Limit empty acquire parsing to its response model

Author: Sayan-

src/kernel/_response.py

@@ -24,7 +24,7 @@
 import httpx
 import pydantic
 
-from ._types import NoneType
+from ._types import NoneType, NoContentAsNone
 from ._utils import is_given, extract_type_arg, is_annotated_type, is_type_alias_type, extract_type_var_from_base
 from ._models import BaseModel, is_basemodel
 from ._constants import RAW_RESPONSE_HEADER, OVERRIDE_CAST_TO_HEADER
@@ -185,7 +185,12 @@ def _parse(self, *, to: type[_T] | None = None) -> R | _T:
             return cast(R, None)
 
         response = self.http_response
-        if response.status_code == 204 and to is None and is_basemodel(cast_to):
+        if (
+            response.status_code == 204
+            and to is None
+            and isinstance(origin, type)
+            and issubclass(origin, NoContentAsNone)
+        ):
             return cast(R, None)
         if cast_to == str:
             return cast(R, response.text)

src/kernel/_types.py

@@ -44,6 +44,12 @@
 Query = Mapping[str, object]
 Body = object
 AnyMapping = Mapping[str, object]
+
+
+class NoContentAsNone:
+    pass
+
+
 ModelT = TypeVar("ModelT", bound=pydantic.BaseModel)
 _T = TypeVar("_T")
 

src/kernel/types/browser_pool_acquire_response.py

@@ -5,6 +5,7 @@
 from typing_extensions import Literal
 
 from .tags import Tags
+from .._types import NoContentAsNone
 from .profile import Profile
 from .._models import BaseModel
 from .browser_proxy import BrowserProxy
@@ -20,7 +21,7 @@
 __all__ = ["BrowserPoolAcquireResponse"]
 
 
-class BrowserPoolAcquireResponse(BaseModel):
+class BrowserPoolAcquireResponse(NoContentAsNone, BaseModel):
     cdp_ws_url: str
     """Websocket URL for Chrome DevTools Protocol connections to the browser session"""
 

tests/test_browser_pool_acquire_response.py

@@ -1,7 +1,7 @@
 import httpx
 import pytest
 
-from kernel import Kernel, AsyncKernel, NotFoundError
+from kernel import Kernel, AsyncKernel, NotFoundError, APIResponseValidationError
 
 
 def test_acquire_returns_browser() -> None:
@@ -58,3 +58,13 @@ def test_acquire_still_raises_not_found() -> None:
     ) as client:
         with pytest.raises(NotFoundError):
             client.browser_pools.acquire("missing")
+
+
+def test_unexpected_204_still_fails_strict_validation() -> None:
+    with Kernel(
+        api_key="test",
+        _strict_response_validation=True,
+        http_client=httpx.Client(transport=httpx.MockTransport(lambda _request: httpx.Response(204))),
+    ) as client:
+        with pytest.raises(APIResponseValidationError):
+            client.browser_pools.retrieve("pool")