LazyBoy2/crates/lazyboy-core/src/box_runtime.rs

//! Named-agent Linux computers (Docker boxes).
//! Session CLI keeps `lazyboy-box`. Each named agent gets its own container.

use crate::computer::{
    settle_before, steps_for, validate_bounds, ComputerAction, ComputerStep, ScreenSize,
};
use anyhow::{anyhow, Context, Result};
use serde_json::{json, Value};
use std::collections::HashMap;
use std::path::{Path, PathBuf};
use std::process::Stdio;
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::{Arc, OnceLock};
use std::time::{Duration, Instant};
use tokio::process::Command;
use tokio::sync::Mutex;

const IMAGE: &str = "lazyboy-box:local";
const SESSION_CONTAINER: &str = "lazyboy-box";
const SESSION_WORKSPACE_VOLUME: &str = "grokboy-box-workspace";
const SESSION_HOME_VOLUME: &str = "grokboy-box-home";
const SESSION_VIEWER_PORT: u16 = 6080;
pub const SESSION_SEAT: &str = "session";
const BOX_REVISION: &str = "computer-use-7";
const BROWSER_PROFILE: &str = "/home/box/chrome-profile";
/// Per-stream cap on shell output returned to the model; the middle is elided.
const JOB_OUTPUT_HEAD_CHARS: usize = 16_000;
const JOB_OUTPUT_TAIL_CHARS: usize = 32_000;
const DEFAULT_MAX_RUNNING: usize = 3;
const COMPUTER_MEMORY: &str = "1536m";
const COMPUTER_CPUS: &str = "2";
const COMPUTER_PIDS: &str = "512";

#[derive(Clone, Debug, PartialEq, Eq)]
pub struct BoxSeat {
    pub id: String,
    pub container: String,
    pub workspace_volume: String,
    pub home_volume: String,
    pub bind_port: Option<u16>,
}

impl BoxSeat {
    pub fn for_id(id: &str) -> Self {
        let id = id.trim();
        if id.is_empty() || id == SESSION_SEAT {
            return Self {
                id: SESSION_SEAT.into(),
                container: SESSION_CONTAINER.into(),
                workspace_volume: SESSION_WORKSPACE_VOLUME.into(),
                home_volume: SESSION_HOME_VOLUME.into(),
                bind_port: Some(SESSION_VIEWER_PORT),
            };
        }
        let safe = sanitize_seat_id(id);
        Self {
            id: id.to_string(),
            container: format!("lazyboy-box-{safe}"),
            workspace_volume: format!("lazyboy-box-workspace-{safe}"),
            home_volume: format!("lazyboy-box-home-{safe}"),
            bind_port: None,
        }
    }

    pub fn web_viewer_url(&self) -> String {
        if self.id == SESSION_SEAT {
            "/novnc/vnc.html?autoconnect=true&resize=off&reconnect=true&show_dot=false&path=novnc/websockify"
                .into()
        } else {
            let id = &self.id;
            format!(
                "/novnc/{id}/vnc.html?autoconnect=true&resize=off&reconnect=true&show_dot=false&path=novnc/{id}/websockify"
            )
        }
    }
}

pub fn sanitize_seat_id(id: &str) -> String {
    let mapped: String = id
        .chars()
        .map(|c| {
            if c.is_ascii_alphanumeric() || c == '-' || c == '_' {
                c
            } else {
                '-'
            }
        })
        .collect();
    let trimmed = mapped.trim_matches('-');
    if trimmed.is_empty() {
        "agent".into()
    } else {
        trimmed.chars().take(64).collect()
    }
}

pub struct BoxHub {
    seat: BoxSeat,
    inner: Mutex<BoxState>,
    computer_use: AtomicBool,
}

struct BoxState {
    ready: bool,
    starting: bool,
    last_error: Option<String>,
    last_used: Instant,
    host_port: Option<u16>,
}

impl BoxHub {
    pub fn new() -> Arc<Self> {
        Self::for_seat(BoxSeat::for_id(SESSION_SEAT))
    }

    pub fn for_seat(seat: BoxSeat) -> Arc<Self> {
        Arc::new(Self {
            seat,
            inner: Mutex::new(BoxState {
                ready: false,
                starting: false,
                last_error: None,
                last_used: Instant::now(),
                host_port: None,
            }),
            computer_use: AtomicBool::new(false),
        })
    }

    pub fn seat_id(&self) -> &str {
        &self.seat.id
    }

    pub fn container(&self) -> &str {
        &self.seat.container
    }

    pub fn web_viewer_url(&self) -> String {
        self.seat.web_viewer_url()
    }

    pub fn viewer_url() -> String {
        format!("http://127.0.0.1:{SESSION_VIEWER_PORT}/vnc.html?autoconnect=true&resize=scale")
    }

    pub fn host_viewer_url_for_port(port: u16) -> String {
        format!("http://127.0.0.1:{port}/vnc.html?autoconnect=true&resize=scale")
    }

    pub fn try_begin_computer_use(&self) -> Result<()> {
        self.computer_use
            .compare_exchange(false, true, Ordering::SeqCst, Ordering::SeqCst)
            .map_err(|_| {
                anyhow!(
                    "A computerUse subagent is already using this agent's desktop. Only one can run at a time on the same computer."
                )
            })?;
        Ok(())
    }

    pub fn end_computer_use(&self) {
        self.computer_use.store(false, Ordering::SeqCst);
    }

    pub fn has_computer_use(&self) -> bool {
        self.computer_use.load(Ordering::SeqCst)
    }

    fn ready_payload(&self) -> Value {
        json!({
            "ready": true,
            "state": "ready",
            "viewer_url": self.web_viewer_url(),
            "host_viewer_url": Self::host_viewer_url_for_port(
                self.seat.bind_port.unwrap_or(SESSION_VIEWER_PORT)
            ),
            "browser_surface": "docker",
            "workspace": "/workspace",
            "browser_profile": BROWSER_PROFILE,
            "revision": BOX_REVISION,
            "seat": self.seat.id,
            "container": self.seat.container,
        })
    }

    fn status_payload(&self, state: &str, ready: bool, error: Option<String>, crowded: bool) -> Value {
        let mut payload = json!({
            "ready": ready,
            "state": state,
            "viewer_url": self.web_viewer_url(),
            "browser_surface": "docker",
            "workspace": "/workspace",
            "browser_profile": BROWSER_PROFILE,
            "revision": BOX_REVISION,
            "seat": self.seat.id,
            "container": self.seat.container,
            "crowded": crowded,
        });
        if let Some(error) = error {
            payload["error"] = json!(error);
        }
        payload
    }

    /// Read-only. Never starts the container.
    pub async fn inspect(&self) -> Value {
        let (starting, last_error) = {
            let state = self.inner.lock().await;
            (state.starting, state.last_error.clone())
        };
        if starting {
            return self.status_payload("starting", false, None, false);
        }
        match docker_running(&self.seat.container).await {
            Ok(true) => {
                if desktop_up(&self.seat.container).await {
                    let mut state = self.inner.lock().await;
                    state.ready = true;
                    if let Some(port) = host_port_of(&self.seat.container).await {
                        state.host_port = Some(port);
                    }
                    let mut payload = self.ready_payload();
                    if let Some(port) = state.host_port {
                        payload["host_viewer_url"] = json!(Self::host_viewer_url_for_port(port));
                    }
                    payload
                } else {
                    self.status_payload("starting", false, None, false)
                }
            }
            Ok(false) => {
                if let Some(error) = last_error {
                    self.status_payload("error", false, Some(error), false)
                } else {
                    self.status_payload("stopped", false, None, false)
                }
            }
            Err(error) => self.status_payload("error", false, Some(error.to_string()), false),
        }
    }

    pub async fn ensure_ready(&self) -> Result<Value> {
        {
            let mut state = self.inner.lock().await;
            if state.ready && docker_running(&self.seat.container).await.unwrap_or(false) {
                if !desktop_up(&self.seat.container).await {
                    state.starting = true;
                    drop(state);
                    if let Err(error) = wait_desktop(&self.seat.container).await {
                        let mut state = self.inner.lock().await;
                        state.starting = false;
                        state.ready = false;
                        state.last_error = Some(error.to_string());
                        return Err(error);
                    }
                    let mut state = self.inner.lock().await;
                    state.starting = false;
                    state.ready = true;
                    state.last_used = Instant::now();
                    state.last_error = None;
                    return Ok(self.finish_payload(&mut state));
                }
                state.last_used = Instant::now();
                return Ok(self.finish_payload(&mut state));
            }
            state.starting = true;
            state.last_error = None;
        }
        let result = self.bring_up().await;
        let mut state = self.inner.lock().await;
        state.starting = false;
        match result {
            Ok(()) => {
                state.ready = true;
                state.last_used = Instant::now();
                state.last_error = None;
                Ok(self.finish_payload(&mut state))
            }
            Err(error) => {
                state.ready = false;
                state.last_error = Some(error.to_string());
                Err(error)
            }
        }
    }

    async fn bring_up(&self) -> Result<()> {
        docker_info().await?;
        let _provision = ProvisionLock::acquire().await?;
        ensure_image().await?;
        let pool = BoxPool::global();
        pool.reconcile().await?;
        pool.reclaim(self.seat_id()).await?;
        let port = ensure_container(&self.seat).await?;
        wait_desktop(&self.seat.container).await?;
        self.inner.lock().await.host_port = Some(port);
        Ok(())
    }

    fn finish_payload(&self, state: &mut BoxState) -> Value {
        let mut payload = self.ready_payload();
        payload["instruction"] = json!(
            "This is my computer. Paths here are /workspace and /home/box, not the user's machine."
        );
        if let Some(port) = state.host_port.or(self.seat.bind_port) {
            payload["host_viewer_url"] = json!(Self::host_viewer_url_for_port(port));
        }
        payload
    }

    /// Reboot the existing container. Volumes (workspace + Chrome profile) stay.
    pub async fn restart(&self) -> Result<Value> {
        {
            let mut state = self.inner.lock().await;
            state.ready = false;
            state.starting = true;
            state.last_error = None;
        }
        let result = async {
            docker_info().await?;
            let _provision = ProvisionLock::acquire().await?;
            let pool = BoxPool::global();
            pool.reconcile().await?;
            pool.reclaim(self.seat_id()).await?;
            if docker(["container", "inspect", self.container()]).await.is_ok() {
                limit_container(self.container()).await?;
                docker(["restart", "-t", "20", self.container()]).await?;
            } else {
                ensure_image().await?;
                let port = ensure_container(&self.seat).await?;
                self.inner.lock().await.host_port = Some(port);
            }
            wait_desktop(self.container()).await?;
            if let Some(port) = host_port_of(self.container()).await {
                self.inner.lock().await.host_port = Some(port);
            }
            Ok(())
        }
        .await;
        self.finish_action(result, "restart").await
    }

    /// Rebuild the image from the repo Dockerfile. Recreate this seat's
    /// container only when the image id actually changed. Volumes stay.
    pub async fn update(&self) -> Result<Value> {
        {
            let mut state = self.inner.lock().await;
            state.ready = false;
            state.starting = true;
            state.last_error = None;
        }
        let result = async {
            docker_info().await?;
            let _provision = ProvisionLock::acquire().await?;
            let pool = BoxPool::global();
            pool.reconcile().await?;
            pool.reclaim(self.seat_id()).await?;
            let before = local_image_id().await;
            build_image().await?;
            let after = local_image_id().await;
            let image_changed = before != after;
            if image_changed {
                if docker(["container", "inspect", self.container()]).await.is_ok() {
                    remove_stale_container(self.container()).await?;
                }
                let port = ensure_container(&self.seat).await?;
                self.inner.lock().await.host_port = Some(port);
            } else if !docker_running(self.container()).await? {
                let port = ensure_container(&self.seat).await?;
                self.inner.lock().await.host_port = Some(port);
            }
            wait_desktop(self.container()).await?;
            Ok(image_changed)
        }
        .await;
        match result {
            Ok(image_changed) => {
                let mut payload = self.finish_action(Ok(()), "update").await?;
                payload["updated"] = json!(image_changed);
                Ok(payload)
            }
            Err(error) => self.finish_action(Err(error), "update").await,
        }
    }

    async fn finish_action(&self, result: Result<()>, action: &str) -> Result<Value> {
        let mut state = self.inner.lock().await;
        state.starting = false;
        match result {
            Ok(()) => {
                state.ready = true;
                state.last_used = Instant::now();
                state.last_error = None;
                let mut payload = self.finish_payload(&mut state);
                payload["action"] = json!(action);
                Ok(payload)
            }
            Err(error) => {
                state.ready = false;
                state.last_error = Some(error.to_string());
                Err(error)
            }
        }
    }

    pub async fn stop_keep_volumes(&self) -> Result<()> {
        let mut state = self.inner.lock().await;
        state.ready = false;
        state.starting = false;
        drop(state);
        if docker_running(self.container()).await.unwrap_or(false) {
            docker(["stop", "-t", "20", self.container()]).await?;
        }
        Ok(())
    }

    pub async fn wipe(&self) -> Result<()> {
        let _ = self.stop_keep_volumes().await;
        if docker(["container", "inspect", self.container()]).await.is_ok() {
            let _ = docker(["rm", "-f", self.container()]).await;
        }
        let _ = docker(["volume", "rm", "-f", &self.seat.workspace_volume]).await;
        let _ = docker(["volume", "rm", "-f", &self.seat.home_volume]).await;
        let mut state = self.inner.lock().await;
        state.ready = false;
        state.host_port = None;
        state.last_error = None;
        Ok(())
    }

    async fn last_used(&self) -> Instant {
        self.inner.lock().await.last_used
    }

    pub async fn host_port(&self) -> Option<u16> {
        if let Some(port) = self.inner.lock().await.host_port {
            return Some(port);
        }
        host_port_of(self.container()).await
    }

    pub async fn ensure_browser_ready(&self) -> Result<()> {
        self.ensure_ready().await?;
        let probe = ["python3", "-c", "import urllib.request; urllib.request.urlopen('http://127.0.0.1:9222/json/version', timeout=1).close()"];
        if self.exec(&probe).await?.status == 0 { return Ok(()); }
        // The desktop autostart may already be launching Chromium; a second
        // launcher would race it for the profile. box-chrome serialises
        // launches, but skipping the launch entirely is cheaper.
        let already_launching = self.exec(&[
            "pgrep", "-f", "--", &format!("--user-data-dir={BROWSER_PROFILE}"),
        ]).await?.status == 0;
        if !already_launching {
            self.exec(&["bash", "-lc", "nohup box-chrome </dev/null >/tmp/lazyboy-browser.log 2>&1 &"]).await?;
        }
        for _ in 0..80 {
            if self.exec(&probe).await?.status == 0 { return Ok(()); }
            tokio::time::sleep(Duration::from_millis(250)).await;
        }
        Err(anyhow!("Box Chromium did not start. Inspect /tmp/lazyboy-browser.log on the box; no local browser was opened."))
    }

    pub async fn shell(&self, cmd: &str, block_until_ms: u64) -> Result<Value> {
        self.ensure_ready().await?;
        let id = uuid::Uuid::new_v4().to_string();
        // All commands run detached in the box. A foreground wait expiring must
        // never kill an install or silently move it onto the user's computer.
        // The exit file is renamed into place so a poller never sees it empty.
        self.exec(&["bash", "-lc", &format!(
            "mkdir -p /tmp/gb-jobs/{id} && {{ nohup bash -lc {q} </dev/null >/tmp/gb-jobs/{id}/stdout 2>/tmp/gb-jobs/{id}/stderr & }}",
            q = shell_quote(&format!(
                "cd /workspace && bash -lc {}; code=$?; printf '%s\\n' \"$code\" >/tmp/gb-jobs/{id}/exit.tmp && mv -f /tmp/gb-jobs/{id}/exit.tmp /tmp/gb-jobs/{id}/exit",
                shell_quote(cmd)
            ))
        )]).await?;
        self.wait_job(&id, block_until_ms).await
    }

    async fn wait_job(&self, id: &str, block_until_ms: u64) -> Result<Value> {
        let deadline = tokio::time::Instant::now() + Duration::from_millis(block_until_ms.min(30_000));
        loop {
            let mut status = self.read_job_status(id).await?;
            status["session_id"] = json!(id);
            status["surface"] = json!("box");
            if status["running"] != true || tokio::time::Instant::now() >= deadline {
                if status["running"] == true {
                    status["instruction"] = json!("Still running on my computer. Use await_shell with this session_id when the result is needed. Do not rerun the command locally.");
                }
                return Ok(status);
            }
            tokio::time::sleep(Duration::from_millis(200)).await;
        }
    }

    pub async fn await_job(&self, session_id: &str) -> Result<Value> {
        self.ensure_ready().await?;
        validate_job_id(session_id)?;
        self.wait_job(session_id, 30_000).await
    }

    async fn read_job_status(&self, session_id: &str) -> Result<Value> {
        validate_job_id(session_id)?;
        let py = r#"
import json, pathlib, sys
root = pathlib.Path('/tmp/gb-jobs') / sys.argv[1]
head, tail = int(sys.argv[2]), int(sys.argv[3])

def stream(name):
    p = root / name
    if not p.exists():
        return '', False
    text = p.read_text(errors='replace')
    if len(text) <= head + tail:
        return text, False
    dropped = len(text) - head - tail
    return text[:head] + f'\n... [{dropped} chars elided] ...\n' + text[-tail:], True

if not root.exists():
    print(json.dumps({'error': 'unknown session'}))
else:
    exitp = root / 'exit'
    raw = exitp.read_text(errors='replace').strip() if exitp.exists() else ''
    code = int(raw) if raw.lstrip('-').isdigit() else None
    out, out_cut = stream('stdout')
    err, err_cut = stream('stderr')
    status = {'running': code is None, 'exit_code': code, 'stdout': out, 'stderr': err}
    if out_cut or err_cut:
        status['truncated'] = True
        status['full_output'] = {'stdout': str(root / 'stdout'), 'stderr': str(root / 'stderr')}
    print(json.dumps(status))
"#;
        let out = self.exec(&[
            "python3",
            "-c",
            py,
            session_id,
            &JOB_OUTPUT_HEAD_CHARS.to_string(),
            &JOB_OUTPUT_TAIL_CHARS.to_string(),
        ])
        .await?;
        if out.status != 0 {
            return Err(anyhow!("box job status failed: {}", out.stderr.trim()));
        }
        serde_json::from_str(out.stdout.trim()).context("parse box_await json")
    }

    pub async fn read(&self, path: &str, offset: Option<i64>, limit: Option<i64>) -> Result<Value> {
        self.ensure_ready().await?;
        let path = resolve_box_path(path)?;
        let offset = offset.unwrap_or(1);
        let limit = limit.unwrap_or(400);
        let py = format!(
            r#"
import json, pathlib, sys
p = pathlib.Path(sys.argv[1])
lines = p.read_text(errors='replace').splitlines()
start = max({offset}-1, 0)
chunk = lines[start:start+{limit}]
print(json.dumps({{'path': str(p), 'offset': start+1, 'lines': len(lines), 'content': chr(10).join(chunk)}}))
"#
        );
        let out = self.exec(&["python3", "-c", &py, &path]).await?;
        if out.status != 0 {
            return Err(anyhow!(out.stderr.trim().to_string()));
        }
        serde_json::from_str(out.stdout.trim()).context("parse box_read")
    }

    pub async fn copy_to_box(&self, host_path: &Path, box_path: Option<&str>) -> Result<Value> {
        self.ensure_ready().await?;
        if !host_path.is_file() {
            return Err(anyhow!("source is not a file: {}", host_path.display()));
        }
        let dest = match box_path {
            Some(p) => resolve_box_path(p)?,
            None => format!(
                "/workspace/uploads/{}",
                host_path
                    .file_name()
                    .and_then(|s| s.to_str())
                    .unwrap_or("file")
            ),
        };
        docker(["exec", self.container(), "mkdir", "-p", parent_dir(&dest)]).await?;
        docker([
            "cp",
            &host_path.to_string_lossy(),
            &format!("{}:{dest}", self.container()),
        ])
        .await?;
        Ok(json!({"box_path": dest, "bytes": std::fs::metadata(host_path)?.len()}))
    }

    pub async fn copy_from_box(&self, box_path: &str, host_path: &Path) -> Result<Value> {
        self.ensure_ready().await?;
        let src = resolve_box_path(box_path)?;
        if let Some(parent) = host_path.parent() {
            std::fs::create_dir_all(parent)?;
        }
        docker([
            "cp",
            &format!("{}:{src}", self.container()),
            &host_path.to_string_lossy(),
        ])
        .await?;
        let is_dir = host_path.is_dir();
        Ok(json!({
            "computer_path": host_path,
            "is_dir": is_dir,
            "bytes": if is_dir { dir_size(host_path) } else { std::fs::metadata(host_path).map(|m| m.len()).unwrap_or(0) },
        }))
    }

    pub async fn screenshot(&self, dest: &Path) -> Result<Value> {
        self.ensure_ready().await?;
        let shot = ShotFile::new();
        self.capture_root_png(&shot).await?;
        shot.fetch(self.container(), dest).await?;
        Ok(json!({
            "path": dest,
            "viewer_url": self.web_viewer_url(),
        }))
    }

    pub async fn computer(&self, actions: &[ComputerAction], dest: &Path) -> Result<Value> {
        self.ensure_ready().await?;
        let screen = self.display_geometry().await?;
        validate_bounds(actions, screen)?;
        let names: Vec<&str> = actions.iter().map(ComputerAction::name).collect();
        let shot = ShotFile::new();
        let mut snapshot = None;
        for (index, action) in actions.iter().enumerate() {
            let settle = settle_before(actions, index);
            if settle > 0 {
                tokio::time::sleep(Duration::from_millis(u64::from(settle))).await;
            }
            self.run_computer_action(action, &shot, screen, &mut snapshot).await?;
        }
        if !actions.iter().any(ComputerAction::is_screenshot) {
            self.capture_root_png(&shot).await?;
        }
        shot.fetch(self.container(), dest).await?;
        let cursor = self.cursor_position().await.ok();
        let mut payload = json!({
            "ok": true,
            "actions": names,
            "path": dest,
            "viewer_url": self.web_viewer_url(),
            "cursor_position": cursor,
            "screen": {"width": screen.width, "height": screen.height},
            "instruction": "Computer action ran on my computer. Read this screenshot before the next action. A batched then sequence returns only this final screen."
        });
        if let Some(text) = snapshot {
            payload["snapshot"] = json!(text);
            payload["instruction"] = json!(
                "Computer action ran on my computer. `snapshot` lists the on-screen elements as `[id] role \"name\" @ (x,y) WxH`; click the (x,y) centre of the element you mean. Read the screenshot too before the next action."
            );
        }
        Ok(payload)
    }

    async fn run_computer_action(
        &self,
        action: &ComputerAction,
        shot: &ShotFile,
        screen: ScreenSize,
        snapshot: &mut Option<String>,
    ) -> Result<()> {
        for step in steps_for(action)? {
            match step {
                ComputerStep::Screenshot => self.capture_root_png(shot).await?,
                ComputerStep::A11ySnapshot => {
                    let width = screen.width.to_string();
                    let height = screen.height.to_string();
                    let out = self
                        .exec_env(
                            &[
                                ("DISPLAY", ":1"),
                                ("LAZYBOY_SCREEN_W", width.as_str()),
                                ("LAZYBOY_SCREEN_H", height.as_str()),
                            ],
                            &["box-a11y"],
                        )
                        .await?;
                    if out.status != 0 {
                        let detail = out.stderr.trim();
                        if detail.contains("not found") {
                            return Err(anyhow!(
                                "My computer image is missing box-a11y. Rebuild the box image and retry."
                            ));
                        }
                        return Err(anyhow!(
                            "computer snapshot failed: {}",
                            if detail.is_empty() { out.stdout.trim() } else { detail }
                        ));
                    }
                    *snapshot = Some(out.stdout.trim_end().to_string());
                }
                ComputerStep::SleepMs(0) => {}
                ComputerStep::SleepMs(ms) => {
                    let secs = format!("{:.3}", f64::from(ms) / 1000.0);
                    let out = self.exec(&[
                        "python3",
                        "-c",
                        "import sys,time; time.sleep(float(sys.argv[1]))",
                        &secs,
                    ])
                    .await?;
                    if out.status != 0 {
                        return Err(anyhow!("computer wait failed: {}", out.stderr.trim()));
                    }
                }
                ComputerStep::Xdotool(args) => {
                    let mut argv: Vec<&str> = vec!["xdotool"];
                    argv.extend(args.iter().map(String::as_str));
                    let out = self.exec_env(&[("DISPLAY", ":1")], &argv).await?;
                    if out.status != 0 {
                        let detail = out.stderr.trim();
                        if detail.contains("xdotool") && detail.contains("not found") {
                            return Err(anyhow!(
                                "My computer image is missing xdotool. Rebuild the box image and retry."
                            ));
                        }
                        return Err(anyhow!(
                            "computer {} failed: {}",
                            action.name(),
                            if detail.is_empty() {
                                out.stdout.trim()
                            } else {
                                detail
                            }
                        ));
                    }
                }
            }
        }
        Ok(())
    }

    async fn display_geometry(&self) -> Result<ScreenSize> {
        let out = self.exec_env(&[("DISPLAY", ":1")], &["xdotool", "getdisplaygeometry"]).await?;
        if out.status == 0 {
            if let Ok(size) = ScreenSize::parse(&out.stdout) {
                return Ok(size);
            }
        }
        let info = self.exec(&["bash", "-lc", "xdpyinfo -display :1 | awk '/dimensions:/{print $2}'"]).await?;
        let raw = info.stdout.trim().replace('x', " ");
        ScreenSize::parse(&raw).map_err(|e| {
            anyhow!("could not read my computer's display size ({e}). Is the desktop up?")
        })
    }

    async fn cursor_position(&self) -> Result<Value> {
        let out = self.exec_env(&[("DISPLAY", ":1")], &["xdotool", "getmouselocation", "--shell"]).await?;
        if out.status != 0 {
            return Err(anyhow!(out.stderr.trim().to_string()));
        }
        let mut x = 0i32;
        let mut y = 0i32;
        for line in out.stdout.lines() {
            if let Some(v) = line.strip_prefix("X=") {
                x = v.trim().parse().unwrap_or(0);
            }
            if let Some(v) = line.strip_prefix("Y=") {
                y = v.trim().parse().unwrap_or(0);
            }
        }
        Ok(json!({"x": x, "y": y}))
    }

    async fn capture_root_png(&self, shot: &ShotFile) -> Result<()> {
        let out = self.exec(&[
            "import",
            "-display",
            ":1",
            "-window",
            "root",
            &shot.box_path,
        ])
        .await?;
        if out.status != 0 {
            return Err(anyhow!(
                "Could not capture my computer's screen (desktop not up yet). {}",
                out.stderr.trim()
            ));
        }
        Ok(())
    }

    async fn exec(&self, args: &[&str]) -> Result<CmdOut> {
        docker_exec(self.container(), args).await
    }

    async fn exec_env(&self, env: &[(&str, &str)], args: &[&str]) -> Result<CmdOut> {
        docker_exec_env(self.container(), env, args).await
    }
}

/// A per-call screenshot file on the box. Concurrent callers (a parent
/// checking in on a computerUse child) must never read each other's frame.
struct ShotFile {
    box_path: String,
}

impl ShotFile {
    fn new() -> Self {
        Self {
            box_path: format!("/tmp/lazyboy-shot-{}.png", uuid::Uuid::new_v4()),
        }
    }

    async fn fetch(&self, container: &str, dest: &Path) -> Result<()> {
        if let Some(parent) = dest.parent() {
            std::fs::create_dir_all(parent)?;
        }
        let copied = docker([
            "cp",
            &format!("{container}:{}", self.box_path),
            &dest.to_string_lossy(),
        ])
        .await;
        let _ = docker_exec(container, &["rm", "-f", &self.box_path]).await;
        copied.map(|_| ())
    }
}

/// Host-wide advisory lock held while the image/container are provisioned.
/// Released when dropped (the fd closes).
struct ProvisionLock {
    _file: std::fs::File,
}

impl ProvisionLock {
    async fn acquire() -> Result<Self> {
        let path = std::env::temp_dir().join("lazyboy-box-provision.lock");
        let file = tokio::task::spawn_blocking(move || -> Result<std::fs::File> {
            let file = std::fs::OpenOptions::new()
                .create(true)
                .truncate(false)
                .write(true)
                .open(&path)
                .with_context(|| format!("open {}", path.display()))?;
            #[cfg(unix)]
            {
                use std::os::fd::AsRawFd;
                if unsafe { libc::flock(file.as_raw_fd(), libc::LOCK_EX) } != 0 {
                    return Err(std::io::Error::last_os_error())
                        .context("lock box provisioning");
                }
            }
            Ok(file)
        })
        .await
        .context("box provisioning lock task")??;
        Ok(Self { _file: file })
    }
}

fn dir_size(path: &Path) -> u64 {
    let Ok(entries) = std::fs::read_dir(path) else {
        return 0;
    };
    entries
        .flatten()
        .map(|entry| {
            let path = entry.path();
            if path.is_dir() {
                dir_size(&path)
            } else {
                std::fs::metadata(&path).map(|m| m.len()).unwrap_or(0)
            }
        })
        .sum()
}

pub fn resolve_box_path(path: &str) -> Result<String> {
    let path = path.trim();
    if path.is_empty() {
        return Err(anyhow!("box path is empty"));
    }
    let abs = if path.starts_with('/') {
        path.to_string()
    } else {
        format!("/workspace/{path}")
    };
    // Normalise by component so `a//b` and `./x` are accepted while only a
    // real `..` segment (not a name like `report..final.txt`) is rejected.
    let mut parts: Vec<&str> = Vec::new();
    for part in abs.split('/') {
        match part {
            "" | "." => {}
            ".." => return Err(anyhow!("box path must not contain ..")),
            other => parts.push(other),
        }
    }
    let clean = format!("/{}", parts.join("/"));
    let allowed = ["/workspace", "/home/box", "/tmp/gb-jobs"];
    if !allowed
        .iter()
        .any(|root| clean == *root || clean.starts_with(&format!("{root}/")))
    {
        return Err(anyhow!(
            "box paths must be under /workspace or /home/box (got {clean}). This is my computer, not the user's."
        ));
    }
    Ok(clean)
}

fn parent_dir(path: &str) -> &str {
    path.rsplit_once('/')
        .map(|(p, _)| if p.is_empty() { "/" } else { p })
        .unwrap_or("/workspace")
}

fn shell_quote(s: &str) -> String {
    format!("'{}'", s.replace('\'', r#"'"'"'"#))
}

fn validate_job_id(id: &str) -> Result<()> {
    if id.chars().all(|c| c.is_ascii_hexdigit() || c == '-') && (8..80).contains(&id.len()) {
        Ok(())
    } else {
        Err(anyhow!("invalid session_id"))
    }
}

fn box_context_dir() -> PathBuf {
    if let Some(dir) = std::env::var_os("LAZYBOY_BOX_DIR").filter(|s| !s.is_empty()) {
        return PathBuf::from(dir);
    }
    PathBuf::from(env!("CARGO_MANIFEST_DIR"))
        .join("../..")
        .join("box")
}

async fn docker_info() -> Result<()> {
    if docker(["info"]).await.is_err() {
        return Err(anyhow!(
            "My computer needs Docker. Start Docker Desktop (or the docker daemon) and try again. I will not run this on your computer."
        ));
    }
    Ok(())
}

async fn image_revision() -> Option<String> {
    docker([
        "inspect",
        "-f",
        "{{index .Config.Labels \"lazyboy.box.revision\"}}",
        IMAGE,
    ])
    .await
    .ok()
    .map(|out| out.stdout.trim().to_string())
    .filter(|s| !s.is_empty() && s != "<no value>")
}

async fn ensure_image() -> Result<()> {
    if image_revision().await.as_deref() == Some(BOX_REVISION) {
        return Ok(());
    }
    build_image().await
}

async fn build_image() -> Result<()> {
    let ctx = box_context_dir();
    if !ctx.join("Dockerfile").is_file() {
        return Err(anyhow!(
            "Box image {IMAGE} is missing and Dockerfile was not found at {}",
            ctx.display()
        ));
    }
    // Stage the helper in the build context; never mount the user's workspace.
    let helper_dir = ctx.join("playwright");
    tokio::fs::create_dir_all(&helper_dir).await?;
    for file in ["package.json", "browser_helper.mjs"] {
        let src = ctx.join("../tools/playwright").join(file);
        tokio::fs::copy(&src, helper_dir.join(file))
            .await
            .with_context(|| format!("stage browser helper {}", src.display()))?;
    }
    eprintln!(
        "box: building image {IMAGE} (revision {BOX_REVISION}) from {}; this can take several minutes on first run",
        ctx.display()
    );
    let started = std::time::Instant::now();
    docker(["build", "-t", IMAGE, &ctx.to_string_lossy()]).await?;
    eprintln!("box: image {IMAGE} ready in {:?}", started.elapsed());
    Ok(())
}

async fn container_image_id(container: &str) -> Option<String> {
    docker(["inspect", "-f", "{{.Image}}", container])
        .await
        .ok()
        .map(|out| out.stdout.trim().to_string())
        .filter(|s| !s.is_empty())
}

async fn host_port_of(container: &str) -> Option<u16> {
    let out = docker([
        "inspect",
        "-f",
        "{{(index (index .NetworkSettings.Ports \"6080/tcp\") 0).HostPort}}",
        container,
    ])
    .await
    .ok()?;
    out.stdout.trim().parse().ok()
}

async fn local_image_id() -> Option<String> {
    docker(["inspect", "-f", "{{.Id}}", IMAGE])
        .await
        .ok()
        .map(|out| out.stdout.trim().to_string())
        .filter(|s| !s.is_empty())
}

// Apply to existing computers too, without recreating them or discarding data.
async fn limit_container(container: &str) -> Result<()> {
    docker(["update", "--memory", COMPUTER_MEMORY, "--memory-swap", COMPUTER_MEMORY,
        "--cpus", COMPUTER_CPUS, "--pids-limit", COMPUTER_PIDS, container]).await?;
    Ok(())
}

async fn ensure_container(seat: &BoxSeat) -> Result<u16> {
    if docker(["container", "inspect", &seat.container]).await.is_ok() {
        limit_container(&seat.container).await?;
    }
    if docker_running(&seat.container).await?
        && container_image_id(&seat.container).await == local_image_id().await
    {
        if let Some(port) = host_port_of(&seat.container).await.or(seat.bind_port) {
            return Ok(port);
        }
    }
    if docker(["container", "inspect", &seat.container]).await.is_ok()
        && container_image_id(&seat.container).await != local_image_id().await
    {
        remove_stale_container(&seat.container).await?;
    }
    if docker_running(&seat.container).await? {
        if let Some(port) = host_port_of(&seat.container).await.or(seat.bind_port) {
            return Ok(port);
        }
    }
    if seat.id == SESSION_SEAT && docker(["container", "inspect", "grokboy-box"]).await.is_ok() {
        let _ = docker(["rm", "-f", "grokboy-box"]).await;
    }
    let publish = match seat.bind_port {
        Some(port) => format!("127.0.0.1:{port}:6080"),
        None => "127.0.0.1::6080".into(),
    };
    // The container name is Docker's cross-process creation lock. Losing a
    // create race must reuse the winner, never remove its container.
    let created = docker([
        "create",
        "--name",
        &seat.container,
        "--memory", COMPUTER_MEMORY,
        "--memory-swap", COMPUTER_MEMORY,
        "--cpus", COMPUTER_CPUS,
        "--pids-limit", COMPUTER_PIDS,
        "--shm-size=256m",
        "-p",
        &publish,
        "--stop-timeout=20",
        "-v",
        &format!("{}:/workspace", seat.workspace_volume),
        "-v",
        &format!("{}:/home/box", seat.home_volume),
        IMAGE,
    ])
    .await;
    if let Err(error) = created {
        // Docker reserves the name before inspect can see the new container.
        let mut visible = false;
        for _ in 0..50 {
            if docker(["container", "inspect", &seat.container]).await.is_ok() {
                visible = true;
                break;
            }
            tokio::time::sleep(Duration::from_millis(100)).await;
        }
        if !visible {
            return Err(error);
        }
    }
    // Starting an existing container also preserves its writable layer.
    docker(["start", &seat.container]).await?;
    host_port_of(&seat.container)
        .await
        .or(seat.bind_port)
        .ok_or_else(|| anyhow!("my computer started but the viewer port is missing"))
}

/// X server, window manager, VNC and noVNC all answering. The WM check
/// matters: xdotool against a bare Xvfb has no focus or window stacking.
const DESKTOP_PROBE: &str = "xdpyinfo -display :1 >/dev/null 2>&1 \
&& xprop -display :1 -root _NET_SUPPORTING_WM_CHECK 2>/dev/null | grep -q 'window id' \
&& python3 -c 'import urllib.request, socket; urllib.request.urlopen(\"http://127.0.0.1:6080/vnc.html\", timeout=1).close(); socket.create_connection((\"127.0.0.1\", 5900), timeout=1).close()'";

async fn desktop_up(container: &str) -> bool {
    docker_exec(container, &["bash", "-c", DESKTOP_PROBE])
        .await
        .map(|o| o.status == 0)
        .unwrap_or(false)
}

/// Stop and remove the container built from an older image. Another process
/// (outside our provisioning lock, e.g. an older binary) may be doing the
/// same; "already in progress" or "no such container" both mean it is gone.
async fn remove_stale_container(container: &str) -> Result<()> {
    if docker_running(container).await? {
        if let Err(error) = docker(["stop", "-t", "20", container]).await {
            if !is_concurrent_removal(&error) {
                return Err(error);
            }
        }
    }
    if let Err(error) = docker(["rm", container]).await {
        if !is_concurrent_removal(&error) {
            return Err(error);
        }
    }
    for _ in 0..100 {
        // Gone, or already replaced by a container on the current image.
        if docker(["container", "inspect", container]).await.is_err()
            || container_image_id(container).await == local_image_id().await
        {
            return Ok(());
        }
        tokio::time::sleep(Duration::from_millis(200)).await;
    }
    Err(anyhow!(
        "stale container {container} is still being removed; retry in a moment"
    ))
}

fn is_concurrent_removal(error: &anyhow::Error) -> bool {
    let text = error.to_string();
    text.contains("already in progress")
        || text.contains("No such container")
        || text.contains("is already stopped")
}

async fn wait_desktop(container: &str) -> Result<()> {
    for _ in 0..120 {
        if desktop_up(container).await {
            return Ok(());
        }
        tokio::time::sleep(Duration::from_millis(250)).await;
    }
    Err(anyhow!("My computer did not become ready: desktop or viewer startup timed out. Check the container desktop logs and try again."))
}

async fn docker_running(name: &str) -> Result<bool> {
    let out = docker(["inspect", "-f", "{{.State.Running}}", name]).await;
    Ok(matches!(out, Ok(s) if s.stdout.trim() == "true"))
}

struct CmdOut {
    status: i32,
    stdout: String,
    stderr: String,
}

async fn docker<I, S>(args: I) -> Result<CmdOut>
where
    I: IntoIterator<Item = S>,
    S: AsRef<std::ffi::OsStr>,
{
    let mut cmd = Command::new("docker");
    cmd.args(args)
        .stdout(Stdio::piped())
        .stderr(Stdio::piped())
        .kill_on_drop(true);
    let out = cmd.output().await.context("run docker")?;
    let result = CmdOut {
        status: out.status.code().unwrap_or(-1),
        stdout: String::from_utf8_lossy(&out.stdout).into_owned(),
        stderr: String::from_utf8_lossy(&out.stderr).into_owned(),
    };
    if result.status != 0 {
        return Err(anyhow!(
            "docker failed ({}): {}",
            result.status,
            result.stderr.trim()
        ));
    }
    Ok(result)
}

fn max_running() -> usize {
    std::env::var("LAZYBOY_COMPUTER_MAX")
        .ok()
        .and_then(|s| s.parse().ok())
        .filter(|&n: &usize| n > 0)
        .unwrap_or(DEFAULT_MAX_RUNNING)
}

pub struct BoxPool {
    provisioning: Mutex<()>,
    hubs: std::sync::Mutex<HashMap<String, Arc<BoxHub>>>,
}

impl BoxPool {
    pub fn new() -> Arc<Self> {
        Arc::new(Self {
            provisioning: Mutex::new(()),
            hubs: std::sync::Mutex::new(HashMap::new()),
        })
    }

    pub fn global() -> Arc<Self> {
        static POOL: OnceLock<Arc<BoxPool>> = OnceLock::new();
        POOL.get_or_init(Self::new).clone()
    }

    pub fn hub(&self, seat_id: &str) -> Arc<BoxHub> {
        let seat = BoxSeat::for_id(seat_id);
        let key = seat.id.clone();
        self.hubs
            .lock()
            .unwrap()
            .entry(key)
            .or_insert_with(|| BoxHub::for_seat(seat))
            .clone()
    }

    pub async fn inspect(&self, seat_id: &str) -> Value {
        self.hub(seat_id).inspect().await
    }

    /// Recover computers left by a previous server, so limits survive make start.
    pub async fn reconcile(&self) -> Result<()> {
        let names = docker(["ps", "-a", "--format", "{{.Names}}"]).await?;
        for name in names.stdout.lines().rev() {
            let id = if name == SESSION_CONTAINER { SESSION_SEAT }
                else if let Some(id) = name.strip_prefix("lazyboy-box-") { id }
                else { continue };
            self.hub(id);
            limit_container(name).await?;
        }
        Ok(())
    }

    pub async fn recover(&self) -> Result<()> {
        self.reconcile().await?;
        self.reclaim("").await?;
        Ok(())
    }

    pub async fn start(&self, seat_id: &str) -> Result<Value> {
        // Serialize admission and launch; concurrent tabs cannot exceed the cap.
        let _guard = self.provisioning.lock().await;
        self.reconcile().await?;
        let crowded = self.reclaim(seat_id).await?;
        let mut payload = self.hub(seat_id).ensure_ready().await?;
        if crowded {
            payload["crowded"] = json!(true);
        }
        Ok(payload)
    }

    pub async fn restart(&self, seat_id: &str) -> Result<Value> {
        self.hub(seat_id).restart().await
    }

    pub async fn update(&self, seat_id: &str) -> Result<Value> {
        self.hub(seat_id).update().await
    }

    pub async fn drop_seat(&self, seat_id: &str) -> Result<()> {
        if BoxSeat::for_id(seat_id).id == SESSION_SEAT {
            return Ok(());
        }
        let hub = self.hub(seat_id);
        hub.wipe().await?;
        self.hubs
            .lock()
            .unwrap()
            .remove(&BoxSeat::for_id(seat_id).id);
        Ok(())
    }

    async fn reclaim(&self, keep: &str) -> Result<bool> {
        let max = max_running();
        let reserve_slot = !keep.is_empty();
        let keep = BoxSeat::for_id(keep).id;
        loop {
            let hubs: Vec<Arc<BoxHub>> = self.hubs.lock().unwrap().values().cloned().collect();
            let mut running = Vec::new();
            for hub in hubs {
                if docker_running(hub.container()).await.unwrap_or(false) {
                    running.push((hub.last_used().await, hub));
                }
            }
            let already_running = running.iter().any(|(_, hub)| hub.seat_id() == keep);
            if running.len() < max || ((!reserve_slot || already_running) && running.len() <= max) {
                return Ok(false);
            }
            running.sort_by_key(|(used, _)| *used);
            let victim = running.into_iter().find(|(_, hub)| {
                hub.seat_id() != keep && hub.seat_id() != SESSION_SEAT && !hub.has_computer_use()
            });
            match victim {
                Some((_, hub)) => {
                    if hub.stop_keep_volumes().await.is_err() {
                        return Err(anyhow!("Could not suspend an idle computer to free memory"));
                    }
                }
                None => return Err(anyhow!("All computer slots are busy; stop an idle computer before starting another")),
            }
        }
    }
}

async fn docker_exec(container: &str, args: &[&str]) -> Result<CmdOut> {
    docker_exec_env(container, &[], args).await
}

async fn docker_exec_env(container: &str, env: &[(&str, &str)], args: &[&str]) -> Result<CmdOut> {
    let mut all = vec!["exec".to_string()];
    for (key, value) in env {
        all.push("-e".into());
        all.push(format!("{key}={value}"));
    }
    all.push(container.to_string());
    all.extend(args.iter().map(|s| (*s).to_string()));
    let mut cmd = Command::new("docker");
    cmd.args(&all)
        .stdout(Stdio::piped())
        .stderr(Stdio::piped())
        .kill_on_drop(true);
    let out = cmd.output().await.context("docker exec")?;
    Ok(CmdOut {
        status: out.status.code().unwrap_or(-1),
        stdout: String::from_utf8_lossy(&out.stdout).into_owned(),
        stderr: String::from_utf8_lossy(&out.stderr).into_owned(),
    })
}

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

    #[test]
    fn box_paths_stay_on_my_computer() {
        assert_eq!(
            resolve_box_path("notes.txt").unwrap(),
            "/workspace/notes.txt"
        );
        assert_eq!(resolve_box_path("/workspace/a").unwrap(), "/workspace/a");
        assert!(resolve_box_path("/etc/passwd").is_err());
        assert!(resolve_box_path("../secret").is_err());
        assert!(resolve_box_path("/workspace/../home").is_err());
        assert!(resolve_box_path("/workspace/../../etc/passwd").is_err());
        assert!(resolve_box_path("/workspaceX/a").is_err());
        assert!(resolve_box_path("/tmp/other").is_err());
    }

    #[test]
    fn box_paths_normalise_without_false_positives() {
        assert_eq!(
            resolve_box_path("/workspace///a/./b").unwrap(),
            "/workspace/a/b"
        );
        assert_eq!(
            resolve_box_path("report..final.txt").unwrap(),
            "/workspace/report..final.txt"
        );
        assert_eq!(resolve_box_path("/home/box/").unwrap(), "/home/box");
        assert_eq!(
            resolve_box_path("/tmp/gb-jobs/abc/stdout").unwrap(),
            "/tmp/gb-jobs/abc/stdout"
        );
    }

    #[test]
    fn dir_size_sums_nested_files() {
        let dir = std::env::temp_dir().join(format!("gb-dirsize-{}", uuid::Uuid::new_v4()));
        std::fs::create_dir_all(dir.join("inner")).unwrap();
        std::fs::write(dir.join("a.bin"), [0u8; 10]).unwrap();
        std::fs::write(dir.join("inner/b.bin"), [0u8; 5]).unwrap();
        assert_eq!(dir_size(&dir), 15);
        std::fs::remove_dir_all(&dir).unwrap();
    }

    #[tokio::test]
    async fn missing_docker_is_explicit() {
        if docker(["info"]).await.is_ok() {
            return;
        }
        let hub = BoxHub::new();
        let err = hub.ensure_ready().await.unwrap_err().to_string();
        assert!(err.contains("Docker"), "{err}");
        assert!(
            err.contains("your computer") || err.contains("My computer"),
            "{err}"
        );
    }

    #[tokio::test]
    async fn restart_and_update_need_docker() {
        if docker(["info"]).await.is_ok() {
            return;
        }
        let hub = BoxHub::new();
        for err in [
            hub.restart().await.unwrap_err().to_string(),
            hub.update().await.unwrap_err().to_string(),
        ] {
            assert!(err.contains("Docker"), "{err}");
        }
    }

    #[test]
    fn ready_payload_names_the_box() {
        let hub = BoxHub::new();
        let payload = hub.ready_payload();
        assert_eq!(payload["ready"], true);
        assert_eq!(payload["workspace"], "/workspace");
        assert_eq!(payload["revision"], BOX_REVISION);
        assert_eq!(payload["seat"], SESSION_SEAT);
        assert!(payload["viewer_url"].as_str().unwrap().contains("/novnc/"));
    }

    #[test]
    fn named_agents_get_isolated_seats() {
        let a = BoxSeat::for_id("11111111-1111-1111-1111-111111111111");
        let b = BoxSeat::for_id("22222222-2222-2222-2222-222222222222");
        assert_ne!(a.container, b.container);
        assert_ne!(a.home_volume, b.home_volume);
        assert_ne!(a.workspace_volume, b.workspace_volume);
        assert!(a.container.starts_with("lazyboy-box-"));
        assert_eq!(BoxSeat::for_id("session").container, SESSION_CONTAINER);
        assert_eq!(BoxSeat::for_id("").container, SESSION_CONTAINER);
        assert_eq!(sanitize_seat_id("../etc"), "etc");
    }

    #[test]
    fn pool_reuses_the_same_hub() {
        let pool = BoxPool::new();
        let one = pool.hub("agent-a");
        let two = pool.hub("agent-a");
        assert!(Arc::ptr_eq(&one, &two));
        assert!(!Arc::ptr_eq(&one, &pool.hub("agent-b")));
    }

    #[tokio::test]
    async fn inspect_does_not_start_a_container() {
        let hub = BoxHub::for_seat(BoxSeat::for_id("missing-agent"));
        let status = hub.inspect().await;
        assert_eq!(status["ready"], false);
        assert!(
            status["state"] == "stopped" || status["state"] == "error",
            "{status}"
        );
        assert_eq!(status["seat"], "missing-agent");
    }

    #[test]
    fn computer_use_lock_is_per_hub() {
        let a = BoxHub::for_seat(BoxSeat::for_id("a"));
        let b = BoxHub::for_seat(BoxSeat::for_id("b"));
        a.try_begin_computer_use().unwrap();
        assert!(a.try_begin_computer_use().is_err());
        b.try_begin_computer_use().unwrap();
        a.end_computer_use();
        a.try_begin_computer_use().unwrap();
    }
}