use codex_api::SearchInput;use codex_core::parse_turn_item;use codex_protocol::items::TurnItem;use codex_protocol::models::ContentItem;use codex_protocol::models::ResponseItem;use codex_protocol::models::plaintext_agent_message_content;use codex_tools::retain_tail_from_last_n_user_messages;use codex_tools::truncate_assistant_output_text_to_token_budget;const ASSISTANT_CONTEXT_TOKEN_LIMIT: usize = 1_000;const ASSISTANT_ROLE: &str = "assistant";const USER_ROLE: &str = "user";/// Builds the conversation tail for standalone web search.////// The tail keeps the previous user text message, up to 1k tokens of assistant/// text that followed it, and the current user text message.pub(crate) fn recent_input(items: &[ResponseItem]) -> Option<SearchInput> {    let mut messages = Vec::new();    for item in items {        push_visible_message(&mut messages, item);    }    retain_tail_from_last_n_user_messages(&mut messages, /*user_message_count*/ 2);    truncate_assistant_output_text_to_token_budget(&mut messages, ASSISTANT_CONTEXT_TOKEN_LIMIT);    (!messages.is_empty()).then_some(SearchInput::Items(messages))}fn push_visible_message(messages: &mut Vec<ResponseItem>, item: &ResponseItem) {    match item {        ResponseItem::Message { role, .. } if role == ASSISTANT_ROLE => {            messages.push(item.clone());        }        ResponseItem::AgentMessage {            author,            content,            metadata,            ..        } => {            if let Some(text) = plaintext_agent_message_content(content) {                messages.push(ResponseItem::Message {                    id: None,                    role: ASSISTANT_ROLE.to_string(),                    content: vec![ContentItem::OutputText {                        text: format!("Agent message from {author}:\n{text}"),                    }],                    phase: None,                    metadata: metadata.clone(),                });            }        }        ResponseItem::Message {            id,            role,            content,            phase,            metadata,        } if role == USER_ROLE            && matches!(parse_turn_item(item), Some(TurnItem::UserMessage(_))) =>        {            let content = content                .iter()                .filter(|item| matches!(item, ContentItem::InputText { .. }))                .cloned()                .collect::<Vec<_>>();            if !content.is_empty() {                messages.push(ResponseItem::Message {                    id: id.clone(),                    role: role.clone(),                    content,                    phase: phase.clone(),                    metadata: metadata.clone(),                });            }        }        _ => {}    }}#[cfg(test)]mod tests {    use codex_api::SearchInput;    use codex_protocol::models::ContentItem;    use codex_protocol::models::ResponseItem;    use pretty_assertions::assert_eq;    use super::ASSISTANT_ROLE;    use super::USER_ROLE;    use super::recent_input;    fn message(role: &str, text: &str) -> ResponseItem {        ResponseItem::Message {            id: None,            role: role.to_string(),            content: vec![if role == ASSISTANT_ROLE {                ContentItem::OutputText {                    text: text.to_string(),                }            } else {                ContentItem::InputText {                    text: text.to_string(),                }            }],            phase: None,            metadata: None,        }    }    #[test]    fn keeps_current_user_and_previous_visible_turn() {        let items = vec![            message("system", "system"),            message(USER_ROLE, "old user"),            message(ASSISTANT_ROLE, "old assistant"),            message(USER_ROLE, "previous user"),            ResponseItem::FunctionCall {                id: None,                name: "tool".to_string(),                namespace: None,                arguments: "{}".to_string(),                call_id: "call-1".to_string(),                metadata: None,            },            message(ASSISTANT_ROLE, "previous assistant"),            message("developer", "developer"),            message(USER_ROLE, "current user"),            message(ASSISTANT_ROLE, "current commentary"),        ];        assert_eq!(            recent_input(&items),            Some(SearchInput::Items(vec![                message(USER_ROLE, "previous user"),                message(ASSISTANT_ROLE, "previous assistant"),                message(USER_ROLE, "current user"),            ]))        );    }    #[test]    fn keeps_only_text_from_recent_user_messages() {        let previous_user = ResponseItem::Message {            id: None,            role: USER_ROLE.to_string(),            content: vec![                ContentItem::InputText {                    text: "previous user".to_string(),                },                ContentItem::InputImage {                    image_url: "data:image/png;base64,image".to_string(),                    detail: None,                },            ],            phase: None,            metadata: None,        };        let items = vec![            previous_user,            message(ASSISTANT_ROLE, "previous assistant"),            message(USER_ROLE, "current user"),        ];        assert_eq!(            recent_input(&items),            Some(SearchInput::Items(vec![                message(USER_ROLE, "previous user"),                message(ASSISTANT_ROLE, "previous assistant"),                message(USER_ROLE, "current user"),            ]))        );    }    #[test]    fn ignores_contextual_user_messages_when_selecting_recent_turns() {        let items = vec![            message(USER_ROLE, "previous user"),            message(ASSISTANT_ROLE, "previous assistant"),            message(                USER_ROLE,                "<environment_context>\n<cwd>/tmp</cwd>\n</environment_context>",            ),            message(USER_ROLE, "current user"),        ];        assert_eq!(            recent_input(&items),            Some(SearchInput::Items(vec![                message(USER_ROLE, "previous user"),                message(ASSISTANT_ROLE, "previous assistant"),                message(USER_ROLE, "current user"),            ]))        );    }}