diff --git a/src/google/protobuf/BUILD.bazel b/src/google/protobuf/BUILD.bazel
index ae6012349aa8..9284b315eb5c 100644
--- a/src/google/protobuf/BUILD.bazel
+++ b/src/google/protobuf/BUILD.bazel
@@ -685,7 +685,6 @@ filegroup(
         "unittest_features.proto",
         "unittest_import.proto",
         "unittest_import_public.proto",
-        "unittest_invalid_features.proto",
         "unittest_lite_imports_nonlite.proto",
         "unittest_mset.proto",
         "unittest_mset_wire_format.proto",
diff --git a/src/google/protobuf/compiler/command_line_interface_unittest.cc b/src/google/protobuf/compiler/command_line_interface_unittest.cc
index 66e81f05237f..af99450f5069 100644
--- a/src/google/protobuf/compiler/command_line_interface_unittest.cc
+++ b/src/google/protobuf/compiler/command_line_interface_unittest.cc
@@ -1564,6 +1564,10 @@ TEST_F(CommandLineInterfaceTest, Plugin_RuntimeFeatures) {
                        message_encoding: LENGTH_PREFIXED
                        json_format: ALLOW
                        raw_features { field_presence: IMPLICIT }
+                       [pb.cpp] {
+                         legacy_closed_enum: false
+                         utf8_validation: VERIFY_PARSE
+                       }
       )pb"));
   EXPECT_THAT(request.source_file_descriptors(0)
                   .message_type(0)
@@ -1577,6 +1581,10 @@ TEST_F(CommandLineInterfaceTest, Plugin_RuntimeFeatures) {
                                message_encoding: LENGTH_PREFIXED
                                json_format: ALLOW
                                raw_features { field_presence: IMPLICIT }
+                               [pb.cpp] {
+                                 legacy_closed_enum: false
+                                 utf8_validation: VERIFY_PARSE
+                               }
               )pb"));
 }
 
diff --git a/src/google/protobuf/descriptor_unittest.cc b/src/google/protobuf/descriptor_unittest.cc
index f1430a8d659a..51e483cecd2a 100644
--- a/src/google/protobuf/descriptor_unittest.cc
+++ b/src/google/protobuf/descriptor_unittest.cc
@@ -69,7 +69,6 @@
 #include "google/protobuf/unittest.pb.h"
 #include "google/protobuf/unittest_custom_options.pb.h"
 #include "google/protobuf/unittest_features.pb.h"
-#include "google/protobuf/unittest_invalid_features.pb.h"
 #include "google/protobuf/unittest_lazy_dependencies.pb.h"
 #include "google/protobuf/unittest_lazy_dependencies_custom_option.pb.h"
 #include "google/protobuf/unittest_lazy_dependencies_enum.pb.h"
@@ -7179,6 +7178,16 @@ const FeatureSet& GetFeatures(const T* descriptor) {
   return internal::InternalFeatureHelper::GetFeatures<T>(*descriptor);
 }
 
+template <typename T>
+FeatureSet GetCoreFeatures(const T* descriptor) {
+  FeatureSet features = GetFeatures(descriptor);
+  // Strip test features to avoid excessive brittleness.
+  features.ClearExtension(pb::test);
+  features.ClearExtension(pb::TestMessage::test_message);
+  features.ClearExtension(pb::TestMessage::Nested::test_nested);
+  return features;
+}
+
 TEST_F(FeaturesTest, InvalidProto2Features) {
   BuildDescriptorMessagesInTestPool();
   BuildFileWithErrors(
@@ -7440,6 +7449,32 @@ TEST_F(FeaturesTest, Proto3Extensions) {
                                     R"pb([bar_ext] { baz: 1 })pb"));
 }
 
+TEST_F(FeaturesTest, Edition2023Defaults) {
+  FileDescriptorProto file_proto =
+      ParseTextOrDie(R"pb(
+        name: "foo.proto" syntax: "editions" edition: "2023"
+      )pb");
+
+  BuildDescriptorMessagesInTestPool();
+  const FileDescriptor* file = ABSL_DIE_IF_NULL(pool_.BuildFile(file_proto));
+  EXPECT_THAT(file->options(), EqualsProto(""));
+  EXPECT_THAT(
+      GetCoreFeatures(file), EqualsProto(R"pb(
+        field_presence: EXPLICIT
+        enum_type: OPEN
+        repeated_field_encoding: PACKED
+        string_field_validation: MANDATORY
+        message_encoding: LENGTH_PREFIXED
+        json_format: ALLOW
+        [pb.cpp] { legacy_closed_enum: false utf8_validation: VERIFY_PARSE }
+      )pb"));
+
+  // Since pb::test is linked in, it should end up with defaults in our
+  // FeatureSet.
+  EXPECT_TRUE(GetFeatures(file).HasExtension(pb::test));
+  EXPECT_EQ(GetFeatures(file).GetExtension(pb::test).int_file_feature(), 1);
+}
+
 TEST_F(FeaturesTest, ClearsOptions) {
   BuildDescriptorMessagesInTestPool();
   const FileDescriptor* file = BuildFile(R"pb(
@@ -7452,13 +7487,17 @@ TEST_F(FeaturesTest, ClearsOptions) {
     }
   )pb");
   EXPECT_THAT(file->options(), EqualsProto("java_package: 'bar'"));
-  EXPECT_THAT(GetFeatures(file), EqualsProto(R"pb(
+  EXPECT_THAT(GetCoreFeatures(file), EqualsProto(R"pb(
                 field_presence: IMPLICIT
                 enum_type: OPEN
                 repeated_field_encoding: PACKED
                 string_field_validation: MANDATORY
                 message_encoding: LENGTH_PREFIXED
-                json_format: ALLOW)pb"));
+                json_format: ALLOW
+                [pb.cpp] {
+                  legacy_closed_enum: false
+                  utf8_validation: VERIFY_PARSE
+                })pb"));
 }
 
 TEST_F(FeaturesTest, RestoresOptionsRoundTrip) {
@@ -7711,13 +7750,17 @@ TEST_F(FeaturesTest, NoOptions) {
         name: "foo.proto" syntax: "editions" edition: "2023"
       )pb");
   EXPECT_EQ(&file->options(), &FileOptions::default_instance());
-  EXPECT_THAT(GetFeatures(file), EqualsProto(R"pb(
+  EXPECT_THAT(GetCoreFeatures(file), EqualsProto(R"pb(
                 field_presence: EXPLICIT
                 enum_type: OPEN
                 repeated_field_encoding: PACKED
                 string_field_validation: MANDATORY
                 message_encoding: LENGTH_PREFIXED
-                json_format: ALLOW)pb"));
+                json_format: ALLOW
+                [pb.cpp] {
+                  legacy_closed_enum: false
+                  utf8_validation: VERIFY_PARSE
+                })pb"));
 }
 
 TEST_F(FeaturesTest, InvalidEdition) {
@@ -7740,13 +7783,17 @@ TEST_F(FeaturesTest, FileFeatures) {
     options { features { field_presence: IMPLICIT } }
   )pb");
   EXPECT_THAT(file->options(), EqualsProto(""));
-  EXPECT_THAT(GetFeatures(file), EqualsProto(R"pb(
+  EXPECT_THAT(GetCoreFeatures(file), EqualsProto(R"pb(
                 field_presence: IMPLICIT
                 enum_type: OPEN
                 repeated_field_encoding: PACKED
                 string_field_validation: MANDATORY
                 message_encoding: LENGTH_PREFIXED
-                json_format: ALLOW)pb"));
+                json_format: ALLOW
+                [pb.cpp] {
+                  legacy_closed_enum: false
+                  utf8_validation: VERIFY_PARSE
+                })pb"));
 }
 
 TEST_F(FeaturesTest, FileFeaturesExtension) {
@@ -7761,7 +7808,7 @@ TEST_F(FeaturesTest, FileFeaturesExtension) {
   )pb");
   EXPECT_THAT(file->options(), EqualsProto(""));
   EXPECT_EQ(GetFeatures(file).field_presence(), FeatureSet::IMPLICIT);
-  EXPECT_EQ(GetFeatures(file).string_field_validation(), FeatureSet::MANDATORY);
+  EXPECT_EQ(GetFeatures(file).enum_type(), FeatureSet::OPEN);
   EXPECT_EQ(GetFeatures(file).GetExtension(pb::test).int_file_feature(), 4);
   EXPECT_EQ(GetFeatures(file)
                 .GetExtension(pb::TestMessage::test_message)
@@ -7792,7 +7839,7 @@ TEST_F(FeaturesTest, FileFeaturesExtensionOverride) {
   )pb");
   EXPECT_THAT(file->options(), EqualsProto(""));
   EXPECT_EQ(GetFeatures(file).field_presence(), FeatureSet::IMPLICIT);
-  EXPECT_EQ(GetFeatures(file).string_field_validation(), FeatureSet::MANDATORY);
+  EXPECT_EQ(GetFeatures(file).enum_type(), FeatureSet::OPEN);
   EXPECT_EQ(GetFeatures(file).GetExtension(pb::test).int_file_feature(), 9);
   EXPECT_EQ(GetFeatures(file)
                 .GetExtension(pb::TestMessage::test_message)
@@ -7814,13 +7861,17 @@ TEST_F(FeaturesTest, MessageFeaturesDefault) {
   )pb");
   const Descriptor* message = file->message_type(0);
   EXPECT_THAT(message->options(), EqualsProto(""));
-  EXPECT_THAT(GetFeatures(message), EqualsProto(R"pb(
+  EXPECT_THAT(GetCoreFeatures(message), EqualsProto(R"pb(
                 field_presence: EXPLICIT
                 enum_type: OPEN
                 repeated_field_encoding: PACKED
                 string_field_validation: MANDATORY
                 message_encoding: LENGTH_PREFIXED
-                json_format: ALLOW)pb"));
+                json_format: ALLOW
+                [pb.cpp] {
+                  legacy_closed_enum: false
+                  utf8_validation: VERIFY_PARSE
+                })pb"));
 }
 
 TEST_F(FeaturesTest, MessageFeaturesInherit) {
@@ -7918,13 +7969,17 @@ TEST_F(FeaturesTest, FieldFeaturesDefault) {
   )pb");
   const FieldDescriptor* field = file->message_type(0)->field(0);
   EXPECT_THAT(field->options(), EqualsProto(""));
-  EXPECT_THAT(GetFeatures(field), EqualsProto(R"pb(
+  EXPECT_THAT(GetCoreFeatures(field), EqualsProto(R"pb(
                 field_presence: EXPLICIT
                 enum_type: OPEN
                 repeated_field_encoding: PACKED
                 string_field_validation: MANDATORY
                 message_encoding: LENGTH_PREFIXED
-                json_format: ALLOW)pb"));
+                json_format: ALLOW
+                [pb.cpp] {
+                  legacy_closed_enum: false
+                  utf8_validation: VERIFY_PARSE
+                })pb"));
 }
 
 TEST_F(FeaturesTest, FieldFeaturesInherit) {
@@ -7968,7 +8023,7 @@ TEST_F(FeaturesTest, FieldFeaturesOverride) {
     dependency: "google/protobuf/unittest_features.proto"
     options {
       features {
-        string_field_validation: HINT
+        enum_type: CLOSED
         field_presence: IMPLICIT
         [pb.test] { int_multiple_feature: 2 }
       }
@@ -7987,7 +8042,7 @@ TEST_F(FeaturesTest, FieldFeaturesOverride) {
         type: TYPE_STRING
         options {
           features {
-            string_field_validation: NONE
+            field_presence: EXPLICIT
             [pb.test] { int_multiple_feature: 9 }
           }
         }
@@ -7996,8 +8051,8 @@ TEST_F(FeaturesTest, FieldFeaturesOverride) {
   )pb");
   const FieldDescriptor* field = file->message_type(0)->field(0);
   EXPECT_THAT(field->options(), EqualsProto(""));
-  EXPECT_EQ(GetFeatures(field).field_presence(), FeatureSet::IMPLICIT);
-  EXPECT_EQ(GetFeatures(field).string_field_validation(), FeatureSet::NONE);
+  EXPECT_EQ(GetFeatures(field).field_presence(), FeatureSet::EXPLICIT);
+  EXPECT_EQ(GetFeatures(field).enum_type(), FeatureSet::CLOSED);
   EXPECT_EQ(GetFeatures(field).GetExtension(pb::test).int_multiple_feature(),
             9);
 }
@@ -8074,7 +8129,6 @@ TEST_F(FeaturesTest, OneofFieldFeaturesOverride) {
         type: TYPE_STRING
         options {
           features {
-            string_field_validation: NONE
             [pb.test] { int_multiple_feature: 9 }
           }
         }
@@ -8213,7 +8267,7 @@ TEST_F(FeaturesTest, RootExtensionFeaturesOverride) {
     dependency: "google/protobuf/unittest_features.proto"
     options {
       features {
-        string_field_validation: HINT
+        enum_type: CLOSED
         field_presence: IMPLICIT
         [pb.test] { int_multiple_feature: 2 }
       }
@@ -8225,7 +8279,7 @@ TEST_F(FeaturesTest, RootExtensionFeaturesOverride) {
       type: TYPE_STRING
       options {
         features {
-          string_field_validation: NONE
+          enum_type: OPEN
           [pb.test] { int_multiple_feature: 9 }
         }
       }
@@ -8239,7 +8293,7 @@ TEST_F(FeaturesTest, RootExtensionFeaturesOverride) {
   const FieldDescriptor* field = file->extension(0);
   EXPECT_THAT(field->options(), EqualsProto(""));
   EXPECT_EQ(GetFeatures(field).field_presence(), FeatureSet::IMPLICIT);
-  EXPECT_EQ(GetFeatures(field).string_field_validation(), FeatureSet::NONE);
+  EXPECT_EQ(GetFeatures(field).enum_type(), FeatureSet::OPEN);
   EXPECT_EQ(GetFeatures(field).GetExtension(pb::test).int_multiple_feature(),
             9);
 }
@@ -8254,7 +8308,7 @@ TEST_F(FeaturesTest, MessageExtensionFeaturesOverride) {
     dependency: "google/protobuf/unittest_features.proto"
     options {
       features {
-        string_field_validation: HINT
+        enum_type: CLOSED
         field_presence: IMPLICIT
         [pb.test] { int_multiple_feature: 2 }
       }
@@ -8271,7 +8325,7 @@ TEST_F(FeaturesTest, MessageExtensionFeaturesOverride) {
         number: 1
         label: LABEL_OPTIONAL
         type: TYPE_STRING
-        options { features { string_field_validation: NONE } }
+        options { features { enum_type: OPEN } }
         extendee: "Foo2"
       }
     }
@@ -8288,7 +8342,7 @@ TEST_F(FeaturesTest, MessageExtensionFeaturesOverride) {
   const FieldDescriptor* field = file->message_type(0)->extension(0);
   EXPECT_THAT(field->options(), EqualsProto(""));
   EXPECT_EQ(GetFeatures(field).field_presence(), FeatureSet::IMPLICIT);
-  EXPECT_EQ(GetFeatures(field).string_field_validation(), FeatureSet::NONE);
+  EXPECT_EQ(GetFeatures(field).enum_type(), FeatureSet::OPEN);
   EXPECT_EQ(GetFeatures(field).GetExtension(pb::test).int_multiple_feature(),
             3);
 }
@@ -8306,13 +8360,17 @@ TEST_F(FeaturesTest, EnumFeaturesDefault) {
   )pb");
   const EnumDescriptor* enm = file->enum_type(0);
   EXPECT_THAT(enm->options(), EqualsProto(""));
-  EXPECT_THAT(GetFeatures(enm), EqualsProto(R"pb(
+  EXPECT_THAT(GetCoreFeatures(enm), EqualsProto(R"pb(
                 field_presence: EXPLICIT
                 enum_type: OPEN
                 repeated_field_encoding: PACKED
                 string_field_validation: MANDATORY
                 message_encoding: LENGTH_PREFIXED
-                json_format: ALLOW)pb"));
+                json_format: ALLOW
+                [pb.cpp] {
+                  legacy_closed_enum: false
+                  utf8_validation: VERIFY_PARSE
+                })pb"));
 }
 
 TEST_F(FeaturesTest, EnumFeaturesInherit) {
@@ -8412,13 +8470,17 @@ TEST_F(FeaturesTest, EnumValueFeaturesDefault) {
   )pb");
   const EnumValueDescriptor* value = file->enum_type(0)->value(0);
   EXPECT_THAT(value->options(), EqualsProto(""));
-  EXPECT_THAT(GetFeatures(value), EqualsProto(R"pb(
+  EXPECT_THAT(GetCoreFeatures(value), EqualsProto(R"pb(
                 field_presence: EXPLICIT
                 enum_type: OPEN
                 repeated_field_encoding: PACKED
                 string_field_validation: MANDATORY
                 message_encoding: LENGTH_PREFIXED
-                json_format: ALLOW)pb"));
+                json_format: ALLOW
+                [pb.cpp] {
+                  legacy_closed_enum: false
+                  utf8_validation: VERIFY_PARSE
+                })pb"));
 }
 
 TEST_F(FeaturesTest, EnumValueFeaturesInherit) {
@@ -8503,13 +8565,17 @@ TEST_F(FeaturesTest, OneofFeaturesDefault) {
   )pb");
   const OneofDescriptor* oneof = file->message_type(0)->oneof_decl(0);
   EXPECT_THAT(oneof->options(), EqualsProto(""));
-  EXPECT_THAT(GetFeatures(oneof), EqualsProto(R"pb(
+  EXPECT_THAT(GetCoreFeatures(oneof), EqualsProto(R"pb(
                 field_presence: EXPLICIT
                 enum_type: OPEN
                 repeated_field_encoding: PACKED
                 string_field_validation: MANDATORY
                 message_encoding: LENGTH_PREFIXED
-                json_format: ALLOW)pb"));
+                json_format: ALLOW
+                [pb.cpp] {
+                  legacy_closed_enum: false
+                  utf8_validation: VERIFY_PARSE
+                })pb"));
 }
 
 TEST_F(FeaturesTest, OneofFeaturesInherit) {
@@ -8601,13 +8667,17 @@ TEST_F(FeaturesTest, ExtensionRangeFeaturesDefault) {
   const Descriptor::ExtensionRange* range =
       file->message_type(0)->extension_range(0);
   EXPECT_THAT(range->options(), EqualsProto(""));
-  EXPECT_THAT(GetFeatures(range), EqualsProto(R"pb(
+  EXPECT_THAT(GetCoreFeatures(range), EqualsProto(R"pb(
                 field_presence: EXPLICIT
                 enum_type: OPEN
                 repeated_field_encoding: PACKED
                 string_field_validation: MANDATORY
                 message_encoding: LENGTH_PREFIXED
-                json_format: ALLOW)pb"));
+                json_format: ALLOW
+                [pb.cpp] {
+                  legacy_closed_enum: false
+                  utf8_validation: VERIFY_PARSE
+                })pb"));
 }
 
 TEST_F(FeaturesTest, ExtensionRangeFeaturesInherit) {
@@ -8684,13 +8754,17 @@ TEST_F(FeaturesTest, ServiceFeaturesDefault) {
   )pb");
   const ServiceDescriptor* service = file->service(0);
   EXPECT_THAT(service->options(), EqualsProto(""));
-  EXPECT_THAT(GetFeatures(service), EqualsProto(R"pb(
+  EXPECT_THAT(GetCoreFeatures(service), EqualsProto(R"pb(
                 field_presence: EXPLICIT
                 enum_type: OPEN
                 repeated_field_encoding: PACKED
                 string_field_validation: MANDATORY
                 message_encoding: LENGTH_PREFIXED
-                json_format: ALLOW)pb"));
+                json_format: ALLOW
+                [pb.cpp] {
+                  legacy_closed_enum: false
+                  utf8_validation: VERIFY_PARSE
+                })pb"));
 }
 
 TEST_F(FeaturesTest, ServiceFeaturesInherit) {
@@ -8749,13 +8823,17 @@ TEST_F(FeaturesTest, MethodFeaturesDefault) {
   )pb");
   const MethodDescriptor* method = file->service(0)->method(0);
   EXPECT_THAT(method->options(), EqualsProto(""));
-  EXPECT_THAT(GetFeatures(method), EqualsProto(R"pb(
+  EXPECT_THAT(GetCoreFeatures(method), EqualsProto(R"pb(
                 field_presence: EXPLICIT
                 enum_type: OPEN
                 repeated_field_encoding: PACKED
                 string_field_validation: MANDATORY
                 message_encoding: LENGTH_PREFIXED
-                json_format: ALLOW)pb"));
+                json_format: ALLOW
+                [pb.cpp] {
+                  legacy_closed_enum: false
+                  utf8_validation: VERIFY_PARSE
+                })pb"));
 }
 
 TEST_F(FeaturesTest, MethodFeaturesInherit) {
@@ -9006,23 +9084,44 @@ TEST_F(FeaturesTest, FeaturesOutsideEditions) {
 
 TEST_F(FeaturesTest, InvalidExtensionNonMessage) {
   BuildDescriptorMessagesInTestPool();
-  BuildFileInTestPool(::pb::TestInvalid::descriptor()->file());
+  ASSERT_NE(BuildFile(R"pb(
+              name: "unittest_invalid_features.proto"
+              syntax: "proto2"
+              package: "pb"
+              dependency: "google/protobuf/descriptor.proto"
+              message_type {
+                name: "TestInvalid"
+                extension {
+                  name: "scalar_extension"
+                  number: 9996
+                  label: LABEL_OPTIONAL
+                  type: TYPE_STRING
+                  extendee: ".google.protobuf.FeatureSet"
+                }
+              }
+            )pb"),
+            nullptr);
   BuildFileWithErrors(
       R"pb(
         name: "foo.proto"
         syntax: "editions"
         edition: "2023"
-        dependency: "google/protobuf/unittest_invalid_features.proto"
+        dependency: "unittest_invalid_features.proto"
         options {
-          features {
-            [pb.TestInvalid.scalar_extension]: "hello"
+          uninterpreted_option {
+            name { name_part: "features" is_extension: false }
+            name {
+              name_part: "pb.TestInvalid.scalar_extension"
+              is_extension: true
+            }
+            identifier_value: "hello"
           }
         }
       )pb",
-      "foo.proto: google/protobuf/unittest_invalid_features.proto: "
-      "EDITIONS: FeatureSet extension pb.TestInvalid.scalar_extension is not "
-      "of message type.  Feature extensions should always use messages to "
-      "allow for evolution.\n");
+      "foo.proto: unittest_invalid_features.proto: EDITIONS: FeatureSet "
+      "extension pb.TestInvalid.scalar_extension is not of message type.  "
+      "Feature extensions should always use messages to allow for "
+      "evolution.\n");
 }
 
 TEST_F(FeaturesTest, InvalidFieldImplicitDefault) {
@@ -9416,13 +9515,17 @@ TEST_F(FeaturesTest, UninterpretedOptions) {
     }
   )pb");
   EXPECT_THAT(file->options(), EqualsProto(""));
-  EXPECT_THAT(GetFeatures(file), EqualsProto(R"pb(
+  EXPECT_THAT(GetCoreFeatures(file), EqualsProto(R"pb(
                 field_presence: IMPLICIT
                 enum_type: OPEN
                 repeated_field_encoding: PACKED
                 string_field_validation: MANDATORY
                 message_encoding: LENGTH_PREFIXED
-                json_format: ALLOW)pb"));
+                json_format: ALLOW
+                [pb.cpp] {
+                  legacy_closed_enum: false
+                  utf8_validation: VERIFY_PARSE
+                })pb"));
 }
 
 TEST_F(FeaturesTest, UninterpretedOptionsMerge) {
@@ -9434,8 +9537,8 @@ TEST_F(FeaturesTest, UninterpretedOptionsMerge) {
     options {
       uninterpreted_option {
         name { name_part: "features" is_extension: false }
-        name { name_part: "string_field_validation" is_extension: false }
-        identifier_value: "HINT"
+        name { name_part: "enum_type" is_extension: false }
+        identifier_value: "CLOSED"
       }
     }
     message_type {
@@ -9448,8 +9551,8 @@ TEST_F(FeaturesTest, UninterpretedOptionsMerge) {
         options {
           uninterpreted_option {
             name { name_part: "features" is_extension: false }
-            name { name_part: "string_field_validation" is_extension: false }
-            identifier_value: "NONE"
+            name { name_part: "enum_type" is_extension: false }
+            identifier_value: "OPEN"
           }
         }
       }
@@ -9458,8 +9561,8 @@ TEST_F(FeaturesTest, UninterpretedOptionsMerge) {
   const FieldDescriptor* field = file->message_type(0)->field(0);
   EXPECT_THAT(file->options(), EqualsProto(""));
   EXPECT_THAT(field->options(), EqualsProto(""));
-  EXPECT_EQ(GetFeatures(file).string_field_validation(), FeatureSet::HINT);
-  EXPECT_EQ(GetFeatures(field).string_field_validation(), FeatureSet::NONE);
+  EXPECT_EQ(GetFeatures(file).enum_type(), FeatureSet::CLOSED);
+  EXPECT_EQ(GetFeatures(field).enum_type(), FeatureSet::OPEN);
 }
 
 TEST_F(FeaturesTest, UninterpretedOptionsMergeExtension) {
@@ -9540,13 +9643,17 @@ TEST_F(FeaturesTest, RawFeatures) {
     options { features { raw_features { field_presence: IMPLICIT } } }
   )pb");
   EXPECT_THAT(file->options(), EqualsProto(""));
-  EXPECT_THAT(GetFeatures(file), EqualsProto(R"pb(
+  EXPECT_THAT(GetCoreFeatures(file), EqualsProto(R"pb(
                 field_presence: IMPLICIT
                 enum_type: OPEN
                 repeated_field_encoding: PACKED
                 string_field_validation: MANDATORY
                 message_encoding: LENGTH_PREFIXED
-                json_format: ALLOW)pb"));
+                json_format: ALLOW
+                [pb.cpp] {
+                  legacy_closed_enum: false
+                  utf8_validation: VERIFY_PARSE
+                })pb"));
 }
 
 TEST_F(FeaturesTest, RawFeaturesConflict) {
@@ -9563,13 +9670,17 @@ TEST_F(FeaturesTest, RawFeaturesConflict) {
     }
   )pb");
   EXPECT_THAT(file->options(), EqualsProto(""));
-  EXPECT_THAT(GetFeatures(file), EqualsProto(R"pb(
+  EXPECT_THAT(GetCoreFeatures(file), EqualsProto(R"pb(
                 field_presence: IMPLICIT
                 enum_type: OPEN
                 repeated_field_encoding: PACKED
                 string_field_validation: MANDATORY
                 message_encoding: LENGTH_PREFIXED
-                json_format: ALLOW)pb"));
+                json_format: ALLOW
+                [pb.cpp] {
+                  legacy_closed_enum: false
+                  utf8_validation: VERIFY_PARSE
+                })pb"));
 }
 
 TEST_F(FeaturesTest, InvalidJsonUniquenessDefaultWarning) {
diff --git a/src/google/protobuf/editions/BUILD b/src/google/protobuf/editions/BUILD
index 9cf1f2530729..8b31ffda8197 100644
--- a/src/google/protobuf/editions/BUILD
+++ b/src/google/protobuf/editions/BUILD
@@ -7,6 +7,11 @@ proto_library(
     deps = ["//src/google/protobuf:cpp_features_proto"],
 )
 
+cc_proto_library(
+    name = "test_messages_proto2_cc_proto",
+    deps = [":test_messages_proto2_proto"],
+)
+
 proto_library(
     name = "test_messages_proto3_proto",
     srcs = ["golden/test_messages_proto3.proto"],
@@ -23,19 +28,26 @@ proto_library(
 )
 
 cc_proto_library(
-    name = "test_messages_proto2_cc_proto",
-    deps = [":test_messages_proto2_proto"],
+    name = "test_messages_proto3_cc_proto",
+    deps = [":test_messages_proto3_proto"],
+)
+
+proto_library(
+    name = "editions_default_features_proto",
+    srcs = ["proto/editions_default_features.proto"],
+    strip_import_prefix = "/src",
 )
 
 cc_proto_library(
-    name = "test_messages_proto3_cc_proto",
-    deps = [":test_messages_proto3_proto"],
+    name = "editions_default_features_cc_proto",
+    deps = [":editions_default_features_proto"],
 )
 
 cc_test(
     name = "generated_files_test",
     srcs = ["generated_files_test.cc"],
     deps = [
+        ":editions_default_features_cc_proto",
         ":test_messages_proto2_cc_proto",
         ":test_messages_proto3_cc_proto",
         "//src/google/protobuf",
diff --git a/src/google/protobuf/editions/generated_files_test.cc b/src/google/protobuf/editions/generated_files_test.cc
index c772230e2787..0f9ab590612e 100644
--- a/src/google/protobuf/editions/generated_files_test.cc
+++ b/src/google/protobuf/editions/generated_files_test.cc
@@ -33,6 +33,7 @@
 #include "google/protobuf/descriptor.h"
 #include "google/protobuf/editions/golden/test_messages_proto2.pb.h"
 #include "google/protobuf/editions/golden/test_messages_proto3.pb.h"
+#include "google/protobuf/editions/proto/editions_default_features.pb.h"
 #include "google/protobuf/test_textproto.h"
 
 // These tests provide some basic minimal coverage that protos work as expected.
@@ -42,12 +43,13 @@ namespace google {
 namespace protobuf {
 namespace {
 
+using ::protobuf_editions_test::EditionsDefaultMessage;
 using ::protobuf_test_messages::proto2::TestAllRequiredTypesProto2;
 using ::protobuf_test_messages::proto2::TestAllTypesProto2;
 using ::protobuf_test_messages::proto3::TestAllTypesProto3;
 using ::testing::NotNull;
 
-TEST(Gemerated, Parsing) {
+TEST(Generated, Parsing) {
   TestAllTypesProto2 message = ParseTextOrDie(R"pb(
     Data { group_int32: 9 }
   )pb");
@@ -55,21 +57,21 @@ TEST(Gemerated, Parsing) {
   EXPECT_EQ(message.data().group_int32(), 9);
 }
 
-TEST(Gemerated, GeneratedMethods) {
+TEST(Generated, GeneratedMethods) {
   TestAllTypesProto3 message;
   message.set_optional_int32(9);
 
   EXPECT_THAT(message, EqualsProto(R"pb(optional_int32: 9)pb"));
 }
 
-TEST(Gemerated, ExplicitPresence) {
+TEST(Generated, ExplicitPresence) {
   const FieldDescriptor* field =
       TestAllTypesProto2::descriptor()->FindFieldByName("default_int32");
   ASSERT_THAT(field, NotNull());
   EXPECT_TRUE(field->has_presence());
 }
 
-TEST(Gemerated, RequiredPresence) {
+TEST(Generated, RequiredPresence) {
   const FieldDescriptor* field =
       TestAllRequiredTypesProto2::descriptor()->FindFieldByName(
           "required_int32");
@@ -79,63 +81,63 @@ TEST(Gemerated, RequiredPresence) {
   EXPECT_EQ(field->label(), FieldDescriptor::LABEL_REQUIRED);
 }
 
-TEST(Gemerated, ImplicitPresence) {
+TEST(Generated, ImplicitPresence) {
   const FieldDescriptor* field =
       TestAllTypesProto3::descriptor()->FindFieldByName("optional_int32");
   ASSERT_THAT(field, NotNull());
   EXPECT_FALSE(field->has_presence());
 }
 
-TEST(Gemerated, ClosedEnum) {
+TEST(Generated, ClosedEnum) {
   const EnumDescriptor* enm =
       TestAllTypesProto2::descriptor()->FindEnumTypeByName("NestedEnum");
   ASSERT_THAT(enm, NotNull());
   EXPECT_TRUE(enm->is_closed());
 }
 
-TEST(Gemerated, OpenEnum) {
+TEST(Generated, OpenEnum) {
   const EnumDescriptor* enm =
       TestAllTypesProto3::descriptor()->FindEnumTypeByName("NestedEnum");
   ASSERT_THAT(enm, NotNull());
   EXPECT_FALSE(enm->is_closed());
 }
 
-TEST(Gemerated, PackedRepeated) {
+TEST(Generated, PackedRepeated) {
   const FieldDescriptor* field =
       TestAllTypesProto2::descriptor()->FindFieldByName("packed_int32");
   ASSERT_THAT(field, NotNull());
   EXPECT_TRUE(field->is_packed());
 }
 
-TEST(Gemerated, ExpandedRepeated) {
+TEST(Generated, ExpandedRepeated) {
   const FieldDescriptor* field =
       TestAllTypesProto2::descriptor()->FindFieldByName("repeated_int32");
   ASSERT_THAT(field, NotNull());
   EXPECT_FALSE(field->is_packed());
 }
 
-TEST(Gemerated, DoesNotEnforceUtf8) {
+TEST(Generated, DoesNotEnforceUtf8) {
   const FieldDescriptor* field =
       TestAllTypesProto2::descriptor()->FindFieldByName("optional_string");
   ASSERT_THAT(field, NotNull());
   EXPECT_FALSE(field->requires_utf8_validation());
 }
 
-TEST(Gemerated, EnforceUtf8) {
+TEST(Generated, EnforceUtf8) {
   const FieldDescriptor* field =
       TestAllTypesProto3::descriptor()->FindFieldByName("optional_string");
   ASSERT_THAT(field, NotNull());
   EXPECT_TRUE(field->requires_utf8_validation());
 }
 
-TEST(Gemerated, DelimitedEncoding) {
+TEST(Generated, DelimitedEncoding) {
   const FieldDescriptor* field =
       TestAllTypesProto2::descriptor()->FindFieldByName("data");
   ASSERT_THAT(field, NotNull());
   EXPECT_EQ(field->type(), FieldDescriptor::TYPE_GROUP);
 }
 
-TEST(Gemerated, LengthPrefixedEncoding) {
+TEST(Generated, LengthPrefixedEncoding) {
   const FieldDescriptor* field =
       TestAllTypesProto2::descriptor()->FindFieldByName(
           "optional_nested_message");
@@ -143,6 +145,34 @@ TEST(Gemerated, LengthPrefixedEncoding) {
   EXPECT_EQ(field->type(), FieldDescriptor::TYPE_MESSAGE);
 }
 
+TEST(Generated, EditionDefaults2023) {
+  const Descriptor* desc = EditionsDefaultMessage::descriptor();
+  EXPECT_TRUE(desc->FindFieldByName("int32_field")->has_presence());
+  EXPECT_TRUE(
+      desc->FindFieldByName("string_field")->requires_utf8_validation());
+  EXPECT_FALSE(desc->FindFieldByName("enum_field")
+                   ->legacy_enum_field_treated_as_closed());
+  EXPECT_FALSE(desc->FindFieldByName("enum_field")->enum_type()->is_closed());
+  EXPECT_TRUE(desc->FindFieldByName("repeated_int32_field")->is_packed());
+  EXPECT_EQ(desc->FindFieldByName("sub_message_field")->type(),
+            FieldDescriptor::TYPE_MESSAGE);
+}
+
+TEST(Generated, EditionDefaults2023InternalFeatures) {
+  EXPECT_THAT(
+      internal::InternalFeatureHelper::GetFeatures(
+          *EditionsDefaultMessage::descriptor()),
+      google::protobuf::EqualsProto(R"pb(
+        field_presence: EXPLICIT
+        enum_type: OPEN
+        repeated_field_encoding: PACKED
+        string_field_validation: MANDATORY
+        message_encoding: LENGTH_PREFIXED
+        json_format: ALLOW
+        [pb.cpp] { legacy_closed_enum: false utf8_validation: VERIFY_PARSE }
+      )pb"));
+}
+
 }  // namespace
 }  // namespace protobuf
 }  // namespace google
diff --git a/src/google/protobuf/unittest_invalid_features.proto b/src/google/protobuf/editions/proto/editions_default_features.proto
similarity index 77%
rename from src/google/protobuf/unittest_invalid_features.proto
rename to src/google/protobuf/editions/proto/editions_default_features.proto
index d19c8c438841..a5755f09ed74 100644
--- a/src/google/protobuf/unittest_invalid_features.proto
+++ b/src/google/protobuf/editions/proto/editions_default_features.proto
@@ -28,14 +28,26 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-syntax = "proto2";
+edition = "2023";
 
-package pb;
+package protobuf_editions_test;
 
-import "google/protobuf/descriptor.proto";
+// This file tests the default features in the absence of any dependencies.
 
-message TestInvalid {
-  extend .google.protobuf.FeatureSet {
-    optional string scalar_extension = 9996;
+enum EditionsDefaultEnum {
+  EDITIONS_DEFAULT_ENUM_UNKNOWN = 0;
+  EDITIONS_DEFAULT_ENUM_VALUE1 = 1;
+}
+
+message EditionsDefaultMessage {
+  int32 int32_field = 1;
+  string string_field = 2;
+  EditionsDefaultEnum enum_field = 3;
+
+  repeated int32 repeated_int32_field = 4;
+
+  message SubMessage {
+    int32 nested_int32_field = 1;
   }
+  SubMessage sub_message_field = 6;
 }
diff --git a/src/google/protobuf/feature_resolver.cc b/src/google/protobuf/feature_resolver.cc
index feda73ed4447..1387d7e9503e 100644
--- a/src/google/protobuf/feature_resolver.cc
+++ b/src/google/protobuf/feature_resolver.cc
@@ -44,6 +44,8 @@
 #include "absl/status/statusor.h"
 #include "absl/strings/str_cat.h"
 #include "absl/strings/str_split.h"
+#include "absl/strings/string_view.h"
+#include "google/protobuf/cpp_features.pb.h"
 #include "google/protobuf/descriptor.h"
 #include "google/protobuf/descriptor.pb.h"
 #include "google/protobuf/dynamic_message.h"
@@ -118,6 +120,29 @@ absl::Status ValidateDescriptor(absl::string_view edition,
   return absl::OkStatus();
 }
 
+absl::Status ValidateExtension(const FieldDescriptor& extension) {
+  if (extension.message_type() == nullptr) {
+    return Error("FeatureSet extension ", extension.full_name(),
+                 " is not of message type.  Feature extensions should "
+                 "always use messages to allow for evolution.");
+  }
+
+  if (extension.is_repeated()) {
+    return Error(
+        "Only singular features extensions are supported.  Found "
+        "repeated extension ",
+        extension.full_name());
+  }
+
+  if (extension.message_type()->extension_count() > 0 ||
+      extension.message_type()->extension_range_count() > 0) {
+    return Error("Nested extensions in feature extension ",
+                 extension.full_name(), " are not supported.");
+  }
+
+  return absl::OkStatus();
+}
+
 absl::Status FillDefaults(absl::string_view edition, Message& msg) {
   const Descriptor& descriptor = *msg.GetDescriptor();
 
@@ -189,10 +214,41 @@ absl::Status ValidateMergedFeatures(const Message& msg) {
   return absl::OkStatus();
 }
 
+// Forces calculation of the defaults for any features from the generated pool
+// that may be missed if the proto file doesn't import them, giving the final
+// resolved FeatureSet object maximal coverage.
+absl::StatusOr<FeatureSet> FillGeneratedDefaults(absl::string_view edition,
+                                                 const DescriptorPool* pool) {
+  const Descriptor* desc =
+      pool->FindMessageTypeByName(FeatureSet::descriptor()->full_name());
+  // If there's no FeatureSet, there's no extensions.
+  if (desc == nullptr) return FeatureSet();
+
+  DynamicMessageFactory message_factory;
+  auto defaults = absl::WrapUnique(message_factory.GetPrototype(desc)->New());
+  std::vector<const FieldDescriptor*> extensions;
+  pool->FindAllExtensions(desc, &extensions);
+  for (const auto* extension : extensions) {
+    RETURN_IF_ERROR(ValidateExtension(*extension));
+    Message* msg =
+        defaults->GetReflection()->MutableMessage(defaults.get(), extension);
+    ABSL_CHECK(msg != nullptr);
+    RETURN_IF_ERROR(FillDefaults(edition, *msg));
+  }
+
+  // Our defaults are reflectively built in a custom pool, while the
+  // returned object here is in the generated pool.  We parse/serialize to
+  // convert from the potentially skewed FeatureSet descriptors.
+  FeatureSet features;
+  ABSL_CHECK(features.MergeFromString(defaults->SerializeAsString()));
+  return features;
+}
+
 }  // namespace
 
 absl::StatusOr<FeatureResolver> FeatureResolver::Create(
-    absl::string_view edition, const Descriptor* descriptor) {
+    absl::string_view edition, const Descriptor* descriptor,
+    const DescriptorPool* generated_pool) {
   if (descriptor == nullptr) {
     return Error(
         "Unable to find definition of google.protobuf.FeatureSet in descriptor pool.");
@@ -206,8 +262,22 @@ absl::StatusOr<FeatureResolver> FeatureResolver::Create(
 
   RETURN_IF_ERROR(FillDefaults(edition, *defaults));
 
+  FeatureSet generated_defaults;
+  if (descriptor->file()->pool() == generated_pool) {
+    // If we're building the generated pool, the best we can do is load the C++
+    // language features, which should always be present for code using the C++
+    // runtime.
+    RETURN_IF_ERROR(
+        FillDefaults(edition, *generated_defaults.MutableExtension(pb::cpp)));
+  } else {
+    absl::StatusOr<FeatureSet> defaults =
+        FillGeneratedDefaults(edition, generated_pool);
+    RETURN_IF_ERROR(defaults.status());
+    generated_defaults = std::move(defaults).value();
+  }
+
   return FeatureResolver(edition, *descriptor, std::move(message_factory),
-                         std::move(defaults));
+                         std::move(defaults), std::move(generated_defaults));
 }
 
 absl::Status FeatureResolver::RegisterExtension(
@@ -221,24 +291,7 @@ absl::Status FeatureResolver::RegisterExtension(
 
   ABSL_CHECK(descriptor_.IsExtensionNumber(extension.number()));
 
-  if (extension.message_type() == nullptr) {
-    return Error("FeatureSet extension ", extension.full_name(),
-                 " is not of message type.  Feature extensions should "
-                 "always use messages to allow for evolution.");
-  }
-
-  if (extension.is_repeated()) {
-    return Error(
-        "Only singular features extensions are supported.  Found "
-        "repeated extension ",
-        extension.full_name());
-  }
-
-  if (extension.message_type()->extension_count() > 0 ||
-      extension.message_type()->extension_range_count() > 0) {
-    return Error("Nested extensions in feature extension ",
-                 extension.full_name(), " are not supported.");
-  }
+  RETURN_IF_ERROR(ValidateExtension(extension));
 
   RETURN_IF_ERROR(ValidateDescriptor(edition_, *extension.message_type()));
 
@@ -273,8 +326,12 @@ absl::Status FeatureResolver::RegisterExtensions(const Descriptor& message) {
 
 absl::StatusOr<FeatureSet> FeatureResolver::MergeFeatures(
     const FeatureSet& merged_parent, const FeatureSet& unmerged_child) const {
-  FeatureSet merged;
-  ABSL_CHECK(merged.ParseFromString(defaults_->SerializeAsString()));
+  FeatureSet merged = generated_defaults_;
+
+  // Our defaults are a dynamic message located in the build pool, while the
+  // returned object here is in the generated pool.  We parse/serialize to
+  // convert from the potentially skewed FeatureSet descriptors.
+  ABSL_CHECK(merged.MergeFromString(defaults_->SerializeAsString()));
   merged.MergeFrom(merged_parent);
   merged.MergeFrom(unmerged_child);
 
diff --git a/src/google/protobuf/feature_resolver.h b/src/google/protobuf/feature_resolver.h
index 013dc65e8508..0d27ee1acf0c 100644
--- a/src/google/protobuf/feature_resolver.h
+++ b/src/google/protobuf/feature_resolver.h
@@ -37,6 +37,7 @@
 
 #include "absl/container/flat_hash_set.h"
 #include "absl/status/status.h"
+#include "absl/status/statusor.h"
 #include "absl/strings/string_view.h"
 #include "google/protobuf/descriptor.h"
 #include "google/protobuf/descriptor.pb.h"
@@ -58,8 +59,10 @@ class PROTOBUF_EXPORT FeatureResolver {
   // Creates a new FeatureResolver at a specific edition.  This validates the
   // built-in features for the given edition, and calculates the default feature
   // set.
-  static absl::StatusOr<FeatureResolver> Create(absl::string_view edition,
-                                                const Descriptor* descriptor);
+  static absl::StatusOr<FeatureResolver> Create(
+      absl::string_view edition, const Descriptor* descriptor,
+      const DescriptorPool* generated_pool =
+          DescriptorPool::internal_generated_pool());
 
   // Registers a potential extension of the FeatureSet proto.  Any visible
   // extensions will be used during merging.  Returns an error if the extension
@@ -69,17 +72,22 @@ class PROTOBUF_EXPORT FeatureResolver {
   // Creates a new feature set using inheritance and default behavior. This is
   // designed to be called recursively, and the parent feature set is expected
   // to be a fully merged one.
+  // The returned FeatureSet will be fully resolved for any extensions that were
+  // explicitly registered (in the custom pool) or linked into this binary (in
+  // the generated pool).
   absl::StatusOr<FeatureSet> MergeFeatures(
       const FeatureSet& merged_parent, const FeatureSet& unmerged_child) const;
 
  private:
   FeatureResolver(absl::string_view edition, const Descriptor& descriptor,
                   std::unique_ptr<DynamicMessageFactory> message_factory,
-                  std::unique_ptr<Message> defaults)
+                  std::unique_ptr<Message> defaults,
+                  FeatureSet generated_defaults)
       : edition_(edition),
         descriptor_(descriptor),
         message_factory_(std::move(message_factory)),
-        defaults_(std::move(defaults)) {}
+        defaults_(std::move(defaults)),
+        generated_defaults_(std::move(generated_defaults)) {}
 
   absl::Status RegisterExtensions(const Descriptor& message);
   absl::Status RegisterExtension(const FieldDescriptor& extension);
@@ -89,6 +97,7 @@ class PROTOBUF_EXPORT FeatureResolver {
   absl::flat_hash_set<const FieldDescriptor*> extensions_;
   std::unique_ptr<DynamicMessageFactory> message_factory_;
   std::unique_ptr<Message> defaults_;
+  FeatureSet generated_defaults_;
 };
 
 }  // namespace protobuf
diff --git a/src/google/protobuf/feature_resolver_test.cc b/src/google/protobuf/feature_resolver_test.cc
index 8d1d7ce47bee..5c5ef41c8ffa 100644
--- a/src/google/protobuf/feature_resolver_test.cc
+++ b/src/google/protobuf/feature_resolver_test.cc
@@ -37,7 +37,9 @@
 #include "absl/memory/memory.h"
 #include "absl/status/status.h"
 #include "absl/status/statusor.h"
+#include "absl/strings/string_view.h"
 #include "google/protobuf/compiler/parser.h"
+#include "google/protobuf/cpp_features.pb.h"
 #include "google/protobuf/descriptor.h"
 #include "google/protobuf/descriptor.pb.h"
 #include "google/protobuf/io/tokenizer.h"
@@ -87,10 +89,17 @@ const FileDescriptor& GetExtensionFile(
               ->file();
 }
 
+const DescriptorPool* EmptyPool() {
+  static DescriptorPool* empty_pool = new DescriptorPool();
+  return empty_pool;
+}
+
 template <typename... Extensions>
-absl::StatusOr<FeatureResolver> SetupFeatureResolver(absl::string_view edition,
-                                                     Extensions... extensions) {
-  auto resolver = FeatureResolver::Create(edition, FeatureSet::descriptor());
+absl::StatusOr<FeatureResolver> SetupFeatureResolverImpl(
+    absl::string_view edition, const DescriptorPool* pool,
+    Extensions... extensions) {
+  auto resolver =
+      FeatureResolver::Create(edition, FeatureSet::descriptor(), pool);
   RETURN_IF_ERROR(resolver.status());
   std::vector<absl::Status> results{
       resolver->RegisterExtensions(GetExtensionFile(extensions))...};
@@ -99,17 +108,35 @@ absl::StatusOr<FeatureResolver> SetupFeatureResolver(absl::string_view edition,
   }
   return resolver;
 }
+template <typename... Extensions>
+absl::StatusOr<FeatureResolver> SetupFeatureResolver(absl::string_view edition,
+                                                     Extensions... extensions) {
+  return SetupFeatureResolverImpl(edition, EmptyPool(), extensions...);
+}
 
 template <typename... Extensions>
-absl::StatusOr<FeatureSet> GetDefaults(absl::string_view edition,
-                                       Extensions... extensions) {
+absl::StatusOr<FeatureSet> GetDefaultsImpl(absl::string_view edition,
+                                           const DescriptorPool* pool,
+                                           Extensions... extensions) {
   absl::StatusOr<FeatureResolver> resolver =
-      SetupFeatureResolver(edition, extensions...);
+      SetupFeatureResolverImpl(edition, pool, extensions...);
   RETURN_IF_ERROR(resolver.status());
   FeatureSet parent, child;
   return resolver->MergeFeatures(parent, child);
 }
 
+template <typename... Extensions>
+absl::StatusOr<FeatureSet> GetDefaults(absl::string_view edition,
+                                       Extensions... extensions) {
+  return GetDefaultsImpl(edition, EmptyPool(), extensions...);
+}
+
+FileDescriptorProto GetProto(const FileDescriptor* file) {
+  FileDescriptorProto proto;
+  file->CopyTo(&proto);
+  return proto;
+}
+
 TEST(FeatureResolverTest, DefaultsCore2023) {
   absl::StatusOr<FeatureSet> merged = GetDefaults("2023");
   ASSERT_OK(merged);
@@ -119,6 +146,7 @@ TEST(FeatureResolverTest, DefaultsCore2023) {
   EXPECT_EQ(merged->repeated_field_encoding(), FeatureSet::PACKED);
   EXPECT_EQ(merged->string_field_validation(), FeatureSet::MANDATORY);
   EXPECT_EQ(merged->message_encoding(), FeatureSet::LENGTH_PREFIXED);
+  EXPECT_FALSE(merged->HasExtension(pb::test));
 }
 
 TEST(FeatureResolverTest, DefaultsTest2023) {
@@ -207,6 +235,34 @@ TEST(FeatureResolverTest, DefaultsTestNestedExtension) {
   EXPECT_EQ(ext.enum_field_feature(), pb::TestFeatures::ENUM_VALUE1);
 }
 
+TEST(FeatureResolverTest, DefaultsGeneratedPoolCustom) {
+  DescriptorPool pool;
+  ASSERT_NE(
+      pool.BuildFile(GetProto(google::protobuf::DescriptorProto::descriptor()->file())),
+      nullptr);
+  ASSERT_NE(pool.BuildFile(GetProto(pb::TestFeatures::descriptor()->file())),
+            nullptr);
+  absl::StatusOr<FeatureSet> merged = GetDefaultsImpl("2023", &pool);
+  ASSERT_OK(merged);
+
+  EXPECT_EQ(merged->field_presence(), FeatureSet::EXPLICIT);
+  EXPECT_TRUE(merged->HasExtension(pb::test));
+  EXPECT_EQ(merged->GetExtension(pb::test).int_file_feature(), 1);
+  EXPECT_FALSE(merged->HasExtension(pb::cpp));
+}
+
+TEST(FeatureResolverTest, DefaultsGeneratedPoolGenerated) {
+  absl::StatusOr<FeatureSet> merged =
+      GetDefaultsImpl("2023", DescriptorPool::generated_pool());
+  ASSERT_OK(merged);
+
+  EXPECT_EQ(merged->field_presence(), FeatureSet::EXPLICIT);
+  EXPECT_FALSE(merged->HasExtension(pb::test));
+  EXPECT_TRUE(merged->HasExtension(pb::cpp));
+  EXPECT_EQ(merged->GetExtension(pb::cpp).utf8_validation(),
+            pb::CppFeatures::VERIFY_PARSE);
+}
+
 TEST(FeatureResolverTest, DefaultsTooEarly) {
   absl::StatusOr<FeatureSet> merged = GetDefaults("2022", pb::test);
   EXPECT_THAT(merged, HasError(AllOf(HasSubstr("No valid default found"),
@@ -278,12 +334,13 @@ TEST(FeatureResolverTest, DefaultsMessageMerge) {
 
 TEST(FeatureResolverTest, InitializePoolMissingDescriptor) {
   DescriptorPool pool;
-  EXPECT_THAT(FeatureResolver::Create("2023", nullptr),
+  EXPECT_THAT(FeatureResolver::Create("2023", nullptr, EmptyPool()),
               HasError(HasSubstr("find definition of google.protobuf.FeatureSet")));
 }
 
 TEST(FeatureResolverTest, RegisterExtensionDifferentContainingType) {
-  auto resolver = FeatureResolver::Create("2023", FeatureSet::descriptor());
+  auto resolver =
+      FeatureResolver::Create("2023", FeatureSet::descriptor(), EmptyPool());
   ASSERT_OK(resolver);
 
   EXPECT_OK(resolver->RegisterExtensions(
@@ -291,7 +348,8 @@ TEST(FeatureResolverTest, RegisterExtensionDifferentContainingType) {
 }
 
 TEST(FeatureResolverTest, RegisterExtensionTwice) {
-  auto resolver = FeatureResolver::Create("2023", FeatureSet::descriptor());
+  auto resolver =
+      FeatureResolver::Create("2023", FeatureSet::descriptor(), EmptyPool());
   ASSERT_OK(resolver);
 
   EXPECT_OK(resolver->RegisterExtensions(GetExtensionFile(pb::test)));
@@ -530,7 +588,7 @@ TEST_F(FeatureResolverPoolTest, RegisterExtensionNonMessage) {
   ASSERT_NE(file, nullptr);
 
   auto resolver = FeatureResolver::Create(
-      "2023", pool_.FindMessageTypeByName("google.protobuf.FeatureSet"));
+      "2023", pool_.FindMessageTypeByName("google.protobuf.FeatureSet"), EmptyPool());
   ASSERT_OK(resolver);
 
   EXPECT_THAT(resolver->RegisterExtensions(*file),
@@ -552,7 +610,7 @@ TEST_F(FeatureResolverPoolTest, RegisterExtensionRepeated) {
   ASSERT_NE(file, nullptr);
 
   auto resolver = FeatureResolver::Create(
-      "2023", pool_.FindMessageTypeByName("google.protobuf.FeatureSet"));
+      "2023", pool_.FindMessageTypeByName("google.protobuf.FeatureSet"), EmptyPool());
   ASSERT_OK(resolver);
 
   EXPECT_THAT(
@@ -582,7 +640,7 @@ TEST_F(FeatureResolverPoolTest, RegisterExtensionWithExtensions) {
   ASSERT_NE(file, nullptr);
 
   auto resolver = FeatureResolver::Create(
-      "2023", pool_.FindMessageTypeByName("google.protobuf.FeatureSet"));
+      "2023", pool_.FindMessageTypeByName("google.protobuf.FeatureSet"), EmptyPool());
   ASSERT_OK(resolver);
 
   EXPECT_THAT(
@@ -615,7 +673,7 @@ TEST_F(FeatureResolverPoolTest, RegisterExtensionWithOneof) {
   ASSERT_NE(file, nullptr);
 
   auto resolver = FeatureResolver::Create(
-      "2023", pool_.FindMessageTypeByName("google.protobuf.FeatureSet"));
+      "2023", pool_.FindMessageTypeByName("google.protobuf.FeatureSet"), EmptyPool());
   ASSERT_OK(resolver);
 
   EXPECT_THAT(resolver->RegisterExtensions(*file),
@@ -642,7 +700,7 @@ TEST_F(FeatureResolverPoolTest, RegisterExtensionWithRequired) {
   ASSERT_NE(file, nullptr);
 
   auto resolver = FeatureResolver::Create(
-      "2023", pool_.FindMessageTypeByName("google.protobuf.FeatureSet"));
+      "2023", pool_.FindMessageTypeByName("google.protobuf.FeatureSet"), EmptyPool());
   ASSERT_OK(resolver);
 
   EXPECT_THAT(resolver->RegisterExtensions(*file),
@@ -669,7 +727,7 @@ TEST_F(FeatureResolverPoolTest, RegisterExtensionWithRepeated) {
   ASSERT_NE(file, nullptr);
 
   auto resolver = FeatureResolver::Create(
-      "2023", pool_.FindMessageTypeByName("google.protobuf.FeatureSet"));
+      "2023", pool_.FindMessageTypeByName("google.protobuf.FeatureSet"), EmptyPool());
   ASSERT_OK(resolver);
 
   EXPECT_THAT(resolver->RegisterExtensions(*file),
@@ -695,7 +753,7 @@ TEST_F(FeatureResolverPoolTest, RegisterExtensionWithMissingTarget) {
   ASSERT_NE(file, nullptr);
 
   auto resolver = FeatureResolver::Create(
-      "2023", pool_.FindMessageTypeByName("google.protobuf.FeatureSet"));
+      "2023", pool_.FindMessageTypeByName("google.protobuf.FeatureSet"), EmptyPool());
   ASSERT_OK(resolver);
 
   EXPECT_THAT(resolver->RegisterExtensions(*file),
@@ -725,7 +783,7 @@ TEST_F(FeatureResolverPoolTest, RegisterExtensionDefaultsMessageParsingError) {
   ASSERT_NE(file, nullptr);
 
   auto resolver = FeatureResolver::Create(
-      "2023", pool_.FindMessageTypeByName("google.protobuf.FeatureSet"));
+      "2023", pool_.FindMessageTypeByName("google.protobuf.FeatureSet"), EmptyPool());
   ASSERT_OK(resolver);
   EXPECT_THAT(
       resolver->RegisterExtensions(*file),
@@ -757,7 +815,7 @@ TEST_F(FeatureResolverPoolTest,
   ASSERT_NE(file, nullptr);
 
   auto resolver = FeatureResolver::Create(
-      "2024", pool_.FindMessageTypeByName("google.protobuf.FeatureSet"));
+      "2024", pool_.FindMessageTypeByName("google.protobuf.FeatureSet"), EmptyPool());
   ASSERT_OK(resolver);
   EXPECT_THAT(
       resolver->RegisterExtensions(*file),
@@ -789,7 +847,7 @@ TEST_F(FeatureResolverPoolTest,
   ASSERT_NE(file, nullptr);
 
   auto resolver = FeatureResolver::Create(
-      "2024", pool_.FindMessageTypeByName("google.protobuf.FeatureSet"));
+      "2024", pool_.FindMessageTypeByName("google.protobuf.FeatureSet"), EmptyPool());
   ASSERT_OK(resolver);
   EXPECT_OK(resolver->RegisterExtensions(*file));
   FeatureSet parent, child;
@@ -815,7 +873,7 @@ TEST_F(FeatureResolverPoolTest, RegisterExtensionDefaultsScalarParsingError) {
   ASSERT_NE(file, nullptr);
 
   auto resolver = FeatureResolver::Create(
-      "2023", pool_.FindMessageTypeByName("google.protobuf.FeatureSet"));
+      "2023", pool_.FindMessageTypeByName("google.protobuf.FeatureSet"), EmptyPool());
   ASSERT_OK(resolver);
   EXPECT_THAT(
       resolver->RegisterExtensions(*file),
@@ -843,13 +901,42 @@ TEST_F(FeatureResolverPoolTest,
   ASSERT_NE(file, nullptr);
 
   auto resolver = FeatureResolver::Create(
-      "2023", pool_.FindMessageTypeByName("google.protobuf.FeatureSet"));
+      "2023", pool_.FindMessageTypeByName("google.protobuf.FeatureSet"), EmptyPool());
   ASSERT_OK(resolver);
   EXPECT_OK(resolver->RegisterExtensions(*file));
   FeatureSet parent, child;
   EXPECT_OK(resolver->MergeFeatures(parent, child));
 }
 
+TEST_F(FeatureResolverPoolTest, GeneratedPoolInvalidExtension) {
+  const FileDescriptor* file = ParseSchema(R"schema(
+    syntax = "proto2";
+    package test;
+    import "google/protobuf/descriptor.proto";
+
+    message Foo {}
+    extend google.protobuf.FeatureSet {
+      optional string bar = 9999;
+    }
+  )schema");
+  ASSERT_NE(file, nullptr);
+
+  EXPECT_THAT(GetDefaultsImpl("2023", &pool_),
+              HasError(AllOf(HasSubstr("test.bar"),
+                             HasSubstr("is not of message type"))));
+}
+
+TEST_F(FeatureResolverPoolTest, GeneratedPoolDefaultsFailure) {
+  ASSERT_NE(
+      pool_.BuildFile(GetProto(google::protobuf::DescriptorProto::descriptor()->file())),
+      nullptr);
+  ASSERT_NE(pool_.BuildFile(GetProto(pb::TestFeatures::descriptor()->file())),
+            nullptr);
+  EXPECT_THAT(
+      GetDefaultsImpl("2022", &pool_),
+      HasError(AllOf(HasSubstr("No valid default found"), HasSubstr("2022"))));
+}
+
 }  // namespace
 }  // namespace protobuf
 }  // namespace google