.
@@ -365,12 +353,6 @@ class _StudysetViewState() extends State<_StudysetView> {
                             ),
                           ),
                           const SizedBox(width: 12),
-                          Expanded(
-                            child: Column(
-                              crossAxisAlignment: CrossAxisAlignment.stretch,
-                              children: [
-                                bibliography,
-                                const SizedBox(height: 12),
                           Expanded(
                             child: SectionCard(
                               padding: EdgeInsets.zero,
@@ -379,9 +361,6 @@ class _StudysetViewState() extends State<_StudysetView> {
                           ),
                         ],
                       ),
-                          ),
-                        ],
-                      ),
                     )
                   : Padding(
                       padding: const EdgeInsets.fromLTRB(12, 4, 12, 12),
@@ -411,7 +390,7 @@ class const _RaisedCenterFloat(final double lift)
   }
 }
 
-/// The bibliography, as an outlined round button beside the content.
+/// The bibliography, as an outlined round button at the foot of the topics.
 class const _BibliographyButton({required final Studyset studyset})
     extends StatelessWidget {
   @override

halkyon_learn_flutter/test/feature/studyset/widget/studyset_screen_test.dart

@@ -19,6 +19,7 @@ import 'package:halkyon_learn_flutter/src/feature/study/widget/study_progress.da
 import 'package:halkyon_learn_flutter/src/feature/studyset/data/studyset_payload.dart';
 import 'package:halkyon_learn_flutter/src/feature/studyset/model/studyset_content.dart';
 import 'package:halkyon_learn_flutter/src/feature/studyset/widget/studyset_breadcrumb.dart';
+import 'package:halkyon_learn_flutter/src/feature/studyset/widget/studyset_rail.dart';
 import 'package:halkyon_learn_flutter/src/feature/studyset/widget/studyset_screen.dart';
 import 'package:lucide_icons_flutter/lucide_icons.dart';
 import 'package:material_ui/material_ui.dart';
@@ -382,8 +383,10 @@ void main() {
     expect(find.byTooltip('Copy'), findsNWidgets(2));
   });
 
-  testWidgets('the bibliography is a button above the content, not in the '
+  testWidgets('the bibliography is a button at the foot of the topics, not '
-      'app bar; on a phone at the foot of the topics', (tester) async {
+      'in the app bar: in the side bar, and on a phone in the drawer', (
+    tester,
+  ) async {
     stored('japanese', 'Japanese');
     await openFromLibrary(tester, 'Japanese');
     expect(
@@ -393,7 +396,13 @@ void main() {
       ),
       findsNothing,
     );
-    expect(find.byTooltip('Bibliography'), findsOneWidget);
+    expect(
+      find.descendant(
+        of: find.byType(StudysetRail),
+        matching: find.byTooltip('Bibliography'),
+      ),
+      findsOneWidget,
+    );
 
     await showApp(
       tester,
@@ -412,6 +421,27 @@ void main() {
     );
   });
 
+  testWidgets('in the side bar, the bibliography shares the foot of the '
+      'topics with New sub-studyset: that at the start, the bibliography at '
+      'the end', (tester) async {
+    stored('japanese', 'Japanese');
+    stored('kana', 'Kana', parent: 'japanese');
+    await showApp(tester, location: RoutePaths.studyset('japanese'));
+    await tester.pumpAndSettle();
+
+    final rail = tester.getRect(find.byType(StudysetRail));
+    final create = tester.getRect(
+      find.ancestor(
+        of: find.text('New sub-studyset'),
+        matching: find.byWidgetPredicate((widget) => widget is FilledButton),
+      ),
+    );
+    final bibliography = tester.getRect(find.byTooltip('Bibliography'));
+    expect(bibliography.center.dy, moreOrLessEquals(create.center.dy));
+    expect(create.left, moreOrLessEquals(rail.left + 16));
+    expect(bibliography.right, moreOrLessEquals(rail.right - 16));
+  });
+
   testWidgets('on a phone, the bibliography shares the foot of the topics '
       'with New sub-studyset: that at the start, the bibliography at the '
       'end', (tester) async {