> For clean Markdown content of this page, append .md to this URL. For the complete documentation index, see https://buildwithfern.com/learn/llms.txt. ## 5.27.0 **`(feat):`** Add an opt-in `prefer_explicit_auth` configuration option. When enabled (and the API composes OAuth client-credentials with basic auth via `auth: any`), auth credentials passed explicitly to the client constructor take precedence over environment-variable defaults when selecting the auth scheme — e.g. explicitly provided basic auth credentials win over OAuth client ID/secret environment variables. Disabled by default, so existing generated output and runtime behavior are unchanged.