🌿 Fern Scribe: Add a comprehensive list of all extension headers...

fern/products/openapi-def/pages/extensions/parameter-names.mdx

@@ -1,16 +1,19 @@
 ---
 title: Customize parameter names
-description: Use `x-fern-parameter-name` to customize query parameter, header and path parameter naming.
+description: Learn about all the available OpenAPI extensions in Fern to customize parameter naming and behavior.
 ---
 
 <Note>
-  The `x-fern-parameter-name` extension allows you to customize the variable names of parameters in your generated SDKs.
+  Extensions allow you to customize how Fern generates SDKs from your OpenAPI spec.
 </Note>
 
-## Headers
+## Parameter Name Customization
 
-In the example below, the header `X-API-Version` is renamed to `version` in the
-generated SDK. The rename makes the SDK more human readable.
+The `x-fern-parameter-name` extension allows you to customize the variable names of parameters in your generated SDKs, making them more readable and intuitive.
+
+### Headers
+
+In the example below, the header `X-API-Version` is renamed to `version` in the generated SDK for better readability:
 
 ```yaml {8}
 paths:
@@ -26,10 +29,9 @@ paths:
           required: true
 ```
 
-## Query parameters
+### Query Parameters
 
-In the example below, the query parameter `q` is renamed to `search_terms` in the
-generated SDK. The rename makes the parameter more approachable for end users.
+Here, the query parameter `q` is renamed to `search_terms` to be more descriptive:
 
 ```yaml {8}
 paths:
@@ -45,10 +47,9 @@ paths:
           required: false
 ```
 
-## Path parameters
+### Path Parameters
 
-In the example below, the path parameter `userId` is renamed to `id` in the
-generated SDK. The rename makes the SDK less verbose.
+The path parameter `userId` is renamed to `id` to reduce verbosity:
 
 ```yaml {8}
 paths:
@@ -63,3 +64,56 @@ paths:
             type: string
           required: false
 ```
+
+## SDK Variables
+
+The `x-fern-sdk-variables` extension lets you define variables that can be reused across multiple endpoints in your API spec. This is particularly useful for common path parameters like `project_id` that appear in many routes.
+
+```yaml
+components:
+  x-fern-sdk-variables:
+    project_id:
+      type: string
+      description: "The ID of the project"
+      pattern: "^proj_[a-zA-Z0-9]+$"
+
+paths:
+  "/v1/connect/{project_id}/accounts":
+    parameters:
+      - name: project_id
+        in: path
+        required: true
+        schema:
+          type: string
+          pattern: "^proj_[a-zA-Z0-9]+$"
+        x-fern-sdk-variable: "project_id"
+```
+
+When using this extension:
+
+- Define variables under `components.x-fern-sdk-variables`
+- Reference them in path parameters using `x-fern-sdk-variable`
+- The SDK client will accept these variables in the constructor
+- Values are automatically injected into API requests
+
+This reduces repetition and makes your SDKs more maintainable, as users only need to provide values like `project_id` once during client initialization rather than passing them to every method call.
+
+<Note>
+  SDK variables are currently supported in Python SDKs from version 4.24.0 and higher.
+</Note>
+
+## API URL Customization
+
+The `x-fern-api-url` extension allows you to customize the base URL for API requests in your generated SDKs:
+
+```yaml {3}
+servers:
+  - url: "https://api.example.com"
+    x-fern-api-url: "api_url"
+```
+
+This renames the URL parameter to `api_url` in the SDK client constructor.
+
+<Tip>
+  Use these extensions to create SDKs that are more intuitive and user-friendly while maintaining consistency with your API's underlying structure.
+</Tip>

fern/products/sdks/overview/python/configuration.mdx

@@ -21,13 +21,15 @@ groups:
 ## SDK Configuration Options
 
 <ParamField path="additional_init_exports" type="array" default="null" required={false} toc={true}>
+  Additional items to export in the package's __init__.py file.
 </ParamField>
 
 <ParamField path="default_bytes_stream_chunk_size" type="number" default="null" required={false} toc={true}>
   The chunk size to use (if any) when processing a response bytes stream within `iter_bytes` or `aiter_bytes` results in: `for chunk in response.iter_bytes(chunk_size=<default_bytes_stream_chunk_size>):`
 </ParamField>
 
 <ParamField path="exclude_types_from_init_exports" type="bool" default="false" required={false} toc={true}>
+  If true, excludes type definitions from being exported in the package's __init__.py file.
 </ParamField>
 
 <ParamField path="extra_dependencies" type="object" default="{}" required={false} toc={true}>
@@ -40,27 +42,31 @@ groups:
 </ParamField>
 
 <ParamField path="extra_dev_dependencies" type="object" default="{}" required={false} toc={true}>
+  Additional development dependencies to include in the generated SDK's pyproject.toml.
 </ParamField>
 
 <ParamField path="extras" type="object" default="{}" required={false} toc={true}>
+  Optional dependency groups to define in pyproject.toml.
 </ParamField>
 
 <ParamField path="flat_layout" type="bool" default="false" required={false} toc={true}>
+  If true, generates a flatter file structure without nested directories.
 </ParamField>
 
 <ParamField path="follow_redirects_by_default" type="bool" default="true" required={false} toc={true}>
   Whether to follow redirects by default in HTTP requests.
 </ParamField>
 
 <ParamField path="improved_imports" type="bool" default="true" required={false} toc={true}>
-  Feature flag that improves imports in the Python SDK by removing nested `resources` directory
+  Feature flag that improves imports in the Python SDK by removing nested `resources` directory.
 </ParamField>
 
 <ParamField path="include_legacy_wire_tests" type="bool" default="false" required={false} toc={true}>
-  Whether or not to include legacy wire tests in the generated SDK
+  Whether or not to include legacy wire tests in the generated SDK.
 </ParamField>
 
 <ParamField path="include_union_utils" type="bool" default="false" required={false} toc={true}>
+  When true, includes utility functions for working with union types.
 </ParamField>
 
 <ParamField path="inline_path_params" type="bool" default="false" required={false} toc={true}>
@@ -72,26 +78,18 @@ groups:
 </ParamField>
 
 <ParamField path="package_name" type="string" default="null" required={false} toc={true}>
-
-Specifies the Python package name that users will import your generated client
-from.
+  Specifies the Python package name that users will import your generated client from.
 
-For example, setting `package_name: "my_custom_package"` enables users to use
-`my_custom_package import Client` to import your client:
+  For example, setting `package_name: "my_custom_package"` enables users to use `from my_custom_package import Client` to import your client:
 
-```yaml {7-10}
-default-group: local
-groups:
-  local:
-    generators:
-      - name: fernapi/fern-python
-        version: 0.7.1
-        config:
-          package_name: "my_custom_package"
-```
+  ```yaml
+  config:
+    package_name: "my_custom_package"
+  ```
 </ParamField>
 
 <ParamField path="pydantic_config" type="SdkPydanticModelCustomConfig" default="SdkPydanticModelCustomConfig()" required={false} toc={true}>
+  Configuration options for Pydantic model generation.
 </ParamField>
 
 <ParamField path="pydantic_config.include_union_utils" type="bool" default="false" required={false} toc={true}>
@@ -112,18 +110,16 @@ groups:
   # Visit every case in the union
   shape = get_shape()
   shape.visit(
-    circle: lambda circle: do_something_with_circle(circle),
-    triangle: lambda triangle: do_something_with_triangle(triangle),
+    circle = lambda circle: do_something_with_circle(circle),
+    triangle = lambda triangle: do_something_with_triangle(triangle),
   )
   ```
-
-  When enabled, the python generator will not run Black formatting in the generated code. Black is slow so this can potentially speed up code generation quite a bit.
 </ParamField>
 
 <ParamField path="pydantic_config.version" type="'v1' | 'v2' | 'both' | 'v1_on_v2'" default="both" required={false} toc={true}>
   By default, the generator generates pydantic models that are v1 and v2 compatible. However you can override them to:
   - `v1`: strictly use Pydantic v1
-  - `v2`: strictly use Pydantic v2
+  - `v2`: strictly use Pydantic v2  
   - `both`: maintain compatibility with both versions
   - `v1_on_v2`: use Pydantic v1 compatibility layer on v2
 
@@ -140,20 +136,23 @@ groups:
 </ParamField>
 
 <ParamField path="pyproject_toml" type="string" default="null" required={false} toc={true}>
+  Custom pyproject.toml content to include in the generated SDK.
 </ParamField>
 
 <ParamField path="should_generate_websocket_clients" type="bool" default="false" required={false} toc={true}>
   Feature flag that enables generation of Python websocket clients.
 </ParamField>
 
 <ParamField path="skip_formatting" type="bool" default="false" required={false} toc={true}>
+  If true, skips code formatting of the generated SDK.
 </ParamField>
 
 <ParamField path="timeout_in_seconds" type="number | 'infinity'" default="60" required={false} toc={true}>
   By default, the generator generates a client that times out after 60 seconds. You can customize this value by providing a different number or setting to `infinity` to get rid of timeouts.
 </ParamField>
 
 <ParamField path="use_api_name_in_package" type="bool" default="false" required={false} toc={true}>
+  When true, includes the API name in the generated package name.
 </ParamField>
 
 <ParamField path="use_inheritance_for_extended_models" type="bool" default="true" required={false} toc={true}>
@@ -168,17 +167,43 @@ groups:
   Whether or not to generate TypedDicts instead of Pydantic Models for file upload request objects. Note that this flag was only introduced due to an oversight in the `use_typeddict_requests` flag implementation; it should be removed in the future.
 </ParamField>
 
-### client
-  Configuration for the generated client class and file structure.
+### Extension Headers
 
-  ```yaml
-  config:
-    client:
-      filename: "my_client.py"
-      class_name: "MyClient"
-      exported_filename: "my_client.py"
-      exported_class_name: "MyClient"
-  ```
+You can specify SDK variables using the `x-fern-sdk-variables` extension in your OpenAPI spec. These will be added as constructor parameters in the generated client:
+
+```yaml
+components:
+  # ...other components
+x-fern-sdk-variables:
+  project_id:
+    type: string
+    description: The ID of the project
+    pattern: "^proj_[a-zA-Z0-9]+$"
+```
+
+This will generate a client constructor that accepts the variable:
+
+```python
+from my_sdk import Client
+
+client = Client(
+    project_id="proj_abc123" # Required variable from x-fern-sdk-variables
+)
+```
+
+The SDK will automatically inject these variables into API paths that contain matching parameter names.
+
+### client
+Configuration for the generated client class and file structure.
+
+```yaml
+config:
+  client:
+    filename: "my_client.py"  
+    class_name: "MyClient"
+    exported_filename: "my_client.py"
+    exported_class_name: "MyClient"
+```
 
 <ParamField path="filename" type="string" default="client.py" required={false} toc={true}>
   The filename for the generated client file.