feat(php): add support for deep object query parameters

generators/php/base/src/asIs/Client/RawClient.Template.php

@@ -252,17 +252,46 @@ private function buildUrl(
      */
     private function encodeQuery(array $query): string
     {
+        $flatParams = $this->flattenQueryParams($query);
         $parts = [];
-        foreach ($query as $key => $value) {
-            if (is_array($value)) {
+        foreach ($flatParams as [$key, $value]) {
+            $parts[] = urlencode($key) . '=' . $this->encodeQueryValue($value);
+        }
+        return implode('&', $parts);
+    }
+
+    /**
+     * Recursively flattens nested arrays into query parameter format with bracket notation.
+     * For example: ['filter' => ['name' => 'john']] becomes [['filter[name]', 'john']]
+     *
+     * @param array<string, mixed> $data
+     * @param string|null $keyPrefix
+     * @return array<array{string, mixed}>
+     */
+    private function flattenQueryParams(array $data, ?string $keyPrefix = null): array
+    {
+        $result = [];
+        foreach ($data as $key => $value) {
+            $fullKey = $keyPrefix !== null ? "{$keyPrefix}[{$key}]" : (string)$key;
+
+            if (is_array($value) && !empty($value) && !self::isSequential($value)) {
+                // Associative array (object-like) - recurse with bracket notation
+                $result = array_merge($result, $this->flattenQueryParams($value, $fullKey));
+            } elseif (is_array($value)) {
+                // Sequential array - each item gets the same key (exploded)
                 foreach ($value as $item) {
-                    $parts[] = urlencode($key) . '=' . $this->encodeQueryValue($item);
+                    if (is_array($item) && !empty($item) && !self::isSequential($item)) {
+                        // Array of objects
+                        $result = array_merge($result, $this->flattenQueryParams($item, $fullKey));
+                    } else {
+                        $result[] = [$fullKey, $item];
+                    }
                 }
             } else {
-                $parts[] = urlencode($key) . '=' . $this->encodeQueryValue($value);
+                $result[] = [$fullKey, $value];
             }
         }
-        return implode('&', $parts);
+        return $result;
     }
 
     private function encodeQueryValue(mixed $value): string

generators/php/base/src/asIs/Client/RawClientTest.Template.php

@@ -667,4 +667,79 @@ public function testMaxDelayCapIsApplied(): void
         $this->assertGreaterThanOrEqual(60000, $delay);
         $this->assertLessThanOrEqual(72000, $delay);
     }
+
+    /**
+     * @throws ClientExceptionInterface
+     */
+    public function testDeepObjectQueryParameters(): void
+    {
+        $this->mockHandler->append(new Response(200));
+
+        $request = new JsonApiRequest(
+            $this->baseUrl,
+            '/test',
+            HttpMethod::GET,
+            [],
+            ['filter' => ['name' => 'john', 'age' => 30]]
+        );
+
+        $this->rawClient->sendRequest($request);
+
+        $lastRequest = $this->mockHandler->getLastRequest();
+        assert($lastRequest instanceof RequestInterface);
+        $this->assertEquals(
+            'https://api.example.com/test?filter%5Bname%5D=john&filter%5Bage%5D=30',
+            (string)$lastRequest->getUri()
+        );
+    }
+
+    /**
+     * @throws ClientExceptionInterface
+     */
+    public function testDeeplyNestedObjectQueryParameters(): void
+    {
+        $this->mockHandler->append(new Response(200));
+
+        $request = new JsonApiRequest(
+            $this->baseUrl,
+            '/test',
+            HttpMethod::GET,
+            [],
+            ['filter' => ['user' => ['name' => 'john', 'role' => 'admin'], 'status' => 'active']]
+        );
+
+        $this->rawClient->sendRequest($request);
+
+        $lastRequest = $this->mockHandler->getLastRequest();
+        assert($lastRequest instanceof RequestInterface);
+        $this->assertEquals(
+            'https://api.example.com/test?filter%5Buser%5D%5Bname%5D=john&filter%5Buser%5D%5Brole%5D=admin&filter%5Bstatus%5D=active',
+            (string)$lastRequest->getUri()
+        );
+    }
+
+    /**
+     * @throws ClientExceptionInterface
+     */
+    public function testArrayOfObjectsQueryParameters(): void
+    {
+        $this->mockHandler->append(new Response(200));
+
+        $request = new JsonApiRequest(
+            $this->baseUrl,
+            '/test',
+            HttpMethod::GET,
+            [],
+            ['objects' => [['key' => 'hello', 'value' => 'world'], ['key' => 'foo', 'value' => 'bar']]]
+        );
+
+        $this->rawClient->sendRequest($request);
+
+        $lastRequest = $this->mockHandler->getLastRequest();
+        assert($lastRequest instanceof RequestInterface);
+        $this->assertEquals(
+            'https://api.example.com/test?objects%5Bkey%5D=hello&objects%5Bvalue%5D=world&objects%5Bkey%5D=foo&objects%5Bvalue%5D=bar',
+            (string)$lastRequest->getUri()
+        );
+    }
 }

generators/php/sdk/versions.yml

@@ -1,5 +1,13 @@
 # yaml-language-server: $schema=../../../fern-versions-yml.schema.json
 
+- version: 1.26.0
+  changelogEntry:
+    - summary: |
+        Add support for deep object query parameters. Nested objects in query parameters are now encoded using bracket notation (e.g., `filter[user][name]=john&filter[user][age]=30`). This matches the OpenAPI 3.0 deepObject serialization style and is consistent with Python, Java, and C# generators.
+      type: feat
+  createdAt: "2026-01-26"
+  irVersion: 62
+
 - version: 1.25.4
   changelogEntry:
     - summary: |