use codex_prompts::BACKEND_PROMPT;const DEFAULT_USER_FIRST_NAME: &str = "there";const USER_FIRST_NAME_PLACEHOLDER: &str = "{{ user_first_name }}";pub(crate) fn prepare_realtime_backend_prompt(    prompt: Option<Option<String>>,    config_prompt: Option<String>,) -> String {    if let Some(config_prompt) = config_prompt        && !config_prompt.trim().is_empty()    {        return config_prompt;    }    match prompt {        Some(Some(prompt)) => return prompt,        Some(None) => return String::new(),        None => {}    }    BACKEND_PROMPT        .trim_end()        .replace(USER_FIRST_NAME_PLACEHOLDER, &current_user_first_name())}fn current_user_first_name() -> String {    [whoami::realname(), whoami::username()]        .into_iter()        .filter_map(|name| name.split_whitespace().next().map(str::to_string))        .find(|name| !name.is_empty())        .unwrap_or_else(|| DEFAULT_USER_FIRST_NAME.to_string())}#[cfg(test)]mod tests {    use super::prepare_realtime_backend_prompt;    #[test]    fn prepare_realtime_backend_prompt_prefers_config_override() {        assert_eq!(            prepare_realtime_backend_prompt(                Some(Some("prompt from request".to_string())),                Some("prompt from config".to_string()),            ),            "prompt from config"        );    }    #[test]    fn prepare_realtime_backend_prompt_uses_request_prompt() {        assert_eq!(            prepare_realtime_backend_prompt(                Some(Some("prompt from request".to_string())),                /*config_prompt*/ None,            ),            "prompt from request"        );    }    #[test]    fn prepare_realtime_backend_prompt_preserves_empty_request_prompt() {        assert_eq!(            prepare_realtime_backend_prompt(Some(Some(String::new())), /*config_prompt*/ None),            ""        );        assert_eq!(            prepare_realtime_backend_prompt(Some(None), /*config_prompt*/ None),            ""        );    }    #[test]    fn prepare_realtime_backend_prompt_renders_default() {        let prompt =            prepare_realtime_backend_prompt(/*prompt*/ None, /*config_prompt*/ None);        assert!(prompt.starts_with("## Identity, tone, and role"));        assert!(prompt.contains("You are Codex, an OpenAI general-purpose agentic assistant"));        assert!(prompt.contains("The user's name is "));        assert!(!prompt.contains("{{ user_first_name }}"));    }}