fix: preserve null overrides and simplify Dart ownership

CHANGELOG.md

@@ -17,6 +17,7 @@ See [Conventional Commits](https://conventionalcommits.org) for commit guideline
   unrelated annotation data untouched.
 * Preserve schema-first alias metadata and strict/passthrough precedence;
   diagnose unsupported shape transformations instead of emitting wrong fields.
+* Accept parenthesized no-op `null` overrides in generated schema metadata.
 * Resolve same-build value-model and getter references, nullable nested Sets,
   generated-name collisions, and application-generic nullability correctly.
 * Substitute nested and recursive type bounds when resolving type-owned schemas.

docs.json

@@ -97,7 +97,7 @@
   ],
   "variables": {
     "versions": {
-      "default": "2.0.0-alpha.1",
+      "default": "2.0.0-alpha.2",
       "isPrerelease": true
     }
   },

docs/guides/ecosystem-integrations.mdx

@@ -137,10 +137,10 @@ Future<WeatherReport> askGeminiWeather(
   );
 
   final response = await model.generateContent([Content.text(prompt)]);
-  final jsonMap = jsonDecode(response.text ?? 'null');
+  final decoded = jsonDecode(response.text ?? 'null');
 
   // Validate and decode Gemini's response into WeatherReport
-  return WeatherReportSchema.fromJson(jsonMap);
+  return WeatherReportSchema.parse(decoded);
 }
 ```
 

packages/ack/lib/src/json_schema/json_schema_compiler.dart

@@ -474,7 +474,6 @@ final class _JsonSchemaCompiler {
 
   bool _discoverBundledDialect(_ImportedNode node) {
     final wanted = node.dialectUri;
-    if (resources.containsKey(wanted)) return true;
 
     bool visit(_ImportedNode parent, List<(_ImportedNode, String)> path) {
       final source = parent.source;

packages/ack/lib/src/schema_model/ack_schema_model_builder.dart

@@ -6,7 +6,6 @@ import 'package:collection/collection.dart';
 import '../constraints/constraint.dart';
 import '../constraints/datetime_constraint.dart';
 import '../context.dart';
-import '../json_schema/json_schema_utils.dart';
 import '../schemas/schema.dart';
 import '../utils/json_utils.dart';
 import 'ack_schema_model.dart';
@@ -153,17 +152,22 @@ final class _SchemaModelBuilder {
     }
 
     final model = switch (schema) {
-      StringSchema() => _string(schema),
-      IntegerSchema() => _integer(schema),
-      DoubleSchema() => _number(
+      StringSchema() => AckStringSchemaModel(
         description: schema.description,
         nullable: schema.isNullable,
       ),
-      NumberSchema() => _number(
+      IntegerSchema() => AckIntegerSchemaModel(
+        description: schema.description,
+        nullable: schema.isNullable,
+      ),
+      DoubleSchema() || NumberSchema() => AckNumberSchemaModel(
+        description: schema.description,
+        nullable: schema.isNullable,
+      ),
+      BooleanSchema() => AckBooleanSchemaModel(
         description: schema.description,
         nullable: schema.isNullable,
       ),
-      BooleanSchema() => _boolean(schema),
       EnumSchema() => _enum(schema),
       ListSchema() => _array(schema),
       MapSchema() => _map(schema),
@@ -393,31 +397,6 @@ final class _SchemaModelBuilder {
     return share(normalize(document, base))! as Map<String, Object?>;
   }
 
-  AckSchemaModel _string(StringSchema schema) {
-    return AckStringSchemaModel(
-      description: schema.description,
-      nullable: schema.isNullable,
-    );
-  }
-
-  AckSchemaModel _integer(IntegerSchema schema) {
-    return AckIntegerSchemaModel(
-      description: schema.description,
-      nullable: schema.isNullable,
-    );
-  }
-
-  AckSchemaModel _number({String? description, required bool nullable}) {
-    return AckNumberSchemaModel(description: description, nullable: nullable);
-  }
-
-  AckSchemaModel _boolean(BooleanSchema schema) {
-    return AckBooleanSchemaModel(
-      description: schema.description,
-      nullable: schema.isNullable,
-    );
-  }
-
   AckSchemaModel _enum(EnumSchema schema) {
     return AckStringSchemaModel(
       description: schema.description,
@@ -451,7 +430,7 @@ final class _SchemaModelBuilder {
 
     for (final entry in schema.properties.entries) {
       ordering.add(entry.key);
-      properties[entry.key] = wrapPropertyConversion(
+      properties[entry.key] = _wrapPropertyConversion(
         entry.key,
         () => _build(entry.value),
       );
@@ -599,9 +578,6 @@ final class _SchemaModelBuilder {
     if (schema.excludesTargetNull) model = _excludeNull(model);
     final constraintCount = schema.runtimeConstraintCount;
     final refinementCount = schema.runtimeRefinementCount;
-    if (constraintCount == 0 && refinementCount == 0) {
-      return model;
-    }
 
     return model.withWarnings([
       ...model.warnings,
@@ -810,8 +786,26 @@ Object? _jsonRoundTripOrNull(Object? value) {
   }
 }
 
-// Only schema-bearing keywords contain resource identities. Values of const,
-// default, examples, and unknown annotations remain ordinary instance data.
+/// Adds the property name to supported conversion errors without losing stacks.
+T _wrapPropertyConversion<T>(String key, T Function() fn) {
+  try {
+    return fn();
+  } catch (e, st) {
+    final msg =
+        'Error converting property "$key": ${e is Error ? e.toString() : e}';
+    if (e is UnsupportedError) {
+      Error.throwWithStackTrace(UnsupportedError(msg), st);
+    } else if (e is ArgumentError) {
+      Error.throwWithStackTrace(ArgumentError(msg), st);
+    } else if (e is StateError) {
+      Error.throwWithStackTrace(StateError(msg), st);
+    }
+    rethrow;
+  }
+}
+
+// Rewrite identities only at compiler-indexed schema locations. Annotation
+// payloads stay ordinary data unless explicitly referenced as schemas.
 Map<String, Object?> _mapImportedChildren(
   Map<String, Object?> schema,
   Object? Function(Object?, List<String>) visit,

packages/ack_generator/CHANGELOG.md

@@ -7,6 +7,8 @@
 
 ### Fixed
 
+* Preserve schema flags and object policies when `copyWith` no-op `null`
+  arguments are parenthesized.
 * Preserve schema-first presence, nullability, and default-wrapper behavior
   through aliases and explicit constant flag overrides. Apply the outermost
   strict/passthrough policy to object models and aliases.

packages/ack_generator/lib/src/analyzer/custom_schema_resolver.dart

@@ -2,11 +2,14 @@ import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/nullability_suffix.dart';
 import 'package:analyzer/dart/element/type.dart';
+// Analyzer 13 has no public API for substituting supplied method arguments
+// into nested or F-bounded types. Keep its complete substituter for these bounds.
+// ignore: implementation_imports
+import 'package:analyzer/src/dart/element/type_algebra.dart' show Substitution;
 import 'package:source_gen/source_gen.dart';
 
 import '../models/schema_model_graph.dart';
 import '../utils/string_literal.dart';
-import '../utils/type_parameter_bounds.dart';
 import 'generated_companion_visibility.dart';
 import 'model_graph_builder_base.dart';
 
@@ -594,14 +597,15 @@ final class CustomSchemaResolver {
           element: field,
         );
       }
-      final bounds = instantiateTypeParameterBounds(
+      final substitution = Substitution.fromPairs2(
         method.typeParameters,
         type.typeArguments,
       );
       for (var i = 0; i < method.typeParameters.length; i++) {
         final typeParam = method.typeParameters[i];
-        final bound = bounds[i];
-        if (bound == null) continue;
+        final rawBound = typeParam.bound;
+        if (rawBound == null) continue;
+        final bound = substitution.substituteType(rawBound);
         final argument = type.typeArguments[i];
         if (!_library.element.typeSystem.isSubtypeOf(argument, bound)) {
           throw InvalidGenerationSource(

packages/ack_generator/lib/src/analyzer/model_graph_builder_base.dart

@@ -155,14 +155,11 @@ abstract base class ModelGraphBuilderBase {
 
   /// Returns the `@Schemable` top-level declaration behind [element], if any.
   Element? schemableDeclaration(Element element) {
-    final declaration = switch (element) {
-      GetterElement(isOriginVariable: true) => element.variable.baseElement,
-      GetterElement() => element.baseElement,
-      TopLevelVariableElement() => element.baseElement,
-      _ => null,
-    };
-    return declaration != null &&
-            schemableChecker.hasAnnotationOfExact(declaration)
+    if (element is! GetterElement && element is! TopLevelVariableElement) {
+      return null;
+    }
+    final declaration = propertyDeclaration(element);
+    return schemableChecker.hasAnnotationOfExact(declaration)
         ? declaration
         : null;
   }
@@ -847,9 +844,7 @@ abstract base class ModelGraphBuilderBase {
       : null;
 
   bool? constantBool(Expression expression) {
-    while (expression is ParenthesizedExpression) {
-      expression = expression.expression;
-    }
+    expression = expression.unParenthesized;
     if (expression is BooleanLiteral) return expression.value;
 
     final element = switch (expression) {

packages/ack_generator/lib/src/analyzer/schema_model_graph_builder.dart

@@ -46,6 +46,12 @@ final class _SchemaMetadata {
   final bool innerOptional;
   final bool innerNullable;
 
+  AckSchemaFieldPresence get presence {
+    if (defaulted) return AckSchemaFieldPresence.defaulted;
+    if (optional) return AckSchemaFieldPresence.optional;
+    return AckSchemaFieldPresence.required;
+  }
+
   _SchemaMetadata copyWith({bool? optional, bool? nullable}) => _SchemaMetadata(
     optional: (optional ?? this.optional) || innerOptional,
     nullable: (nullable ?? this.nullable) || innerNullable,
@@ -417,7 +423,7 @@ final class SchemaModelGraphBuilder extends ModelGraphBuilderBase {
         AckFieldNode(
           dartName: jsonKey,
           jsonKey: jsonKey,
-          presence: _fieldPresence(fieldMetadata),
+          presence: fieldMetadata.presence,
           nullable: fieldMetadata.nullable,
           runtimeRef: runtimeRef,
           description: descriptionFromExpression(entry.value),
@@ -546,7 +552,7 @@ final class SchemaModelGraphBuilder extends ModelGraphBuilderBase {
     required String path,
     required Element context,
     required bool throughLazy,
-    Set<Element>? visited,
+    Set<Element> visited = const {},
     int depth = 0,
     String? followedName,
     bool collectionElement = false,
@@ -708,7 +714,7 @@ final class SchemaModelGraphBuilder extends ModelGraphBuilderBase {
           path: path,
           context: context,
           throughLazy: throughLazy,
-          visited: visited ?? {},
+          visited: visited,
           depth: depth,
         );
         if (followed != null) return followed;
@@ -1142,12 +1148,6 @@ final class SchemaModelGraphBuilder extends ModelGraphBuilderBase {
     ];
   }
 
-  AckSchemaFieldPresence _fieldPresence(_SchemaMetadata metadata) {
-    if (metadata.defaulted) return AckSchemaFieldPresence.defaulted;
-    if (metadata.optional) return AckSchemaFieldPresence.optional;
-    return AckSchemaFieldPresence.required;
-  }
-
   String _className(
     String declarationName,
     String? customName,
@@ -1447,7 +1447,10 @@ final class SchemaModelGraphBuilder extends ModelGraphBuilderBase {
         for (final argument in current.argumentList.arguments) {
           final entry = namedArgument(argument);
           if (entry?.name != 'additionalProperties') continue;
-          if (entry!.expression is NullLiteral && name == 'copyWith') continue;
+          if (entry!.expression.unParenthesized is NullLiteral &&
+              name == 'copyWith') {
+            continue;
+          }
           final value = constantBool(entry.expression);
           if (value != null) return value;
           throw InvalidGenerationSource(
@@ -1568,10 +1571,12 @@ final class SchemaModelGraphBuilder extends ModelGraphBuilderBase {
             final nullable = named('isNullable');
             final optional = named('isOptional');
             return inner.copyWith(
-              nullable: nullable == null || nullable is NullLiteral
+              nullable:
+                  nullable == null || nullable.unParenthesized is NullLiteral
                   ? null
                   : flag(nullable, '$name isNullable'),
-              optional: optional == null || optional is NullLiteral
+              optional:
+                  optional == null || optional.unParenthesized is NullLiteral
                   ? null
                   : flag(optional, '$name isOptional'),
             );

packages/ack_generator/test/integration/ack_infer_graph_test.dart

@@ -111,6 +111,30 @@ final titleSchema = Ack.string().nullable().nullable(value: false);
     );
   });
 
+  for (final omitted in ['null', '(null)', '((null))']) {
+    test('treats copyWith null arguments as no-ops: $omitted', () async {
+      await _expectOutput(
+        '''
+$_head
+final name = Ack.string().nullable().optional().copyWith(
+  isNullable: $omitted, isOptional: $omitted,
+);
+@Schemable()
+final flagsSchema = Ack.object({'name': name});
+@Schemable()
+final policySchema = Ack.object({}, additionalProperties: true).copyWith(
+  additionalProperties: $omitted,
+);
+''',
+        allOf([
+          contains('final String? name;'),
+          isNot(contains('required this.name')),
+          contains('Policy({Map<String, Object?> additionalProperties'),
+        ]),
+      );
+    });
+  }
+
   test('preserves wrapper flag and outer default semantics', () async {
     await _expectOutput(
       '''