feat(authenticator): allow SignUp form fields to be disabled or hidden

- Add enabledOverride and visible to AuthenticatorFormField and include in diagnostics
- Use enabledOverride to determine enabled state; honor override in ConfirmSignUpFormField
- Render hidden fields offstage with Visibility maintaining state (so programmatic updates still sync)
- Propagate enabled/visible through SignUpFormField factory APIs and concrete field constructors
- Add tests verifying disabled fields still sync with controllers and hidden fields retain state synchronization

Author: angelorodem

packages/authenticator/amplify_authenticator/CHANGELOG.md

@@ -8,6 +8,7 @@
   - Enables pre-populating fields (e.g., from GPS/API data) and auto-filling verification codes
   - Bidirectional sync between controller and internal state
   - Compatible with standard `TextEditingController` for flexibility
+- feat(authenticator): Allow SignUpFormField inputs to be disabled or hidden so apps can prefill values programmatically or keep legacy attributes off-screen
 
 ## 2.3.8
 

packages/authenticator/amplify_authenticator/lib/src/widgets/form_field.dart

@@ -66,6 +66,8 @@ abstract class AuthenticatorFormField<
     FormFieldValidator<FieldValue>? validator,
     this.requiredOverride,
     this.autofillHints,
+    this.enabledOverride,
+    this.visible = true,
   }) : validatorOverride = validator;
 
   /// Resolver key for the title
@@ -99,6 +101,17 @@ abstract class AuthenticatorFormField<
   /// Optional text controller exposed by text-driven form fields.
   TextEditingController? get controller => null;
 
+  /// Whether the field can receive manual input.
+  ///
+  /// When `null`, the widget decides its enabled state.
+  final bool? enabledOverride;
+
+  /// Whether the field should be rendered.
+  ///
+  /// When `false`, the field stays offstage so programmatic updates can still
+  /// run without occupying layout space.
+  final bool visible;
+
   /// Whether the field is required in the form.
   ///
   /// Defaults to `false`.
@@ -131,7 +144,9 @@ abstract class AuthenticatorFormField<
       ..add(IterableProperty<String>('autofillHints', autofillHints))
       ..add(
         DiagnosticsProperty<TextEditingController?>('controller', controller),
-      );
+      )
+      ..add(DiagnosticsProperty<bool?>('enabledOverride', enabledOverride))
+      ..add(DiagnosticsProperty<bool>('visible', visible));
   }
 }
 
@@ -172,7 +187,7 @@ abstract class AuthenticatorFormFieldState<
   FieldValue? get initialValue => null;
 
   /// Whether the form field accepts input.
-  bool get enabled => true;
+  bool get enabled => widget.enabledOverride ?? true;
 
   /// Widget to show at leading end, typically an [Icon].
   Widget? get prefix => null;
@@ -270,7 +285,7 @@ abstract class AuthenticatorFormFieldState<
   @nonVirtual
   @override
   Widget build(BuildContext context) {
-    return Container(
+    final field = Container(
       margin: EdgeInsets.only(bottom: marginBottom ?? 0),
       child: Stack(
         children: [
@@ -286,6 +301,17 @@ abstract class AuthenticatorFormFieldState<
         ],
       ),
     );
+    if (widget.visible) {
+      return field;
+    }
+    return Visibility(
+      visible: false,
+      maintainState: true,
+      maintainAnimation: true,
+      maintainSemantics: false,
+      maintainInteractivity: false,
+      child: field,
+    );
   }
 
   @override

packages/authenticator/amplify_authenticator/lib/src/widgets/form_fields/confirm_sign_up_form_field.dart

@@ -94,6 +94,10 @@ abstract class _ConfirmSignUpFormFieldState<FieldValue extends Object>
 
   @override
   bool get enabled {
+    final override = widget.enabledOverride;
+    if (override != null) {
+      return override;
+    }
     switch (widget.field) {
       case ConfirmSignUpField.code:
         return true;