fix(app): a sign-out or deletion that failed says so, its tile showing it under way

The account's tiles show a spinner on Sign out or Delete account while it
runs, start neither again meanwhile, and say once, in a snack bar, why one
failed ("Couldn't delete your account: the instance wasn't reached. Try
again."; "Couldn't sign out on this device. Try again."), in English and
German. The session gate no longer builds the person's app anew for that:
only the tiles follow it.

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/test/auth/widget/account_tiles_test.dart

@@ -1,7 +1,10 @@
+import 'dart:async';
+
 import 'package:clock/clock.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:halkyon_app/halkyon_app.dart';
 import 'package:halkyon_app/testing.dart';
+import 'package:halkyon_ui/halkyon_ui.dart';
 import 'package:material_ui/material_ui.dart';
 
 /// A signed-in person's app as a test makes one: whose it is, and the
@@ -344,6 +347,75 @@ void main() {
     expect(find.text('Signed out'), findsOneWidget);
   });
 
+  testWidgets('while the account is deleted, the person stays in their app, '
+      'Delete account showing it is under way', (tester) async {
+    await start(tester);
+    gateway.deletionWaits = Completer();
+
+    await tester.tap(find.text('Delete account'));
+    await tester.pumpAndSettle();
+    await tester.tap(find.text('Delete account').last);
+    // The spinner never settles while it runs.
+    await tester.pump();
+    await tester.pump(const Duration(milliseconds: 100));
+
+    expect(
+      find.text('App of anonymous-1'),
+      findsOneWidget,
+      reason: 'never the launch screen in between',
+    );
+    expect(
+      find.descendant(
+        of: find.widgetWithText(ListTile, 'Delete account'),
+        matching: find.byType(ButtonLoadingIndicator),
+      ),
+      findsOneWidget,
+    );
+
+    gateway.deletionWaits!.complete();
+    await tester.pumpAndSettle();
+    expect(find.text('Signed out'), findsOneWidget);
+  });
+
+  testWidgets('a deletion the instance never got keeps the person in their '
+      'app, and says so once', (tester) async {
+    await start(tester);
+    gateway.deletionError = Exception('No connection');
+
+    await tester.tap(find.text('Delete account'));
+    await tester.pumpAndSettle();
+    await tester.tap(find.text('Delete account').last);
+    await tester.pumpAndSettle();
+
+    expect(
+      find.text(
+        "Couldn't delete your account: the instance wasn't reached. "
+        'Try again.',
+      ),
+      findsOneWidget,
+    );
+    expect(find.text('App of anonymous-1'), findsOneWidget);
+    expect(gateway.status, isA<SignedIn>());
+    expect(find.byType(ButtonLoadingIndicator), findsNothing);
+  });
+
+  testWidgets("a sign-out the device's storage failed keeps the person in "
+      'their app, and says so', (tester) async {
+    gateway = FakeAuthGateway(
+      status: const SignedIn(authUserId: 'github-1', isIdentified: true),
+    )..signOutError = Exception('The keyring is locked');
+    await start(tester);
+
+    await tester.tap(find.text('Sign out'));
+    await tester.pumpAndSettle();
+
+    expect(
+      find.text("Couldn't sign out on this device. Try again."),
+      findsOneWidget,
+    );
+    expect(find.text('App of github-1'), findsOneWidget);
+  });
+
   testWidgets('speaks German', (tester) async {
     await start(tester);
     final german = lookupHalkyonAppLocalizations(const Locale('de'));
@@ -358,5 +430,14 @@ void main() {
     expect(german.accountSignOutTitle, 'Abmelden?');
     expect(german.accountDelete, 'Konto löschen');
     expect(german.accountDeleteTitle, 'Dein Konto löschen?');
+    expect(
+      german.accountSignOutFailed,
+      'Abmelden auf diesem Gerät hat nicht geklappt. Versuch es noch einmal.',
+    );
+    expect(
+      german.accountDeleteFailed,
+      'Dein Konto wurde nicht gelöscht: Die Instanz war nicht erreichbar. '
+      'Versuch es noch einmal.',
+    );
   });
 }

packages/halkyon_app/test/auth/widget/session_gate_test.dart

@@ -225,4 +225,36 @@ void main() {
     await tester.pumpAndSettle();
     expect(find.text('Signed out'), findsOneWidget);
   });
+
+  testWidgets("a sign-out under way or failed leaves the person's app as it "
+      'is, built once', (tester) async {
+    gateway = FakeAuthGateway(
+      status: const SignedIn(authUserId: 'ada', isIdentified: true),
+    )..signOutError = Exception('The keyring is locked');
+    dependencies = TestAppDependencies(gateway: gateway);
+    var builds = 0;
+    await tester.pumpWidget(
+      AppFrameScope(
+        frame: testFrame(),
+        child: AppScope(
+          dependencies: dependencies,
+          child: SessionGate(
+            look: (context) => (themeMode: ThemeMode.light, locale: null),
+            app: (person) {
+              builds++;
+              return _PersonApp(person);
+            },
+          ),
+        ),
+      ),
+    );
+    await tester.pumpAndSettle();
+    expect(builds, 1);
+
+    await tester.tap(find.text('Sign out'));
+    await tester.pumpAndSettle();
+
+    expect(find.text('App of ada'), findsOneWidget);
+    expect(builds, 1, reason: "busy and its problem are the account tiles'");
+  });
 }