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

fern/products/openapi-def/openapi-def.yml

@@ -4,7 +4,7 @@ navigation:
   - page: Authentication
     path: ./pages/auth.mdx
   - page: Servers
-    path: ./pages/servers.mdx            
+    path: ./pages/servers.mdx
   - section: Endpoints
     slug: endpoints
     contents:
@@ -17,6 +17,9 @@ navigation:
       - page: Server-Sent Events
         path: ./pages/endpoints/sse.mdx
         slug: sse
+      - page: others
+        title: Other
+        path: ./pages/extensions/others.mdx
   - section: Extensions
     slug: extensions
     contents:
@@ -38,7 +41,7 @@ navigation:
       - page: Overlay Customizations
         path: ./pages/overrides.mdx
       - page: Sync your OpenAPI Specification
-        path: ./pages/automation.mdx            
+        path: ./pages/automation.mdx
   - section: Integrate your Server Framework
     slug: frameworks
     contents:

fern/products/openapi-definition/pages/extensions/others.mdx

@@ -0,0 +1,77 @@
+---
+title: Other Extensions
+description: Documentation for various custom OpenAPI extensions used in Fern
+---
+
+## X-Fern-SDK-Variables
+
+The `x-fern-sdk-variables` extension allows you to define variables that can be injected into paths across your OpenAPI spec. This enables cleaner path definitions and avoids repetition.
+
+### Example Usage
+
+```yaml
+openapi: 3.0.0
+x-fern-sdk-variables:
+  project_id:
+    type: string 
+    description: "The project ID"
+    pattern: "^proj_[a-zA-Z0-9]+$"
+paths:
+  /v1/projects/{project_id}/widgets:
+    parameters:
+      - name: project_id
+        in: path
+        required: true
+        schema:
+          type: string
+        x-fern-sdk-variable: project_id
+```
+
+When using a generated SDK, the variable will be set in the client constructor rather than passed to individual methods:
+
+```typescript
+const client = new Client({
+  projectId: "proj_123" // Set once in constructor
+});
+
+// projectId automatically injected into path
+await client.widgets.list();
+```
+
+### Configuration Options
+
+<ParamField query="type" type="string" required>
+  The type of the variable (string, integer, etc)
+</ParamField>
+
+<ParamField query="description" type="string">
+  Description of what the variable represents
+</ParamField>
+
+<ParamField query="pattern" type="string">
+  Optional regex pattern the variable must match
+</ParamField>
+
+### Parameter Setup
+
+To use a defined variable in a path parameter:
+
+1. Define the variable in `x-fern-sdk-variables`
+2. Add the path parameter normally in your OpenAPI spec
+3. Add `x-fern-sdk-variable: variable_name` to the parameter definition
+
+### Generated SDK Behavior
+
+- Variables are passed via the SDK client constructor
+- The SDK injects variable values automatically into paths
+- Type checking and validation happen at the SDK level
+- Error handling for missing/invalid variables is built in
+
+The SDK will validate the variable values match any defined patterns or constraints before making requests.
+
+### Best Practices
+
+- Use consistent variable names across your API spec
+- Add clear descriptions for what each variable represents
+- Define patterns when variables must match specific formats
+- Consider SDK usability when choosing variable names

fern/products/sdks/guides/configure-global-headers.mdx

@@ -77,8 +77,10 @@ If you'd like to see this feature, please upvote [this issue](https://github.com
 </Accordion>
 <Accordion title="OpenAPI">
 
-Use the `x-fern-global-headers` extension to label additional headers as global
-or to alias the names of global headers:
+Use one of the following extensions to specify global configuration:
+
+### x-fern-global-headers
+Use this to label additional headers as global or to alias header names:
 
 ```yaml title="openapi.yml"
 x-fern-global-headers:
@@ -97,5 +99,56 @@ class Client:
 
   def __init__(self, *, apiKey: str, userpoolId: typing.Optional[str])
 ```
+
+### x-fern-sdk-variables
+Use this to specify variables that should be part of the SDK client constructor and injected into paths:
+
+```yaml title="openapi.yml"
+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 that accepts the variable in the constructor and automatically injects it into paths:
+
+```python
+class Client:
+  def __init__(self, *, project_id: str):
+    # Variable will be injected into paths like /v1/connect/{project_id}/accounts
+```
+
 </Accordion>
-</AccordionGroup>
+</AccordionGroup>
+
+## Supported Extension Fields
+
+The following extension fields are supported for configuring global headers and variables:
+
+<ParamField query="x-fern-global-headers" type="array">
+  Array of header configurations with fields:
+  - `header`: The original header name
+  - `name`: Optional alias for the header in the SDK
+  - `optional`: Whether the header is optional
+</ParamField>
+
+<ParamField query="x-fern-sdk-variables" type="object">
+  Object mapping variable names to their configuration:
+  - `type`: The variable type (string, integer, etc)
+  - `description`: Description of the variable 
+  - `pattern`: Optional regex pattern for validation
+</ParamField>
+
+## Language Support
+
+Global configuration support varies by language:
+
+- TypeScript/JavaScript: Full support for global headers and variables
+- Python: Full support as of version 4.24.0+
+- Java: Full support for global headers and variables
+- Go: Full support for global headers and variables
+
+<Note>
+Make sure you're using the latest generator versions to access all global configuration features. You can update your generator versions in `generators.yml`.
+</Note>