feat(python): add environment_class_name config option (#10712)

* feat: add environment_class_name config option to Python and Java generators

Co-Authored-By: adi@buildwithfern.com <aditya.arolkar@berkeley.edu>

* feat(python): revert Java changes and keep default as {ClientName}Environment

Co-Authored-By: adi@buildwithfern.com <aditya.arolkar@berkeley.edu>

* Reset generators/java to match main branch

---------

Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>
Co-authored-by: adi@buildwithfern.com <aditya.arolkar@berkeley.edu>

Author: devin-ai-integration[bot]

generators/python/sdk/versions.yml

@@ -1,5 +1,12 @@
 # yaml-language-server: $schema=../../../fern-versions-yml.schema.json
 # For unreleased changes, use unreleased.yml
+- version: 4.39.0
+  changelogEntry:
+    - summary: Add environment_class_name config option to customize the environment class name. Default remains {ClientName}Environment.
+      type: feat
+  createdAt: "2025-11-25"
+  irVersion: 61
+
 - version: 4.38.5
   changelogEntry:
     - summary: Fix discriminated union Field(discriminator=...) and UnionMetadata(discriminant=...) to use Python field names instead of JSON aliases for Pydantic v2 compatibility.

generators/python/src/fern_python/generators/sdk/context/sdk_generator_context_impl.py

@@ -75,8 +75,10 @@ def __init__(
         self._error_declaration_referencer = ErrorDeclarationReferencer(
             skip_resources_module=custom_config.improved_imports
         )
+        default_env_class_name = f"{exported_client_class_name}Environment"
+        final_env_class_name = custom_config.environment_class_name or default_env_class_name
         self._environments_enum_declaration_referencer = EnvironmentsEnumDeclarationReferencer(
-            client_class_name=exported_client_class_name,
+            environment_class_name=final_env_class_name,
             skip_resources_module=custom_config.improved_imports,
         )
         self._subpackage_client_declaration_referencer = SubpackageClientDeclarationReferencer(

generators/python/src/fern_python/generators/sdk/custom_config.py

@@ -64,6 +64,8 @@ class SDKCustomConfig(pydantic.BaseModel):
 
     follow_redirects_by_default: Optional[bool] = True
 
+    environment_class_name: Optional[str] = None
+
     # Feature flag that removes the usage of request objects, and instead
     # parameters in function signatures where possible.
     inline_request_params: bool = True

generators/python/src/fern_python/generators/sdk/declaration_referencers/environments_enum_declaration_referencer.py

@@ -3,9 +3,9 @@
 
 
 class EnvironmentsEnumDeclarationReferencer(SdkDeclarationReferencer[None]):
-    def __init__(self, client_class_name: str, skip_resources_module: bool):
+    def __init__(self, environment_class_name: str, skip_resources_module: bool):
         super().__init__(skip_resources_module=skip_resources_module)
-        self._client_class_name = client_class_name
+        self._environment_class_name = environment_class_name
 
     def get_filepath(self, *, name: None, as_request: bool = False) -> Filepath:
         return Filepath(
@@ -14,4 +14,4 @@ def get_filepath(self, *, name: None, as_request: bool = False) -> Filepath:
         )
 
     def get_class_name(self, *, name: None, as_request: bool = False) -> str:
-        return self._client_class_name + "Environment"
+        return self._environment_class_name