feat(app): an authenticator's key copied, marked sensitive, and its code six digits

A phone without a camera whose authenticator doesn't open otpauth: had no
way but typing the key. It is copied again, the key alone (ADR 0017
amended, the developer's decision of 3 Nov 2026): on Android through each
app's SensitiveClipboard.kt, marked EXTRA_IS_SENSITIVE, so Gboard and the
system show no preview and keep it out of their histories; elsewhere through
Flutter's clipboard. Emptied 60 seconds later if the clipboard still holds
it. The recovery phrase and codes stay never copied.

The code's field counted "/7", taking an optional space for a seventh
character: it now takes six digits alone, a pasted space dropped, and counts
nothing.

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/password/widget/secret_copies_test.dart

@@ -51,7 +51,8 @@ void main() {
   // 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.
+  // Android an app in the background can't empty the clipboard again. But
+  // for an authenticator's key (3 Nov 2026), copied marked sensitive.
 
   testWidgets('the recovery phrase is saved, never copied', (tester) async {
     mockClipboard(tester);
@@ -82,26 +83,129 @@ void main() {
     expect(clipboard, isNull);
   });
 
-  testWidgets("an authenticator's key is scanned, opened or typed from the "
-      'screen, never copied', (tester) async {
-    mockClipboard(tester);
-    final code = TextEditingController();
-    addTearDown(code.dispose);
-    await pumpView(
-      tester,
-      AuthenticatorSetupView(
-        setup: const AuthenticatorSetup(
-          id: 'a',
-          uri: 'otpauth://totp/x:anna?secret=JBSWY3DPEHPK3PXP',
-        ),
-        code: code,
-      ),
+  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)', () {
+    const setup = AuthenticatorSetup(
+      id: 'a',
+      uri: 'otpauth://totp/x:anna?secret=JBSWY3DPEHPK3PXP',
     );
-    expect(find.text('JBSW Y3DP EHPK 3PXP'), findsOneWidget);
-    expect(find.byTooltip('Copy'), findsNothing);
-    expect(find.text('Copy'), findsNothing);
-    expect(find.byType(SelectableText), findsNothing);
-    expect(clipboard, isNull);
+
+    /// What each app's Android activity was asked
+    /// (`app.halkyon/clipboard`), and what it held.
+    late List<String> asked;
+    String? sensitive;
+
+    void mockActivity(WidgetTester tester) {
+      asked = [];
+      sensitive = null;
+      tester.binding.defaultBinaryMessenger.setMockMethodCallHandler(
+        PlatformSecretClipboard.channel,
+        (call) async {
+          asked.add(call.method);
+          switch (call.method) {
+            case 'copySensitive':
+              sensitive = call.arguments as String;
+            case 'clearIf':
+              if (sensitive == call.arguments) {
+                sensitive = null;
+              }
+          }
+          return null;
+        },
+      );
+      addTearDown(
+        () => tester.binding.defaultBinaryMessenger.setMockMethodCallHandler(
+          PlatformSecretClipboard.channel,
+          null,
+        ),
+      );
+    }
+
+    Future<void> pumpSetup(WidgetTester tester, SecretClipboard clipboard) {
+      final code = TextEditingController();
+      addTearDown(code.dispose);
+      return pumpView(
+        tester,
+        AuthenticatorSetupView(setup: setup, code: code, clipboard: clipboard),
+      );
+    }
+
+    testWidgets('on Android, marked sensitive through the activity, never '
+        "through Flutter's clipboard", (tester) async {
+      mockClipboard(tester);
+      mockActivity(tester);
+      await pumpSetup(
+        tester,
+        const PlatformSecretClipboard(marksSensitive: true),
+      );
+      expect(find.text('JBSW Y3DP EHPK 3PXP'), findsOneWidget);
+      expect(find.byType(SelectableText), findsNothing);
+
+      await tester.tap(find.byTooltip('Copy'));
+      await tester.pump();
+      expect(sensitive, 'JBSWY3DPEHPK3PXP');
+      expect(clipboard, isNull);
+      expect(find.textContaining('Key copied'), findsOneWidget);
+
+      await tester.pump(const Duration(seconds: 59));
+      expect(sensitive, 'JBSWY3DPEHPK3PXP');
+      await tester.pump(const Duration(seconds: 1));
+      expect(asked, ['copySensitive', 'clearIf']);
+      expect(sensitive, isNull);
+    });
+
+    testWidgets("elsewhere, through Flutter's clipboard, emptied after a "
+        'minute while it still holds the key', (tester) async {
+      mockClipboard(tester);
+      await pumpSetup(
+        tester,
+        const PlatformSecretClipboard(marksSensitive: false),
+      );
+      await tester.tap(find.byTooltip('Copy'));
+      await tester.pump();
+      expect(clipboard, 'JBSWY3DPEHPK3PXP');
+      await tester.pump(const Duration(seconds: 60));
+      expect(clipboard, '');
+    });
+
+    testWidgets('what was copied since stays', (tester) async {
+      mockClipboard(tester);
+      await pumpSetup(
+        tester,
+        const PlatformSecretClipboard(marksSensitive: false),
+      );
+      await tester.tap(find.byTooltip('Copy'));
+      await tester.pump();
+      clipboard = 'something else';
+      await tester.pump(const Duration(seconds: 60));
+      expect(clipboard, 'something else');
+    });
+
+    testWidgets("an app without the activity's channel copies through "
+        "Flutter's clipboard", (tester) async {
+      mockClipboard(tester);
+      // No activity answering, as on an app without SensitiveClipboard.kt.
+      tester.binding.defaultBinaryMessenger.setMockMethodCallHandler(
+        PlatformSecretClipboard.channel,
+        (call) async => throw MissingPluginException(),
+      );
+      addTearDown(
+        () => tester.binding.defaultBinaryMessenger.setMockMethodCallHandler(
+          PlatformSecretClipboard.channel,
+          null,
+        ),
+      );
+      await pumpSetup(
+        tester,
+        const PlatformSecretClipboard(marksSensitive: true),
+      );
+      await tester.tap(find.byTooltip('Copy'));
+      await tester.pump();
+      expect(clipboard, 'JBSWY3DPEHPK3PXP');
+      await tester.pump(const Duration(seconds: 60));
+      expect(clipboard, '');
+    });
   });
 
   group('the phrase typed back is never copied, cut or shared from its '

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

@@ -108,4 +108,18 @@ void main() {
     );
     expect(find.byType(QrCodeView), findsOneWidget);
   });
+
+  testWidgets("an authenticator's code is six digits: a space pasted between "
+      'them dropped, nothing counted', (tester) async {
+    final controller = TextEditingController();
+    addTearDown(controller.dispose);
+    await pump(tester, CodeField(controller: controller, kind: CodeKind.totp));
+
+    await tester.enterText(find.byType(TextField), '123 456');
+    expect(controller.text, '123456');
+    expect(find.textContaining('/'), findsNothing);
+
+    await tester.enterText(find.byType(TextField), '1234567');
+    expect(controller.text, '123456');
+  });
 }