diff --git a/seed/php-sdk/unions/src/Union/Types/Shape.php b/seed/php-sdk/unions/src/Union/Types/Shape.php
new file mode 100644
index 00000000000..d988fc3a13c
--- /dev/null
+++ b/seed/php-sdk/unions/src/Union/Types/Shape.php
@@ -0,0 +1,93 @@
+<?php
+
+use Seed\Core\Json\JsonSerializableType;
+use Seed\Union\Types\Circle;
+use Seed\Union\Square;
+
+class Shape extends JsonSerializableType
+{
+    /**
+     * @var 'circle'|'square'|'_unknown' $type 
+     */
+    public string $type;
+
+    /**
+     * @var ?Circle $circle
+     */
+    public ?Circle $circle;
+
+    /**
+     * @var ?Square $square
+     */
+    public ?Square $square;
+
+    /**
+     * @var ?object $_unknown
+     */
+    public ?object $_unknown;
+
+    /**
+     * @param ?array{
+     *   type?: 'circle'|'square'|'_unknown',
+     *   circle?: ?Circle,
+     *   square?: ?Square,
+     *   _unknown?: ?object,
+     * } $options
+     */
+    private function __construct(
+        private readonly ?array $options = null,
+    ) {
+        $this->type = $this->options['type'] ?? '_unknown';
+        $this->circle = $this->options['circle'] ?? null;
+        $this->square = $this->options['square'] ?? null;
+        $this->_unknown = $this->options['_unknown'] ?? null;
+    }
+
+    public static function circle(
+        Circle $circle
+    ): Shape {
+        return new Shape([
+            'type' => 'circle',
+            'circle' => $circle
+        ]);
+    }
+
+    public static function square(
+        Square $square
+    ): Shape {
+        return new Shape([
+            'type' => 'square',
+            'square' => $square
+        ]);
+    }
+
+    public static function _unknown(
+        mixed $_unknown
+    ): Shape {
+        return new Shape([
+            'unknown' => $_unknown
+        ]);
+    }
+
+    public function asCircle(): Circle
+    {
+        if ($this->type == 'circle') {
+            return $this->circle;
+        } else {
+            throw new \Exception(
+                "Expected type to be 'circle'; got '$this->type.'"
+            );
+        }
+    }
+
+    public function asSquare(): Square
+    {
+        if ($this->type == 'square') {
+            return $this->square;
+        } else {
+            throw new \Exception(
+                "Expected type to be 'square'; got '$this->type.'"
+            );
+        }
+    }
+}
diff --git a/seed/php-sdk/unions/src/Union/UnionClient.php b/seed/php-sdk/unions/src/Union/UnionClient.php
index 70e8f419c9b..9a7d63d159a 100644
--- a/seed/php-sdk/unions/src/Union/UnionClient.php
+++ b/seed/php-sdk/unions/src/Union/UnionClient.php
@@ -10,6 +10,7 @@
 use Seed\Core\Json\JsonDecoder;
 use JsonException;
 use Psr\Http\Client\ClientExceptionInterface;
+use Shape;
 
 class UnionClient
 {
@@ -36,7 +37,7 @@ public function __construct(
      * @throws SeedException
      * @throws SeedApiException
      */
-    public function get(string $id, ?array $options = null): mixed
+    public function get(string $id, ?array $options = null): Shape
     {
         try {
             $response = $this->client->sendRequest(
@@ -49,7 +50,7 @@ public function get(string $id, ?array $options = null): mixed
             $statusCode = $response->getStatusCode();
             if ($statusCode >= 200 && $statusCode < 400) {
                 $json = $response->getBody()->getContents();
-                return JsonDecoder::decodeMixed($json);
+                return Shape::fromJson($json);
             }
         } catch (JsonException $e) {
             throw new SeedException(message: "Failed to deserialize response: {$e->getMessage()}", previous: $e);
@@ -72,7 +73,7 @@ public function get(string $id, ?array $options = null): mixed
      * @throws SeedException
      * @throws SeedApiException
      */
-    public function update(mixed $request, ?array $options = null): bool
+    public function update(Shape $request, ?array $options = null): bool
     {
         try {
             $response = $this->client->sendRequest(
diff --git a/seed/php-sdk/unions/tests/Seed/Core/Client/RawClientTest.php b/seed/php-sdk/unions/tests/Seed/Core/Client/RawClientTest.php
index a1052cff3a5..8a99911eb73 100644
--- a/seed/php-sdk/unions/tests/Seed/Core/Client/RawClientTest.php
+++ b/seed/php-sdk/unions/tests/Seed/Core/Client/RawClientTest.php
@@ -12,12 +12,16 @@
 use Seed\Core\Client\HttpMethod;
 use Seed\Core\Client\RawClient;
 use Seed\Core\Json\JsonApiRequest;
+use Seed\Union\Types\Circle;
+use Seed\Union\UnionClient;
+use Shape;
 
 class RawClientTest extends TestCase
 {
     private string $baseUrl = 'https://api.example.com';
     private MockHandler $mockHandler;
     private RawClient $rawClient;
+    private UnionClient $unionClient;
 
     protected function setUp(): void
     {
@@ -25,6 +29,7 @@ protected function setUp(): void
         $handlerStack = HandlerStack::create($this->mockHandler);
         $client = new Client(['handler' => $handlerStack]);
         $this->rawClient = new RawClient(['client' => $client]);
+        $this->unionClient = new UnionClient($this->rawClient);
     }
 
     public function testHeaders(): void
@@ -98,4 +103,27 @@ private function sendRequest(BaseApiRequest $request): void
             $this->fail('An exception was thrown: ' . $e->getMessage());
         }
     }
+
+    private function useShapeResponse(): void
+    {
+        try {
+            $shape = $this->unionClient->get("circle");
+            $this->assertEquals($shape->type, "circle");
+            $circle = $shape->circle;
+            $this->assertEquals($circle->radius, 1.0);
+        } catch (\Throwable $e) {
+            $this->fail('An exception was thrown: ' . $e->getMessage());
+        }
+    }
+
+    private function useShapeRequest(): void
+    {
+        try {
+            $shape = Shape::circle(new Circle(['radius' => 1.0]));
+            $success = $this->unionClient->update($shape);
+            $this->assertEquals($success, true);
+        } catch (\Throwable $e) {
+            $this->fail('An exception was thrown: ' . $e->getMessage());
+        }
+    }
 }