diff --git a/README.md b/README.md
index 81405e6..883240f 100644
--- a/README.md
+++ b/README.md
@@ -166,7 +166,8 @@ enum-bearing branch without requiring consumers to inspect the union shape:
 use Utopia\OpenAPI\Model\CompositeSchema;
 
 if ($schema instanceof CompositeSchema) {
-    $suggestedValues = $schema->openStringEnumBranch()?->enum ?? [];
+    $enumBranch = $schema->openStringEnumBranch();
+    $suggestedValues = $enumBranch?->enum ?? [];
 }
 ```
 
diff --git a/src/Model/CompositeSchema.php b/src/Model/CompositeSchema.php
index 78d3de8..b326543 100644
--- a/src/Model/CompositeSchema.php
+++ b/src/Model/CompositeSchema.php
@@ -6,10 +6,13 @@
 
 final readonly class CompositeSchema extends Schema
 {
+    /** @var list<Schema> */
+    public array $schemas;
+
     /** @param list<Schema> $schemas */
     public function __construct(
         public ?Composition $composition,
-        public array $schemas = [],
+        array $schemas = [],
         public ?Schema $not = null,
         public ?Discriminator $discriminator = null,
         ?string $title = null,
@@ -24,6 +27,32 @@ public function __construct(
         mixed $example = null,
         array $extensions = [],
     ) {
+        $openEnumIndex = self::openStringEnumBranchIndex($composition, $schemas);
+        if ($openEnumIndex !== null) {
+            /** @var StringSchema $enumBranch */
+            $enumBranch = $schemas[$openEnumIndex];
+            $schemas[$openEnumIndex] = new StringSchema(
+                minLength: $enumBranch->minLength,
+                maxLength: $enumBranch->maxLength,
+                pattern: $enumBranch->pattern,
+                title: $enumBranch->title,
+                description: $enumBranch->description,
+                nullable: $enumBranch->nullable,
+                default: $enumBranch->default,
+                enum: $enumBranch->enum,
+                format: $enumBranch->format,
+                readOnly: $enumBranch->readOnly,
+                writeOnly: $enumBranch->writeOnly,
+                deprecated: $enumBranch->deprecated,
+                example: $enumBranch->example,
+                extensions: $enumBranch->extensions,
+                enumName: $enumBranch->enumName,
+                enumKeys: $enumBranch->enumKeys,
+                open: true,
+            );
+        }
+        $this->schemas = $schemas;
+
         parent::__construct($title, $description, $nullable, $default, $enum, $format, $readOnly, $writeOnly, $deprecated, $example, $extensions);
     }
 
@@ -35,14 +64,22 @@ public function __construct(
      */
     public function openStringEnumBranch(): ?StringSchema
     {
-        if ($this->composition !== Composition::ANY_OF) {
+        $index = self::openStringEnumBranchIndex($this->composition, $this->schemas);
+
+        return $index === null ? null : $this->schemas[$index];
+    }
+
+    /** @param list<Schema> $schemas */
+    private static function openStringEnumBranchIndex(?Composition $composition, array $schemas): ?int
+    {
+        if ($composition !== Composition::ANY_OF) {
             return null;
         }
 
-        $enumBranch = null;
+        $enumBranchIndex = null;
         $hasOpenBranch = false;
 
-        foreach ($this->schemas as $schema) {
+        foreach ($schemas as $index => $schema) {
             if (! $schema instanceof StringSchema) {
                 return null;
             }
@@ -53,13 +90,13 @@ public function openStringEnumBranch(): ?StringSchema
                 continue;
             }
 
-            if ($enumBranch !== null) {
+            if ($enumBranchIndex !== null) {
                 return null;
             }
 
-            $enumBranch = $schema;
+            $enumBranchIndex = $index;
         }
 
-        return $hasOpenBranch ? $enumBranch : null;
+        return $hasOpenBranch ? $enumBranchIndex : null;
     }
 }
diff --git a/src/Model/StringSchema.php b/src/Model/StringSchema.php
index 906b554..c984677 100644
--- a/src/Model/StringSchema.php
+++ b/src/Model/StringSchema.php
@@ -6,6 +6,7 @@
 
 final readonly class StringSchema extends Schema
 {
+    /** @param list<string> $enumKeys */
     public function __construct(
         public ?int $minLength = null,
         public ?int $maxLength = null,
@@ -21,6 +22,9 @@ public function __construct(
         bool $deprecated = false,
         mixed $example = null,
         array $extensions = [],
+        public ?string $enumName = null,
+        public array $enumKeys = [],
+        public bool $open = false,
     ) {
         parent::__construct($title, $description, $nullable, $default, $enum, $format, $readOnly, $writeOnly, $deprecated, $example, $extensions);
     }
diff --git a/src/Parser/Schema/Reader.php b/src/Parser/Schema/Reader.php
index 08663c5..fdce161 100644
--- a/src/Parser/Schema/Reader.php
+++ b/src/Parser/Schema/Reader.php
@@ -116,6 +116,8 @@ public function read(mixed $raw, string $location): Schema
                 default: $common['default'], enum: $common['enum'], readOnly: $common['readOnly'],
                 writeOnly: $common['writeOnly'], deprecated: $common['deprecated'], example: $common['example'],
                 extensions: $common['extensions'],
+                enumName: Value::optionalString($data, 'x-enum-name'),
+                enumKeys: isset($data['x-enum-keys']) ? Value::stringList($data['x-enum-keys'], "{$location}/x-enum-keys") : [],
             ),
             'integer' => $this->integer($data, $location, $common),
             'number' => $this->number($data, $location, $common),
diff --git a/src/Parser/Value.php b/src/Parser/Value.php
index fc3d7f5..075c4bc 100644
--- a/src/Parser/Value.php
+++ b/src/Parser/Value.php
@@ -35,6 +35,19 @@ public static function list(mixed $value, string $location): array
         return $value;
     }
 
+    /** @return list<string> */
+    public static function stringList(mixed $value, string $location): array
+    {
+        $values = self::list($value, $location);
+        foreach ($values as $index => $item) {
+            if (! is_string($item)) {
+                throw new InvalidSpecification("Expected string at {$location}/{$index}");
+            }
+        }
+
+        return $values;
+    }
+
     /** @param array<string, mixed> $data */
     public static function requiredString(array $data, string $key, string $location): string
     {
diff --git a/tests/Schema/ReaderTest.php b/tests/Schema/ReaderTest.php
index 142db9d..fc7c75f 100644
--- a/tests/Schema/ReaderTest.php
+++ b/tests/Schema/ReaderTest.php
@@ -108,14 +108,24 @@ public function test_composition_and_not(): void
     public function test_open_string_enum_branch_is_exposed_regardless_of_branch_order(): void
     {
         $reader = $this->reader(Version::V3_0);
-        $enum = ['type' => 'string', 'enum' => ['network.requests', 'network.inbound']];
+        $enum = [
+            'type' => 'string',
+            'enum' => ['network.requests', 'network.inbound'],
+            'x-enum-name' => 'UsageEventMetric',
+            'x-enum-keys' => ['NetworkRequests', 'NetworkInbound'],
+        ];
         $open = ['type' => 'string'];
 
         foreach ([[$enum, $open], [$open, $enum]] as $branches) {
             $schema = $reader->read(['anyOf' => $branches], '#/x');
 
             self::assertInstanceOf(CompositeSchema::class, $schema);
-            self::assertSame(['network.requests', 'network.inbound'], $schema->openStringEnumBranch()?->enum);
+            $enumBranch = $schema->openStringEnumBranch();
+            self::assertSame(['network.requests', 'network.inbound'], $enumBranch?->enum);
+            self::assertSame('UsageEventMetric', $enumBranch?->enumName);
+            self::assertSame(['NetworkRequests', 'NetworkInbound'], $enumBranch?->enumKeys);
+            self::assertTrue($enumBranch?->open);
+            self::assertFalse($schema->schemas[$enumBranch === $schema->schemas[0] ? 1 : 0]->open);
         }
     }
 
diff --git a/tests/ValueTest.php b/tests/ValueTest.php
index 87ea0ad..4f6f25e 100644
--- a/tests/ValueTest.php
+++ b/tests/ValueTest.php
@@ -52,6 +52,15 @@ public function test_list_rejects_maps_and_scalars(): void
         }
     }
 
+    public function test_string_list_rejects_non_string_items(): void
+    {
+        self::assertSame(['first', 'second'], Value::stringList(['first', 'second'], '#/x-enum-keys'));
+
+        $this->expectException(InvalidSpecification::class);
+        $this->expectExceptionMessage('Expected string at #/x-enum-keys/1');
+        Value::stringList(['first', 2], '#/x-enum-keys');
+    }
+
     public function test_required_string_names_the_missing_key(): void
     {
         self::assertSame('Pets', Value::requiredString(['title' => 'Pets'], 'title', '#/info'));