diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index 9aa540f7..6b7b74c5 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,3 +1,3 @@
 {
-  ".": "0.2.4"
+  ".": "0.3.0"
 }
\ No newline at end of file
diff --git a/.stats.yml b/.stats.yml
index b120b664..93fe5d17 100644
--- a/.stats.yml
+++ b/.stats.yml
@@ -1,4 +1,4 @@
 configured_endpoints: 7
-openapi_spec_url: https://storage.googleapis.com/stainless-sdk-openapi-specs/browserbase%2Fstagehand-39cd9547d16412cf0568f6ce2ad8d43805dffe65bde830beeff630b903ae3b38.yml
-openapi_spec_hash: 9cd7c9fefa686f9711392782d948470f
-config_hash: 3c21550e2c94cad4339d3093d794beb0
+openapi_spec_url: https://storage.googleapis.com/stainless-sdk-openapi-specs/browserbase%2Fstagehand-119383e808f394a7676e901bac8b97b6d7402d187d03452fd8d62b31d4085580.yml
+openapi_spec_hash: 8a8d7be19d95f849098690863fe9a71a
+config_hash: 1f709f8775e13029dc60064ef3a94355
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 989b483e..297a5680 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,14 @@
 # Changelog
 
+## 0.3.0 (2026-01-12)
+
+Full Changelog: [v0.2.4...v0.3.0](https://github.com/browserbase/stagehand-python/compare/v0.2.4...v0.3.0)
+
+### Features
+
+* Removed requiring x-language and x-sdk-version from openapi spec ([618266f](https://github.com/browserbase/stagehand-python/commit/618266f3fe397a2d346fc1f3adaad225db443cdf))
+* Using provider/model syntax in modelName examples within openapi spec ([98d8ab9](https://github.com/browserbase/stagehand-python/commit/98d8ab97cb1115b9cff7f6e831b7dfa98e27f15a))
+
 ## 0.2.4 (2026-01-07)
 
 Full Changelog: [v0.2.3...v0.2.4](https://github.com/browserbase/stagehand-python/compare/v0.2.3...v0.2.4)
diff --git a/pyproject.toml b/pyproject.toml
index 2a7f591c..36781d10 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "stagehand-alpha"
-version = "0.2.4"
+version = "0.3.0"
 description = "The official Python library for the stagehand API"
 dynamic = ["readme"]
 license = "Apache-2.0"
diff --git a/src/stagehand/_version.py b/src/stagehand/_version.py
index f26dd6ac..a162c62a 100644
--- a/src/stagehand/_version.py
+++ b/src/stagehand/_version.py
@@ -1,4 +1,4 @@
 # File generated from our OpenAPI spec by Stainless. See CONTRIBUTING.md for details.
 
 __title__ = "stagehand"
-__version__ = "0.2.4"  # x-release-please-version
+__version__ = "0.3.0"  # x-release-please-version
diff --git a/src/stagehand/resources/sessions.py b/src/stagehand/resources/sessions.py
index def9de51..22cdc0d2 100644
--- a/src/stagehand/resources/sessions.py
+++ b/src/stagehand/resources/sessions.py
@@ -77,8 +77,6 @@ def act(
         frame_id: str | Omit = omit,
         options: session_act_params.Options | Omit = omit,
         stream_response: Literal[False] | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -101,10 +99,6 @@ def act(
 
           stream_response: Whether to stream the response via SSE
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -128,8 +122,6 @@ def act(
         stream_response: Literal[True],
         frame_id: str | Omit = omit,
         options: session_act_params.Options | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -152,10 +144,6 @@ def act(
 
           frame_id: Target frame ID for the action
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -179,8 +167,6 @@ def act(
         stream_response: bool,
         frame_id: str | Omit = omit,
         options: session_act_params.Options | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -203,10 +189,6 @@ def act(
 
           frame_id: Target frame ID for the action
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -230,8 +212,6 @@ def act(
         frame_id: str | Omit = omit,
         options: session_act_params.Options | Omit = omit,
         stream_response: Literal[False] | Literal[True] | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -246,9 +226,7 @@ def act(
         extra_headers = {
             **strip_not_given(
                 {
-                    "x-language": str(x_language) if is_given(x_language) else not_given,
-                    "x-sdk-version": x_sdk_version,
-                    "x-sent-at": _format_x_sent_at(x_sent_at),
+                    "x-sent-at": x_sent_at.isoformat() if is_given(x_sent_at) else not_given,
                     "x-stream-response": str(x_stream_response) if is_given(x_stream_response) else not_given,
                 }
             ),
@@ -279,8 +257,7 @@ def end(
         self,
         id: str,
         *,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
+        _force_body: object | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -296,10 +273,6 @@ def end(
         Args:
           id: Unique session identifier
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -317,9 +290,7 @@ def end(
         extra_headers = {
             **strip_not_given(
                 {
-                    "x-language": str(x_language) if is_given(x_language) else not_given,
-                    "x-sdk-version": x_sdk_version,
-                    "x-sent-at": _format_x_sent_at(x_sent_at),
+                    "x-sent-at": x_sent_at.isoformat() if is_given(x_sent_at) else not_given,
                     "x-stream-response": str(x_stream_response) if is_given(x_stream_response) else not_given,
                 }
             ),
@@ -343,8 +314,6 @@ def execute(
         execute_options: session_execute_params.ExecuteOptions,
         frame_id: str | Omit = omit,
         stream_response: Literal[False] | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -364,10 +333,6 @@ def execute(
 
           stream_response: Whether to stream the response via SSE
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -391,8 +356,6 @@ def execute(
         execute_options: session_execute_params.ExecuteOptions,
         stream_response: Literal[True],
         frame_id: str | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -412,10 +375,6 @@ def execute(
 
           frame_id: Target frame ID for the agent
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -439,8 +398,6 @@ def execute(
         execute_options: session_execute_params.ExecuteOptions,
         stream_response: bool,
         frame_id: str | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -460,10 +417,6 @@ def execute(
 
           frame_id: Target frame ID for the agent
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -487,8 +440,6 @@ def execute(
         execute_options: session_execute_params.ExecuteOptions,
         frame_id: str | Omit = omit,
         stream_response: Literal[False] | Literal[True] | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -503,9 +454,7 @@ def execute(
         extra_headers = {
             **strip_not_given(
                 {
-                    "x-language": str(x_language) if is_given(x_language) else not_given,
-                    "x-sdk-version": x_sdk_version,
-                    "x-sent-at": _format_x_sent_at(x_sent_at),
+                    "x-sent-at": x_sent_at.isoformat() if is_given(x_sent_at) else not_given,
                     "x-stream-response": str(x_stream_response) if is_given(x_stream_response) else not_given,
                 }
             ),
@@ -542,8 +491,6 @@ def extract(
         options: session_extract_params.Options | Omit = omit,
         schema: Dict[str, object] | Omit = omit,
         stream_response: Literal[False] | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -567,10 +514,6 @@ def extract(
 
           stream_response: Whether to stream the response via SSE
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -595,8 +538,6 @@ def extract(
         instruction: str | Omit = omit,
         options: session_extract_params.Options | Omit = omit,
         schema: Dict[str, object] | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -620,10 +561,6 @@ def extract(
 
           schema: JSON Schema defining the structure of data to extract
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -648,8 +585,6 @@ def extract(
         instruction: str | Omit = omit,
         options: session_extract_params.Options | Omit = omit,
         schema: Dict[str, object] | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -673,10 +608,6 @@ def extract(
 
           schema: JSON Schema defining the structure of data to extract
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -700,8 +631,6 @@ def extract(
         options: session_extract_params.Options | Omit = omit,
         schema: Dict[str, object] | Omit = omit,
         stream_response: Literal[False] | Literal[True] | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -716,9 +645,7 @@ def extract(
         extra_headers = {
             **strip_not_given(
                 {
-                    "x-language": str(x_language) if is_given(x_language) else not_given,
-                    "x-sdk-version": x_sdk_version,
-                    "x-sent-at": _format_x_sent_at(x_sent_at),
+                    "x-sent-at": x_sent_at.isoformat() if is_given(x_sent_at) else not_given,
                     "x-stream-response": str(x_stream_response) if is_given(x_stream_response) else not_given,
                 }
             ),
@@ -754,8 +681,6 @@ def navigate(
         frame_id: str | Omit = omit,
         options: session_navigate_params.Options | Omit = omit,
         stream_response: bool | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -777,10 +702,6 @@ def navigate(
 
           stream_response: Whether to stream the response via SSE
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -798,9 +719,7 @@ def navigate(
         extra_headers = {
             **strip_not_given(
                 {
-                    "x-language": str(x_language) if is_given(x_language) else not_given,
-                    "x-sdk-version": x_sdk_version,
-                    "x-sent-at": _format_x_sent_at(x_sent_at),
+                    "x-sent-at": x_sent_at.isoformat() if is_given(x_sent_at) else not_given,
                     "x-stream-response": str(x_stream_response) if is_given(x_stream_response) else not_given,
                 }
             ),
@@ -832,8 +751,6 @@ def observe(
         instruction: str | Omit = omit,
         options: session_observe_params.Options | Omit = omit,
         stream_response: Literal[False] | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -856,10 +773,6 @@ def observe(
 
           stream_response: Whether to stream the response via SSE
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -883,8 +796,6 @@ def observe(
         frame_id: str | Omit = omit,
         instruction: str | Omit = omit,
         options: session_observe_params.Options | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -907,10 +818,6 @@ def observe(
 
           instruction: Natural language instruction for what actions to find
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -934,8 +841,6 @@ def observe(
         frame_id: str | Omit = omit,
         instruction: str | Omit = omit,
         options: session_observe_params.Options | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -958,10 +863,6 @@ def observe(
 
           instruction: Natural language instruction for what actions to find
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -984,8 +885,6 @@ def observe(
         instruction: str | Omit = omit,
         options: session_observe_params.Options | Omit = omit,
         stream_response: Literal[False] | Literal[True] | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -1000,9 +899,7 @@ def observe(
         extra_headers = {
             **strip_not_given(
                 {
-                    "x-language": str(x_language) if is_given(x_language) else not_given,
-                    "x-sdk-version": x_sdk_version,
-                    "x-sent-at": _format_x_sent_at(x_sent_at),
+                    "x-sent-at": x_sent_at.isoformat() if is_given(x_sent_at) else not_given,
                     "x-stream-response": str(x_stream_response) if is_given(x_stream_response) else not_given,
                 }
             ),
@@ -1043,8 +940,6 @@ def start(
         system_prompt: str | Omit = omit,
         verbose: Literal[0, 1, 2] | Omit = omit,
         wait_for_captcha_solves: bool | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -1076,10 +971,6 @@ def start(
 
           wait_for_captcha_solves: Wait for captcha solves (deprecated, v2 only)
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -1095,9 +986,7 @@ def start(
         extra_headers = {
             **strip_not_given(
                 {
-                    "x-language": str(x_language) if is_given(x_language) else not_given,
-                    "x-sdk-version": x_sdk_version,
-                    "x-sent-at": _format_x_sent_at(x_sent_at),
+                    "x-sent-at": x_sent_at.isoformat() if is_given(x_sent_at) else not_given,
                     "x-stream-response": str(x_stream_response) if is_given(x_stream_response) else not_given,
                 }
             ),
@@ -1157,8 +1046,6 @@ async def act(
         frame_id: str | Omit = omit,
         options: session_act_params.Options | Omit = omit,
         stream_response: Literal[False] | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -1181,10 +1068,6 @@ async def act(
 
           stream_response: Whether to stream the response via SSE
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -1208,8 +1091,6 @@ async def act(
         stream_response: Literal[True],
         frame_id: str | Omit = omit,
         options: session_act_params.Options | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -1232,10 +1113,6 @@ async def act(
 
           frame_id: Target frame ID for the action
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -1259,8 +1136,6 @@ async def act(
         stream_response: bool,
         frame_id: str | Omit = omit,
         options: session_act_params.Options | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -1283,10 +1158,6 @@ async def act(
 
           frame_id: Target frame ID for the action
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -1310,8 +1181,6 @@ async def act(
         frame_id: str | Omit = omit,
         options: session_act_params.Options | Omit = omit,
         stream_response: Literal[False] | Literal[True] | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -1326,9 +1195,7 @@ async def act(
         extra_headers = {
             **strip_not_given(
                 {
-                    "x-language": str(x_language) if is_given(x_language) else not_given,
-                    "x-sdk-version": x_sdk_version,
-                    "x-sent-at": _format_x_sent_at(x_sent_at),
+                    "x-sent-at": x_sent_at.isoformat() if is_given(x_sent_at) else not_given,
                     "x-stream-response": str(x_stream_response) if is_given(x_stream_response) else not_given,
                 }
             ),
@@ -1359,8 +1226,7 @@ async def end(
         self,
         id: str,
         *,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
+        _force_body: object | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -1376,10 +1242,6 @@ async def end(
         Args:
           id: Unique session identifier
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -1397,9 +1259,7 @@ async def end(
         extra_headers = {
             **strip_not_given(
                 {
-                    "x-language": str(x_language) if is_given(x_language) else not_given,
-                    "x-sdk-version": x_sdk_version,
-                    "x-sent-at": _format_x_sent_at(x_sent_at),
+                    "x-sent-at": x_sent_at.isoformat() if is_given(x_sent_at) else not_given,
                     "x-stream-response": str(x_stream_response) if is_given(x_stream_response) else not_given,
                 }
             ),
@@ -1423,8 +1283,6 @@ async def execute(
         execute_options: session_execute_params.ExecuteOptions,
         frame_id: str | Omit = omit,
         stream_response: Literal[False] | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -1444,10 +1302,6 @@ async def execute(
 
           stream_response: Whether to stream the response via SSE
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -1471,8 +1325,6 @@ async def execute(
         execute_options: session_execute_params.ExecuteOptions,
         stream_response: Literal[True],
         frame_id: str | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -1492,10 +1344,6 @@ async def execute(
 
           frame_id: Target frame ID for the agent
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -1519,8 +1367,6 @@ async def execute(
         execute_options: session_execute_params.ExecuteOptions,
         stream_response: bool,
         frame_id: str | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -1540,10 +1386,6 @@ async def execute(
 
           frame_id: Target frame ID for the agent
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -1567,8 +1409,6 @@ async def execute(
         execute_options: session_execute_params.ExecuteOptions,
         frame_id: str | Omit = omit,
         stream_response: Literal[False] | Literal[True] | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -1583,9 +1423,7 @@ async def execute(
         extra_headers = {
             **strip_not_given(
                 {
-                    "x-language": str(x_language) if is_given(x_language) else not_given,
-                    "x-sdk-version": x_sdk_version,
-                    "x-sent-at": _format_x_sent_at(x_sent_at),
+                    "x-sent-at": x_sent_at.isoformat() if is_given(x_sent_at) else not_given,
                     "x-stream-response": str(x_stream_response) if is_given(x_stream_response) else not_given,
                 }
             ),
@@ -1622,8 +1460,6 @@ async def extract(
         options: session_extract_params.Options | Omit = omit,
         schema: Dict[str, object] | Omit = omit,
         stream_response: Literal[False] | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -1647,10 +1483,6 @@ async def extract(
 
           stream_response: Whether to stream the response via SSE
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -1675,8 +1507,6 @@ async def extract(
         instruction: str | Omit = omit,
         options: session_extract_params.Options | Omit = omit,
         schema: Dict[str, object] | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -1700,10 +1530,6 @@ async def extract(
 
           schema: JSON Schema defining the structure of data to extract
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -1728,8 +1554,6 @@ async def extract(
         instruction: str | Omit = omit,
         options: session_extract_params.Options | Omit = omit,
         schema: Dict[str, object] | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -1753,10 +1577,6 @@ async def extract(
 
           schema: JSON Schema defining the structure of data to extract
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -1780,8 +1600,6 @@ async def extract(
         options: session_extract_params.Options | Omit = omit,
         schema: Dict[str, object] | Omit = omit,
         stream_response: Literal[False] | Literal[True] | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -1796,9 +1614,7 @@ async def extract(
         extra_headers = {
             **strip_not_given(
                 {
-                    "x-language": str(x_language) if is_given(x_language) else not_given,
-                    "x-sdk-version": x_sdk_version,
-                    "x-sent-at": _format_x_sent_at(x_sent_at),
+                    "x-sent-at": x_sent_at.isoformat() if is_given(x_sent_at) else not_given,
                     "x-stream-response": str(x_stream_response) if is_given(x_stream_response) else not_given,
                 }
             ),
@@ -1834,8 +1650,6 @@ async def navigate(
         frame_id: str | Omit = omit,
         options: session_navigate_params.Options | Omit = omit,
         stream_response: bool | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -1857,10 +1671,6 @@ async def navigate(
 
           stream_response: Whether to stream the response via SSE
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -1878,9 +1688,7 @@ async def navigate(
         extra_headers = {
             **strip_not_given(
                 {
-                    "x-language": str(x_language) if is_given(x_language) else not_given,
-                    "x-sdk-version": x_sdk_version,
-                    "x-sent-at": _format_x_sent_at(x_sent_at),
+                    "x-sent-at": x_sent_at.isoformat() if is_given(x_sent_at) else not_given,
                     "x-stream-response": str(x_stream_response) if is_given(x_stream_response) else not_given,
                 }
             ),
@@ -1912,8 +1720,6 @@ async def observe(
         instruction: str | Omit = omit,
         options: session_observe_params.Options | Omit = omit,
         stream_response: Literal[False] | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -1936,10 +1742,6 @@ async def observe(
 
           stream_response: Whether to stream the response via SSE
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -1963,8 +1765,6 @@ async def observe(
         frame_id: str | Omit = omit,
         instruction: str | Omit = omit,
         options: session_observe_params.Options | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -1987,10 +1787,6 @@ async def observe(
 
           instruction: Natural language instruction for what actions to find
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -2014,8 +1810,6 @@ async def observe(
         frame_id: str | Omit = omit,
         instruction: str | Omit = omit,
         options: session_observe_params.Options | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -2038,10 +1832,6 @@ async def observe(
 
           instruction: Natural language instruction for what actions to find
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -2064,8 +1854,6 @@ async def observe(
         instruction: str | Omit = omit,
         options: session_observe_params.Options | Omit = omit,
         stream_response: Literal[False] | Literal[True] | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -2080,9 +1868,7 @@ async def observe(
         extra_headers = {
             **strip_not_given(
                 {
-                    "x-language": str(x_language) if is_given(x_language) else not_given,
-                    "x-sdk-version": x_sdk_version,
-                    "x-sent-at": _format_x_sent_at(x_sent_at),
+                    "x-sent-at": x_sent_at.isoformat() if is_given(x_sent_at) else not_given,
                     "x-stream-response": str(x_stream_response) if is_given(x_stream_response) else not_given,
                 }
             ),
@@ -2123,8 +1909,6 @@ async def start(
         system_prompt: str | Omit = omit,
         verbose: Literal[0, 1, 2] | Omit = omit,
         wait_for_captcha_solves: bool | Omit = omit,
-        x_language: Literal["typescript", "python", "playground"] | Omit = omit,
-        x_sdk_version: str | Omit = omit,
         x_sent_at: Union[str, datetime] | Omit = omit,
         x_stream_response: Literal["true", "false"] | Omit = omit,
         # Use the following arguments if you need to pass additional parameters to the API that aren't available via kwargs.
@@ -2156,10 +1940,6 @@ async def start(
 
           wait_for_captcha_solves: Wait for captcha solves (deprecated, v2 only)
 
-          x_language: Client SDK language
-
-          x_sdk_version: Version of the Stagehand SDK
-
           x_sent_at: ISO timestamp when request was sent
 
           x_stream_response: Whether to stream the response via SSE
@@ -2175,9 +1955,7 @@ async def start(
         extra_headers = {
             **strip_not_given(
                 {
-                    "x-language": str(x_language) if is_given(x_language) else not_given,
-                    "x-sdk-version": x_sdk_version,
-                    "x-sent-at": _format_x_sent_at(x_sent_at),
+                    "x-sent-at": x_sent_at.isoformat() if is_given(x_sent_at) else not_given,
                     "x-stream-response": str(x_stream_response) if is_given(x_stream_response) else not_given,
                 }
             ),
diff --git a/src/stagehand/types/model_config_param.py b/src/stagehand/types/model_config_param.py
index 8d3df0ef..f633db12 100644
--- a/src/stagehand/types/model_config_param.py
+++ b/src/stagehand/types/model_config_param.py
@@ -12,7 +12,7 @@
 
 class ModelConfigObject(TypedDict, total=False):
     model_name: Required[Annotated[str, PropertyInfo(alias="modelName")]]
-    """Model name string without prefix (e.g., 'gpt-5-nano', 'claude-4.5-opus')"""
+    """Model name string (e.g., 'openai/gpt-5-nano', 'anthropic/claude-4.5-opus')"""
 
     api_key: Annotated[str, PropertyInfo(alias="apiKey")]
     """API key for the model provider"""
diff --git a/src/stagehand/types/session_act_params.py b/src/stagehand/types/session_act_params.py
index 153ac6c8..605019b8 100644
--- a/src/stagehand/types/session_act_params.py
+++ b/src/stagehand/types/session_act_params.py
@@ -22,12 +22,6 @@ class SessionActParamsBase(TypedDict, total=False):
 
     options: Options
 
-    x_language: Annotated[Literal["typescript", "python", "playground"], PropertyInfo(alias="x-language")]
-    """Client SDK language"""
-
-    x_sdk_version: Annotated[str, PropertyInfo(alias="x-sdk-version")]
-    """Version of the Stagehand SDK"""
-
     x_sent_at: Annotated[Union[str, datetime], PropertyInfo(alias="x-sent-at", format="iso8601")]
     """ISO timestamp when request was sent"""
 
diff --git a/src/stagehand/types/session_end_params.py b/src/stagehand/types/session_end_params.py
index defdf60a..1998cd27 100644
--- a/src/stagehand/types/session_end_params.py
+++ b/src/stagehand/types/session_end_params.py
@@ -14,12 +14,6 @@
 class SessionEndParams(TypedDict, total=False):
     _force_body: Annotated[object, PropertyInfo(alias="_forceBody")]
 
-    x_language: Annotated[Literal["typescript", "python", "playground"], PropertyInfo(alias="x-language")]
-    """Client SDK language"""
-
-    x_sdk_version: Annotated[str, PropertyInfo(alias="x-sdk-version")]
-    """Version of the Stagehand SDK"""
-
     x_sent_at: Annotated[Union[str, datetime], PropertyInfo(alias="x-sent-at", format="iso8601")]
     """ISO timestamp when request was sent"""
 
diff --git a/src/stagehand/types/session_execute_params.py b/src/stagehand/types/session_execute_params.py
index 794181d7..eb8678ff 100644
--- a/src/stagehand/types/session_execute_params.py
+++ b/src/stagehand/types/session_execute_params.py
@@ -26,12 +26,6 @@ class SessionExecuteParamsBase(TypedDict, total=False):
     frame_id: Annotated[str, PropertyInfo(alias="frameId")]
     """Target frame ID for the agent"""
 
-    x_language: Annotated[Literal["typescript", "python", "playground"], PropertyInfo(alias="x-language")]
-    """Client SDK language"""
-
-    x_sdk_version: Annotated[str, PropertyInfo(alias="x-sdk-version")]
-    """Version of the Stagehand SDK"""
-
     x_sent_at: Annotated[Union[str, datetime], PropertyInfo(alias="x-sent-at", format="iso8601")]
     """ISO timestamp when request was sent"""
 
diff --git a/src/stagehand/types/session_extract_params.py b/src/stagehand/types/session_extract_params.py
index c18800f8..c763cbb5 100644
--- a/src/stagehand/types/session_extract_params.py
+++ b/src/stagehand/types/session_extract_params.py
@@ -24,12 +24,6 @@ class SessionExtractParamsBase(TypedDict, total=False):
     schema: Dict[str, object]
     """JSON Schema defining the structure of data to extract"""
 
-    x_language: Annotated[Literal["typescript", "python", "playground"], PropertyInfo(alias="x-language")]
-    """Client SDK language"""
-
-    x_sdk_version: Annotated[str, PropertyInfo(alias="x-sdk-version")]
-    """Version of the Stagehand SDK"""
-
     x_sent_at: Annotated[Union[str, datetime], PropertyInfo(alias="x-sent-at", format="iso8601")]
     """ISO timestamp when request was sent"""
 
diff --git a/src/stagehand/types/session_navigate_params.py b/src/stagehand/types/session_navigate_params.py
index 59a86eae..39bb2b2e 100644
--- a/src/stagehand/types/session_navigate_params.py
+++ b/src/stagehand/types/session_navigate_params.py
@@ -23,12 +23,6 @@ class SessionNavigateParams(TypedDict, total=False):
     stream_response: Annotated[bool, PropertyInfo(alias="streamResponse")]
     """Whether to stream the response via SSE"""
 
-    x_language: Annotated[Literal["typescript", "python", "playground"], PropertyInfo(alias="x-language")]
-    """Client SDK language"""
-
-    x_sdk_version: Annotated[str, PropertyInfo(alias="x-sdk-version")]
-    """Version of the Stagehand SDK"""
-
     x_sent_at: Annotated[Union[str, datetime], PropertyInfo(alias="x-sent-at", format="iso8601")]
     """ISO timestamp when request was sent"""
 
diff --git a/src/stagehand/types/session_observe_params.py b/src/stagehand/types/session_observe_params.py
index 9d18b185..7cad4c85 100644
--- a/src/stagehand/types/session_observe_params.py
+++ b/src/stagehand/types/session_observe_params.py
@@ -21,12 +21,6 @@ class SessionObserveParamsBase(TypedDict, total=False):
 
     options: Options
 
-    x_language: Annotated[Literal["typescript", "python", "playground"], PropertyInfo(alias="x-language")]
-    """Client SDK language"""
-
-    x_sdk_version: Annotated[str, PropertyInfo(alias="x-sdk-version")]
-    """Version of the Stagehand SDK"""
-
     x_sent_at: Annotated[Union[str, datetime], PropertyInfo(alias="x-sent-at", format="iso8601")]
     """ISO timestamp when request was sent"""
 
diff --git a/src/stagehand/types/session_start_params.py b/src/stagehand/types/session_start_params.py
index 479d1fef..03735673 100644
--- a/src/stagehand/types/session_start_params.py
+++ b/src/stagehand/types/session_start_params.py
@@ -61,12 +61,6 @@ class SessionStartParams(TypedDict, total=False):
     wait_for_captcha_solves: Annotated[bool, PropertyInfo(alias="waitForCaptchaSolves")]
     """Wait for captcha solves (deprecated, v2 only)"""
 
-    x_language: Annotated[Literal["typescript", "python", "playground"], PropertyInfo(alias="x-language")]
-    """Client SDK language"""
-
-    x_sdk_version: Annotated[str, PropertyInfo(alias="x-sdk-version")]
-    """Version of the Stagehand SDK"""
-
     x_sent_at: Annotated[Union[str, datetime], PropertyInfo(alias="x-sent-at", format="iso8601")]
     """ISO timestamp when request was sent"""
 
diff --git a/tests/api_resources/test_sessions.py b/tests/api_resources/test_sessions.py
index daef296d..473a917d 100644
--- a/tests/api_resources/test_sessions.py
+++ b/tests/api_resources/test_sessions.py
@@ -48,8 +48,6 @@ def test_method_act_with_all_params_overload_1(self, client: Stagehand) -> None:
                 "variables": {"username": "john_doe"},
             },
             stream_response=False,
-            x_language="typescript",
-            x_sdk_version="3.0.6",
             x_sent_at=parse_datetime("2025-01-15T10:30:00Z"),
             x_stream_response="true",
         )
@@ -115,8 +113,6 @@ def test_method_act_with_all_params_overload_2(self, client: Stagehand) -> None:
                 "timeout": 30000,
                 "variables": {"username": "john_doe"},
             },
-            x_language="typescript",
-            x_sdk_version="3.0.6",
             x_sent_at=parse_datetime("2025-01-15T10:30:00Z"),
             x_stream_response="true",
         )
@@ -174,8 +170,7 @@ def test_method_end(self, client: Stagehand) -> None:
     def test_method_end_with_all_params(self, client: Stagehand) -> None:
         session = client.sessions.end(
             id="c4dbf3a9-9a58-4b22-8a1c-9f20f9f9e123",
-            x_language="typescript",
-            x_sdk_version="3.0.6",
+            _force_body={},
             x_sent_at=parse_datetime("2025-01-15T10:30:00Z"),
             x_stream_response="true",
         )
@@ -245,8 +240,6 @@ def test_method_execute_with_all_params_overload_1(self, client: Stagehand) -> N
             },
             frame_id="frameId",
             stream_response=False,
-            x_language="typescript",
-            x_sdk_version="3.0.6",
             x_sent_at=parse_datetime("2025-01-15T10:30:00Z"),
             x_stream_response="true",
         )
@@ -329,8 +322,6 @@ def test_method_execute_with_all_params_overload_2(self, client: Stagehand) -> N
             },
             stream_response=True,
             frame_id="frameId",
-            x_language="typescript",
-            x_sdk_version="3.0.6",
             x_sent_at=parse_datetime("2025-01-15T10:30:00Z"),
             x_stream_response="true",
         )
@@ -406,8 +397,6 @@ def test_method_extract_with_all_params_overload_1(self, client: Stagehand) -> N
             },
             schema={"foo": "bar"},
             stream_response=False,
-            x_language="typescript",
-            x_sdk_version="3.0.6",
             x_sent_at=parse_datetime("2025-01-15T10:30:00Z"),
             x_stream_response="true",
         )
@@ -470,8 +459,6 @@ def test_method_extract_with_all_params_overload_2(self, client: Stagehand) -> N
                 "timeout": 30000,
             },
             schema={"foo": "bar"},
-            x_language="typescript",
-            x_sdk_version="3.0.6",
             x_sent_at=parse_datetime("2025-01-15T10:30:00Z"),
             x_stream_response="true",
         )
@@ -535,8 +522,6 @@ def test_method_navigate_with_all_params(self, client: Stagehand) -> None:
                 "wait_until": "networkidle",
             },
             stream_response=True,
-            x_language="typescript",
-            x_sdk_version="3.0.6",
             x_sent_at=parse_datetime("2025-01-15T10:30:00Z"),
             x_stream_response="true",
         )
@@ -600,8 +585,6 @@ def test_method_observe_with_all_params_overload_1(self, client: Stagehand) -> N
                 "timeout": 30000,
             },
             stream_response=False,
-            x_language="typescript",
-            x_sdk_version="3.0.6",
             x_sent_at=parse_datetime("2025-01-15T10:30:00Z"),
             x_stream_response="true",
         )
@@ -663,8 +646,6 @@ def test_method_observe_with_all_params_overload_2(self, client: Stagehand) -> N
                 "selector": "nav",
                 "timeout": 30000,
             },
-            x_language="typescript",
-            x_sdk_version="3.0.6",
             x_sent_at=parse_datetime("2025-01-15T10:30:00Z"),
             x_stream_response="true",
         )
@@ -710,7 +691,7 @@ def test_path_params_observe_overload_2(self, client: Stagehand) -> None:
     @parametrize
     def test_method_start(self, client: Stagehand) -> None:
         session = client.sessions.start(
-            model_name="gpt-4o",
+            model_name="openai/gpt-4o",
         )
         assert_matches_type(SessionStartResponse, session, path=["response"])
 
@@ -718,7 +699,7 @@ def test_method_start(self, client: Stagehand) -> None:
     @parametrize
     def test_method_start_with_all_params(self, client: Stagehand) -> None:
         session = client.sessions.start(
-            model_name="gpt-4o",
+            model_name="openai/gpt-4o",
             act_timeout_ms=0,
             browser={
                 "cdp_url": "ws://localhost:9222",
@@ -797,8 +778,6 @@ def test_method_start_with_all_params(self, client: Stagehand) -> None:
             system_prompt="systemPrompt",
             verbose=1,
             wait_for_captcha_solves=True,
-            x_language="typescript",
-            x_sdk_version="3.0.6",
             x_sent_at=parse_datetime("2025-01-15T10:30:00Z"),
             x_stream_response="true",
         )
@@ -808,7 +787,7 @@ def test_method_start_with_all_params(self, client: Stagehand) -> None:
     @parametrize
     def test_raw_response_start(self, client: Stagehand) -> None:
         response = client.sessions.with_raw_response.start(
-            model_name="gpt-4o",
+            model_name="openai/gpt-4o",
         )
 
         assert response.is_closed is True
@@ -820,7 +799,7 @@ def test_raw_response_start(self, client: Stagehand) -> None:
     @parametrize
     def test_streaming_response_start(self, client: Stagehand) -> None:
         with client.sessions.with_streaming_response.start(
-            model_name="gpt-4o",
+            model_name="openai/gpt-4o",
         ) as response:
             assert not response.is_closed
             assert response.http_request.headers.get("X-Stainless-Lang") == "python"
@@ -858,8 +837,6 @@ async def test_method_act_with_all_params_overload_1(self, async_client: AsyncSt
                 "variables": {"username": "john_doe"},
             },
             stream_response=False,
-            x_language="typescript",
-            x_sdk_version="3.0.6",
             x_sent_at=parse_datetime("2025-01-15T10:30:00Z"),
             x_stream_response="true",
         )
@@ -925,8 +902,6 @@ async def test_method_act_with_all_params_overload_2(self, async_client: AsyncSt
                 "timeout": 30000,
                 "variables": {"username": "john_doe"},
             },
-            x_language="typescript",
-            x_sdk_version="3.0.6",
             x_sent_at=parse_datetime("2025-01-15T10:30:00Z"),
             x_stream_response="true",
         )
@@ -984,8 +959,7 @@ async def test_method_end(self, async_client: AsyncStagehand) -> None:
     async def test_method_end_with_all_params(self, async_client: AsyncStagehand) -> None:
         session = await async_client.sessions.end(
             id="c4dbf3a9-9a58-4b22-8a1c-9f20f9f9e123",
-            x_language="typescript",
-            x_sdk_version="3.0.6",
+            _force_body={},
             x_sent_at=parse_datetime("2025-01-15T10:30:00Z"),
             x_stream_response="true",
         )
@@ -1055,8 +1029,6 @@ async def test_method_execute_with_all_params_overload_1(self, async_client: Asy
             },
             frame_id="frameId",
             stream_response=False,
-            x_language="typescript",
-            x_sdk_version="3.0.6",
             x_sent_at=parse_datetime("2025-01-15T10:30:00Z"),
             x_stream_response="true",
         )
@@ -1139,8 +1111,6 @@ async def test_method_execute_with_all_params_overload_2(self, async_client: Asy
             },
             stream_response=True,
             frame_id="frameId",
-            x_language="typescript",
-            x_sdk_version="3.0.6",
             x_sent_at=parse_datetime("2025-01-15T10:30:00Z"),
             x_stream_response="true",
         )
@@ -1216,8 +1186,6 @@ async def test_method_extract_with_all_params_overload_1(self, async_client: Asy
             },
             schema={"foo": "bar"},
             stream_response=False,
-            x_language="typescript",
-            x_sdk_version="3.0.6",
             x_sent_at=parse_datetime("2025-01-15T10:30:00Z"),
             x_stream_response="true",
         )
@@ -1280,8 +1248,6 @@ async def test_method_extract_with_all_params_overload_2(self, async_client: Asy
                 "timeout": 30000,
             },
             schema={"foo": "bar"},
-            x_language="typescript",
-            x_sdk_version="3.0.6",
             x_sent_at=parse_datetime("2025-01-15T10:30:00Z"),
             x_stream_response="true",
         )
@@ -1345,8 +1311,6 @@ async def test_method_navigate_with_all_params(self, async_client: AsyncStagehan
                 "wait_until": "networkidle",
             },
             stream_response=True,
-            x_language="typescript",
-            x_sdk_version="3.0.6",
             x_sent_at=parse_datetime("2025-01-15T10:30:00Z"),
             x_stream_response="true",
         )
@@ -1410,8 +1374,6 @@ async def test_method_observe_with_all_params_overload_1(self, async_client: Asy
                 "timeout": 30000,
             },
             stream_response=False,
-            x_language="typescript",
-            x_sdk_version="3.0.6",
             x_sent_at=parse_datetime("2025-01-15T10:30:00Z"),
             x_stream_response="true",
         )
@@ -1473,8 +1435,6 @@ async def test_method_observe_with_all_params_overload_2(self, async_client: Asy
                 "selector": "nav",
                 "timeout": 30000,
             },
-            x_language="typescript",
-            x_sdk_version="3.0.6",
             x_sent_at=parse_datetime("2025-01-15T10:30:00Z"),
             x_stream_response="true",
         )
@@ -1520,7 +1480,7 @@ async def test_path_params_observe_overload_2(self, async_client: AsyncStagehand
     @parametrize
     async def test_method_start(self, async_client: AsyncStagehand) -> None:
         session = await async_client.sessions.start(
-            model_name="gpt-4o",
+            model_name="openai/gpt-4o",
         )
         assert_matches_type(SessionStartResponse, session, path=["response"])
 
@@ -1528,7 +1488,7 @@ async def test_method_start(self, async_client: AsyncStagehand) -> None:
     @parametrize
     async def test_method_start_with_all_params(self, async_client: AsyncStagehand) -> None:
         session = await async_client.sessions.start(
-            model_name="gpt-4o",
+            model_name="openai/gpt-4o",
             act_timeout_ms=0,
             browser={
                 "cdp_url": "ws://localhost:9222",
@@ -1607,8 +1567,6 @@ async def test_method_start_with_all_params(self, async_client: AsyncStagehand)
             system_prompt="systemPrompt",
             verbose=1,
             wait_for_captcha_solves=True,
-            x_language="typescript",
-            x_sdk_version="3.0.6",
             x_sent_at=parse_datetime("2025-01-15T10:30:00Z"),
             x_stream_response="true",
         )
@@ -1618,7 +1576,7 @@ async def test_method_start_with_all_params(self, async_client: AsyncStagehand)
     @parametrize
     async def test_raw_response_start(self, async_client: AsyncStagehand) -> None:
         response = await async_client.sessions.with_raw_response.start(
-            model_name="gpt-4o",
+            model_name="openai/gpt-4o",
         )
 
         assert response.is_closed is True
@@ -1630,7 +1588,7 @@ async def test_raw_response_start(self, async_client: AsyncStagehand) -> None:
     @parametrize
     async def test_streaming_response_start(self, async_client: AsyncStagehand) -> None:
         async with async_client.sessions.with_streaming_response.start(
-            model_name="gpt-4o",
+            model_name="openai/gpt-4o",
         ) as response:
             assert not response.is_closed
             assert response.http_request.headers.get("X-Stainless-Lang") == "python"
diff --git a/tests/test_client.py b/tests/test_client.py
index b1d79c7a..b04449bf 100644
--- a/tests/test_client.py
+++ b/tests/test_client.py
@@ -891,7 +891,7 @@ def test_retrying_timeout_errors_doesnt_leak(self, respx_mock: MockRouter, clien
         respx_mock.post("/v1/sessions/start").mock(side_effect=httpx.TimeoutException("Test timeout error"))
 
         with pytest.raises(APITimeoutError):
-            client.sessions.with_streaming_response.start(model_name="gpt-4o").__enter__()
+            client.sessions.with_streaming_response.start(model_name="openai/gpt-4o").__enter__()
 
         assert _get_open_connections(client) == 0
 
@@ -901,7 +901,7 @@ def test_retrying_status_errors_doesnt_leak(self, respx_mock: MockRouter, client
         respx_mock.post("/v1/sessions/start").mock(return_value=httpx.Response(500))
 
         with pytest.raises(APIStatusError):
-            client.sessions.with_streaming_response.start(model_name="gpt-4o").__enter__()
+            client.sessions.with_streaming_response.start(model_name="openai/gpt-4o").__enter__()
         assert _get_open_connections(client) == 0
 
     @pytest.mark.parametrize("failures_before_success", [0, 2, 4])
@@ -930,7 +930,7 @@ def retry_handler(_request: httpx.Request) -> httpx.Response:
 
         respx_mock.post("/v1/sessions/start").mock(side_effect=retry_handler)
 
-        response = client.sessions.with_raw_response.start(model_name="gpt-4o")
+        response = client.sessions.with_raw_response.start(model_name="openai/gpt-4o")
 
         assert response.retries_taken == failures_before_success
         assert int(response.http_request.headers.get("x-stainless-retry-count")) == failures_before_success
@@ -955,7 +955,7 @@ def retry_handler(_request: httpx.Request) -> httpx.Response:
         respx_mock.post("/v1/sessions/start").mock(side_effect=retry_handler)
 
         response = client.sessions.with_raw_response.start(
-            model_name="gpt-4o", extra_headers={"x-stainless-retry-count": Omit()}
+            model_name="openai/gpt-4o", extra_headers={"x-stainless-retry-count": Omit()}
         )
 
         assert len(response.http_request.headers.get_list("x-stainless-retry-count")) == 0
@@ -980,7 +980,7 @@ def retry_handler(_request: httpx.Request) -> httpx.Response:
         respx_mock.post("/v1/sessions/start").mock(side_effect=retry_handler)
 
         response = client.sessions.with_raw_response.start(
-            model_name="gpt-4o", extra_headers={"x-stainless-retry-count": "42"}
+            model_name="openai/gpt-4o", extra_headers={"x-stainless-retry-count": "42"}
         )
 
         assert response.http_request.headers.get("x-stainless-retry-count") == "42"
@@ -1870,7 +1870,7 @@ async def test_retrying_timeout_errors_doesnt_leak(
         respx_mock.post("/v1/sessions/start").mock(side_effect=httpx.TimeoutException("Test timeout error"))
 
         with pytest.raises(APITimeoutError):
-            await async_client.sessions.with_streaming_response.start(model_name="gpt-4o").__aenter__()
+            await async_client.sessions.with_streaming_response.start(model_name="openai/gpt-4o").__aenter__()
 
         assert _get_open_connections(async_client) == 0
 
@@ -1882,7 +1882,7 @@ async def test_retrying_status_errors_doesnt_leak(
         respx_mock.post("/v1/sessions/start").mock(return_value=httpx.Response(500))
 
         with pytest.raises(APIStatusError):
-            await async_client.sessions.with_streaming_response.start(model_name="gpt-4o").__aenter__()
+            await async_client.sessions.with_streaming_response.start(model_name="openai/gpt-4o").__aenter__()
         assert _get_open_connections(async_client) == 0
 
     @pytest.mark.parametrize("failures_before_success", [0, 2, 4])
@@ -1911,7 +1911,7 @@ def retry_handler(_request: httpx.Request) -> httpx.Response:
 
         respx_mock.post("/v1/sessions/start").mock(side_effect=retry_handler)
 
-        response = await client.sessions.with_raw_response.start(model_name="gpt-4o")
+        response = await client.sessions.with_raw_response.start(model_name="openai/gpt-4o")
 
         assert response.retries_taken == failures_before_success
         assert int(response.http_request.headers.get("x-stainless-retry-count")) == failures_before_success
@@ -1936,7 +1936,7 @@ def retry_handler(_request: httpx.Request) -> httpx.Response:
         respx_mock.post("/v1/sessions/start").mock(side_effect=retry_handler)
 
         response = await client.sessions.with_raw_response.start(
-            model_name="gpt-4o", extra_headers={"x-stainless-retry-count": Omit()}
+            model_name="openai/gpt-4o", extra_headers={"x-stainless-retry-count": Omit()}
         )
 
         assert len(response.http_request.headers.get_list("x-stainless-retry-count")) == 0
@@ -1961,7 +1961,7 @@ def retry_handler(_request: httpx.Request) -> httpx.Response:
         respx_mock.post("/v1/sessions/start").mock(side_effect=retry_handler)
 
         response = await client.sessions.with_raw_response.start(
-            model_name="gpt-4o", extra_headers={"x-stainless-retry-count": "42"}
+            model_name="openai/gpt-4o", extra_headers={"x-stainless-retry-count": "42"}
         )
 
         assert response.http_request.headers.get("x-stainless-retry-count") == "42"