Function assemble

atomic-agent/src/transcript/opencode.rs:236–384

Fold messages and parts into [`TurnData`]. The current turn starts at the last user message; reasoning, response, and step statistics are scoped to that window, while the transcript covers the whole session (mirroring how Claude Code's transcript file is a full-session record).

(messages: &[(String, String)], parts: &[(String, Value)])

/// covers the whole session (mirroring how Claude Code's transcript file
/// is a full-session record).
fn assemble(messages: &[(String, String)], parts: &[(String, Value)]) -> TurnData {
    let role_of: HashMap<&str, &str> = messages
        .iter()
        .map(|(id, role)| (id.as_str(), role.as_str()))
        .collect();

    // Turn window: message indices from the last user message onward.
    let turn_start = messages
        .iter()
        .rposition(|(_, role)| role == "user")
        .unwrap_or(0);
    let in_turn: HashMap<&str, bool> = messages
        .iter()
        .enumerate()
        .map(|(i, (id, _))| (id.as_str(), i >= turn_start))
        .collect();

    let mut data = TurnData {
        transcript_jsonl: String::new(),
        reasoning_blocks: Vec::new(),
        response: None,
        input_tokens: 0,
        output_tokens: 0,
        reasoning_tokens: 0,
        cache_read_tokens: 0,
        cache_write_tokens: 0,
        cost_usd: 0.0,
        finish_reason: None,
        step_count: 0,
        tool_parts: Vec::new(),
    };

    let push_line = |line: Value, out: &mut TurnData| {
        if let Ok(s) = serde_json::to_string(&line) {
            out.transcript_jsonl.push_str(&s);
            out.transcript_jsonl.push('\n');
        }
    };

    for (message_id, part) in parts {
        let part_type = part.get("type").and_then(Value::as_str).unwrap_or("");
        let in_turn = in_turn.get(message_id.as_str()).copied().unwrap_or(false);
        let role = role_of
            .get(message_id.as_str())
            .copied()
            .unwrap_or("assistant");

        match part_type {
            "text" => {
                let Some(text) = part.get("text").and_then(Value::as_str) else {
                    continue;
                };
                if text.trim().is_empty() {
                    continue;
                }
                let line = serde_json::json!({ "type": role, "text": text });
                push_line(line, &mut data);
                if in_turn && role == "assistant" {