Enhance authentication error handling with specific error codes and inline validation feedback

b0esche_cloud/lib/blocs/auth/auth_bloc.dart

@@ -56,7 +56,8 @@ class AuthBloc extends Bloc<AuthEvent, AuthState> {
       add(RegistrationChallengeRequested(userId: userId));
     } catch (e) {
       final errorMessage = _extractErrorMessage(e);
-      emit(AuthFailure(errorMessage));
+      final code = e is ApiError ? e.code : null;
+      emit(AuthFailure(errorMessage, code: code));
     }
   }
 
@@ -82,7 +83,8 @@ class AuthBloc extends Bloc<AuthEvent, AuthState> {
       );
     } catch (e) {
       final errorMessage = _extractErrorMessage(e);
-      emit(AuthFailure(errorMessage));
+      final code = e is ApiError ? e.code : null;
+      emit(AuthFailure(errorMessage, code: code));
     }
   }
 
@@ -135,7 +137,8 @@ class AuthBloc extends Bloc<AuthEvent, AuthState> {
       }
     } catch (e) {
       final errorMessage = _extractErrorMessage(e);
-      emit(AuthFailure(errorMessage));
+      final code = e is ApiError ? e.code : null;
+      emit(AuthFailure(errorMessage, code: code));
     }
   }
 
@@ -148,7 +151,8 @@ class AuthBloc extends Bloc<AuthEvent, AuthState> {
       add(AuthenticationChallengeRequested(username: event.username));
     } catch (e) {
       final errorMessage = _extractErrorMessage(e);
-      emit(AuthFailure(errorMessage));
+      final code = e is ApiError ? e.code : null;
+      emit(AuthFailure(errorMessage, code: code));
     }
   }
 
@@ -177,7 +181,8 @@ class AuthBloc extends Bloc<AuthEvent, AuthState> {
       );
     } catch (e) {
       final errorMessage = _extractErrorMessage(e);
-      emit(AuthFailure(errorMessage));
+      final code = e is ApiError ? e.code : null;
+      emit(AuthFailure(errorMessage, code: code));
     }
   }
 
@@ -230,7 +235,8 @@ class AuthBloc extends Bloc<AuthEvent, AuthState> {
       }
     } catch (e) {
       final errorMessage = _extractErrorMessage(e);
-      emit(AuthFailure(errorMessage));
+      final code = e is ApiError ? e.code : null;
+      emit(AuthFailure(errorMessage, code: code));
     }
   }
 
@@ -286,7 +292,8 @@ class AuthBloc extends Bloc<AuthEvent, AuthState> {
       }
     } catch (e) {
       final errorMessage = _extractErrorMessage(e);
-      emit(AuthFailure(errorMessage));
+      final code = e is ApiError ? e.code : null;
+      emit(AuthFailure(errorMessage, code: code));
     }
   }
 

b0esche_cloud/lib/blocs/auth/auth_state.dart

@@ -85,11 +85,12 @@ class AuthAuthenticated extends AuthState {
 
 class AuthFailure extends AuthState {
   final String error;
+  final String? code;
 
-  const AuthFailure(this.error);
+  const AuthFailure(this.error, {this.code});
 
   @override
-  List<Object> get props => [error];
+  List<Object?> get props => [error, code];
 }
 
 class AuthUnauthenticated extends AuthState {

b0esche_cloud/lib/pages/login_form.dart

@@ -32,6 +32,12 @@ class _LoginFormState extends State<LoginForm> {
   bool _usePasskey = true;
   bool _isSignup = false;
 
+  // UI error state for inline validation
+  String? _usernameErrorText;
+  String? _passwordErrorText;
+  bool _usernameHasError = false;
+  bool _passwordHasError = false;
+
   @override
   void dispose() {
     _usernameController.dispose();
@@ -112,6 +118,12 @@ class _LoginFormState extends State<LoginForm> {
     _passwordController.clear();
     _displayNameController.clear();
     _usePasskey = true;
+
+    // Clear inline error state
+    _usernameHasError = false;
+    _passwordHasError = false;
+    _usernameErrorText = null;
+    _passwordErrorText = null;
   }
 
   void _setSignupMode(bool isSignup) {
@@ -124,9 +136,33 @@ class _LoginFormState extends State<LoginForm> {
     return BlocListener<AuthBloc, AuthState>(
       listener: (context, state) {
         if (state is AuthFailure) {
+          // Handle specific credential errors inline
+          if (state.code == 'INVALID_PASSWORD' ||
+              state.error.toLowerCase().contains('incorrect')) {
+            setState(() {
+              _passwordHasError = true;
+              _passwordErrorText = 'incorrect password';
+              _passwordController.clear();
+              // clear username error if any
+              _usernameHasError = false;
+              _usernameErrorText = null;
+            });
+          } else if (state.code == 'INVALID_CREDENTIALS' ||
+              state.error.toLowerCase().contains('invalid credentials')) {
+            setState(() {
+              // Border both fields red but show the helper text only under the password field
+              _usernameHasError = true;
+              _passwordHasError = true;
+              _usernameErrorText = null;
+              _passwordErrorText = 'invalid credentials';
+              _usernameController.clear();
+              _passwordController.clear();
+            });
+          } else {
             ScaffoldMessenger.of(
               context,
             ).showSnackBar(SnackBar(content: Text(state.error)));
+          }
         } else if (state is AuthenticationChallengeReceived) {
           _handleAuthentication(context, state);
         } else if (state is RegistrationChallengeReceived) {
@@ -171,7 +207,9 @@ class _LoginFormState extends State<LoginForm> {
                         ),
                         borderRadius: BorderRadius.circular(16),
                         border: Border.all(
-                          color: AppTheme.accentColor.withValues(alpha: 0.3),
+                          color: _usernameHasError
+                              ? Colors.red
+                              : AppTheme.accentColor.withValues(alpha: 0.3),
                         ),
                       ),
                       child: TextField(
@@ -179,6 +217,14 @@ class _LoginFormState extends State<LoginForm> {
                         textInputAction: TextInputAction.next,
                         keyboardType: TextInputType.text,
                         cursorColor: AppTheme.accentColor,
+                        onChanged: (_) {
+                          if (_usernameHasError || _usernameErrorText != null) {
+                            setState(() {
+                              _usernameHasError = false;
+                              _usernameErrorText = null;
+                            });
+                          }
+                        },
                         decoration: InputDecoration(
                           hintText: 'username',
                           hintStyle: TextStyle(color: AppTheme.secondaryText),
@@ -193,6 +239,17 @@ class _LoginFormState extends State<LoginForm> {
                         style: const TextStyle(color: AppTheme.primaryText),
                       ),
                     ),
+                    if (_usernameErrorText != null)
+                      Padding(
+                        padding: const EdgeInsets.only(top: 6, left: 8),
+                        child: Text(
+                          _usernameErrorText!,
+                          style: const TextStyle(
+                            color: Colors.red,
+                            fontSize: 12,
+                          ),
+                        ),
+                      ),
                     const SizedBox(height: 16),
                     if (!_isSignup && _usePasskey)
                       const SizedBox.shrink()
@@ -204,7 +261,9 @@ class _LoginFormState extends State<LoginForm> {
                           ),
                           borderRadius: BorderRadius.circular(16),
                           border: Border.all(
-                            color: AppTheme.accentColor.withValues(alpha: 0.3),
+                            color: _passwordHasError
+                                ? Colors.red
+                                : AppTheme.accentColor.withValues(alpha: 0.3),
                           ),
                         ),
                         child: TextField(
@@ -213,6 +272,15 @@ class _LoginFormState extends State<LoginForm> {
                           keyboardType: TextInputType.visiblePassword,
                           obscureText: true,
                           cursorColor: AppTheme.accentColor,
+                          onChanged: (_) {
+                            if (_passwordHasError ||
+                                _passwordErrorText != null) {
+                              setState(() {
+                                _passwordHasError = false;
+                                _passwordErrorText = null;
+                              });
+                            }
+                          },
                           decoration: InputDecoration(
                             hintText: 'password',
                             hintStyle: TextStyle(color: AppTheme.secondaryText),
@@ -227,6 +295,17 @@ class _LoginFormState extends State<LoginForm> {
                           style: const TextStyle(color: AppTheme.primaryText),
                         ),
                       ),
+                    if (_passwordErrorText != null)
+                      Padding(
+                        padding: const EdgeInsets.only(top: 6, left: 8),
+                        child: Text(
+                          _passwordErrorText!,
+                          style: const TextStyle(
+                            color: Colors.red,
+                            fontSize: 12,
+                          ),
+                        ),
+                      ),
                     if (!_isSignup && _usePasskey)
                       const SizedBox.shrink()
                     else
@@ -362,7 +441,12 @@ class _LoginFormState extends State<LoginForm> {
                             children: [
                               GestureDetector(
                                 onTap: () {
-                                  setState(() => _usePasskey = !_usePasskey);
+                                  setState(() {
+                                    _usePasskey = !_usePasskey;
+                                    // Clear password errors when switching modes
+                                    _passwordHasError = false;
+                                    _passwordErrorText = null;
+                                  });
                                   widget.onPasswordModeChanged?.call(
                                     !_usePasskey,
                                   );

go_cloud/internal/errors/errors.go

@@ -15,6 +15,10 @@ type ErrorCode string
 
 const (
 	CodeUnauthenticated ErrorCode = "UNAUTHENTICATED"
+	// More specific authentication error codes
+	CodeInvalidCredentials ErrorCode = "INVALID_CREDENTIALS"
+	CodeInvalidPassword    ErrorCode = "INVALID_PASSWORD"
+
 	CodePermissionDenied ErrorCode = "PERMISSION_DENIED"
 	CodeNotFound         ErrorCode = "NOT_FOUND"
 	CodeConflict         ErrorCode = "CONFLICT"

go_cloud/internal/http/routes.go

@@ -1921,6 +1921,18 @@ func passwordLoginHandler(w http.ResponseWriter, r *http.Request, db *database.D
 			Metadata: map[string]interface{}{"error": err.Error()},
 		})
 		errors.LogError(r, err, "Password login failed")
+		// Map internal errors to more specific API error responses so the client
+		// can indicate which field was incorrect.
+		errMsg := err.Error()
+		if strings.Contains(errMsg, "invalid password") {
+			errors.WriteError(w, errors.CodeInvalidPassword, "Incorrect password", http.StatusUnauthorized)
+			return
+		}
+		if strings.Contains(errMsg, "user not found") {
+			errors.WriteError(w, errors.CodeInvalidCredentials, "Invalid credentials", http.StatusUnauthorized)
+			return
+		}
+
 		errors.WriteError(w, errors.CodeUnauthenticated, "Invalid credentials", http.StatusUnauthorized)
 		return
 	}