feat(api): add back env var auth (#49)

Author: stainless-app[bot]

README.md

@@ -39,6 +39,11 @@ project_return_schema = client.projects.create(
 print(project_return_schema.id)
 ```
 
+While you can provide an `api_key` keyword argument,
+we recommend using [python-dotenv](https://pypi.org/project/python-dotenv/)
+to add `CODEX_API_KEY="My API Key"` to your `.env` file
+so that your API Key is not stored in source control.
+
 ## Async usage
 
 Simply import `AsyncCodex` instead of `Codex` and use `await` with each API call:

src/codex/_client.py

@@ -95,9 +95,18 @@ def __init__(
         # part of our public interface in the future.
         _strict_response_validation: bool = False,
     ) -> None:
-        """Construct a new synchronous Codex client instance."""
+        """Construct a new synchronous Codex client instance.
+
+        This automatically infers the following arguments from their corresponding environment variables if they are not provided:
+        - `api_key` from `CODEX_API_KEY`
+        - `access_key` from `CODEX_ACCESS_KEY`
+        """
+        if api_key is None:
+            api_key = os.environ.get("CODEX_API_KEY")
         self.api_key = api_key
 
+        if access_key is None:
+            access_key = os.environ.get("CODEX_ACCESS_KEY")
         self.access_key = access_key
 
         self._environment = environment
@@ -325,9 +334,18 @@ def __init__(
         # part of our public interface in the future.
         _strict_response_validation: bool = False,
     ) -> None:
-        """Construct a new async Codex client instance."""
+        """Construct a new async Codex client instance.
+
+        This automatically infers the following arguments from their corresponding environment variables if they are not provided:
+        - `api_key` from `CODEX_API_KEY`
+        - `access_key` from `CODEX_ACCESS_KEY`
+        """
+        if api_key is None:
+            api_key = os.environ.get("CODEX_API_KEY")
         self.api_key = api_key
 
+        if access_key is None:
+            access_key = os.environ.get("CODEX_ACCESS_KEY")
         self.access_key = access_key
 
         self._environment = environment