fix(app): a recovery phrase's and codes' files name the instance

Saved from several apps or instances, they differed by " (1)" alone. They
name the instance now, without the app's word, as an operator's apps share
one account: halkyon.eu-recovery-phrase.txt, localhost-8280-recovery-codes.txt.

Whats-New: A saved recovery phrase or recovery codes file now names its instance.
Whats-New-De: Gespeicherte Wiederherstellungsphrasen und -codes nennen jetzt ihre Instanz im Dateinamen.

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

packages/halkyon_app/lib/src/password/widget/password_widgets.dart

@@ -3,6 +3,7 @@ import 'dart:io';
 
 import 'package:flutter/services.dart';
 import 'package:halkyon_app/l10n/halkyon_app_localizations.dart';
+import 'package:halkyon_app/src/app/app_frame.dart';
 import 'package:halkyon_app/src/app/app_scope.dart';
 import 'package:halkyon_app/src/password/model/account_authenticator.dart';
 import 'package:halkyon_app/src/password/model/phrase_check.dart';
@@ -328,26 +329,46 @@ class const SheetProblem(final String text, {super.key})
   }
 }
 
-/// Save for [text], kept as [fileName]. Nothing secret is copied (the
-/// reading of the fixes): no app can mark a copy as sensitive through
+/// How the file of a secret names the instance called [name] (its host, with
+/// the port if it has one), for the app called [product]: without the app's
+/// word, as an operator's apps share one account (`learn.halkyon.eu`,
+/// `todo.halkyon.eu`: `halkyon.eu`), and safe in a file's name
+/// (`localhost:8280`: `localhost-8280`).
+String instanceFileLabel(String name, {required String product}) {
+  final host = name.toLowerCase();
+  final prefix = '${product.toLowerCase()}.';
+  return (host.startsWith(prefix) ? host.substring(prefix.length) : host)
+      .replaceAll(RegExp('[^a-z0-9.-]+'), '-');
+}
+
+/// Save for [text], in a file named after the instance and [fileKind].
+/// Nothing secret is copied (the reading of the fixes): no app can mark a copy as sensitive through
 /// Flutter, so clipboard histories (Windows, KDE, Gboard, Samsung's) and
 /// cloud clipboards would keep it, and on Android an app in the background
 /// can't empty the clipboard again.
 class const KeepTextButtons({
   required final String text,
-  required final String fileName,
+
+  /// What the file holds; its name adds the instance's, whose account it
+  /// belongs to whichever app showed it (`halkyon.eu-recovery-phrase.txt`).
+  required final String fileKind,
   super.key,
 }) extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     final l10n = HalkyonAppLocalizations.of(context);
+    final dependencies = AppScope.of(context);
+    final instance = instanceFileLabel(
+      dependencies.serverName,
+      product: AppFrameScope.of(context).product(context),
+    );
     return Align(
       alignment: AlignmentDirectional.centerStart,
       child: OutlinedButton.icon(
         icon: const Icon(LucideIcons.download),
         label: Text(l10n.passwordSave),
-        onPressed: () => AppScope.of(context).fileSaver.save(
-          name: fileName,
+        onPressed: () => dependencies.fileSaver.save(
+          name: '$instance-$fileKind.txt',
           bytes: utf8.encode('$text\n'),
           mimeType: 'text/plain',
         ),
@@ -426,7 +447,7 @@ class const RecoveryPhraseView({required final String phrase, super.key})
           // Saved or written down, never copied ([KeepTextButtons]).
           KeepTextButtons(
             text: phrase,
-            fileName: 'halkyon-recovery-phrase.txt',
+            fileKind: 'recovery-phrase',
           ),
         ],
       ),
@@ -683,7 +704,7 @@ class const RecoveryCodesView({required final List<String> codes, super.key})
           const SizedBox(height: 12),
           KeepTextButtons(
             text: codes.join('\n'),
-            fileName: 'halkyon-recovery-codes.txt',
+            fileKind: 'recovery-codes',
           ),
         ],
       ),

packages/halkyon_app/test/password/widget/secret_copies_test.dart

@@ -32,17 +32,23 @@ void main() {
     );
   }
 
+  late TestAppDependencies dependencies;
+
   Future<void> pumpView(WidgetTester tester, Widget view) async {
     tester.view.physicalSize = const Size(412, 1400);
     tester.view.devicePixelRatio = 1;
     addTearDown(tester.view.reset);
+    dependencies = TestAppDependencies(gateway: FakeAuthGateway());
     await tester.pumpWidget(
-      AppScope(
-        dependencies: TestAppDependencies(gateway: FakeAuthGateway()),
-        child: MaterialApp(
-          localizationsDelegates: testLocalizationsDelegates,
-          supportedLocales: HalkyonAppLocalizations.supportedLocales,
-          home: Scaffold(body: SingleChildScrollView(child: view)),
+      AppFrameScope(
+        frame: testFrame(),
+        child: AppScope(
+          dependencies: dependencies,
+          child: MaterialApp(
+            localizationsDelegates: testLocalizationsDelegates,
+            supportedLocales: HalkyonAppLocalizations.supportedLocales,
+            home: Scaffold(body: SingleChildScrollView(child: view)),
+          ),
         ),
       ),
     );
@@ -83,6 +89,36 @@ void main() {
     expect(clipboard, isNull);
   });
 
+  test("a secret's file names the instance, without the app's word, whose "
+      'account it belongs to whichever app showed it (5 Nov 2026)', () {
+    const label = instanceFileLabel;
+    expect(label('learn.halkyon.eu', product: 'Learn'), 'halkyon.eu');
+    expect(label('todo.halkyon.eu', product: 'Todo'), 'halkyon.eu');
+    expect(label('notes.example.org', product: 'Learn'), 'notes.example.org');
+    expect(label('learn.example.org', product: 'Todo'), 'learn.example.org');
+    expect(label('localhost:8280', product: 'Meditate'), 'localhost-8280');
+  });
+
+  testWidgets("a saved phrase's file names the instance", (tester) async {
+    await pumpView(tester, const RecoveryPhraseView(phrase: 'one two'));
+    await tester.tap(find.text('Save as a file'));
+    await tester.pump();
+    expect(dependencies.fileSaver.saved.map((file) => file.name), [
+      'example.org-recovery-phrase.txt',
+    ]);
+  });
+
+  testWidgets("saved recovery codes' file names the instance too", (
+    tester,
+  ) async {
+    await pumpView(tester, const RecoveryCodesView(codes: ['AAAA-BBBB']));
+    await tester.tap(find.text('Save as a file'));
+    await tester.pump();
+    expect(dependencies.fileSaver.saved.map((file) => file.name), [
+      'example.org-recovery-codes.txt',
+    ]);
+  });
+
   group("an authenticator's key, for a device without a camera, is copied "
       'and emptied again a minute later; never selectable (decided 3 Nov '
       '2026)', () {

packages/halkyon_app/test/password/widget/secret_screen_test.dart

@@ -111,13 +111,9 @@ void main() {
       ),
     ]) {
       await tester.pumpWidget(
-        AppScope(
+        testApp(
+          Scaffold(body: SingleChildScrollView(child: view)),
           dependencies: TestAppDependencies(gateway: FakeAuthGateway()),
-          child: MaterialApp(
-            localizationsDelegates: testLocalizationsDelegates,
-            supportedLocales: HalkyonAppLocalizations.supportedLocales,
-            home: Scaffold(body: SingleChildScrollView(child: view)),
-          ),
         ),
       );
       expect(find.byType(SecretScreen), findsOneWidget, reason: '$view');