//! Codex app-server notifications into the common event model.
//!
//! The CLI promises JSONL but deliberately leaves room for new item kinds. We
//! therefore match only the records that have a useful common equivalent and
//! ignore the rest; an added Codex item must not make a live session go deaf.

use std::collections::{HashMap, HashSet};
use std::sync::{Arc, Mutex};

use serde_json::{Value, json};

use super::super::driver::{Event, SessionStatus, patch_start, prefixed_lines};
use super::super::subagent::Subagents;

#[derive(Default)]
pub(super) struct Translator {
    pub(super) thread_id: Option<String>,
    completed: bool,
    limited: bool,
    subagents: Option<Arc<Subagents>>,
    background_processes: Option<Arc<Mutex<HashSet<String>>>>,
    children: HashMap<String, Translator>,
    prompts: HashMap<String, String>,
    async_messages: HashSet<String>,
    in_turn: bool,
}

impl Translator {
    pub(super) fn new(
        subagents: Arc<Subagents>,
        background_processes: Arc<Mutex<HashSet<String>>>,
        thread_id: Option<String>,
        in_turn: bool,
    ) -> Self {
        Self {
            thread_id,
            subagents: Some(subagents),
            background_processes: Some(background_processes),
            in_turn,
            ..Self::default()
        }
    }

    /// Whether a protocol notification belongs to the session's root thread.
    /// App-server multiplexes every spawned thread onto the same stdout, so
    /// the process-state bookkeeping in `codex.rs` must not mistake a child's
    /// turn for the session's own.
    pub(super) fn is_parent(&self, line: &Value) -> bool {
        if line.get("id").is_some() && line.get("method").is_none() {
            return true;
        }
        let kind = line.get("method").and_then(Value::as_str);
        let body = kind.and_then(|_| line.get("params")).unwrap_or(line);
        if let Some(root) = started_thread_is_root(kind, body) {
            // A clear or missing-rollout recovery replaces the root id inside this same
            // app-server. The new root cannot match the id this translator still holds; its null
            // parent is the authoritative distinction from a newly spawned subagent.
            return root;
        }
        match (self.thread_id.as_deref(), notification_thread(line)) {
            (Some(parent), Some(thread)) => parent == thread,
            _ => true,
        }
    }

    #[cfg(test)]
    pub(super) fn translate(&mut self, line: &Value) -> Vec<Event> {
        self.translate_with_prefix(line, Vec::new())
    }

    /// Translates one multiplexed app-server record. `prefix` contains image
    /// events extracted by the driver and must precede the item's ToolEnd in
    /// whichever transcript owns the record.
    pub(super) fn translate_with_prefix(&mut self, line: &Value, prefix: Vec<Event>) -> Vec<Event> {
        let before = self.background_task_count();
        let mut events = self.translate_inner(line, prefix);
        let after = self.background_task_count();
        if after != before
            && let Some(count) = after
        {
            events.push(Event::BackgroundTasks { count });
        }
        events
    }

    fn translate_inner(&mut self, line: &Value, mut prefix: Vec<Event>) -> Vec<Event> {
        let method = line.get("method").and_then(Value::as_str);
        let body = method.and_then(|_| line.get("params")).unwrap_or(line);
        let kind = method.or_else(|| line.get("type").and_then(Value::as_str));
        let item = body.get("item").unwrap_or(&Value::Null);

        self.remember_collaboration(item);
        if item.get("type").and_then(Value::as_str) == Some("subAgentActivity") {
            return self.translate_activity(item);
        }
        self.remember_spawned_thread(kind, body);

        let thread = notification_thread(line);
        let root_started = started_thread_is_root(kind, body) == Some(true);
        let child = thread.filter(|thread| {
            !root_started
                && self
                    .thread_id
                    .as_deref()
                    .is_some_and(|parent| parent != *thread)
        });
        if let Some(id) = child {
            self.ensure_child(id, "subagent", None);
            if let Some(subagents) = &self.subagents {
                subagents.reopen(id);
            }
            let translator = self.children.entry(id.to_string()).or_default();
            prefix.extend(translator.translate_line(kind, body, line));
            return self.record_child(id, prefix);
        }

        if matches!(kind, Some("turn.started" | "turn/started")) {
            self.in_turn = true;
        }
        prefix.extend(self.translate_line(kind, body, line));
        if matches!(kind, Some("turn.completed" | "turn/completed")) {
            self.in_turn = false;
        }
        prefix
    }

    fn background_task_count(&self) -> Option<usize> {
        self.subagents.as_ref().map(|subagents| {
            subagents.open_count()
                + self
                    .background_processes
                    .as_ref()
                    .map(|processes| processes.lock().unwrap().len())
                    .unwrap_or(0)
        })
    }

    fn translate_line(&mut self, kind: Option<&str>, body: &Value, line: &Value) -> Vec<Event> {
        match kind {
            Some("thread.started") => {
                self.thread_id = line
                    .get("thread_id")
                    .and_then(Value::as_str)
                    .map(str::to_string);
                Vec::new()
            }
            Some("thread/started") => {
                self.thread_id = body
                    .pointer("/thread/id")
                    .and_then(Value::as_str)
                    .map(str::to_string);
                Vec::new()
            }
            Some("turn.started") | Some("turn/started") => {
                self.completed = false;
                self.limited = false;
                vec![Event::Status {
                    state: SessionStatus::Running,
                }]
            }
            Some("item.started") | Some("item/started") => {
                let item = &body["item"];
                if let Some(id) = item.get("id").and_then(Value::as_str)
                    && item.get("delivery").and_then(Value::as_str) == Some("async")
                {
                    self.async_messages.insert(id.to_string());
                }
                start_item(item)
            }
            Some("item.updated") => update_item(&line["item"]),
            // The old `codex exec --json` dialect reports only the completed message. App-server
            // also reports deltas, but they are provisional: safety buffering can revise their
            // text before completion. Keep its completed copy as an append-only correction rather
            // than guessing that the two representations concatenate to the same answer.
            Some("item.completed") => complete_item(&body["item"], true),
            Some("item/completed") => {
                let item = &body["item"];
                let events = final_item(item);
                if let Some(id) = item.get("id").and_then(Value::as_str) {
                    self.async_messages.remove(id);
                }
                events
            }
            Some("item/agentMessage/delta") => {
                if body
                    .get("itemId")
                    .and_then(Value::as_str)
                    .is_some_and(|id| self.async_messages.contains(id))
                {
                    // The delta notification does not repeat `delivery`.
                    // Appending an asynchronously delivered peer report as
                    // assistant text merges it into the recipient's current
                    // reply; the next completed assistant item then replaces
                    // that whole row. The item/started record did identify it,
                    // so leave its text to the PeerMessage emitted at completion.
                    return Vec::new();
                }
                let Some(delta) = body.get("delta").and_then(Value::as_str) else {
                    return Vec::new();
                };
                vec![Event::AssistantText {
                    delta: delta.to_string(),
                }]
            }
            Some("item/commandExecution/outputDelta") => {
                let (Some(id), Some(output)) = (
                    body.get("itemId").and_then(Value::as_str),
                    body.get("delta").and_then(Value::as_str),
                ) else {
                    return Vec::new();
                };
                vec![Event::ToolUpdate {
                    id: id.to_string(),
                    output: output.to_string(),
                }]
            }
            // One of these per *model request*, not per turn: app-server's `last` is the
            // request that just finished, and a turn is as many requests as it made tool
            // calls. Reported as each arrives, so `tokens` adds up to what the turn cost --
            // held to the end of the turn it was the last request's cost alone, which on a
            // two-request turn measured 28,878 against the 51,399 actually spent -- and so
            // the context figure moves while a long turn is still running rather than
            // standing at what it was before the turn began.
            Some("thread/tokenUsage/updated") => {
                let last = &body["tokenUsage"]["last"];
                last.get("totalTokens")
                    .and_then(Value::as_u64)
                    .map(|tokens| Event::UsageDelta {
                        tokens,
                        // Cached input is a subset of this figure, not an additional count.
                        context: last.get("inputTokens").and_then(Value::as_u64),
                        tokens_per_second: None,
                        prefill_ms: None,
                    })
                    .into_iter()
                    .collect()
            }
            Some("turn.completed") | Some("turn/completed") => {
                self.completed = true;
                let mut events = Vec::new();
                // The old `codex exec --json` dialect reports the turn's usage here and
                // sends no `thread/tokenUsage/updated` at all.
                if let Some(usage) = line.get("usage") {
                    let input = number(usage, "input_tokens");
                    let output = number(usage, "output_tokens");
                    if input.is_some() || output.is_some() {
                        events.push(Event::UsageDelta {
                            tokens: input.unwrap_or(0) + output.unwrap_or(0),
                            context: input,
                            tokens_per_second: None,
                            prefill_ms: None,
                        });
                    }
                }
                if let Some(error) = body.pointer("/turn/error")
                    && !error.is_null()
                {
                    events.extend(self.failure(error));
                }
                events.push(Event::Status {
                    state: if self.background_task_count().is_some_and(|count| count > 0) {
                        SessionStatus::Waiting
                    } else {
                        SessionStatus::Idle
                    },
                });
                events
            }
            Some("turn.failed") | Some("error") => self.failure(body),
            _ => Vec::new(),
        }
    }

    /// Remembers prompts before the separate activity item announces which
    /// child thread a spawn produced. Interactions with an existing child are
    /// also real user turns in that child's transcript.
    fn remember_collaboration(&mut self, item: &Value) {
        if item.get("type").and_then(Value::as_str) != Some("collabAgentToolCall") {
            return;
        }
        let prompt = item
            .get("prompt")
            .and_then(Value::as_str)
            .filter(|prompt| !prompt.is_empty())
            .map(str::to_string);
        if let (Some(id), Some(prompt)) = (item.get("id").and_then(Value::as_str), &prompt) {
            self.prompts.insert(id.to_string(), prompt.clone());
        }
        let Some(receivers) = item.get("receiverThreadIds").and_then(Value::as_array) else {
            return;
        };
        for receiver in receivers.iter().filter_map(Value::as_str) {
            if let Some(prompt) = &prompt {
                self.prompts.insert(receiver.to_string(), prompt.clone());
            }
        }
        if item.get("status").and_then(Value::as_str) != Some("completed")
            || item.get("tool").and_then(Value::as_str) == Some("spawnAgent")
        {
            return;
        }
        let Some(prompt) = prompt else {
            return;
        };
        for receiver in receivers.iter().filter_map(Value::as_str) {
            if self.thread_id.as_deref() == Some(receiver) {
                continue;
            }
            self.ensure_child(receiver, "subagent", None);
            if let Some(subagents) = &self.subagents {
                subagents.reopen(receiver);
                subagents.record(
                    receiver,
                    Event::UserMessage {
                        id: None,
                        text: prompt.clone(),
                        attachments: Vec::new(),
                    },
                );
            }
        }
    }

    fn remember_spawned_thread(&mut self, kind: Option<&str>, body: &Value) {
        if kind != Some("thread/started") {
            return;
        }
        let thread = &body["thread"];
        if thread.get("parentThreadId").is_none_or(Value::is_null) {
            return;
        }
        let Some(id) = thread.get("id").and_then(Value::as_str) else {
            return;
        };
        let title = thread
            .get("name")
            .and_then(Value::as_str)
            .or_else(|| {
                thread
                    .pointer("/source/subAgent/thread_spawn/agent_path")
                    .and_then(Value::as_str)
            })
            .map(subagent_title)
            .unwrap_or_else(|| "subagent".to_string());
        let prompt = self.prompts.get(id).cloned().or_else(|| {
            thread
                .get("preview")
                .and_then(Value::as_str)
                .map(str::to_string)
        });
        self.ensure_child(id, &title, prompt.as_deref());
        if let Some(subagents) = &self.subagents {
            subagents.reopen(id);
        }
    }

    fn translate_activity(&mut self, item: &Value) -> Vec<Event> {
        let Some(id) = item.get("agentThreadId").and_then(Value::as_str) else {
            return Vec::new();
        };
        let title = item
            .get("agentPath")
            .and_then(Value::as_str)
            .map(subagent_title)
            .unwrap_or_else(|| "subagent".to_string());
        match item.get("kind").and_then(Value::as_str) {
            Some("started") => {
                let prompt = item
                    .get("id")
                    .and_then(Value::as_str)
                    .and_then(|call| self.prompts.get(call))
                    .cloned()
                    .or_else(|| self.prompts.get(id).cloned());
                self.ensure_child(id, &title, prompt.as_deref());
                if let Some(subagents) = &self.subagents {
                    subagents.reopen(id);
                }
                item.get("id")
                    .and_then(Value::as_str)
                    .map(|call| {
                        vec![Event::ToolEnd {
                            id: call.to_string(),
                            output: String::new(),
                        }]
                    })
                    .unwrap_or_default()
            }
            Some("interacted") => {
                self.ensure_child(id, &title, None);
                if let Some(subagents) = &self.subagents {
                    subagents.reopen(id);
                }
                Vec::new()
            }
            Some("interrupted" | "completed") => {
                self.ensure_child(id, &title, None);
                let was_open = self
                    .subagents
                    .as_ref()
                    .is_some_and(|subagents| subagents.is_open(id));
                if let Some(subagents) = &self.subagents {
                    subagents.finish(id);
                }
                self.prompts.remove(id);
                if was_open && !self.in_turn && self.background_task_count() == Some(0) {
                    vec![Event::Status {
                        state: SessionStatus::Idle,
                    }]
                } else {
                    Vec::new()
                }
            }
            _ => Vec::new(),
        }
    }

    fn ensure_child(&mut self, id: &str, title: &str, prompt: Option<&str>) {
        let Some(subagents) = &self.subagents else {
            return;
        };
        if subagents.get(id).is_none() {
            subagents.start(id, title, prompt);
        }
        self.children.entry(id.to_string()).or_default();
    }

    fn record_child(&self, id: &str, events: Vec<Event>) -> Vec<Event> {
        let Some(subagents) = &self.subagents else {
            return events;
        };
        let mut parent = Vec::new();
        for event in events {
            // A child remains running between its own turns and is closed by
            // SubAgentActivity, not by its turn/completed notification.
            if matches!(
                event,
                Event::Status {
                    state: SessionStatus::Idle | SessionStatus::Waiting | SessionStatus::Exited
                }
            ) {
                continue;
            }
            if matches!(event, Event::LimitReached { .. }) {
                parent.push(event.clone());
            }
            subagents.record(id, event);
        }
        parent
    }

    #[cfg(test)]
    pub(super) fn completed(&self) -> bool {
        self.completed
    }

    #[cfg(test)]
    pub(super) fn limited(&self) -> bool {
        self.limited
    }

    fn failure(&mut self, line: &Value) -> Vec<Event> {
        let detail = error_text(line);
        if is_limit(&detail) {
            if self.limited {
                return Vec::new();
            }
            self.limited = true;
            vec![Event::LimitReached {
                resets_at: find_reset(line),
            }]
        } else {
            vec![Event::Error { message: detail }]
        }
    }
}

fn notification_thread(line: &Value) -> Option<&str> {
    let method = line.get("method").and_then(Value::as_str)?;
    let body = &line["params"];
    if method == "thread/started" {
        body.pointer("/thread/id").and_then(Value::as_str)
    } else {
        body.get("threadId").and_then(Value::as_str)
    }
}

fn subagent_title(path: &str) -> String {
    path.rsplit('/')
        .find(|part| !part.is_empty())
        .unwrap_or(path)
        .replace('_', " ")
}

fn started_thread_is_root(kind: Option<&str>, body: &Value) -> Option<bool> {
    (kind == Some("thread/started")).then(|| {
        body.pointer("/thread/parentThreadId")
            .is_none_or(Value::is_null)
    })
}

fn start_item(item: &Value) -> Vec<Event> {
    if matches!(
        item.get("type").and_then(Value::as_str),
        Some("file_change" | "fileChange")
    ) {
        // Unlike command execution, a file change's start notification has no payload. Its
        // completed copy carries the diff, so that is where both common events are made; recording
        // this empty shell produced a Patch card containing only `diff:`.
        return Vec::new();
    }
    let Some((id, tool, input)) = tool(item) else {
        return Vec::new();
    };
    vec![Event::ToolStart { id, tool, input }]
}

fn update_item(item: &Value) -> Vec<Event> {
    let Some(id) = item.get("id").and_then(Value::as_str) else {
        return Vec::new();
    };
    let output = item
        .get("aggregated_output")
        .or_else(|| item.get("output"))
        .and_then(value_text);
    output
        .filter(|text| !text.is_empty())
        .map(|output| {
            vec![Event::ToolUpdate {
                id: id.to_string(),
                output,
            }]
        })
        .unwrap_or_default()
}

fn complete_item(item: &Value, include_agent_message: bool) -> Vec<Event> {
    match item.get("type").and_then(Value::as_str) {
        Some("agent_message" | "agentMessage")
            if item.get("delivery").and_then(Value::as_str) == Some("async") =>
        {
            delivered_agent_message(item).into_iter().collect()
        }
        Some("agent_message" | "agentMessage") => item
            .get("text")
            .and_then(Value::as_str)
            .filter(|text| !text.is_empty())
            .filter(|_| include_agent_message)
            .map(|delta| {
                vec![Event::AssistantText {
                    delta: delta.to_string(),
                }]
            })
            .unwrap_or_default(),
        Some("reasoning" | "userMessage") => Vec::new(),
        Some("file_change" | "fileChange") => item
            .get("id")
            .and_then(Value::as_str)
            .map(|id| {
                vec![
                    patch_start(id.to_string(), file_change_diff(item)),
                    Event::ToolEnd {
                        id: id.to_string(),
                        output: tool_output(item),
                    },
                ]
            })
            .unwrap_or_default(),
        _ => {
            let Some((id, _, _)) = tool(item) else {
                return Vec::new();
            };
            let output = tool_output(item);
            vec![Event::ToolEnd { id, output }]
        }
    }
}

fn final_item(item: &Value) -> Vec<Event> {
    match item.get("type").and_then(Value::as_str) {
        Some("agentMessage") if item.get("delivery").and_then(Value::as_str) == Some("async") => {
            delivered_agent_message(item).into_iter().collect()
        }
        Some("agentMessage") => item
            .get("text")
            .and_then(Value::as_str)
            .map(|text| {
                vec![Event::AssistantTextFinal {
                    text: text.to_string(),
                }]
            })
            .unwrap_or_default(),
        _ => complete_item(item, false),
    }
}

fn tool(item: &Value) -> Option<(String, String, Value)> {
    let id = item.get("id")?.as_str()?.to_string();
    let kind = item.get("type")?.as_str()?;
    let (name, input) = match kind {
        "command_execution" | "commandExecution" => command_tool(item),
        "file_change" | "fileChange" => return None,
        "mcp_tool_call" | "mcpToolCall" => (
            item.get("tool")
                .or_else(|| item.get("name"))
                .and_then(Value::as_str)
                .map(|tool| format!("mcp:{tool}"))
                .unwrap_or_else(|| "mcp".to_string()),
            item.get("arguments").cloned().unwrap_or(Value::Null),
        ),
        "dynamicToolCall" => (
            item.get("tool")
                .and_then(Value::as_str)
                .unwrap_or("tool")
                .to_string(),
            item.get("arguments").cloned().unwrap_or(Value::Null),
        ),
        "collabAgentToolCall" => {
            let name = match item.get("tool").and_then(Value::as_str) {
                Some("spawnAgent") => "Task",
                Some("sendInput" | "sendMessage" | "followupTask") => "SendMessage",
                Some("wait") => "TaskOutput",
                Some("closeAgent") => "CloseAgent",
                Some("interruptAgent") => "InterruptAgent",
                Some("listAgents") => "ListAgents",
                Some("resumeAgent") => "ResumeAgent",
                Some(tool) => tool,
                None => "Agent",
            };
            let mut input = json!({});
            if let Some(prompt) = item.get("prompt").and_then(Value::as_str) {
                input["prompt"] = Value::String(prompt.to_string());
            }
            if let Some(model) = item.get("model").and_then(Value::as_str) {
                input["model"] = Value::String(model.to_string());
            }
            if let Some(effort) = item.get("reasoningEffort").and_then(Value::as_str) {
                input["reasoningEffort"] = Value::String(effort.to_string());
            }
            (name.to_string(), input)
        }
        "functionCallOutput" => (
            item.get("name")
                .and_then(Value::as_str)
                .unwrap_or("tool")
                .to_string(),
            Value::Null,
        ),
        "imageView" => (
            "view_image".to_string(),
            json!({"path": item.get("path").cloned().unwrap_or(Value::Null)}),
        ),
        "web_search" | "webSearch" => (
            "WebSearch".to_string(),
            json!({"query": item.get("query").cloned().unwrap_or(Value::Null)}),
        ),
        "todo_list" | "todoList" | "plan" => ("update_plan".to_string(), item.clone()),
        _ => return None,
    };
    Some((id, name, input))
}

fn delivered_agent_message(item: &Value) -> Option<Event> {
    let text = item.get("text").and_then(Value::as_str)?;
    if text.is_empty() {
        return None;
    }
    let from = text
        .lines()
        .find_map(|line| line.strip_prefix("Sender: "))
        .unwrap_or("another agent")
        .to_string();
    let text = text
        .split_once("Payload:\n")
        .map(|(_, payload)| payload.trim())
        .filter(|payload| !payload.is_empty())
        .unwrap_or(text)
        .to_string();
    Some(Event::PeerMessage {
        from,
        text,
        turn_start: None,
    })
}

/// Codex records the executor's argv, while Claude reports the script handed to its Bash tool.
/// Collapse Codex's standard wrapper to the same common shape so the transcript describes the
/// command a person wrote, not the implementation used to start it. An unfamiliar executable is
/// left intact: hiding that would make a deliberately selected shell look like Bash.
fn command_tool(item: &Value) -> (String, Value) {
    let command = item.get("command").cloned().unwrap_or(Value::Null);
    if let Some(script) = command.as_str() {
        let script = rendered_bash_script(script).unwrap_or_else(|| script.to_string());
        return ("Bash".to_string(), json!({"command": script}));
    }
    if let Some(argv) = command.as_array()
        && let [program, option, script] = argv.as_slice()
        && program
            .as_str()
            .and_then(|program| program.rsplit('/').next())
            == Some("bash")
        && matches!(option.as_str(), Some("-c" | "-lc"))
        && let Some(script) = script.as_str()
    {
        return ("Bash".to_string(), json!({"command": script}));
    }
    let command = command
        .as_array()
        .map(|argv| argv.iter().map(shell_word).collect::<Vec<_>>().join(" "))
        .unwrap_or_else(|| command.to_string());
    ("Shell".to_string(), json!({"command": command}))
}

/// App-server renders the executor argv into one shell-quoted string. Unwrap only an exact Bash
/// invocation whose script has matching outer quotes; extra arguments stay visible rather than
/// being mistaken for part of the script.
fn rendered_bash_script(command: &str) -> Option<String> {
    let quoted = ["/usr/bin/bash -lc ", "/bin/bash -lc ", "bash -lc "]
        .iter()
        .find_map(|prefix| command.strip_prefix(prefix))?;
    if quoted.len() >= 2
        && ((quoted.starts_with('\'') && quoted.ends_with('\''))
            || (quoted.starts_with('"') && quoted.ends_with('"')))
    {
        return Some(quoted[1..quoted.len() - 1].to_string());
    }
    (!quoted.is_empty() && !quoted.chars().any(char::is_whitespace)).then(|| quoted.to_string())
}

fn shell_word(word: &Value) -> String {
    let Some(word) = word.as_str() else {
        return word.to_string();
    };
    if !word.is_empty()
        && word
            .chars()
            .all(|character| character.is_ascii_alphanumeric() || "/_-.=:,@+".contains(character))
    {
        return word.to_string();
    }
    format!("'{}'", word.replace('\'', "'\\''"))
}

fn file_change_diff(item: &Value) -> String {
    match item.get("changes") {
        // Current app-server protocol: [{path, kind: {type, move_path?}, diff}].
        Some(Value::Array(changes)) => changes
            .iter()
            .filter_map(|change| {
                let path = change.get("path")?.as_str()?;
                let kind = change.pointer("/kind/type").and_then(Value::as_str);
                let moved = change.pointer("/kind/move_path").and_then(Value::as_str);
                let body = change
                    .get("diff")
                    .and_then(Value::as_str)
                    .unwrap_or_default();
                Some(render_file_diff(path, kind, moved, body))
            })
            .collect::<Vec<_>>()
            .join("\n"),
        // Older exec protocol and durable Codex rollouts: {path: {type, unified_diff, ...}}.
        Some(Value::Object(changes)) => changes
            .iter()
            .map(|(path, change)| {
                let kind = change.get("type").and_then(Value::as_str);
                render_file_diff(
                    path,
                    kind,
                    change.get("move_path").and_then(Value::as_str),
                    change
                        .get(if matches!(kind, Some("add" | "delete")) {
                            "content"
                        } else {
                            "unified_diff"
                        })
                        .and_then(Value::as_str)
                        .unwrap_or_default(),
                )
            })
            .collect::<Vec<_>>()
            .join("\n"),
        _ => String::new(),
    }
}

fn render_file_diff(path: &str, kind: Option<&str>, moved: Option<&str>, body: &str) -> String {
    // Some protocol revisions carry complete unified diffs and some carry only their hunks.
    if !matches!(kind, Some("add" | "delete"))
        && (body.starts_with("--- ") || body.starts_with("diff --git "))
    {
        return body.to_string();
    }
    let from = if kind == Some("add") {
        "/dev/null"
    } else {
        path
    };
    let to = if kind == Some("delete") {
        "/dev/null"
    } else {
        moved.unwrap_or(path)
    };
    let body = match kind {
        // Add and delete carry file content, not a unified diff. Prefixing it here makes the
        // protocol's change kind authoritative: a '-' that belongs to a Markdown bullet can never
        // be mistaken for diff syntax.
        Some("add") => prefixed_lines('+', body),
        Some("delete") => prefixed_lines('-', body),
        _ => body.to_string(),
    };
    format!("--- {from}\n+++ {to}\n{body}")
}

fn tool_output(item: &Value) -> String {
    match item.get("type").and_then(Value::as_str) {
        Some("file_change" | "fileChange")
            if item.get("status").and_then(Value::as_str) == Some("completed") =>
        {
            return String::new();
        }
        Some("collabAgentToolCall")
            if item.get("status").and_then(Value::as_str) == Some("completed") =>
        {
            return String::new();
        }
        Some("dynamicToolCall") => {
            return content_text(item.get("contentItems"), "inputText");
        }
        Some("mcpToolCall") => {
            if let Some(message) = item.pointer("/error/message").and_then(Value::as_str) {
                return message.to_string();
            }
            return content_text(item.pointer("/result/content"), "text");
        }
        Some("functionCallOutput") => return content_text(item.get("output"), "input_text"),
        Some("imageView") => return String::new(),
        _ => {}
    }
    for key in [
        "aggregated_output",
        "aggregatedOutput",
        "output",
        "result",
        "error",
    ] {
        if let Some(text) = item.get(key).and_then(value_text)
            && !text.is_empty()
        {
            return text;
        }
    }
    match item.get("status").and_then(Value::as_str) {
        Some(status) => status.to_string(),
        None => String::new(),
    }
}

/// Text from a structured result, deliberately excluding its image data. The driver saves images
/// beside the transcript; serializing a data URL here makes a screenshot a megabytes-long line and
/// still cannot draw it.
fn content_text(value: Option<&Value>, text_kind: &str) -> String {
    match value {
        Some(Value::String(text)) => text.clone(),
        Some(Value::Array(parts)) => parts
            .iter()
            .filter(|part| part.get("type").and_then(Value::as_str) == Some(text_kind))
            .filter_map(|part| part.get("text").and_then(Value::as_str))
            .collect::<Vec<_>>()
            .join("\n"),
        _ => String::new(),
    }
}

fn value_text(value: &Value) -> Option<String> {
    value
        .as_str()
        .map(str::to_string)
        .or_else(|| (!value.is_null()).then(|| value.to_string()))
}

fn number(value: &Value, key: &str) -> Option<u64> {
    value.get(key).and_then(Value::as_u64)
}

fn error_text(line: &Value) -> String {
    line.get("message")
        .and_then(Value::as_str)
        .or_else(|| line.pointer("/error/message").and_then(Value::as_str))
        .or_else(|| line.get("error").and_then(Value::as_str))
        .unwrap_or("Codex ended the turn with an unknown error")
        .to_string()
}

fn is_limit(detail: &str) -> bool {
    let lower = detail.to_ascii_lowercase();
    lower.contains("usage limit")
        || lower.contains("rate limit")
        || lower.contains("quota exceeded")
        || lower.contains("credits depleted")
}

fn find_reset(value: &Value) -> Option<f64> {
    for key in ["resets_at", "resetsAt", "reset_at", "resetAt"] {
        if let Some(at) = value.get(key).and_then(Value::as_f64) {
            return Some(at);
        }
    }
    value.as_object()?.values().find_map(find_reset)
}

#[cfg(test)]
mod tests {
    use super::*;

    fn line(text: &str) -> Value {
        serde_json::from_str(text).expect("fixture")
    }

    #[test]
    fn translates_the_observed_minimal_stream() {
        let mut translator = Translator::default();
        assert!(
            translator
                .translate(&line(r#"{"type":"thread.started","thread_id":"thread-1"}"#))
                .is_empty()
        );
        assert_eq!(translator.thread_id.as_deref(), Some("thread-1"));
        assert_eq!(
            translator.translate(&line(
                r#"{"type":"item.completed","item":{"id":"item_0","type":"agent_message","text":"hello"}}"#
            )),
            vec![Event::AssistantText {
                delta: "hello".to_string()
            }]
        );
        let events = translator.translate(&line(
            r#"{"type":"turn.completed","usage":{"input_tokens":13,"cached_input_tokens":8,"output_tokens":5}}"#,
        ));
        assert_eq!(
            events[0],
            Event::UsageDelta {
                tokens: 18,
                context: Some(13),
                tokens_per_second: None,
                prefill_ms: None,
            }
        );
        assert!(translator.completed());
    }

    #[test]
    fn translates_tools_and_limits_without_matching_whole_records() {
        let mut translator = Translator::default();
        let started = translator.translate(&line(
            r#"{"type":"item.started","item":{"id":"item_1","type":"command_execution","command":["/usr/bin/bash","-lc","pwd"],"status":"in_progress"}}"#,
        ));
        assert_eq!(
            started,
            vec![Event::ToolStart {
                id: "item_1".to_string(),
                tool: "Bash".to_string(),
                input: json!({"command": "pwd"})
            }]
        );
        let ended = translator.translate(&line(
            r#"{"type":"item.completed","item":{"id":"item_1","type":"command_execution","command":"pwd","aggregated_output":"/tmp\n","exit_code":0,"status":"completed"}}"#,
        ));
        assert_eq!(
            ended,
            vec![Event::ToolEnd {
                id: "item_1".to_string(),
                output: "/tmp\n".to_string()
            }]
        );
        let limit = translator.translate(&line(
            r#"{"type":"turn.failed","error":{"message":"usage limit reached","resetsAt":1234}}"#,
        ));
        assert_eq!(
            limit,
            vec![Event::LimitReached {
                resets_at: Some(1234.0)
            }]
        );
        assert!(translator.limited());
    }

    #[test]
    fn a_replacement_root_is_not_mistaken_for_a_subagent() {
        let mut translator = Translator {
            thread_id: Some("old-root".to_string()),
            ..Translator::default()
        };
        let replacement = line(
            r#"{"method":"thread/started","params":{"thread":{"id":"new-root","parentThreadId":null}}}"#,
        );
        assert!(translator.is_parent(&replacement));
        assert!(translator.translate(&replacement).is_empty());
        assert_eq!(translator.thread_id.as_deref(), Some("new-root"));

        let child = line(
            r#"{"method":"thread/started","params":{"thread":{"id":"child","parentThreadId":"new-root"}}}"#,
        );
        assert!(!translator.is_parent(&child));
    }

    #[test]
    fn command_translation_only_hides_the_known_bash_wrapper() {
        let legacy = tool(&line(
            r#"{"id":"old","type":"command_execution","command":"pwd"}"#,
        ));
        assert_eq!(
            legacy,
            Some((
                "old".to_string(),
                "Bash".to_string(),
                json!({"command": "pwd"})
            ))
        );

        let rendered = tool(&json!({
            "id": "rendered",
            "type": "commandExecution",
            "command": "/usr/bin/bash -lc 'printf \"%s\\n\" hello'"
        }));
        assert_eq!(
            rendered,
            Some((
                "rendered".to_string(),
                "Bash".to_string(),
                json!({"command": "printf \"%s\\n\" hello"})
            ))
        );

        let double_quoted = tool(&json!({
            "id": "double-quoted",
            "type": "commandExecution",
            "command": r#"/usr/bin/bash -lc "printf '%s\n' "$HOME" \path""#
        }));
        assert_eq!(
            double_quoted,
            Some((
                "double-quoted".to_string(),
                "Bash".to_string(),
                json!({"command": "printf '%s\\n' \"$HOME\" \\path"})
            ))
        );

        let fish = tool(&line(
            r#"{"id":"fish","type":"commandExecution","command":["/usr/bin/fish","-c","pwd"]}"#,
        ));
        assert_eq!(
            fish,
            Some((
                "fish".to_string(),
                "Shell".to_string(),
                json!({"command": "/usr/bin/fish -c pwd"})
            ))
        );
    }

    #[test]
    fn web_search_uses_the_common_tool_shape() {
        assert_eq!(
            tool(&line(
                r#"{"id":"search-1","type":"webSearch","query":"Codex app-server protocol"}"#,
            )),
            Some((
                "search-1".to_string(),
                "WebSearch".to_string(),
                json!({"query": "Codex app-server protocol"})
            ))
        );
    }

    #[test]
    fn a_file_change_becomes_the_common_patch_shape() {
        let mut translator = Translator::default();
        let started = translator.translate(&line(
            r#"{"method":"item/started","params":{"item":{"id":"patch-1","type":"fileChange","changes":{},"status":"inProgress"}}}"#,
        ));
        assert!(started.is_empty());
        assert_eq!(
            translator.translate(&line(
                r#"{"method":"item/completed","params":{"item":{"id":"patch-1","type":"fileChange","changes":[{"path":"src/main.rs","kind":{"type":"update","move_path":null},"diff":"@@ -1 +1 @@\n-old\n+new\n"}],"status":"completed","stdout":"Success"}}}"#
            )),
            vec![
                patch_start(
                    "patch-1".to_string(),
                    "--- src/main.rs\n+++ src/main.rs\n@@ -1 +1 @@\n-old\n+new\n".to_string()
                ),
                Event::ToolEnd {
                    id: "patch-1".to_string(),
                    output: String::new()
                }
            ]
        );
    }

    #[test]
    fn the_legacy_file_change_shape_remains_readable() {
        let item = line(
            r#"{"changes":{"old.rs":{"type":"update","unified_diff":"@@ -1 +1 @@\n-a\n+b\n","move_path":"new.rs"}}}"#,
        );
        assert_eq!(
            file_change_diff(&item),
            "--- old.rs\n+++ new.rs\n@@ -1 +1 @@\n-a\n+b\n"
        );
    }

    #[test]
    fn whole_file_changes_get_markers_from_their_kind_not_their_content() {
        let item = line(
            r#"{"changes":[{"path":"added.md","kind":{"type":"add"},"diff":"--- a rule\n- a bullet\nplain\n"},{"path":"deleted.md","kind":{"type":"delete"},"diff":"- another bullet\nplain\n"}]}"#,
        );
        assert_eq!(
            file_change_diff(&item),
            "--- /dev/null\n+++ added.md\n+--- a rule\n+- a bullet\n+plain\n\n--- deleted.md\n+++ /dev/null\n-- another bullet\n-plain\n"
        );
    }

    #[test]
    fn legacy_whole_file_changes_show_the_content_they_changed() {
        let item = line(
            r#"{"changes":{"added.md":{"type":"add","content":"new\n"},"deleted.md":{"type":"delete","content":"old\n"}}}"#,
        );
        assert_eq!(
            file_change_diff(&item),
            "--- /dev/null\n+++ added.md\n+new\n\n--- deleted.md\n+++ /dev/null\n-old\n"
        );
    }

    #[test]
    fn native_app_server_completion_corrects_provisional_streaming() {
        let mut translator = Translator::default();
        assert_eq!(
            translator.translate(&line(
                r#"{"method":"turn/started","params":{"threadId":"thread-1","turn":{"id":"turn-1"}}}"#
            )),
            vec![Event::Status {
                state: SessionStatus::Running
            }]
        );
        assert_eq!(
            translator.translate(&line(
                r#"{"method":"item/agentMessage/delta","params":{"itemId":"message-1","delta":"hello"}}"#
            )),
            vec![Event::AssistantText {
                delta: "hello".to_string()
            }]
        );
        assert_eq!(
            translator.translate(&line(
                r#"{"method":"item/completed","params":{"item":{"id":"message-1","type":"agentMessage","text":"hello, revised"}}}"#
            )),
            vec![Event::AssistantTextFinal {
                text: "hello, revised".to_string()
            }]
        );
        // One per model request, as it arrives. A turn that made two of them costs both,
        // and the context figure moves while the turn is still running.
        assert_eq!(
            translator.translate(&line(
                r#"{"method":"thread/tokenUsage/updated","params":{"tokenUsage":{"last":{"inputTokens":39,"cachedInputTokens":30,"outputTokens":3,"reasoningOutputTokens":1,"totalTokens":42},"total":{"inputTokens":100,"cachedInputTokens":80,"outputTokens":9,"reasoningOutputTokens":2,"totalTokens":109},"modelContextWindow":258400}}}"#
            )),
            vec![Event::UsageDelta {
                tokens: 42,
                context: Some(39),
                tokens_per_second: None,
                prefill_ms: None,
            }]
        );
        assert_eq!(
            translator.translate(&line(
                r#"{"method":"thread/tokenUsage/updated","params":{"tokenUsage":{"last":{"inputTokens":61,"cachedInputTokens":39,"outputTokens":4,"reasoningOutputTokens":1,"totalTokens":65},"total":{"inputTokens":161,"cachedInputTokens":119,"outputTokens":13,"reasoningOutputTokens":3,"totalTokens":174},"modelContextWindow":258400}}}"#
            )),
            vec![Event::UsageDelta {
                tokens: 65,
                context: Some(61),
                tokens_per_second: None,
                prefill_ms: None,
            }]
        );
        assert_eq!(
            translator.translate(&line(
                r#"{"method":"turn/completed","params":{"turn":{"id":"turn-1","status":"completed","error":null}}}"#
            )),
            vec![Event::Status {
                state: SessionStatus::Idle
            }]
        );
    }

    #[test]
    fn structured_tool_results_keep_text_but_not_image_data() {
        let mut translator = Translator::default();
        let started = translator.translate(&line(
            r#"{"method":"item/started","params":{"item":{"id":"tool-1","type":"dynamicToolCall","tool":"view_image","arguments":{"path":"shot.png"},"status":"inProgress"}}}"#,
        ));
        assert!(matches!(&started[0], Event::ToolStart { tool, .. } if tool == "view_image"));

        let ended = translator.translate(&line(
            r#"{"method":"item/completed","params":{"item":{"id":"tool-1","type":"dynamicToolCall","tool":"view_image","arguments":{},"status":"completed","contentItems":[{"type":"inputText","text":"looked"},{"type":"inputImage","imageUrl":"data:image/png;base64,aGVsbG8="}]}}}"#,
        ));
        assert_eq!(
            ended,
            vec![Event::ToolEnd {
                id: "tool-1".to_string(),
                output: "looked".to_string()
            }]
        );
    }

    #[test]
    fn an_app_server_completion_corrects_streamed_text_after_adoption() {
        // A newly adopted translator has not seen the deltas already recorded by the previous
        // backend. The dialect, rather than process-local memory, decides that this is a copy.
        let mut adopted = Translator::default();
        assert_eq!(
            adopted.translate(&line(
                r#"{"method":"item/completed","params":{"item":{"id":"message-1","type":"agentMessage","text":"the complete message"}}}"#
            )),
            vec![Event::AssistantTextFinal {
                text: "the complete message".to_string()
            }]
        );
    }

    #[test]
    fn codex_subagents_get_their_own_transcripts_and_hold_the_parent_waiting() {
        let dir = tempfile::tempdir().expect("tempdir");
        let subagents = Arc::new(Subagents::new(dir.path().to_path_buf()));
        let background_processes = Arc::new(Mutex::new(HashSet::new()));
        let mut translator = Translator::new(
            Arc::clone(&subagents),
            Arc::clone(&background_processes),
            Some("parent-thread".to_string()),
            false,
        );

        assert_eq!(
            translator.translate(&line(
                r#"{"method":"item/started","params":{"threadId":"parent-thread","turnId":"turn-1","item":{"id":"spawn-1","type":"collabAgentToolCall","tool":"spawnAgent","status":"inProgress","senderThreadId":"parent-thread","receiverThreadIds":[],"agentsStates":{},"prompt":"audit the history","model":null,"reasoningEffort":null}}}"#
            )),
            vec![Event::ToolStart {
                id: "spawn-1".to_string(),
                tool: "Task".to_string(),
                input: json!({"prompt": "audit the history"})
            }]
        );
        assert_eq!(
            translator.translate(&line(
                r#"{"method":"item/completed","params":{"threadId":"parent-thread","turnId":"turn-1","item":{"id":"spawn-1","type":"subAgentActivity","kind":"started","agentThreadId":"child-thread","agentPath":"/root/history_boundaries"}}}"#
            )),
            vec![
                Event::ToolEnd {
                    id: "spawn-1".to_string(),
                    output: String::new()
                },
                Event::BackgroundTasks { count: 1 }
            ]
        );
        let rows = subagents.list(true);
        assert_eq!(rows.len(), 1);
        assert_eq!(rows[0].id, "child-thread");
        assert_eq!(rows[0].title, "history boundaries");

        assert!(
            translator
                .translate(&line(
                    r#"{"method":"turn/started","params":{"threadId":"child-thread","turn":{"id":"child-turn"}}}"#
                ))
                .is_empty()
        );
        assert!(
            translator
                .translate(&line(
                    r#"{"method":"item/completed","params":{"threadId":"child-thread","turnId":"child-turn","item":{"id":"child-message","type":"agentMessage","text":"the audit result","phase":"final_answer","delivery":null}}}"#
                ))
                .is_empty()
        );
        assert!(
            translator
                .translate(&line(
                    r#"{"method":"turn/completed","params":{"threadId":"child-thread","turn":{"id":"child-turn","status":"completed","error":null}}}"#
                ))
                .is_empty()
        );
        assert_eq!(
            translator.translate(&line(
                r#"{"method":"turn/completed","params":{"threadId":"parent-thread","turn":{"id":"turn-1","status":"completed","error":null}}}"#
            )),
            vec![Event::Status {
                state: SessionStatus::Waiting
            }]
        );
        assert_eq!(
            translator.translate(&line(
                r#"{"method":"item/completed","params":{"threadId":"parent-thread","turnId":"turn-1","item":{"id":"subagent-completed-1","type":"subAgentActivity","kind":"completed","agentThreadId":"child-thread","agentPath":"/root/history_boundaries"}}}"#
            )),
            vec![
                Event::Status {
                    state: SessionStatus::Idle
                },
                Event::BackgroundTasks { count: 0 }
            ]
        );

        let child = subagents.get("child-thread").expect("child");
        let events = crate::session::transcript::read_after(&child.transcript_path(), 0)
            .expect("child transcript");
        assert!(matches!(
            &events[1].event,
            Event::UserMessage { text, .. } if text == "audit the history"
        ));
        assert!(events.iter().any(|event| matches!(
            &event.event,
            Event::AssistantTextFinal { text } if text == "the audit result"
        )));
        assert_eq!(
            events.last().map(|event| &event.event),
            Some(&Event::Status {
                state: SessionStatus::Exited
            })
        );
    }

    #[test]
    fn codex_reports_each_change_to_its_live_background_count() {
        let dir = tempfile::tempdir().expect("tempdir");
        let subagents = Arc::new(Subagents::new(dir.path().to_path_buf()));
        let background_processes = Arc::new(Mutex::new(HashSet::new()));
        let mut translator = Translator::new(
            Arc::clone(&subagents),
            Arc::clone(&background_processes),
            Some("parent-thread".to_string()),
            false,
        );

        for (call, child, count) in [("spawn-a", "child-a", 1), ("spawn-b", "child-b", 2)] {
            let events = translator.translate(&json!({
                "method": "item/completed",
                "params": {
                    "threadId": "parent-thread",
                    "item": {
                        "id": call,
                        "type": "subAgentActivity",
                        "kind": "started",
                        "agentThreadId": child,
                        "agentPath": format!("/root/{child}")
                    }
                }
            }));
            assert_eq!(events.last(), Some(&Event::BackgroundTasks { count }));
        }
        background_processes
            .lock()
            .unwrap()
            .insert("command-a".to_string());
        for (child, count) in [("child-a", 2), ("child-b", 1)] {
            let events = translator.translate(&json!({
                "method": "item/completed",
                "params": {
                    "threadId": "parent-thread",
                    "item": {
                        "id": format!("completed-{child}"),
                        "type": "subAgentActivity",
                        "kind": "completed",
                        "agentThreadId": child,
                        "agentPath": format!("/root/{child}")
                    }
                }
            }));
            assert_eq!(events.last(), Some(&Event::BackgroundTasks { count }));
            assert!(!events.iter().any(|event| {
                matches!(
                    event,
                    Event::Status {
                        state: SessionStatus::Idle
                    }
                )
            }));
        }
    }

    #[test]
    fn codex_collaboration_coordination_has_clean_parent_tool_cards() {
        let mut translator = Translator::default();
        for (tool, name) in [
            ("wait", "TaskOutput"),
            ("sendInput", "SendMessage"),
            ("sendMessage", "SendMessage"),
            ("followupTask", "SendMessage"),
            ("closeAgent", "CloseAgent"),
            ("interruptAgent", "InterruptAgent"),
            ("listAgents", "ListAgents"),
            ("resumeAgent", "ResumeAgent"),
        ] {
            let started = json!({
                "method": "item/started",
                "params": {
                    "threadId": "parent-thread",
                    "turnId": "turn-1",
                    "item": {
                        "id": format!("{tool}-1"),
                        "type": "collabAgentToolCall",
                        "tool": tool,
                        "status": "inProgress",
                        "senderThreadId": "parent-thread",
                        "receiverThreadIds": [],
                        "agentsStates": {},
                        "prompt": null,
                        "model": null,
                        "reasoningEffort": null
                    }
                }
            });
            let completed = json!({
                "method": "item/completed",
                "params": {
                    "threadId": "parent-thread",
                    "turnId": "turn-1",
                    "item": {
                        "id": format!("{tool}-1"),
                        "type": "collabAgentToolCall",
                        "tool": tool,
                        "status": "completed",
                        "senderThreadId": "parent-thread",
                        "receiverThreadIds": [],
                        "agentsStates": {},
                        "prompt": null,
                        "model": null,
                        "reasoningEffort": null
                    }
                }
            });
            assert_eq!(
                translator.translate(&started),
                vec![Event::ToolStart {
                    id: format!("{tool}-1"),
                    tool: name.to_string(),
                    input: json!({})
                }],
                "{tool} start"
            );
            assert_eq!(
                translator.translate(&completed),
                vec![Event::ToolEnd {
                    id: format!("{tool}-1"),
                    output: String::new()
                }],
                "{tool} completion"
            );
        }
    }

    #[test]
    fn delivered_agent_messages_are_peer_messages_not_the_parents_reply() {
        let event = final_item(&json!({
            "id": "delivery-1",
            "type": "agentMessage",
            "delivery": "async",
            "text": "Message Type: FINAL_ANSWER\nSender: /root/audit\nPayload:\nFound it."
        }));
        assert_eq!(
            event,
            vec![Event::PeerMessage {
                from: "/root/audit".to_string(),
                text: "Found it.".to_string(),
                turn_start: None
            }]
        );
    }

    #[test]
    fn delivered_agent_message_deltas_do_not_replace_the_recipients_text() {
        let mut translator = Translator::default();

        assert!(
            translator
                .translate(&line(
                    r#"{"method":"item/started","params":{"threadId":"parent-thread","turnId":"turn-1","item":{"id":"delivery-1","type":"agentMessage","text":"","phase":null,"delivery":"async"}}}"#
                ))
                .is_empty()
        );
        assert!(
            translator
                .translate(&line(
                    r#"{"method":"item/agentMessage/delta","params":{"threadId":"parent-thread","turnId":"turn-1","itemId":"delivery-1","delta":"a child report"}}"#
                ))
                .is_empty()
        );
        assert_eq!(
            translator.translate(&line(
                r#"{"method":"item/completed","params":{"threadId":"parent-thread","turnId":"turn-1","item":{"id":"delivery-1","type":"agentMessage","text":"a child report","phase":null,"delivery":"async"}}}"#
            )),
            vec![Event::PeerMessage {
                from: "another agent".to_string(),
                text: "a child report".to_string(),
                turn_start: None
            }]
        );

        // Removing the completed id is the path out for this state: a later
        // item reusing it is not silently suppressed.
        assert_eq!(
            translator.translate(&line(
                r#"{"method":"item/agentMessage/delta","params":{"threadId":"parent-thread","turnId":"turn-2","itemId":"delivery-1","delta":"ordinary text"}}"#
            )),
            vec![Event::AssistantText {
                delta: "ordinary text".to_string()
            }]
        );
    }

    #[test]
    fn an_adopted_turn_does_not_go_idle_when_its_last_child_finishes() {
        let dir = tempfile::tempdir().expect("tempdir");
        let subagents = Arc::new(Subagents::new(dir.path().to_path_buf()));
        subagents.start("child-thread", "child", Some("work"));
        let mut translator = Translator::new(
            Arc::clone(&subagents),
            Arc::new(Mutex::new(HashSet::new())),
            Some("parent-thread".to_string()),
            true,
        );

        assert_eq!(
            translator.translate(&line(
                r#"{"method":"item/completed","params":{"threadId":"parent-thread","turnId":"turn-1","item":{"id":"subagent-completed-1","type":"subAgentActivity","kind":"completed","agentThreadId":"child-thread","agentPath":"/root/child"}}}"#
            )),
            vec![Event::BackgroundTasks { count: 0 }]
        );
        assert_eq!(subagents.list(true)[0].status, SessionStatus::Exited);
    }
}