Developed runtime configuration file support for stack deployment and preview in the spacelift-io/spacectl repository, focusing on enhancing deployment flexibility and reproducibility. Introduced a new CLI flag to accept user-defined runtime configuration files, and designed a dedicated RuntimeConfig input struct to encapsulate these settings. Modified the run trigger logic to read and pass the configuration to the underlying GraphQL mutation, enabling seamless integration with existing deployment workflows. This work, implemented in Go and leveraging skills in CLI development and configuration management, reduced manual configuration steps and potential errors, allowing users to manage environment-specific settings more efficiently during stack operations.