fix: revert pydantic v2 extra="ignore" and update ExtensionRetrieveResponse usage

Reverts the change from 9cae18c that set extra="ignore" in pydantic v2,
which caused unknown/extra API fields to be silently dropped. Also updates
examples to use the consolidated Extension type instead of the removed
ExtensionRetrieveResponse.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: derekmeegan

examples/playwright_extensions.py

@@ -10,7 +10,7 @@
     BROWSERBASE_PROJECT_ID,
     bb,
 )
-from browserbase.types import SessionCreateResponse, ExtensionRetrieveResponse
+from browserbase.types import SessionCreateResponse, Extension
 
 PATH_TO_EXTENSION = Path.cwd() / "examples" / "packages" / "extensions" / "browserbase-test"
 
@@ -51,7 +51,7 @@ def create_extension() -> str:
     return extension.id
 
 
-def get_extension(id: str) -> ExtensionRetrieveResponse:
+def get_extension(id: str) -> Extension:
     return bb.extensions.retrieve(id)
 
 

src/browserbase/_models.py

@@ -107,7 +107,7 @@ class Config(pydantic.BaseConfig):  # pyright: ignore[reportDeprecated]
             extra: Any = pydantic.Extra.allow  # type: ignore
     else:
         model_config: ClassVar[ConfigDict] = ConfigDict(
-            extra="ignore", defer_build=coerce_boolean(os.environ.get("DEFER_PYDANTIC_BUILD", "true"))
+            extra="allow", defer_build=coerce_boolean(os.environ.get("DEFER_PYDANTIC_BUILD", "true"))
         )
 
     def to_dict(