kcode-k1-codex-adapter 0.2.1

Concrete multiplexed Codex app-server adapter and per-conversation K1 shim
Documentation
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use crate::*;
use serde_json::{Value, json};
use std::{
    collections::{HashMap, HashSet},
    process::Stdio,
    time::Duration,
};
use tokio::{
    io::{AsyncBufReadExt, AsyncReadExt, AsyncWriteExt, BufReader, Lines},
    process::{Child, ChildStdin, ChildStdout, Command as ProcessCommand},
    sync::mpsc,
    task::JoinHandle,
    time::timeout,
};

const INITIALIZE_TIMEOUT: Duration = Duration::from_secs(30);
const SHUTDOWN_TIMEOUT: Duration = Duration::from_secs(2);
const EARLY_EVENT_LIMIT: usize = 1024;

type ToolToken = (String, u64, String);

struct Active {
    serial: u64,
    turn: Option<String>,
    events: Option<Events>,
    early: Vec<Value>,
    cancelled: bool,
    interrupted: bool,
    failure: Option<Value>,
}

#[derive(Default)]
struct Conversation {
    thread: Option<String>,
    active: Option<Active>,
}

enum Pending {
    Thread {
        key: String,
        serial: u64,
        input: String,
    },
    Turn {
        key: String,
        serial: u64,
    },
}

struct PendingTool {
    id: Value,
    rpc_key: String,
}

struct Actor {
    child: Child,
    writer: ChildStdin,
    lines: Lines<BufReader<ChildStdout>>,
    stderr_task: Option<JoinHandle<()>>,
    commands: mpsc::UnboundedReceiver<crate::Command>,
    config: Config,
    diagnostics: Diagnostics,
    conversations: HashMap<String, Conversation>,
    by_thread: HashMap<String, String>,
    pending: HashMap<u64, Pending>,
    tools: HashMap<ToolToken, PendingTool>,
    rpc_ids: HashSet<String>,
    next_id: u64,
    next_turn: u64,
}

pub(crate) async fn open(config: Config) -> Result<Adapter, Error> {
    validate_config(&config)?;

    let diagnostics = Diagnostics::default();
    let mut command = ProcessCommand::new(&config.executable);
    command.arg("app-server");
    for setting in [
        r#"web_search="disabled""#,
        "mcp_servers={}",
        "agents.enabled=false",
        "features.shell_tool=false",
        "features.unified_exec=false",
        "features.apps=false",
        "apps._default.enabled=false",
        "features.multi_agent=false",
        "features.goals=false",
        "features.hooks=false",
        "features.memories=false",
        "features.remote_plugin=false",
        "features.code_mode.enabled=false",
        "features.skill_mcp_dependency_install=false",
        "tools.view_image=false",
        r#"history.persistence="none""#,
    ] {
        command.args(["-c", setting]);
    }
    if let Some(effort) = &config.reasoning_effort {
        let setting = format!("model_reasoning_effort={}", json!(effort));
        command.args(["-c", &setting]);
    }

    let mut child = command
        .current_dir(&config.working_directory)
        .stdin(Stdio::piped())
        .stdout(Stdio::piped())
        .stderr(Stdio::piped())
        .kill_on_drop(true)
        .spawn()
        .map_err(|error| {
            fault(
                ErrorKind::Unavailable,
                format!("failed to start Codex app-server: {error}"),
                &diagnostics,
            )
        })?;
    let mut writer = child.stdin.take().expect("stdin was configured as a pipe");
    let stdout = child
        .stdout
        .take()
        .expect("stdout was configured as a pipe");
    let mut stderr = child
        .stderr
        .take()
        .expect("stderr was configured as a pipe");
    let captured = diagnostics.clone();
    let mut stderr_task = Some(tokio::spawn(async move {
        let mut buffer = [0_u8; 8192];
        loop {
            match stderr.read(&mut buffer).await {
                Ok(0) | Err(_) => break,
                Ok(length) => captured
                    .lock()
                    .unwrap_or_else(|poisoned| poisoned.into_inner())
                    .extend_from_slice(&buffer[..length]),
            }
        }
    }));
    let mut lines = BufReader::new(stdout).lines();

    let initialized = timeout(
        INITIALIZE_TIMEOUT,
        initialize(&mut writer, &mut lines, &diagnostics),
    )
    .await
    .unwrap_or_else(|_| {
        Err(fault(
            ErrorKind::Unavailable,
            "Codex app-server initialization timed out",
            &diagnostics,
        ))
    });
    if let Err(mut error) = initialized {
        stop(&mut child, &mut writer, &mut stderr_task).await;
        error.diagnostics = snapshot(&diagnostics);
        return Err(error);
    }

    let (commands, receiver) = mpsc::unbounded_channel();
    let adapter = Adapter {
        client: Arc::new(Client {
            commands,
            diagnostics: diagnostics.clone(),
        }),
    };
    tokio::spawn(async move {
        let mut actor = Actor {
            child,
            writer,
            lines,
            stderr_task,
            commands: receiver,
            config,
            diagnostics,
            conversations: HashMap::new(),
            by_thread: HashMap::new(),
            pending: HashMap::new(),
            tools: HashMap::new(),
            rpc_ids: HashSet::new(),
            next_id: 1,
            next_turn: 1,
        };
        let outcome = actor.run().await;
        let _ = actor.reject_all("adapter stopped").await;
        let sinks = actor.take_sinks();
        actor.shutdown().await;
        let mut error = outcome
            .err()
            .unwrap_or_else(|| actor.error(ErrorKind::Unavailable, "Codex app-server was closed"));
        error.diagnostics = snapshot(&actor.diagnostics);
        for sink in sinks {
            let _ = sink.send(Event::Error(error.clone()));
        }
    });
    Ok(adapter)
}

fn validate_config(config: &Config) -> Result<(), Error> {
    let diagnostics = Diagnostics::default();
    let mut names = HashSet::new();
    for tool in &config.tools {
        if tool.name.is_empty() {
            return Err(fault(
                ErrorKind::Protocol,
                "dynamic tool names must not be empty",
                &diagnostics,
            ));
        }
        if !names.insert(&tool.name) {
            return Err(fault(
                ErrorKind::Protocol,
                format!("duplicate dynamic tool name: {}", tool.name),
                &diagnostics,
            ));
        }
    }
    Ok(())
}

async fn initialize(
    writer: &mut ChildStdin,
    lines: &mut Lines<BufReader<ChildStdout>>,
    diagnostics: &Diagnostics,
) -> Result<(), Error> {
    write_json(
        writer,
        &json!({
            "method": "initialize",
            "id": 0,
            "params": {
                "clientInfo": {
                    "name": "kcode-k1-codex-adapter",
                    "title": "K1 Codex Adapter",
                    "version": env!("CARGO_PKG_VERSION")
                },
                "capabilities": { "experimentalApi": true }
            }
        }),
    )
    .await
    .map_err(|message| fault(ErrorKind::Unavailable, message, diagnostics))?;

    loop {
        let line = lines
            .next_line()
            .await
            .map_err(|error| fault(ErrorKind::Unavailable, error.to_string(), diagnostics))?
            .ok_or_else(|| {
                fault(
                    ErrorKind::Unavailable,
                    "Codex app-server closed during initialization",
                    diagnostics,
                )
            })?;
        let message: Value = serde_json::from_str(&line)
            .map_err(|error| fault(ErrorKind::Protocol, error.to_string(), diagnostics))?;
        if message.get("id").and_then(Value::as_u64) != Some(0) {
            continue;
        }
        if let Some(error) = message.get("error") {
            return Err(server_fault(error, diagnostics));
        }
        if message.get("result").is_some() {
            break;
        }
        return Err(fault(
            ErrorKind::Protocol,
            "initialize response omitted result",
            diagnostics,
        ));
    }

    write_json(writer, &json!({"method": "initialized", "params": {}}))
        .await
        .map_err(|message| fault(ErrorKind::Unavailable, message, diagnostics))
}

impl Actor {
    async fn run(&mut self) -> Result<(), Error> {
        loop {
            tokio::select! {
                command = self.commands.recv() => match command {
                    Some(command) => self.command(command).await?,
                    None => return Ok(()),
                },
                line = self.lines.next_line() => {
                    let line = line
                        .map_err(|error| self.error(ErrorKind::Unavailable, error.to_string()))?
                        .ok_or_else(|| self.error(ErrorKind::Unavailable, "Codex app-server closed stdout"))?;
                    let message = serde_json::from_str(&line)
                        .map_err(|error| self.error(ErrorKind::Protocol, error.to_string()))?;
                    self.message(message).await?;
                }
            }
        }
    }

    async fn command(&mut self, command: crate::Command) -> Result<(), Error> {
        match command {
            crate::Command::Start {
                key,
                input,
                events,
                reply,
            } => {
                if self
                    .conversations
                    .get(&key)
                    .and_then(|conversation| conversation.active.as_ref())
                    .is_some()
                {
                    let _ = reply.send(Err(
                        self.error(ErrorKind::Busy, "conversation already has an active turn")
                    ));
                    return Ok(());
                }

                let serial = self.next_turn;
                self.next_turn = self.next_turn.checked_add(1).ok_or_else(|| {
                    self.error(ErrorKind::Protocol, "turn serial space was exhausted")
                })?;
                let thread = self
                    .conversations
                    .get(&key)
                    .and_then(|conversation| conversation.thread.clone());
                self.conversations.entry(key.clone()).or_default().active = Some(Active {
                    serial,
                    turn: None,
                    events: Some(events),
                    early: Vec::new(),
                    cancelled: false,
                    interrupted: false,
                    failure: None,
                });

                let (id, pending) = if let Some(thread) = thread {
                    (
                        self.request("turn/start", turn_params(&thread, input))
                            .await?,
                        Pending::Turn {
                            key: key.clone(),
                            serial,
                        },
                    )
                } else {
                    (
                        self.request("thread/start", thread_params(&self.config))
                            .await?,
                        Pending::Thread {
                            key: key.clone(),
                            serial,
                            input,
                        },
                    )
                };
                self.pending.insert(id, pending);
                if reply.send(Ok(serial)).is_err() {
                    self.cancel(&key, serial).await?;
                }
            }
            crate::Command::ToolResult {
                key,
                turn,
                call_id,
                result,
                reply,
            } => {
                let Some(pending) = self.tools.remove(&(key, turn, call_id)) else {
                    let _ = reply.send(Err(self.error(
                        ErrorKind::InvalidToolResult,
                        "tool call is not pending on this turn",
                    )));
                    return Ok(());
                };
                self.rpc_ids.remove(&pending.rpc_key);
                let response = json!({
                    "id": pending.id,
                    "result": {
                        "contentItems": [{"type": "inputText", "text": result.output}],
                        "success": result.success
                    }
                });
                match write_json(&mut self.writer, &response).await {
                    Ok(()) => {
                        let _ = reply.send(Ok(()));
                    }
                    Err(message) => {
                        let error = self.error(ErrorKind::Unavailable, message);
                        let _ = reply.send(Err(error.clone()));
                        return Err(error);
                    }
                }
            }
            crate::Command::Abandon { key, turn } => {
                self.cancel(&key, turn).await?;
            }
        }
        Ok(())
    }

    async fn message(&mut self, message: Value) -> Result<(), Error> {
        if let Some(method) = message
            .get("method")
            .and_then(Value::as_str)
            .map(str::to_owned)
        {
            match method.as_str() {
                "item/agentMessage/delta" | "item/tool/call" | "turn/completed" => {
                    self.scoped(message).await?;
                }
                "turn/started" | "error" if has_scope(message.get("params")) => {
                    self.scoped(message).await?;
                }
                "serverRequest/resolved" => {
                    self.resolved(message.get("params").unwrap_or(&Value::Null));
                }
                "turn/started" => {}
                "error" => {
                    let details = message.get("params").unwrap_or(&message);
                    return Err(server_fault(details, &self.diagnostics));
                }
                _ if message.get("id").is_some() => {
                    let (id, _) = valid_rpc_id(message.get("id").expect("id was checked"))
                        .map_err(|error| self.error(ErrorKind::Protocol, error))?;
                    self.rpc_error(id, -32601, "unsupported server request")
                        .await?;
                }
                _ => {}
            }
            return Ok(());
        }

        if message.get("id").is_some() {
            return self.response(message).await;
        }
        Err(self.error(
            ErrorKind::Protocol,
            "app-server message omitted method and id",
        ))
    }

    async fn response(&mut self, message: Value) -> Result<(), Error> {
        let id = message.get("id").and_then(Value::as_u64).ok_or_else(|| {
            self.error(
                ErrorKind::Protocol,
                "app-server response id was not an unsigned integer",
            )
        })?;
        let Some(pending) = self.pending.remove(&id) else {
            return Ok(());
        };
        let (key, serial) = match &pending {
            Pending::Thread { key, serial, .. } | Pending::Turn { key, serial } => {
                (key.clone(), *serial)
            }
        };
        if let Some(details) = message.get("error") {
            self.prestart_fail(&key, serial, server_fault(details, &self.diagnostics))
                .await?;
            return Ok(());
        }
        if message.get("result").is_none() {
            let error = self.error(
                ErrorKind::Protocol,
                "app-server response omitted result and error",
            );
            self.prestart_fail(&key, serial, error).await?;
            return Ok(());
        }

        match pending {
            Pending::Thread { key, serial, input } => {
                let Some(thread) = message
                    .pointer("/result/thread/id")
                    .and_then(Value::as_str)
                    .map(str::to_owned)
                else {
                    let error = self.error(
                        ErrorKind::Protocol,
                        "thread/start response omitted thread.id",
                    );
                    self.prestart_fail(&key, serial, error).await?;
                    return Ok(());
                };
                if self
                    .by_thread
                    .get(&thread)
                    .is_some_and(|owner| owner != &key)
                {
                    let error = self.error(
                        ErrorKind::Protocol,
                        "thread/start reused another conversation's thread.id",
                    );
                    self.prestart_fail(&key, serial, error).await?;
                    return Ok(());
                }
                self.by_thread.insert(thread.clone(), key.clone());
                if let Some(conversation) = self.conversations.get_mut(&key) {
                    conversation.thread = Some(thread.clone());
                }
                let cancelled = self
                    .conversations
                    .get(&key)
                    .and_then(|conversation| conversation.active.as_ref())
                    .is_none_or(|active| active.serial != serial || active.cancelled);
                if cancelled {
                    self.take_active(&key, serial);
                } else {
                    let id = self
                        .request("turn/start", turn_params(&thread, input))
                        .await?;
                    self.pending.insert(id, Pending::Turn { key, serial });
                }
            }
            Pending::Turn { key, serial } => {
                let Some(turn) = message
                    .pointer("/result/turn/id")
                    .and_then(Value::as_str)
                    .map(str::to_owned)
                else {
                    let error =
                        self.error(ErrorKind::Protocol, "turn/start response omitted turn.id");
                    self.prestart_fail(&key, serial, error).await?;
                    return Ok(());
                };
                let Some(active) = self
                    .conversations
                    .get_mut(&key)
                    .and_then(|conversation| conversation.active.as_mut())
                    .filter(|active| active.serial == serial)
                else {
                    self.interrupt_orphan(&key, &turn).await?;
                    return Ok(());
                };
                active.turn = Some(turn);
                let early = std::mem::take(&mut active.early);

                for event in early {
                    let cancelled = self
                        .conversations
                        .get(&key)
                        .and_then(|conversation| conversation.active.as_ref())
                        .is_none_or(|active| active.serial != serial || active.cancelled);
                    if cancelled {
                        self.reject_if_request(&event, "turn was abandoned").await?;
                    } else {
                        self.scoped(event).await?;
                    }
                }
                let cancelled = self
                    .conversations
                    .get(&key)
                    .and_then(|conversation| conversation.active.as_ref())
                    .is_some_and(|active| active.serial == serial && active.cancelled);
                if cancelled {
                    self.interrupt(&key, serial).await?;
                }
            }
        }
        Ok(())
    }

    async fn scoped(&mut self, message: Value) -> Result<(), Error> {
        let (thread, turn) =
            scope(message.get("params")).map_err(|error| self.error(ErrorKind::Protocol, error))?;
        let Some(key) = self.by_thread.get(thread).cloned() else {
            self.reject_if_request(&message, "tool call has an unknown thread")
                .await?;
            return Ok(());
        };
        let Some(active) = self
            .conversations
            .get_mut(&key)
            .and_then(|conversation| conversation.active.as_mut())
        else {
            self.reject_if_request(&message, "tool call does not belong to an active turn")
                .await?;
            return Ok(());
        };
        let serial = active.serial;
        match active.turn.as_deref() {
            Some(current) if current != turn => {
                self.reject_if_request(&message, "tool call does not belong to the active turn")
                    .await?;
                return Ok(());
            }
            None => {
                if active.early.len() == EARLY_EVENT_LIMIT {
                    return Err(self.error(
                        ErrorKind::Protocol,
                        "too many events arrived before turn/start completed",
                    ));
                }
                active.early.push(message);
                return Ok(());
            }
            _ => {}
        }
        self.dispatch(key, serial, message).await
    }

    async fn dispatch(&mut self, key: String, serial: u64, message: Value) -> Result<(), Error> {
        let method = message
            .get("method")
            .and_then(Value::as_str)
            .expect("only method-bearing messages are dispatched");
        let params = message
            .get("params")
            .expect("scoped messages contain params");
        match method {
            "item/agentMessage/delta" => {
                let delta = params
                    .get("delta")
                    .and_then(Value::as_str)
                    .ok_or_else(|| {
                        self.error(ErrorKind::Protocol, "agent-message delta omitted delta")
                    })?
                    .to_owned();
                if !self.emit(&key, serial, Event::TextDelta(delta)) {
                    self.cancel(&key, serial).await?;
                }
            }
            "item/tool/call" => self.tool_call(&key, serial, &message).await?,
            "turn/completed" => self.complete(&key, serial, params).await?,
            "error" => {
                if let Some(active) = self
                    .conversations
                    .get_mut(&key)
                    .and_then(|conversation| conversation.active.as_mut())
                    .filter(|active| active.serial == serial)
                {
                    active.failure = params.get("error").cloned();
                }
            }
            "turn/started" => {}
            _ => unreachable!("message filtering guarantees a known method"),
        }
        Ok(())
    }

    async fn tool_call(&mut self, key: &str, serial: u64, message: &Value) -> Result<(), Error> {
        let (id, rpc_key) =
            valid_rpc_id(message.get("id").ok_or_else(|| {
                self.error(ErrorKind::Protocol, "dynamic tool request omitted id")
            })?)
            .map_err(|error| self.error(ErrorKind::Protocol, error))?;
        if !self.rpc_ids.insert(rpc_key.clone()) {
            return Err(self.error(ErrorKind::Protocol, "duplicate app-server request id"));
        }
        let params = message
            .get("params")
            .expect("scoped messages contain params");
        let fields = params
            .get("callId")
            .and_then(Value::as_str)
            .zip(params.get("tool").and_then(Value::as_str))
            .zip(params.get("arguments"));
        let Some(((call_id, name), arguments)) = fields else {
            self.rpc_ids.remove(&rpc_key);
            self.rpc_error(id, -32602, "malformed dynamic tool request")
                .await?;
            let error = self.error(ErrorKind::Protocol, "malformed dynamic tool request");
            return self.fail_turn(key, serial, error).await;
        };
        if !self.config.tools.iter().any(|tool| tool.name == name) {
            self.rpc_ids.remove(&rpc_key);
            self.rpc_error(id, -32602, "unconfigured dynamic tool requested")
                .await?;
            let error = self.error(ErrorKind::Protocol, "unconfigured dynamic tool requested");
            return self.fail_turn(key, serial, error).await;
        }
        let token = (key.to_owned(), serial, call_id.to_owned());
        if self.tools.contains_key(&token) {
            self.rpc_ids.remove(&rpc_key);
            self.rpc_error(id, -32602, "duplicate dynamic tool call id")
                .await?;
            let error = self.error(ErrorKind::Protocol, "duplicate dynamic tool call id");
            return self.fail_turn(key, serial, error).await;
        }
        self.tools.insert(token, PendingTool { id, rpc_key });
        if !self.emit(
            key,
            serial,
            Event::ToolCall(ToolCall {
                call_id: call_id.to_owned(),
                name: name.to_owned(),
                arguments: arguments.clone(),
            }),
        ) {
            self.cancel(key, serial).await?;
        }
        Ok(())
    }

    async fn complete(&mut self, key: &str, serial: u64, params: &Value) -> Result<(), Error> {
        let pending_count = self
            .tools
            .keys()
            .filter(|(tool_key, tool_serial, _)| tool_key == key && *tool_serial == serial)
            .count();
        if pending_count != 0 {
            self.reject_tools(
                key,
                serial,
                "turn completed before its tool calls were answered",
            )
            .await?;
        }
        let Some(active) = self.take_active(key, serial) else {
            return Ok(());
        };
        if active.cancelled {
            return Ok(());
        }
        let event = match params.pointer("/turn/status").and_then(Value::as_str) {
            Some("completed") if pending_count == 0 => Event::Done,
            Some("completed") => Event::Error(self.error(
                ErrorKind::Protocol,
                "turn completed with pending tool calls",
            )),
            Some("interrupted") => {
                Event::Error(self.error(ErrorKind::Interrupted, "Codex turn was interrupted"))
            }
            Some("failed") => Event::Error(server_fault(
                params
                    .pointer("/turn/error")
                    .or(active.failure.as_ref())
                    .unwrap_or(params),
                &self.diagnostics,
            )),
            _ => Event::Error(
                self.error(ErrorKind::Protocol, "turn/completed had an invalid status"),
            ),
        };
        if let Some(events) = active.events {
            let _ = events.send(event);
        }
        Ok(())
    }

    async fn fail_turn(&mut self, key: &str, serial: u64, error: Error) -> Result<(), Error> {
        if let Some(active) = self
            .conversations
            .get_mut(key)
            .and_then(|conversation| conversation.active.as_mut())
            .filter(|active| active.serial == serial)
        {
            if let Some(events) = active.events.take() {
                let _ = events.send(Event::Error(error));
            }
            active.cancelled = true;
        }
        self.reject_tools(key, serial, "turn failed").await?;
        self.interrupt(key, serial).await
    }

    async fn prestart_fail(&mut self, key: &str, serial: u64, error: Error) -> Result<(), Error> {
        let active = self.take_active(key, serial);
        self.reject_tools(key, serial, "turn failed to start")
            .await?;
        if let Some(events) = active.and_then(|active| active.events) {
            let _ = events.send(Event::Error(error));
        }
        Ok(())
    }

    async fn cancel(&mut self, key: &str, serial: u64) -> Result<(), Error> {
        if let Some(active) = self
            .conversations
            .get_mut(key)
            .and_then(|conversation| conversation.active.as_mut())
            .filter(|active| active.serial == serial)
        {
            active.events.take();
            active.cancelled = true;
        }
        self.reject_tools(key, serial, "turn was abandoned").await?;
        self.interrupt(key, serial).await
    }

    async fn interrupt(&mut self, key: &str, serial: u64) -> Result<(), Error> {
        let target = self.conversations.get_mut(key).and_then(|conversation| {
            let thread = conversation.thread.clone()?;
            let active = conversation.active.as_mut()?;
            if active.serial != serial || active.interrupted {
                return None;
            }
            let turn = active.turn.clone()?;
            active.interrupted = true;
            Some((thread, turn))
        });
        if let Some((thread, turn)) = target {
            self.request(
                "turn/interrupt",
                json!({"threadId": thread, "turnId": turn}),
            )
            .await?;
        }
        Ok(())
    }

    async fn interrupt_orphan(&mut self, key: &str, turn: &str) -> Result<(), Error> {
        if let Some(thread) = self
            .conversations
            .get(key)
            .and_then(|conversation| conversation.thread.clone())
        {
            self.request(
                "turn/interrupt",
                json!({"threadId": thread, "turnId": turn}),
            )
            .await?;
        }
        Ok(())
    }

    fn emit(&mut self, key: &str, serial: u64, event: Event) -> bool {
        self.conversations
            .get_mut(key)
            .and_then(|conversation| conversation.active.as_mut())
            .filter(|active| active.serial == serial)
            .and_then(|active| active.events.as_ref())
            .is_some_and(|events| events.send(event).is_ok())
    }

    fn resolved(&mut self, params: &Value) {
        let Some(rpc_key) = params
            .get("requestId")
            .and_then(|id| valid_rpc_id(id).ok())
            .map(|(_, key)| key)
        else {
            return;
        };
        if let Some(token) = self
            .tools
            .iter()
            .find_map(|(token, pending)| (pending.rpc_key == rpc_key).then(|| token.clone()))
        {
            self.tools.remove(&token);
            self.rpc_ids.remove(&rpc_key);
        }
    }

    async fn reject_if_request(&mut self, message: &Value, reason: &str) -> Result<(), Error> {
        if message.get("method").and_then(Value::as_str) == Some("item/tool/call") {
            let (id, _) = valid_rpc_id(message.get("id").ok_or_else(|| {
                self.error(ErrorKind::Protocol, "dynamic tool request omitted id")
            })?)
            .map_err(|error| self.error(ErrorKind::Protocol, error))?;
            self.rpc_error(id, -32602, reason).await?;
        }
        Ok(())
    }

    async fn reject_tools(&mut self, key: &str, serial: u64, reason: &str) -> Result<(), Error> {
        let tokens: Vec<_> = self
            .tools
            .keys()
            .filter(|(tool_key, tool_serial, _)| tool_key == key && *tool_serial == serial)
            .cloned()
            .collect();
        for token in tokens {
            if let Some(pending) = self.tools.remove(&token) {
                self.rpc_ids.remove(&pending.rpc_key);
                self.rpc_error(pending.id, -32800, reason).await?;
            }
        }
        Ok(())
    }

    async fn reject_all(&mut self, reason: &str) -> Result<(), Error> {
        let tokens: Vec<_> = self.tools.keys().cloned().collect();
        for token in tokens {
            if let Some(pending) = self.tools.remove(&token) {
                self.rpc_ids.remove(&pending.rpc_key);
                self.rpc_error(pending.id, -32800, reason).await?;
            }
        }
        Ok(())
    }

    async fn request(&mut self, method: &str, params: Value) -> Result<u64, Error> {
        let id = self.next_id;
        self.next_id = self.next_id.checked_add(1).ok_or_else(|| {
            self.error(ErrorKind::Protocol, "client request id space was exhausted")
        })?;
        write_json(
            &mut self.writer,
            &json!({"method": method, "id": id, "params": params}),
        )
        .await
        .map_err(|message| self.error(ErrorKind::Unavailable, message))?;
        Ok(id)
    }

    async fn rpc_error(&mut self, id: Value, code: i64, message: &str) -> Result<(), Error> {
        write_json(
            &mut self.writer,
            &json!({"id": id, "error": {"code": code, "message": message}}),
        )
        .await
        .map_err(|error| self.error(ErrorKind::Unavailable, error))
    }

    fn take_active(&mut self, key: &str, serial: u64) -> Option<Active> {
        let conversation = self.conversations.get_mut(key)?;
        if conversation
            .active
            .as_ref()
            .is_some_and(|active| active.serial == serial)
        {
            conversation.active.take()
        } else {
            None
        }
    }

    fn take_sinks(&mut self) -> Vec<Events> {
        self.conversations
            .values_mut()
            .filter_map(|conversation| conversation.active.take().and_then(|active| active.events))
            .collect()
    }

    async fn shutdown(&mut self) {
        stop(&mut self.child, &mut self.writer, &mut self.stderr_task).await;
    }

    fn error(&self, kind: ErrorKind, message: impl Into<String>) -> Error {
        fault(kind, message, &self.diagnostics)
    }
}

fn has_scope(params: Option<&Value>) -> bool {
    params.and_then(|params| params.get("threadId")).is_some()
        && params.and_then(native_turn).is_some()
}

fn scope(params: Option<&Value>) -> Result<(&str, &str), String> {
    let params = params.ok_or_else(|| "omitted params".to_owned())?;
    let thread = params
        .get("threadId")
        .and_then(Value::as_str)
        .ok_or_else(|| "omitted threadId".to_owned())?;
    let turn = native_turn(params).ok_or_else(|| "omitted turn id".to_owned())?;
    Ok((thread, turn))
}

fn native_turn(params: &Value) -> Option<&str> {
    params
        .get("turnId")
        .and_then(Value::as_str)
        .or_else(|| params.pointer("/turn/id").and_then(Value::as_str))
}

fn valid_rpc_id(id: &Value) -> Result<(Value, String), String> {
    match id {
        Value::String(value) => Ok((id.clone(), format!("s:{value}"))),
        Value::Number(value) => Ok((id.clone(), format!("n:{value}"))),
        _ => Err("server request id must be a string or number".to_owned()),
    }
}

fn thread_params(config: &Config) -> Value {
    let tools: Vec<_> = config
        .tools
        .iter()
        .map(|tool| {
            json!({
                "name": tool.name,
                "description": tool.description,
                "inputSchema": tool.input_schema
            })
        })
        .collect();
    json!({
        "model": config.model,
        "cwd": config.working_directory,
        "approvalPolicy": "never",
        "sandbox": "readOnly",
        "baseInstructions": config.base_instructions,
        "serviceName": "kcode-k1-codex-adapter",
        "ephemeral": true,
        "dynamicTools": tools
    })
}

fn turn_params(thread: &str, input: String) -> Value {
    json!({
        "threadId": thread,
        "input": [{"type": "text", "text": input}]
    })
}

async fn write_json(writer: &mut ChildStdin, value: &Value) -> Result<(), String> {
    let mut bytes = serde_json::to_vec(value).map_err(|error| error.to_string())?;
    bytes.push(b'\n');
    writer
        .write_all(&bytes)
        .await
        .map_err(|error| error.to_string())?;
    writer.flush().await.map_err(|error| error.to_string())
}

async fn stop(
    child: &mut Child,
    writer: &mut ChildStdin,
    stderr_task: &mut Option<JoinHandle<()>>,
) {
    let _ = writer.shutdown().await;
    if timeout(SHUTDOWN_TIMEOUT, child.wait()).await.is_err() {
        let _ = child.start_kill();
        let _ = child.wait().await;
    }
    if let Some(task) = stderr_task.take() {
        let _ = timeout(SHUTDOWN_TIMEOUT, task).await;
    }
}

fn server_fault(value: &Value, diagnostics: &Diagnostics) -> Error {
    let details = value.to_string();
    let message = value
        .get("message")
        .and_then(Value::as_str)
        .map(|message| format!("{message}: {details}"))
        .unwrap_or(details);
    fault(ErrorKind::Server, message, diagnostics)
}

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

    #[test]
    fn rpc_id_keys_preserve_json_type() {
        assert_eq!(valid_rpc_id(&json!(7)).unwrap().1, "n:7");
        assert_eq!(valid_rpc_id(&json!("7")).unwrap().1, "s:7");
        assert!(valid_rpc_id(&Value::Null).is_err());
    }

    #[test]
    fn thread_configuration_is_locked_down() {
        let config = Config {
            executable: "codex".into(),
            working_directory: "/tmp".to_owned(),
            model: "example-model".to_owned(),
            reasoning_effort: None,
            base_instructions: "base".to_owned(),
            tools: vec![DynamicTool {
                name: "lookup".to_owned(),
                description: "Look something up".to_owned(),
                input_schema: json!({"type": "object"}),
            }],
        };
        let params = thread_params(&config);
        assert_eq!(params["approvalPolicy"], "never");
        assert_eq!(params["sandbox"], "readOnly");
        assert_eq!(params["ephemeral"], true);
        assert_eq!(params["dynamicTools"][0]["name"], "lookup");
    }
}