added feature to configure contextual tab bar buttons

app/lib/features/user/data/database/daos/toolbar_button_config.dart

@@ -0,0 +1,134 @@
+/*
+ * Copyright (c) 2024-2026 Fabian Freund.
+ *
+ * This file is part of WebLibre
+ * (see https://weblibre.eu).
+ *
+ * This program 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:drift/drift.dart';
+import 'package:weblibre/features/user/data/database/daos/toolbar_button_config.drift.dart';
+import 'package:weblibre/features/user/data/database/database.dart';
+import 'package:weblibre/features/user/data/database/definitions.drift.dart';
+
+@DriftAccessor()
+class ToolbarButtonConfigDao extends DatabaseAccessor<UserDatabase>
+    with $ToolbarButtonConfigDaoMixin {
+  ToolbarButtonConfigDao(super.attachedDatabase);
+
+  Selectable<ToolbarButtonConfig> selectAll() =>
+      db.toolbarButtonConfigs.select()
+        ..orderBy([(t) => OrderingTerm.asc(t.orderKey)]);
+
+  Stream<List<ToolbarButtonConfig>> watchAll() => selectAll().watch();
+
+  Future<List<ToolbarButtonConfig>> getAll() => selectAll().get();
+
+  Future<void> upsert(ToolbarButtonConfig config) =>
+      into(db.toolbarButtonConfigs).insertOnConflictUpdate(config);
+
+  Future<void> assignOrderKey(String buttonId, {required String orderKey}) =>
+      (update(db.toolbarButtonConfigs)
+            ..where((t) => t.buttonId.equals(buttonId)))
+          .write(ToolbarButtonConfigsCompanion(orderKey: Value(orderKey)));
+
+  Future<void> assignVisibility(String buttonId, {required bool visible}) =>
+      (update(db.toolbarButtonConfigs)
+            ..where((t) => t.buttonId.equals(buttonId)))
+          .write(ToolbarButtonConfigsCompanion(isVisible: Value(visible)));
+
+  Future<void> assignFallback(String buttonId, String? fallbackId) =>
+      (update(db.toolbarButtonConfigs)
+            ..where((t) => t.buttonId.equals(buttonId)))
+          .write(ToolbarButtonConfigsCompanion(fallbackId: Value(fallbackId)));
+
+  Future<void> replaceAll(List<ToolbarButtonConfig> configs) =>
+      transaction(() async {
+        await delete(db.toolbarButtonConfigs).go();
+        await _insertWithDeferredFallbacks(configs);
+      });
+
+  Future<void> seedMissing(
+    List<({String buttonId, bool defaultVisible, String? defaultFallback})>
+    defaults,
+  ) async {
+    final existing = await getAll();
+    final existingIds = {for (final r in existing) r.buttonId};
+
+    final missing = defaults
+        .where((d) => !existingIds.contains(d.buttonId))
+        .toList();
+    if (missing.isEmpty) return;
+
+    await transaction(() async {
+      final inserted = <ToolbarButtonConfig>[];
+      for (final def in missing) {
+        final orderKey = await generateTrailingOrderKey().getSingle();
+        inserted.add(
+          ToolbarButtonConfig(
+            buttonId: def.buttonId,
+            orderKey: orderKey,
+            isVisible: def.defaultVisible,
+            fallbackId: def.defaultFallback,
+          ),
+        );
+        await into(db.toolbarButtonConfigs).insert(
+          ToolbarButtonConfig(
+            buttonId: def.buttonId,
+            orderKey: orderKey,
+            isVisible: def.defaultVisible,
+          ),
+        );
+      }
+
+      await _assignFallbacks(inserted);
+    });
+  }
+
+  SingleSelectable<String> generateLeadingOrderKey({int bucket = 0}) =>
+      db.definitionsDrift.toolbarLeadingOrderKey(bucket: bucket);
+
+  SingleSelectable<String> generateTrailingOrderKey({int bucket = 0}) =>
+      db.definitionsDrift.toolbarTrailingOrderKey(bucket: bucket);
+
+  SingleOrNullSelectable<String> generateOrderKeyAfterButtonId(
+    String buttonId,
+  ) => db.definitionsDrift.toolbarOrderKeyAfterButton(buttonId: buttonId);
+
+  SingleSelectable<String> generateOrderKeyBeforeButtonId(String buttonId) =>
+      db.definitionsDrift.toolbarOrderKeyBeforeButton(buttonId: buttonId);
+
+  Future<void> _insertWithDeferredFallbacks(
+    List<ToolbarButtonConfig> configs,
+  ) async {
+    for (final config in configs) {
+      await into(db.toolbarButtonConfigs).insert(
+        ToolbarButtonConfig(
+          buttonId: config.buttonId,
+          orderKey: config.orderKey,
+          isVisible: config.isVisible,
+        ),
+      );
+    }
+
+    await _assignFallbacks(configs);
+  }
+
+  Future<void> _assignFallbacks(List<ToolbarButtonConfig> configs) async {
+    for (final config in configs) {
+      if (config.fallbackId == null) continue;
+      await assignFallback(config.buttonId, config.fallbackId);
+    }
+  }
+}

app/lib/features/user/data/database/daos/toolbar_button_config.drift.dart

@@ -0,0 +1,14 @@
+// dart format width=80
+// ignore_for_file: type=lint
+import 'package:drift/drift.dart' as i0;
+import 'package:weblibre/features/user/data/database/database.dart' as i1;
+
+mixin $ToolbarButtonConfigDaoMixin on i0.DatabaseAccessor<i1.UserDatabase> {
+  ToolbarButtonConfigDaoManager get managers =>
+      ToolbarButtonConfigDaoManager(this);
+}
+
+class ToolbarButtonConfigDaoManager {
+  final $ToolbarButtonConfigDaoMixin _db;
+  ToolbarButtonConfigDaoManager(this._db);
+}