Developed a language override feature for the Contacts API within the intercom/Intercom-OpenAPI repository, enabling per-contact language configuration using ISO 639-1 codes. Focused on backend and API development, the implementation updated both create and update contact request schemas in YAML, ensuring that invalid language codes are automatically set to null to maintain data integrity. The feature was integrated into the Unstable API version, aligning language preferences across Fin and Messenger workflows to enhance localization consistency. Work included revising API schemas, request handlers, and response descriptions, laying the groundwork for improved localization and user experience in downstream Intercom products.