fix(app): no sheet is left busy by an error nothing expected

An instance's salt of another length made the device's cryptography throw
an ArgumentError, a wrapping's nonce a RangeError, and libsodium or the
keyring may throw their own; none was a refusal, so the step's error
escaped and the sheet stayed busy, which can't be closed. halkyon_keys
now checks the lengths of what comes from elsewhere before libsodium sees
it (KeyRefusal.malformed: a salt, a wrapping, a sealed key's box, a sealed
payload), the device's cryptography turns anything else into the general
failure, and so does every password cubit, the error logged by its type
alone.

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/bloc/account_recovery_cubit.dart

@@ -1,5 +1,6 @@
 import 'package:equatable/equatable.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
+import 'package:halkyon_app/src/password/bloc/unexpected_failure.dart';
 import 'package:halkyon_app/src/password/data/password_repository.dart';
 import 'package:halkyon_app/src/password/model/mail_code_purpose.dart';
 import 'package:halkyon_app/src/password/model/password_failed.dart';
@@ -162,7 +163,8 @@ class AccountRecoveryCubit(
       if (!isClosed) {
         emit(state.copyWith(busy: false));
       }
-    } on PasswordFailed catch (failed) {
+    } on Object catch (error) {
+      final failed = asPasswordFailed(error);
       if (!isClosed) {
         emit(state.copyWith(busy: false, problem: failed));
       }

packages/halkyon_app/lib/src/password/bloc/account_security_cubit.dart

@@ -2,6 +2,7 @@ import 'dart:async';
 
 import 'package:equatable/equatable.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
+import 'package:halkyon_app/src/password/bloc/unexpected_failure.dart';
 import 'package:halkyon_app/src/password/data/password_repository.dart';
 import 'package:halkyon_app/src/password/model/account_authenticator.dart';
 import 'package:halkyon_app/src/password/model/account_security.dart';
@@ -43,7 +44,10 @@ class AccountSecurityCubit(final PasswordRepository _passwords)
       if (!isClosed) {
         emit(AccountSecurityState(security: security));
       }
-    } on PasswordFailed {
+    } on Object catch (error) {
+      if (error is! PasswordFailed) {
+        logUnexpected(error);
+      }
       if (!isClosed) {
         emit(AccountSecurityState(security: state.security, failed: true));
       }
@@ -79,7 +83,8 @@ class SecurityStepCubit<T>() extends Cubit<SecurityStepState<T>> {
         emit(SecurityStepState<T>(result: result));
       }
       return true;
-    } on PasswordFailed catch (failed) {
+    } on Object catch (error) {
+      final failed = asPasswordFailed(error);
       if (!isClosed) {
         emit(SecurityStepState<T>(problem: failed, result: state.result));
       }
@@ -140,7 +145,8 @@ class AddAuthenticatorCubit(
           AddAuthenticatorState(step: AddAuthenticatorStep.code, setup: setup),
         );
       }
-    } on PasswordFailed catch (failed) {
+    } on Object catch (error) {
+      final failed = asPasswordFailed(error);
       if (!isClosed) {
         emit(AddAuthenticatorState(problem: failed));
       }
@@ -180,7 +186,8 @@ class AddAuthenticatorCubit(
           ),
         );
       }
-    } on PasswordFailed catch (failed) {
+    } on Object catch (error) {
+      final failed = asPasswordFailed(error);
       if (!isClosed) {
         emit(
           AddAuthenticatorState(
@@ -250,7 +257,8 @@ class NewPhraseCubit(final PasswordRepository _passwords)
       if (!isClosed) {
         emit(NewPhraseState(step: NewPhraseStep.shown, phrase: made.phrase));
       }
-    } on PasswordFailed catch (failed) {
+    } on Object catch (error) {
+      final failed = asPasswordFailed(error);
       if (!isClosed) {
         emit(NewPhraseState(problem: failed));
       }
@@ -287,7 +295,8 @@ class NewPhraseCubit(final PasswordRepository _passwords)
       if (!isClosed) {
         emit(NewPhraseState(step: NewPhraseStep.done, phrase: state.phrase));
       }
-    } on PasswordFailed catch (failed) {
+    } on Object catch (error) {
+      final failed = asPasswordFailed(error);
       if (!isClosed) {
         emit(_again(problem: failed));
       }

packages/halkyon_app/lib/src/password/bloc/account_setup_cubit.dart

@@ -1,5 +1,6 @@
 import 'package:equatable/equatable.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
+import 'package:halkyon_app/src/password/bloc/unexpected_failure.dart';
 import 'package:halkyon_app/src/password/data/account_crypto.dart';
 import 'package:halkyon_app/src/password/data/password_repository.dart';
 import 'package:halkyon_app/src/password/model/account_authenticator.dart';
@@ -338,7 +339,8 @@ class AccountSetupCubit(
       if (!isClosed) {
         emit(state.copyWith(busy: false));
       }
-    } on PasswordFailed catch (failed) {
+    } on Object catch (error) {
+      final failed = asPasswordFailed(error);
       if (isClosed) {
         return;
       }

packages/halkyon_app/lib/src/password/bloc/password_sign_in_cubit.dart

@@ -1,5 +1,6 @@
 import 'package:equatable/equatable.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
+import 'package:halkyon_app/src/password/bloc/unexpected_failure.dart';
 import 'package:halkyon_app/src/password/data/password_repository.dart';
 import 'package:halkyon_app/src/password/model/account_authenticator.dart';
 import 'package:halkyon_app/src/password/model/mail_code_purpose.dart';
@@ -351,7 +352,8 @@ class PasswordSignInCubit(
       if (!isClosed) {
         emit(state.copyWith(busy: false));
       }
-    } on PasswordFailed catch (failed) {
+    } on Object catch (error) {
+      final failed = asPasswordFailed(error);
       if (!isClosed) {
         emit(state.copyWith(busy: false, problem: failed));
       }

packages/halkyon_app/lib/src/password/bloc/unexpected_failure.dart

@@ -0,0 +1,20 @@
+import 'dart:developer';
+
+import 'package:halkyon_app/src/password/model/password_failed.dart';
+
+/// [error] as the refusal a sheet shows: a [PasswordFailed] as it is,
+/// anything else (an instance's malformed answer, libsodium's or the
+/// keyring's own errors) as [PasswordProblem.failed], logged by its type
+/// alone, so a sheet is never left busy and never closes on an error it
+/// didn't expect (ADR 0017's full reading).
+PasswordFailed asPasswordFailed(Object error) {
+  if (error is PasswordFailed) {
+    return error;
+  }
+  logUnexpected(error);
+  return const PasswordFailed(PasswordProblem.failed);
+}
+
+/// Logs [error] by its type alone: what it says may hold a secret.
+void logUnexpected(Object error) =>
+    log('Failed unexpectedly: ${error.runtimeType}', name: 'Passwords');

packages/halkyon_app/lib/src/password/data/sodium_account_crypto.dart

@@ -1,3 +1,4 @@
+import 'dart:developer';
 import 'dart:isolate';
 import 'dart:typed_data';
 
@@ -301,8 +302,20 @@ Future<T> _guarded<T>(Future<T> Function() step) async {
       PasswordRefusal.empty ||
       PasswordRefusal.controlCharacter => PasswordProblem.passwordUnusable,
     });
-  } on KeyRefused {
-    throw const PasswordFailed(PasswordProblem.keysMissing);
+  } on KeyRefused catch (refused) {
+    throw PasswordFailed(switch (refused.reason) {
+      // What the instance sent isn't of the lengths it must have.
+      KeyRefusal.malformed => PasswordProblem.failed,
+      _ => PasswordProblem.keysMissing,
+    });
+  } on PasswordFailed {
+    rethrow;
+  } on Object catch (error) {
+    // Anything else (libsodium's own errors, Argon2id without the memory
+    // it asks for) fails the step rather than escaping it, which left the
+    // sheet busy for good; logged by its type alone.
+    log('The keys failed: ${error.runtimeType}', name: 'Keys');
+    throw const PasswordFailed(PasswordProblem.failed);
   }
 }