diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 5721b93..d4a9bcb 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -22,10 +22,10 @@ jobs:
     if: github.event_name == 'push' || github.event.pull_request.head.repo.fork
 
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
 
       - name: Set up PHP
-        uses: 'shivammathur/setup-php@v2'
+        uses: shivammathur/setup-php@accd6127cb78bee3e8082180cb391013d204ef9f # 2.37.0
         with:
           php-version: '8.3'
 
@@ -40,10 +40,10 @@ jobs:
     runs-on: ${{ github.repository == 'stainless-sdks/stagehand-php' && 'depot-ubuntu-24.04' || 'ubuntu-latest' }}
     if: github.event_name == 'push' || github.event.pull_request.head.repo.fork
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
 
       - name: Set up PHP
-        uses: 'shivammathur/setup-php@v2'
+        uses: shivammathur/setup-php@accd6127cb78bee3e8082180cb391013d204ef9f # 2.37.0
         with:
           php-version: '8.3'
 
diff --git a/.github/workflows/publish-packagist.yml b/.github/workflows/publish-packagist.yml
index 6c6f68e..dc56960 100644
--- a/.github/workflows/publish-packagist.yml
+++ b/.github/workflows/publish-packagist.yml
@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
 
       - name: Publish to Packagist
         run: |-
diff --git a/.github/workflows/release-doctor.yml b/.github/workflows/release-doctor.yml
index 1358383..ebc8b13 100644
--- a/.github/workflows/release-doctor.yml
+++ b/.github/workflows/release-doctor.yml
@@ -12,7 +12,7 @@ jobs:
     if: github.repository == 'browserbase/stagehand-php' && (github.event_name == 'push' || github.event_name == 'workflow_dispatch' || startsWith(github.head_ref, 'release-please') || github.head_ref == 'next')
 
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
 
       - name: Check release environment
         run: |
diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index d11c8fc..eba8a04 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,3 +1,3 @@
 {
-  ".": "3.20.0"
+  ".": "3.21.0"
 }
\ No newline at end of file
diff --git a/.stats.yml b/.stats.yml
index 391cde3..0339c57 100644
--- a/.stats.yml
+++ b/.stats.yml
@@ -1,4 +1,4 @@
 configured_endpoints: 8
-openapi_spec_url: https://storage.googleapis.com/stainless-sdk-openapi-specs/browserbase/stagehand-6f6bfb81d092f30a5e2005328c97d61b9ea36132bb19e9e79e55294b9534ce20.yml
-openapi_spec_hash: f3fc1e3688a38dc2c28f7178f7d534e5
+openapi_spec_url: https://storage.googleapis.com/stainless-sdk-openapi-specs/browserbase/stagehand-eae8400fade7b2c8329c4148f56de92e147c34c0feecb420c015aab6544a9acc.yml
+openapi_spec_hash: 0a9eff1ac1d464e89cbd9db64709b08a
 config_hash: 1fb12ae9b478488bc1e56bfbdc210b01
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4ba66f7..0716adb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,18 @@
 # Changelog
 
+## 3.21.0 (2026-05-13)
+
+Full Changelog: [v3.20.0...v3.21.0](https://github.com/browserbase/stagehand-php/compare/v3.20.0...v3.21.0)
+
+### Features
+
+* [feat]: add `ignoreSelectors` to `observe()` ([872590f](https://github.com/browserbase/stagehand-php/commit/872590fe228fd2f0ce70d7cbefdddbf3c22fe147))
+
+
+### Bug Fixes
+
+* guzzle requires special handling to enable streaming ([9d1c43a](https://github.com/browserbase/stagehand-php/commit/9d1c43a1435dc0ba0f66094ffaf4c3e6d463b17a))
+
 ## 3.20.0 (2026-05-06)
 
 Full Changelog: [v3.19.3...v3.20.0](https://github.com/browserbase/stagehand-php/compare/v3.19.3...v3.20.0)
diff --git a/README.md b/README.md
index 574163f..dd7e623 100644
--- a/README.md
+++ b/README.md
@@ -80,7 +80,7 @@ The REST API documentation can be found on [docs.stagehand.dev](https://docs.sta
 <!-- x-release-please-start-version -->
 
 ```
-composer require "browserbase/stagehand 3.20.0"
+composer require "browserbase/stagehand 3.21.0"
 ```
 
 <!-- x-release-please-end -->
@@ -258,6 +258,15 @@ foreach ($stream as $response) {
 }
 ```
 
+Streaming requests are dispatched through a separate `streamingTransporter` PSR-18 HTTP client. When unset, the SDK uses the configured `transporter`.
+Some PSR-18 HTTP clients will by default try to read the entire response, so you may need to specify a streaming capable implementation.
+
+```php
+$client = new Stagehand\Client(
+    requestOptions: Stagehand\RequestOptions::with(streamingTransporter: $myStreamingClient),
+);
+```
+
 ### Handling errors
 
 When the library is unable to connect to the API, or if the API returns a non-success status code (i.e., 4xx or 5xx response), a subclass of `Stagehand\Core\Exceptions\APIException` will be thrown:
diff --git a/composer.json b/composer.json
index 5d324e7..1d6aac5 100644
--- a/composer.json
+++ b/composer.json
@@ -38,6 +38,7 @@
   },
   "require-dev": {
     "friendsofphp/php-cs-fixer": "^3",
+    "guzzlehttp/guzzle": "^7",
     "nyholm/psr7": "^1",
     "pestphp/pest": "^3",
     "php-http/mock-client": "^1",
diff --git a/composer.lock b/composer.lock
index 7a5e63d..b0e2283 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
     "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
     "This file is @generated automatically"
   ],
-  "content-hash": "ffa287ea8babf60e021f37e62c6c207a",
+  "content-hash": "bbae64cb4d21c987158bc3723eda4226",
   "packages": [
     {
       "name": "php-http/discovery",
@@ -968,6 +968,332 @@
       ],
       "time": "2026-01-08T21:57:37+00:00"
     },
+    {
+      "name": "guzzlehttp/guzzle",
+      "version": "7.10.0",
+      "source": {
+        "type": "git",
+        "url": "https://github.com/guzzle/guzzle.git",
+        "reference": "b51ac707cfa420b7bfd4e4d5e510ba8008e822b4"
+      },
+      "dist": {
+        "type": "zip",
+        "url": "https://api.github.com/repos/guzzle/guzzle/zipball/b51ac707cfa420b7bfd4e4d5e510ba8008e822b4",
+        "reference": "b51ac707cfa420b7bfd4e4d5e510ba8008e822b4",
+        "shasum": ""
+      },
+      "require": {
+        "ext-json": "*",
+        "guzzlehttp/promises": "^2.3",
+        "guzzlehttp/psr7": "^2.8",
+        "php": "^7.2.5 || ^8.0",
+        "psr/http-client": "^1.0",
+        "symfony/deprecation-contracts": "^2.2 || ^3.0"
+      },
+      "provide": {
+        "psr/http-client-implementation": "1.0"
+      },
+      "require-dev": {
+        "bamarni/composer-bin-plugin": "^1.8.2",
+        "ext-curl": "*",
+        "guzzle/client-integration-tests": "3.0.2",
+        "php-http/message-factory": "^1.1",
+        "phpunit/phpunit": "^8.5.39 || ^9.6.20",
+        "psr/log": "^1.1 || ^2.0 || ^3.0"
+      },
+      "suggest": {
+        "ext-curl": "Required for CURL handler support",
+        "ext-intl": "Required for Internationalized Domain Name (IDN) support",
+        "psr/log": "Required for using the Log middleware"
+      },
+      "type": "library",
+      "extra": {
+        "bamarni-bin": {
+          "bin-links": true,
+          "forward-command": false
+        }
+      },
+      "autoload": {
+        "files": [
+          "src/functions_include.php"
+        ],
+        "psr-4": {
+          "GuzzleHttp\\": "src/"
+        }
+      },
+      "notification-url": "https://packagist.org/downloads/",
+      "license": [
+        "MIT"
+      ],
+      "authors": [
+        {
+          "name": "Graham Campbell",
+          "email": "hello@gjcampbell.co.uk",
+          "homepage": "https://github.com/GrahamCampbell"
+        },
+        {
+          "name": "Michael Dowling",
+          "email": "mtdowling@gmail.com",
+          "homepage": "https://github.com/mtdowling"
+        },
+        {
+          "name": "Jeremy Lindblom",
+          "email": "jeremeamia@gmail.com",
+          "homepage": "https://github.com/jeremeamia"
+        },
+        {
+          "name": "George Mponos",
+          "email": "gmponos@gmail.com",
+          "homepage": "https://github.com/gmponos"
+        },
+        {
+          "name": "Tobias Nyholm",
+          "email": "tobias.nyholm@gmail.com",
+          "homepage": "https://github.com/Nyholm"
+        },
+        {
+          "name": "Márk Sági-Kazár",
+          "email": "mark.sagikazar@gmail.com",
+          "homepage": "https://github.com/sagikazarmark"
+        },
+        {
+          "name": "Tobias Schultze",
+          "email": "webmaster@tubo-world.de",
+          "homepage": "https://github.com/Tobion"
+        }
+      ],
+      "description": "Guzzle is a PHP HTTP client library",
+      "keywords": [
+        "client",
+        "curl",
+        "framework",
+        "http",
+        "http client",
+        "psr-18",
+        "psr-7",
+        "rest",
+        "web service"
+      ],
+      "support": {
+        "issues": "https://github.com/guzzle/guzzle/issues",
+        "source": "https://github.com/guzzle/guzzle/tree/7.10.0"
+      },
+      "funding": [
+        {
+          "url": "https://github.com/GrahamCampbell",
+          "type": "github"
+        },
+        {
+          "url": "https://github.com/Nyholm",
+          "type": "github"
+        },
+        {
+          "url": "https://tidelift.com/funding/github/packagist/guzzlehttp/guzzle",
+          "type": "tidelift"
+        }
+      ],
+      "time": "2025-08-23T22:36:01+00:00"
+    },
+    {
+      "name": "guzzlehttp/promises",
+      "version": "2.3.0",
+      "source": {
+        "type": "git",
+        "url": "https://github.com/guzzle/promises.git",
+        "reference": "481557b130ef3790cf82b713667b43030dc9c957"
+      },
+      "dist": {
+        "type": "zip",
+        "url": "https://api.github.com/repos/guzzle/promises/zipball/481557b130ef3790cf82b713667b43030dc9c957",
+        "reference": "481557b130ef3790cf82b713667b43030dc9c957",
+        "shasum": ""
+      },
+      "require": {
+        "php": "^7.2.5 || ^8.0"
+      },
+      "require-dev": {
+        "bamarni/composer-bin-plugin": "^1.8.2",
+        "phpunit/phpunit": "^8.5.44 || ^9.6.25"
+      },
+      "type": "library",
+      "extra": {
+        "bamarni-bin": {
+          "bin-links": true,
+          "forward-command": false
+        }
+      },
+      "autoload": {
+        "psr-4": {
+          "GuzzleHttp\\Promise\\": "src/"
+        }
+      },
+      "notification-url": "https://packagist.org/downloads/",
+      "license": [
+        "MIT"
+      ],
+      "authors": [
+        {
+          "name": "Graham Campbell",
+          "email": "hello@gjcampbell.co.uk",
+          "homepage": "https://github.com/GrahamCampbell"
+        },
+        {
+          "name": "Michael Dowling",
+          "email": "mtdowling@gmail.com",
+          "homepage": "https://github.com/mtdowling"
+        },
+        {
+          "name": "Tobias Nyholm",
+          "email": "tobias.nyholm@gmail.com",
+          "homepage": "https://github.com/Nyholm"
+        },
+        {
+          "name": "Tobias Schultze",
+          "email": "webmaster@tubo-world.de",
+          "homepage": "https://github.com/Tobion"
+        }
+      ],
+      "description": "Guzzle promises library",
+      "keywords": [
+        "promise"
+      ],
+      "support": {
+        "issues": "https://github.com/guzzle/promises/issues",
+        "source": "https://github.com/guzzle/promises/tree/2.3.0"
+      },
+      "funding": [
+        {
+          "url": "https://github.com/GrahamCampbell",
+          "type": "github"
+        },
+        {
+          "url": "https://github.com/Nyholm",
+          "type": "github"
+        },
+        {
+          "url": "https://tidelift.com/funding/github/packagist/guzzlehttp/promises",
+          "type": "tidelift"
+        }
+      ],
+      "time": "2025-08-22T14:34:08+00:00"
+    },
+    {
+      "name": "guzzlehttp/psr7",
+      "version": "2.9.0",
+      "source": {
+        "type": "git",
+        "url": "https://github.com/guzzle/psr7.git",
+        "reference": "7d0ed42f28e42d61352a7a79de682e5e67fec884"
+      },
+      "dist": {
+        "type": "zip",
+        "url": "https://api.github.com/repos/guzzle/psr7/zipball/7d0ed42f28e42d61352a7a79de682e5e67fec884",
+        "reference": "7d0ed42f28e42d61352a7a79de682e5e67fec884",
+        "shasum": ""
+      },
+      "require": {
+        "php": "^7.2.5 || ^8.0",
+        "psr/http-factory": "^1.0",
+        "psr/http-message": "^1.1 || ^2.0",
+        "ralouphie/getallheaders": "^3.0"
+      },
+      "provide": {
+        "psr/http-factory-implementation": "1.0",
+        "psr/http-message-implementation": "1.0"
+      },
+      "require-dev": {
+        "bamarni/composer-bin-plugin": "^1.8.2",
+        "http-interop/http-factory-tests": "0.9.0",
+        "jshttp/mime-db": "1.54.0.1",
+        "phpunit/phpunit": "^8.5.44 || ^9.6.25"
+      },
+      "suggest": {
+        "laminas/laminas-httphandlerrunner": "Emit PSR-7 responses"
+      },
+      "type": "library",
+      "extra": {
+        "bamarni-bin": {
+          "bin-links": true,
+          "forward-command": false
+        }
+      },
+      "autoload": {
+        "psr-4": {
+          "GuzzleHttp\\Psr7\\": "src/"
+        }
+      },
+      "notification-url": "https://packagist.org/downloads/",
+      "license": [
+        "MIT"
+      ],
+      "authors": [
+        {
+          "name": "Graham Campbell",
+          "email": "hello@gjcampbell.co.uk",
+          "homepage": "https://github.com/GrahamCampbell"
+        },
+        {
+          "name": "Michael Dowling",
+          "email": "mtdowling@gmail.com",
+          "homepage": "https://github.com/mtdowling"
+        },
+        {
+          "name": "George Mponos",
+          "email": "gmponos@gmail.com",
+          "homepage": "https://github.com/gmponos"
+        },
+        {
+          "name": "Tobias Nyholm",
+          "email": "tobias.nyholm@gmail.com",
+          "homepage": "https://github.com/Nyholm"
+        },
+        {
+          "name": "Márk Sági-Kazár",
+          "email": "mark.sagikazar@gmail.com",
+          "homepage": "https://github.com/sagikazarmark"
+        },
+        {
+          "name": "Tobias Schultze",
+          "email": "webmaster@tubo-world.de",
+          "homepage": "https://github.com/Tobion"
+        },
+        {
+          "name": "Márk Sági-Kazár",
+          "email": "mark.sagikazar@gmail.com",
+          "homepage": "https://sagikazarmark.hu"
+        }
+      ],
+      "description": "PSR-7 message implementation that also provides common utility methods",
+      "keywords": [
+        "http",
+        "message",
+        "psr-7",
+        "request",
+        "response",
+        "stream",
+        "uri",
+        "url"
+      ],
+      "support": {
+        "issues": "https://github.com/guzzle/psr7/issues",
+        "source": "https://github.com/guzzle/psr7/tree/2.9.0"
+      },
+      "funding": [
+        {
+          "url": "https://github.com/GrahamCampbell",
+          "type": "github"
+        },
+        {
+          "url": "https://github.com/Nyholm",
+          "type": "github"
+        },
+        {
+          "url": "https://tidelift.com/funding/github/packagist/guzzlehttp/psr7",
+          "type": "tidelift"
+        }
+      ],
+      "time": "2026-03-10T16:41:02+00:00"
+    },
     {
       "name": "jean85/pretty-package-versions",
       "version": "2.1.1",
@@ -3250,6 +3576,50 @@
       },
       "time": "2021-10-29T13:26:27+00:00"
     },
+    {
+      "name": "ralouphie/getallheaders",
+      "version": "3.0.3",
+      "source": {
+        "type": "git",
+        "url": "https://github.com/ralouphie/getallheaders.git",
+        "reference": "120b605dfeb996808c31b6477290a714d356e822"
+      },
+      "dist": {
+        "type": "zip",
+        "url": "https://api.github.com/repos/ralouphie/getallheaders/zipball/120b605dfeb996808c31b6477290a714d356e822",
+        "reference": "120b605dfeb996808c31b6477290a714d356e822",
+        "shasum": ""
+      },
+      "require": {
+        "php": ">=5.6"
+      },
+      "require-dev": {
+        "php-coveralls/php-coveralls": "^2.1",
+        "phpunit/phpunit": "^5 || ^6.5"
+      },
+      "type": "library",
+      "autoload": {
+        "files": [
+          "src/getallheaders.php"
+        ]
+      },
+      "notification-url": "https://packagist.org/downloads/",
+      "license": [
+        "MIT"
+      ],
+      "authors": [
+        {
+          "name": "Ralph Khattar",
+          "email": "ralph.khattar@gmail.com"
+        }
+      ],
+      "description": "A polyfill for getallheaders.",
+      "support": {
+        "issues": "https://github.com/ralouphie/getallheaders/issues",
+        "source": "https://github.com/ralouphie/getallheaders/tree/develop"
+      },
+      "time": "2019-03-08T08:55:37+00:00"
+    },
     {
       "name": "react/cache",
       "version": "v1.2.0",
@@ -6680,5 +7050,5 @@
   "platform-overrides": {
     "php": "8.3"
   },
-  "plugin-api-version": "2.9.0"
+  "plugin-api-version": "2.6.0"
 }
diff --git a/src/Client.php b/src/Client.php
index c571bb6..5a3ebb0 100644
--- a/src/Client.php
+++ b/src/Client.php
@@ -7,6 +7,7 @@
 use Http\Discovery\Psr17FactoryDiscovery;
 use Http\Discovery\Psr18ClientDiscovery;
 use Stagehand\Core\BaseClient;
+use Stagehand\Core\Implementation\StreamingHttpClient;
 use Stagehand\Core\Util;
 use Stagehand\Services\SessionsService;
 
@@ -63,6 +64,11 @@ public function __construct(
             $requestOptions,
         );
 
+        if (is_null($options->streamingTransporter)) {
+            assert(!is_null($options->transporter));
+            $options->streamingTransporter = new StreamingHttpClient($options->transporter);
+        }
+
         /** @var array<string, string|null> $headers */
         $headers = [
             'Content-Type' => 'application/json',
diff --git a/src/Core/BaseClient.php b/src/Core/BaseClient.php
index 98f540d..29e21ec 100644
--- a/src/Core/BaseClient.php
+++ b/src/Core/BaseClient.php
@@ -241,11 +241,15 @@ protected function sendRequest(
         $req = $req->withHeader('X-Stainless-Retry-Count', strval($retryCount));
         $req = Util::withSetBody($opts->streamFactory, req: $req, body: $data);
 
+        $transporter = Util::isStreamingRequest($req)
+            ? ($opts->streamingTransporter ?? $opts->transporter)
+            : $opts->transporter;
+
         $rsp = null;
         $err = null;
 
         try {
-            $rsp = $opts->transporter->sendRequest($req);
+            $rsp = $transporter->sendRequest($req);
         } catch (ClientExceptionInterface $e) {
             $err = $e;
         }
diff --git a/src/Core/FileParam.php b/src/Core/FileParam.php
index bc52309..5924990 100644
--- a/src/Core/FileParam.php
+++ b/src/Core/FileParam.php
@@ -41,7 +41,7 @@ public static function fromResource(mixed $resource, ?string $filename = null, s
             throw new \InvalidArgumentException('Expected a resource, got '.get_debug_type($resource));
         }
 
-        if (null === $filename) {
+        if (is_null($filename)) {
             $meta = stream_get_meta_data($resource);
             $filename = basename($meta['uri'] ?? 'upload');
         }
diff --git a/src/Core/Implementation/StreamingHttpClient.php b/src/Core/Implementation/StreamingHttpClient.php
new file mode 100644
index 0000000..fcc7983
--- /dev/null
+++ b/src/Core/Implementation/StreamingHttpClient.php
@@ -0,0 +1,29 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Stagehand\Core\Implementation;
+
+use Psr\Http\Client\ClientInterface;
+use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\ResponseInterface;
+
+/**
+ * @internal
+ *
+ * Wraps a PSR-18 client and produces a response with a non-buffered body when
+ * the underlying client requires an opt-in for streaming
+ */
+final class StreamingHttpClient implements ClientInterface
+{
+    public function __construct(private ClientInterface $inner) {}
+
+    public function sendRequest(RequestInterface $request): ResponseInterface
+    {
+        if (is_a($this->inner, '\GuzzleHttp\Client')) {
+            return $this->inner->send($request, ['stream' => true]);
+        }
+
+        return $this->inner->sendRequest($request);
+    }
+}
diff --git a/src/Core/Util.php b/src/Core/Util.php
index 19a90c3..1285cc0 100644
--- a/src/Core/Util.php
+++ b/src/Core/Util.php
@@ -25,6 +25,8 @@ final class Util
 
     public const JSONL_CONTENT_TYPE = '/^application\/(:?x-(?:n|l)djson)|(:?(?:x-)?jsonl)/';
 
+    public const STREAMING_CONTENT_TYPE = ['/^text\/event-stream/', self::JSONL_CONTENT_TYPE];
+
     public static function getenv(string $key): ?string
     {
         if (array_key_exists($key, array: $_ENV)) {
@@ -217,6 +219,16 @@ public static function joinUri(
         return $base->withQuery($qs);
     }
 
+    public static function isStreamingRequest(RequestInterface $request): bool
+    {
+        $accept = $request->getHeaderLine('Accept');
+
+        return !empty(array_filter(
+            self::STREAMING_CONTENT_TYPE,
+            static fn (string $pattern) => (bool) preg_match($pattern, subject: $accept),
+        ));
+    }
+
     /**
      * @param array<string,string|int|list<string|int>|null> $headers
      */
diff --git a/src/RequestOptions.php b/src/RequestOptions.php
index 3c8fbd0..4aea98b 100644
--- a/src/RequestOptions.php
+++ b/src/RequestOptions.php
@@ -23,6 +23,7 @@
  *   extraQueryParams?: array<string,mixed>|null,
  *   extraBodyParams?: mixed,
  *   transporter?: ClientInterface|null,
+ *   streamingTransporter?: ClientInterface|null,
  *   uriFactory?: UriFactoryInterface|null,
  *   streamFactory?: StreamFactoryInterface|null,
  *   requestFactory?: RequestFactoryInterface|null,
@@ -60,6 +61,9 @@ final class RequestOptions implements BaseModel
     #[Optional]
     public ?ClientInterface $transporter;
 
+    #[Optional]
+    public ?ClientInterface $streamingTransporter;
+
     #[Optional]
     public ?UriFactoryInterface $uriFactory;
 
@@ -98,6 +102,7 @@ public static function with(
         ?array $extraQueryParams = null,
         mixed $extraBodyParams = null,
         ?ClientInterface $transporter = null,
+        ?ClientInterface $streamingTransporter = null,
         ?UriFactoryInterface $uriFactory = null,
         ?StreamFactoryInterface $streamFactory = null,
         ?RequestFactoryInterface $requestFactory = null,
@@ -114,6 +119,9 @@ public static function with(
         null !== $extraQueryParams && $self->extraQueryParams = $extraQueryParams;
         null !== $extraBodyParams && $self->extraBodyParams = $extraBodyParams;
         null !== $transporter && $self->transporter = $transporter;
+        null !== $streamingTransporter && $self
+            ->streamingTransporter = $streamingTransporter
+        ;
         null !== $uriFactory && $self->uriFactory = $uriFactory;
         null !== $streamFactory && $self->streamFactory = $streamFactory;
         null !== $requestFactory && $self->requestFactory = $requestFactory;
@@ -191,6 +199,15 @@ public function withTransporter(ClientInterface $transporter): self
         return $self;
     }
 
+    public function withStreamingTransporter(
+        ClientInterface $streamingTransporter
+    ): self {
+        $self = clone $this;
+        $self->streamingTransporter = $streamingTransporter;
+
+        return $self;
+    }
+
     public function withUriFactory(UriFactoryInterface $uriFactory): self
     {
         $self = clone $this;
diff --git a/src/Sessions/SessionObserveParams/Options.php b/src/Sessions/SessionObserveParams/Options.php
index 02bc11c..5130e30 100644
--- a/src/Sessions/SessionObserveParams/Options.php
+++ b/src/Sessions/SessionObserveParams/Options.php
@@ -17,6 +17,7 @@
  * @phpstan-import-type VariableShape from \Stagehand\Sessions\SessionObserveParams\Options\Variable
  *
  * @phpstan-type OptionsShape = array{
+ *   ignoreSelectors?: list<string>|null,
  *   model?: ModelShape|null,
  *   selector?: string|null,
  *   timeout?: float|null,
@@ -28,6 +29,14 @@ final class Options implements BaseModel
     /** @use SdkModel<OptionsShape> */
     use SdkModel;
 
+    /**
+     * Selectors for elements and subtrees that should be excluded from observation.
+     *
+     * @var list<string>|null $ignoreSelectors
+     */
+    #[Optional(list: 'string')]
+    public ?array $ignoreSelectors;
+
     /**
      * Model configuration object or model name string (e.g., 'openai/gpt-5-nano').
      *
@@ -66,10 +75,12 @@ public function __construct()
      *
      * You must use named parameters to construct any parameters with a default value.
      *
+     * @param list<string>|null $ignoreSelectors
      * @param ModelShape|null $model
      * @param array<string,VariableShape>|null $variables
      */
     public static function with(
+        ?array $ignoreSelectors = null,
         string|ModelConfig|array|null $model = null,
         ?string $selector = null,
         ?float $timeout = null,
@@ -77,6 +88,7 @@ public static function with(
     ): self {
         $self = new self;
 
+        null !== $ignoreSelectors && $self['ignoreSelectors'] = $ignoreSelectors;
         null !== $model && $self['model'] = $model;
         null !== $selector && $self['selector'] = $selector;
         null !== $timeout && $self['timeout'] = $timeout;
@@ -85,6 +97,19 @@ public static function with(
         return $self;
     }
 
+    /**
+     * Selectors for elements and subtrees that should be excluded from observation.
+     *
+     * @param list<string> $ignoreSelectors
+     */
+    public function withIgnoreSelectors(array $ignoreSelectors): self
+    {
+        $self = clone $this;
+        $self['ignoreSelectors'] = $ignoreSelectors;
+
+        return $self;
+    }
+
     /**
      * Model configuration object or model name string (e.g., 'openai/gpt-5-nano').
      *
diff --git a/src/Version.php b/src/Version.php
index 7c36484..b10e37c 100644
--- a/src/Version.php
+++ b/src/Version.php
@@ -5,5 +5,5 @@
 namespace Stagehand;
 
 // x-release-please-start-version
-const VERSION = '3.20.0';
+const VERSION = '3.21.0';
 // x-release-please-end
diff --git a/tests/Core/StreamingTransportTest.php b/tests/Core/StreamingTransportTest.php
new file mode 100644
index 0000000..0f3e046
--- /dev/null
+++ b/tests/Core/StreamingTransportTest.php
@@ -0,0 +1,122 @@
+<?php
+
+namespace Tests\Core;
+
+use Http\Discovery\Psr17FactoryDiscovery;
+use Http\Mock\Client as MockClient;
+use PHPUnit\Framework\Attributes\CoversNothing;
+use PHPUnit\Framework\Attributes\Test;
+use PHPUnit\Framework\TestCase;
+use Psr\Http\Message\ResponseInterface;
+use Stagehand\Core\BaseClient;
+use Stagehand\Core\Util;
+use Stagehand\RequestOptions;
+
+/**
+ * @internal
+ *
+ * @coversNothing
+ */
+#[CoversNothing]
+class StreamingTransportTest extends TestCase
+{
+    #[Test]
+    public function testIsStreamingRequestTable(): void
+    {
+        $factory = Psr17FactoryDiscovery::findRequestFactory();
+        $cases = [
+            'text/event-stream' => true,
+            'application/x-ndjson' => true,
+            'application/x-ldjson' => true,
+            'application/jsonl' => true,
+            'application/x-jsonl' => true,
+            'text/event-stream; charset=utf-8' => true,
+            'application/json' => false,
+            'text/plain' => false,
+            '' => false,
+        ];
+
+        foreach ($cases as $accept => $expected) {
+            $req = $factory->createRequest('GET', 'http://localhost');
+            if ('' !== $accept) {
+                $req = $req->withHeader('Accept', $accept);
+            }
+            $this->assertSame(
+                $expected,
+                Util::isStreamingRequest($req),
+                "Accept: '{$accept}'",
+            );
+        }
+    }
+
+    #[Test]
+    public function testRoutesNonStreamingRequestToTransporter(): void
+    {
+        [$client, $plain, $streaming] = $this->buildClient();
+
+        $client->request('GET', '/');
+
+        $this->assertCount(1, $plain->getRequests());
+        $this->assertCount(0, $streaming->getRequests());
+    }
+
+    #[Test]
+    public function testRoutesStreamingRequestToStreamingTransporter(): void
+    {
+        [$client, $plain, $streaming] = $this->buildClient();
+
+        $client->request('GET', '/', headers: ['Accept' => 'text/event-stream']);
+
+        $this->assertCount(0, $plain->getRequests());
+        $this->assertCount(1, $streaming->getRequests());
+
+        $sent = $streaming->getRequests()[0];
+        $this->assertStringContainsString('text/event-stream', $sent->getHeaderLine('Accept'));
+    }
+
+    /**
+     * @return array{BaseClient, MockClient, MockClient}
+     */
+    private function buildClient(): array
+    {
+        $plain = new MockClient;
+        $plain->setDefaultResponse($this->jsonResponse());
+
+        $streaming = new MockClient;
+        $streaming->setDefaultResponse($this->sseResponse());
+
+        $options = RequestOptions::with(
+            transporter: $plain,
+            streamingTransporter: $streaming,
+            uriFactory: Psr17FactoryDiscovery::findUriFactory(),
+            requestFactory: Psr17FactoryDiscovery::findRequestFactory(),
+            streamFactory: Psr17FactoryDiscovery::findStreamFactory(),
+        );
+
+        $client = new class(headers: [], baseUrl: 'http://localhost', options: $options) extends BaseClient {};
+
+        return [$client, $plain, $streaming];
+    }
+
+    private function jsonResponse(): ResponseInterface
+    {
+        $responseFactory = Psr17FactoryDiscovery::findResponseFactory();
+        $streamFactory = Psr17FactoryDiscovery::findStreamFactory();
+
+        return $responseFactory->createResponse(200)
+            ->withHeader('Content-Type', 'application/json')
+            ->withBody($streamFactory->createStream('{}'))
+        ;
+    }
+
+    private function sseResponse(): ResponseInterface
+    {
+        $responseFactory = Psr17FactoryDiscovery::findResponseFactory();
+        $streamFactory = Psr17FactoryDiscovery::findStreamFactory();
+
+        return $responseFactory->createResponse(200)
+            ->withHeader('Content-Type', 'text/event-stream')
+            ->withBody($streamFactory->createStream(''))
+        ;
+    }
+}