feat: added e2e (#5)

* feat: added e2e

* fix: try fix

* fix: try fix

* fix: try fix

* fix: added more observability

* ci: fixed double trigger

* feat: partial e2e test with mock vm

* feat: more monkey tests

* feat: added coverage

tests/e2e_cli.rs

@@ -0,0 +1,58 @@
+use assert_cmd::cargo::cargo_bin_cmd;
+use tempfile::TempDir;
+
+#[test]
+fn cli_version_shows_binary_name() {
+    let output = cargo_bin_cmd!("vibebox").arg("--version").output().unwrap();
+    print_output("e2e_cli", &output);
+    assert!(
+        output.status.success(),
+        "expected success, got status: {}",
+        output.status
+    );
+    let stdout = String::from_utf8_lossy(&output.stdout);
+    assert!(
+        stdout.contains("vibebox"),
+        "expected --version output to contain 'vibebox', got: {}",
+        stdout
+    );
+}
+
+#[test]
+fn list_reports_no_sessions_when_empty() {
+    let temp = TempDir::new().unwrap();
+    let home = temp.path().join("home");
+    let project = temp.path().join("project");
+    std::fs::create_dir_all(&home).unwrap();
+    std::fs::create_dir_all(&project).unwrap();
+
+    let output = cargo_bin_cmd!("vibebox")
+        .current_dir(&project)
+        .env("HOME", &home)
+        .arg("list")
+        .output()
+        .unwrap();
+    print_output("e2e_cli", &output);
+    assert!(
+        output.status.success(),
+        "expected success, got status: {}",
+        output.status
+    );
+    let stdout = String::from_utf8_lossy(&output.stdout);
+    assert!(
+        stdout.contains("No sessions were found."),
+        "expected empty sessions message, got: {}",
+        stdout
+    );
+}
+
+fn print_output(prefix: &str, output: &std::process::Output) {
+    let stdout = String::from_utf8_lossy(&output.stdout);
+    for line in stdout.lines() {
+        println!("[{}] {}", prefix, line);
+    }
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    for line in stderr.lines() {
+        eprintln!("[{}] {}", prefix, line);
+    }
+}

tests/e2e_vm.rs

@@ -0,0 +1,278 @@
+use std::{
+    fs,
+    io::{BufRead, BufReader, Read},
+    path::{Path, PathBuf},
+    process::{Child, Command, Stdio},
+    thread,
+    time::{Duration, Instant},
+};
+
+use tempfile::TempDir;
+
+#[cfg(target_os = "macos")]
+#[test]
+#[ignore]
+fn vm_boots_and_runs_command() {
+    if std::env::var("VIBEBOX_E2E_VM").as_deref() != Ok("1") {
+        eprintln!("skipping: set VIBEBOX_E2E_VM=1 to run this test");
+        return;
+    }
+    if !virtualization_available() {
+        eprintln!("[e2e_vm] skipping: virtualization not available on this hardware");
+        return;
+    }
+
+    let temp = TempDir::new().unwrap();
+    let home = temp.path().join("home");
+    let cache_home = temp.path().join("cache");
+    let project = temp.path().join("project");
+    fs::create_dir_all(&home).unwrap();
+    fs::create_dir_all(&cache_home).unwrap();
+    fs::create_dir_all(&project).unwrap();
+
+    write_config(&project);
+
+    let mut child = Command::new(assert_cmd::cargo_bin!("vibebox-supervisor"))
+        .current_dir(&project)
+        .env("HOME", &home)
+        .env("XDG_CACHE_HOME", &cache_home)
+        .env("VIBEBOX_INTERNAL", "1")
+        .stdout(Stdio::piped())
+        .stderr(Stdio::piped())
+        .spawn()
+        .unwrap();
+    if let Some(stdout) = child.stdout.take() {
+        spawn_prefix_reader("e2e_vm", "stdout", stdout);
+    }
+    if let Some(stderr) = child.stderr.take() {
+        spawn_prefix_reader("e2e_vm", "stderr", stderr);
+    }
+    let _child_guard = ChildGuard::new(child);
+
+    log_line("e2e_vm", "waiting for vm manager socket");
+    let socket_path = project.join(".vibebox").join("vm.sock");
+    let _socket_guard = wait_for_socket(&socket_path, Duration::from_secs(30));
+    log_line("e2e_vm", "vm manager socket ready");
+
+    log_line("e2e_vm", "waiting for vm ipv4");
+    let instance_path = project.join(".vibebox").join("instance.toml");
+    let (ip, user) = wait_for_vm_ip(&instance_path, Duration::from_secs(180));
+    log_line("e2e_vm", &format!("vm ipv4={ip} user={user}"));
+
+    let ssh_key = project.join(".vibebox").join("ssh_key");
+    wait_for_file(&ssh_key, Duration::from_secs(30));
+    log_line("e2e_vm", "ssh key ready");
+
+    let output = wait_for_ssh_command(&ssh_key, &user, &ip, Duration::from_secs(90));
+    print_output("e2e_vm", &output);
+    let stdout = String::from_utf8_lossy(&output.stdout);
+    assert!(
+        stdout.contains("Linux"),
+        "expected ssh command output to contain 'Linux', got: {}",
+        stdout
+    );
+}
+
+#[cfg(not(target_os = "macos"))]
+#[test]
+#[ignore]
+fn vm_boots_and_runs_command() {
+    eprintln!("skipping: vm e2e test requires macOS virtualization");
+}
+
+struct ChildGuard {
+    child: Option<Child>,
+}
+
+impl ChildGuard {
+    fn new(child: Child) -> Self {
+        Self { child: Some(child) }
+    }
+}
+
+impl Drop for ChildGuard {
+    fn drop(&mut self) {
+        if let Some(child) = &mut self.child {
+            let _ = child.kill();
+            let _ = child.wait();
+        }
+    }
+}
+
+struct SocketGuard {
+    _path: PathBuf,
+    _stream: std::os::unix::net::UnixStream,
+}
+
+fn write_config(project: &Path) {
+    let config = r#"[box]
+cpu_count = 2
+ram_mb = 2048
+disk_gb = 5
+mounts = []
+
+[supervisor]
+auto_shutdown_ms = 120000
+"#;
+    fs::write(project.join("vibebox.toml"), config).unwrap();
+}
+
+fn wait_for_socket(path: &Path, timeout: Duration) -> SocketGuard {
+    let start = Instant::now();
+    loop {
+        if let Ok(stream) = std::os::unix::net::UnixStream::connect(path) {
+            return SocketGuard {
+                _path: path.to_path_buf(),
+                _stream: stream,
+            };
+        }
+        if start.elapsed() > timeout {
+            panic!(
+                "timed out waiting for vm manager socket at {}",
+                path.display()
+            );
+        }
+        thread::sleep(Duration::from_millis(200));
+    }
+}
+
+fn wait_for_vm_ip(instance_path: &Path, timeout: Duration) -> (String, String) {
+    let start = Instant::now();
+    loop {
+        if let Ok(raw) = fs::read_to_string(instance_path)
+            && let Ok(value) = toml::from_str::<toml::Value>(&raw)
+        {
+            let ip = value
+                .get("vm_ipv4")
+                .and_then(|v| v.as_str())
+                .map(|s| s.trim().to_string())
+                .filter(|s| !s.is_empty());
+            if let Some(ip) = ip {
+                let user = value
+                    .get("ssh_user")
+                    .and_then(|v| v.as_str())
+                    .map(|s| s.trim().to_string())
+                    .filter(|s| !s.is_empty())
+                    .unwrap_or_else(|| "vibecoder".to_string());
+                return (ip, user);
+            }
+        }
+        if start.elapsed() > timeout {
+            panic!(
+                "timed out waiting for vm_ipv4 in {}",
+                instance_path.display()
+            );
+        }
+        thread::sleep(Duration::from_millis(500));
+    }
+}
+
+fn wait_for_file(path: &Path, timeout: Duration) {
+    let start = Instant::now();
+    loop {
+        if path.exists() {
+            return;
+        }
+        if start.elapsed() > timeout {
+            panic!("timed out waiting for file {}", path.display());
+        }
+        thread::sleep(Duration::from_millis(200));
+    }
+}
+
+fn wait_for_ssh_command(
+    ssh_key: &Path,
+    user: &str,
+    ip: &str,
+    timeout: Duration,
+) -> std::process::Output {
+    let start = Instant::now();
+    loop {
+        let output = Command::new("ssh")
+            .args([
+                "-i",
+                ssh_key.to_str().unwrap_or(".vibebox/ssh_key"),
+                "-o",
+                "IdentitiesOnly=yes",
+                "-o",
+                "StrictHostKeyChecking=no",
+                "-o",
+                "UserKnownHostsFile=/dev/null",
+                "-o",
+                "GlobalKnownHostsFile=/dev/null",
+                "-o",
+                "PasswordAuthentication=no",
+                "-o",
+                "BatchMode=yes",
+                "-o",
+                "LogLevel=ERROR",
+                "-o",
+                "ConnectTimeout=5",
+                &format!("{user}@{ip}"),
+                "uname -s",
+            ])
+            .output()
+            .unwrap();
+        if output.status.success() {
+            return output;
+        }
+        if start.elapsed() > timeout {
+            let stderr = String::from_utf8_lossy(&output.stderr);
+            panic!("ssh command failed and timed out: {}", stderr);
+        }
+        thread::sleep(Duration::from_millis(1000));
+    }
+}
+
+fn spawn_prefix_reader(
+    label: &'static str,
+    stream: &'static str,
+    reader: impl Read + Send + 'static,
+) {
+    thread::spawn(move || {
+        let buf = BufReader::new(reader);
+        for line in buf.lines() {
+            match line {
+                Ok(line) => {
+                    println!("[{}][{}] {}", label, stream, line);
+                }
+                Err(err) => {
+                    eprintln!("[{}][{}] read error: {}", label, stream, err);
+                    break;
+                }
+            }
+        }
+    });
+}
+
+fn log_line(prefix: &str, message: &str) {
+    println!("[{}] {}", prefix, message);
+}
+
+fn print_output(prefix: &str, output: &std::process::Output) {
+    let stdout = String::from_utf8_lossy(&output.stdout);
+    for line in stdout.lines() {
+        println!("[{}] {}", prefix, line);
+    }
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    for line in stderr.lines() {
+        eprintln!("[{}] {}", prefix, line);
+    }
+}
+
+fn virtualization_available() -> bool {
+    let output = Command::new("sysctl")
+        .args(["-n", "kern.hv_support"])
+        .output();
+    match output {
+        Ok(output) if output.status.success() => {
+            let value = String::from_utf8_lossy(&output.stdout);
+            match value.trim() {
+                "1" => true,
+                "0" => false,
+                _ => true,
+            }
+        }
+        _ => true,
+    }
+}

tests/e2e_vm_mock.rs

@@ -0,0 +1,455 @@
+#![cfg(all(feature = "mock-vm", target_os = "macos"))]
+
+use std::{
+    fs,
+    io::{BufRead, BufReader, Read},
+    os::unix::net::UnixStream,
+    path::{Path, PathBuf},
+    process::{Child, Command, Stdio},
+    sync::mpsc,
+    thread,
+    time::{Duration, Instant},
+};
+
+use tempfile::TempDir;
+
+#[test]
+fn mock_vm_allows_refcount_concurrency() {
+    let temp = TempDir::new().unwrap();
+    let mut supervisor = spawn_supervisor(&temp, 0, 1200, "e2e_vm_mock".to_string());
+
+    supervisor.clients = connect_clients(
+        &supervisor.socket_path,
+        12,
+        Duration::from_secs(2),
+        true,
+        "e2e_vm_mock",
+    );
+    log_line("e2e_vm_mock", "connected 12 clients");
+
+    assert_manager_alive_for(
+        &mut supervisor.child,
+        Duration::from_millis(900),
+        "vm manager exited while clients active",
+    );
+
+    let remaining = supervisor.clients.split_off(6);
+    supervisor.clients = remaining;
+    log_line("e2e_vm_mock", "dropped 6 clients");
+    assert_manager_alive_for(
+        &mut supervisor.child,
+        Duration::from_millis(900),
+        "vm manager exited while clients active",
+    );
+
+    supervisor.clients.clear();
+    log_line("e2e_vm_mock", "dropped remaining clients");
+    wait_for_exit(&mut supervisor.child, Duration::from_secs(10));
+    let status = supervisor.child.wait().unwrap();
+    assert!(status.success(), "vm manager exited with {status}");
+}
+
+#[test]
+fn mock_vm_many_managers_many_clients() {
+    let temp = TempDir::new().unwrap();
+    let mut supervisors = Vec::new();
+
+    for idx in 0..3 {
+        supervisors.push(spawn_supervisor(
+            &temp,
+            idx + 1,
+            1400,
+            format!("e2e_vm_mock_{idx}"),
+        ));
+    }
+
+    for supervisor in &mut supervisors {
+        supervisor.clients = connect_clients(
+            &supervisor.socket_path,
+            8,
+            Duration::from_secs(2),
+            true,
+            "e2e_vm_mock",
+        );
+    }
+    log_line("e2e_vm_mock", "connected 8 clients per manager");
+
+    for supervisor in &mut supervisors {
+        assert_manager_alive_for(
+            &mut supervisor.child,
+            Duration::from_millis(900),
+            "manager exited while clients active",
+        );
+    }
+
+    supervisors[0].clients.clear();
+    log_line("e2e_vm_mock", "dropped all clients for manager 0");
+    wait_for_exit(&mut supervisors[0].child, Duration::from_secs(10));
+    let status = supervisors[0].child.wait().unwrap();
+    assert!(status.success(), "manager 0 exited with {status}");
+
+    for supervisor in supervisors.iter_mut().skip(1) {
+        assert_manager_alive_for(
+            &mut supervisor.child,
+            Duration::from_millis(900),
+            "another manager exited early",
+        );
+    }
+
+    for supervisor in supervisors.iter_mut().skip(1) {
+        supervisor.clients.clear();
+    }
+    log_line("e2e_vm_mock", "dropped remaining clients");
+    for supervisor in supervisors.iter_mut().skip(1) {
+        wait_for_exit(&mut supervisor.child, Duration::from_secs(10));
+        let status = supervisor.child.wait().unwrap();
+        assert!(status.success(), "manager exited with {status}");
+    }
+}
+
+#[test]
+fn mock_vm_monkey_processes() {
+    let temp = TempDir::new().unwrap();
+    let mut rng = Lcg::new(0x5eed_f00d_dead_beef);
+    let mut supervisors = Vec::new();
+    let mut next_id = 0usize;
+    let max_supervisors = 4usize;
+    let steps = 25usize;
+
+    supervisors.push(spawn_supervisor(
+        &temp,
+        next_id,
+        1200,
+        format!("e2e_vm_monkey_{next_id}"),
+    ));
+    next_id += 1;
+
+    for step in 0..steps {
+        prune_exited_supervisors(&mut supervisors, "e2e_vm_monkey");
+        let roll = rng.gen_range(100);
+        log_line(
+            "e2e_vm_monkey",
+            &format!("step {step} roll={roll} supervisors={}", supervisors.len()),
+        );
+        if roll < 20 && supervisors.len() < max_supervisors {
+            supervisors.push(spawn_supervisor(
+                &temp,
+                next_id,
+                1200,
+                format!("e2e_vm_monkey_{next_id}"),
+            ));
+            log_line("e2e_vm_monkey", &format!("spawned supervisor {next_id}"));
+            next_id += 1;
+        } else if roll < 45 && !supervisors.is_empty() {
+            let idx = rng.gen_range(supervisors.len());
+            let mut supervisor = supervisors.swap_remove(idx);
+            log_line(
+                "e2e_vm_monkey",
+                &format!("killing supervisor {}", supervisor.label),
+            );
+            kill_supervisor(&mut supervisor, Duration::from_secs(5));
+        } else if roll < 80 && !supervisors.is_empty() {
+            let idx = rng.gen_range(supervisors.len());
+            let burst = 1 + rng.gen_range(3);
+            let new_clients = connect_clients(
+                &supervisors[idx].socket_path,
+                burst,
+                Duration::from_secs(1),
+                false,
+                "e2e_vm_monkey",
+            );
+            supervisors[idx].clients.extend(new_clients);
+            log_line(
+                "e2e_vm_monkey",
+                &format!("connected {burst} clients to {}", supervisors[idx].label),
+            );
+        } else if !supervisors.is_empty() {
+            let idx = rng.gen_range(supervisors.len());
+            if !supervisors[idx].clients.is_empty() {
+                let len = supervisors[idx].clients.len();
+                let drop_count = 1 + rng.gen_range(len);
+                supervisors[idx].clients.drain(0..drop_count.min(len));
+                log_line(
+                    "e2e_vm_monkey",
+                    &format!(
+                        "dropped {drop_count} clients from {}",
+                        supervisors[idx].label
+                    ),
+                );
+            }
+        }
+        thread::sleep(Duration::from_millis(200));
+    }
+
+    log_line("e2e_vm_monkey", "final cleanup");
+    for supervisor in supervisors.iter_mut() {
+        shutdown_supervisor(supervisor, Duration::from_secs(10));
+    }
+}
+
+#[test]
+fn mock_vm_exits_without_clients() {
+    let temp = TempDir::new().unwrap();
+    let mut supervisor = spawn_supervisor(&temp, 99, 300, "e2e_vm_no_clients".to_string());
+    wait_for_exit(&mut supervisor.child, Duration::from_secs(5));
+    let status = supervisor.child.wait().unwrap();
+    assert!(status.success(), "vm manager exited with {status}");
+}
+
+#[test]
+fn mock_vm_reconnect_resets_shutdown() {
+    let temp = TempDir::new().unwrap();
+    let mut supervisor = spawn_supervisor(&temp, 100, 800, "e2e_vm_reconnect".to_string());
+
+    supervisor.clients = connect_clients(
+        &supervisor.socket_path,
+        1,
+        Duration::from_secs(2),
+        true,
+        "e2e_vm_reconnect",
+    );
+    supervisor.clients.clear();
+    thread::sleep(Duration::from_millis(400));
+
+    supervisor.clients = connect_clients(
+        &supervisor.socket_path,
+        1,
+        Duration::from_secs(2),
+        true,
+        "e2e_vm_reconnect",
+    );
+    assert_manager_alive_for(
+        &mut supervisor.child,
+        Duration::from_millis(600),
+        "vm manager exited despite reconnect",
+    );
+
+    supervisor.clients.clear();
+    wait_for_exit(&mut supervisor.child, Duration::from_secs(10));
+    let status = supervisor.child.wait().unwrap();
+    assert!(status.success(), "vm manager exited with {status}");
+}
+
+struct Supervisor {
+    child: Child,
+    socket_path: PathBuf,
+    clients: Vec<UnixStream>,
+    label: String,
+}
+
+fn write_config(project: &Path, auto_shutdown_ms: u64) {
+    let config = format!(
+        r#"[box]
+cpu_count = 2
+ram_mb = 2048
+disk_gb = 5
+mounts = []
+
+[supervisor]
+auto_shutdown_ms = {auto_shutdown_ms}
+"#
+    );
+    fs::write(project.join("vibebox.toml"), config).unwrap();
+}
+
+fn spawn_supervisor(
+    temp: &TempDir,
+    idx: usize,
+    auto_shutdown_ms: u64,
+    label: String,
+) -> Supervisor {
+    let home = temp.path().join(format!("home-{idx}"));
+    let cache_home = temp.path().join(format!("cache-{idx}"));
+    let project = temp.path().join(format!("project-{idx}"));
+    fs::create_dir_all(&home).unwrap();
+    fs::create_dir_all(&cache_home).unwrap();
+    fs::create_dir_all(&project).unwrap();
+    write_config(&project, auto_shutdown_ms);
+
+    let mut child = Command::new(assert_cmd::cargo_bin!("vibebox-supervisor"))
+        .current_dir(&project)
+        .env("HOME", &home)
+        .env("XDG_CACHE_HOME", &cache_home)
+        .env("VIBEBOX_INTERNAL", "1")
+        .stdout(Stdio::piped())
+        .stderr(Stdio::piped())
+        .spawn()
+        .unwrap();
+    if let Some(stdout) = child.stdout.take() {
+        spawn_prefix_reader(label.clone(), "stdout", stdout);
+    }
+    if let Some(stderr) = child.stderr.take() {
+        spawn_prefix_reader(label.clone(), "stderr", stderr);
+    }
+
+    let socket_path = project.join(".vibebox").join("vm.sock");
+    wait_for_socket(&socket_path, Duration::from_secs(10));
+
+    Supervisor {
+        child,
+        socket_path,
+        clients: Vec::new(),
+        label,
+    }
+}
+
+fn connect_clients(
+    socket_path: &Path,
+    count: usize,
+    timeout: Duration,
+    require_all: bool,
+    label: &str,
+) -> Vec<UnixStream> {
+    let (tx, rx) = mpsc::channel();
+    let mut handles = Vec::with_capacity(count);
+    for _ in 0..count {
+        let path = socket_path.to_path_buf();
+        let tx = tx.clone();
+        handles.push(thread::spawn(move || {
+            let stream = connect_client_with_retry(&path, timeout);
+            let _ = tx.send(stream);
+        }));
+    }
+    drop(tx);
+    let mut clients = Vec::with_capacity(count);
+    for stream in rx.into_iter().flatten() {
+        clients.push(stream);
+    }
+    for handle in handles {
+        handle.join().unwrap();
+    }
+    if require_all && clients.len() != count {
+        panic!(
+            "client count mismatch: expected {count} got {}",
+            clients.len()
+        );
+    }
+    if !require_all && clients.len() != count {
+        log_line(
+            label,
+            &format!("connected {} of {count} clients", clients.len()),
+        );
+    }
+    clients
+}
+
+fn connect_client_with_retry(path: &Path, timeout: Duration) -> Option<UnixStream> {
+    let start = Instant::now();
+    loop {
+        match UnixStream::connect(path) {
+            Ok(stream) => return Some(stream),
+            Err(_) => {
+                if start.elapsed() > timeout {
+                    return None;
+                }
+                thread::sleep(Duration::from_millis(50));
+            }
+        }
+    }
+}
+
+fn wait_for_socket(path: &Path, timeout: Duration) {
+    let start = Instant::now();
+    loop {
+        if UnixStream::connect(path).is_ok() {
+            return;
+        }
+        if start.elapsed() > timeout {
+            panic!("timed out waiting for socket {}", path.display());
+        }
+        thread::sleep(Duration::from_millis(100));
+    }
+}
+
+fn assert_manager_alive(child: &mut Child, message: &str) {
+    assert!(child.try_wait().unwrap().is_none(), "{message}");
+}
+
+fn assert_manager_alive_for(child: &mut Child, duration: Duration, message: &str) {
+    let start = Instant::now();
+    while start.elapsed() < duration {
+        assert_manager_alive(child, message);
+        thread::sleep(Duration::from_millis(100));
+    }
+}
+
+fn kill_supervisor(supervisor: &mut Supervisor, timeout: Duration) {
+    supervisor.clients.clear();
+    let _ = supervisor.child.kill();
+    wait_for_exit(&mut supervisor.child, timeout);
+    let _ = supervisor.child.wait();
+}
+
+fn prune_exited_supervisors(supervisors: &mut Vec<Supervisor>, label: &str) {
+    supervisors.retain_mut(|supervisor| {
+        if supervisor.child.try_wait().unwrap().is_some() {
+            log_line(label, &format!("removed exited {}", supervisor.label));
+            false
+        } else {
+            true
+        }
+    });
+}
+
+fn shutdown_supervisor(supervisor: &mut Supervisor, timeout: Duration) {
+    supervisor.clients.clear();
+    wait_for_exit(&mut supervisor.child, timeout);
+    if supervisor.child.try_wait().unwrap().is_none() {
+        let _ = supervisor.child.kill();
+        let _ = supervisor.child.wait();
+    }
+}
+
+fn wait_for_exit(child: &mut Child, timeout: Duration) {
+    let start = Instant::now();
+    loop {
+        if child.try_wait().unwrap().is_some() {
+            return;
+        }
+        if start.elapsed() > timeout {
+            panic!("timed out waiting for mock vm supervisor exit");
+        }
+        thread::sleep(Duration::from_millis(200));
+    }
+}
+
+fn spawn_prefix_reader(label: String, stream: &'static str, reader: impl Read + Send + 'static) {
+    thread::spawn(move || {
+        let buf = BufReader::new(reader);
+        for line in buf.lines() {
+            match line {
+                Ok(line) => println!("[{}][{}] {}", label, stream, line),
+                Err(err) => {
+                    eprintln!("[{}][{}] read error: {}", label, stream, err);
+                    break;
+                }
+            }
+        }
+    });
+}
+
+fn log_line(prefix: &str, message: &str) {
+    println!("[{}] {}", prefix, message);
+}
+
+struct Lcg {
+    state: u64,
+}
+
+impl Lcg {
+    fn new(seed: u64) -> Self {
+        Self { state: seed }
+    }
+
+    fn next_u32(&mut self) -> u32 {
+        self.state = self.state.wrapping_mul(6364136223846793005).wrapping_add(1);
+        (self.state >> 32) as u32
+    }
+
+    fn gen_range(&mut self, upper: usize) -> usize {
+        if upper == 0 {
+            return 0;
+        }
+        (self.next_u32() as usize) % upper
+    }
+}

tests/explain_integration.rs

@@ -0,0 +1,113 @@
+use std::{env, ffi::OsString, fs, path::Path, sync::Mutex};
+
+use tempfile::TempDir;
+
+use vibebox::session_manager::INSTANCE_DIR_NAME;
+use vibebox::{config, explain};
+
+static ENV_MUTEX: Mutex<()> = Mutex::new(());
+
+struct EnvGuard {
+    key: &'static str,
+    previous: Option<OsString>,
+}
+
+impl EnvGuard {
+    fn set(key: &'static str, value: &Path) -> Self {
+        let previous = env::var_os(key);
+        unsafe {
+            env::set_var(key, value);
+        }
+        Self { key, previous }
+    }
+}
+
+impl Drop for EnvGuard {
+    fn drop(&mut self) {
+        match &self.previous {
+            Some(value) => unsafe {
+                env::set_var(self.key, value);
+            },
+            None => unsafe {
+                env::remove_var(self.key);
+            },
+        }
+    }
+}
+
+#[test]
+fn build_mount_rows_includes_defaults_and_custom_mounts() {
+    let _lock = ENV_MUTEX.lock().unwrap();
+    let temp = TempDir::new().unwrap();
+    let home = temp.path().join("home");
+    let project = home.join("project");
+    let cache_home = home.join("cache");
+    fs::create_dir_all(&project).unwrap();
+    fs::create_dir_all(&cache_home).unwrap();
+
+    let _home_guard = EnvGuard::set("HOME", &home);
+    let _cache_guard = EnvGuard::set("XDG_CACHE_HOME", &cache_home);
+
+    let box_cfg = config::BoxConfig {
+        mounts: vec!["data:~/data:read-only".to_string()],
+        ..Default::default()
+    };
+    let cfg = config::Config {
+        box_cfg,
+        supervisor: config::SupervisorConfig::default(),
+    };
+
+    let rows = explain::build_mount_rows(&project, &cfg).unwrap();
+
+    assert_eq!(rows.len(), 3);
+    assert_eq!(rows[0].host, "~/project");
+    assert_eq!(rows[0].guest, "~/project");
+    assert_eq!(rows[0].mode, "read-write");
+    assert_eq!(rows[0].default_mount, "yes");
+
+    assert_eq!(rows[1].host, "~/cache/vibebox/.guest-mise-cache");
+    assert_eq!(rows[1].guest, "/root/.local/share/mise");
+    assert_eq!(rows[1].mode, "read-write");
+    assert_eq!(rows[1].default_mount, "yes");
+
+    assert_eq!(rows[2].host, "~/project/data");
+    assert_eq!(rows[2].guest, "~/data");
+    assert_eq!(rows[2].mode, "read-only");
+    assert_eq!(rows[2].default_mount, "no");
+}
+
+#[test]
+fn build_network_rows_pending_without_instance_file() {
+    let temp = TempDir::new().unwrap();
+    let project = temp.path().join("project");
+    fs::create_dir_all(&project).unwrap();
+
+    let rows = explain::build_network_rows(&project).unwrap();
+
+    assert_eq!(rows.len(), 1);
+    assert_eq!(rows[0].network_type, "NAT");
+    assert_eq!(rows[0].vm_ip, "-");
+    assert_eq!(rows[0].host_to_vm, "ssh: <pending>:22");
+    assert_eq!(rows[0].vm_to_host, "none");
+}
+
+#[test]
+fn build_network_rows_uses_instance_vm_ip() {
+    let temp = TempDir::new().unwrap();
+    let project = temp.path().join("project");
+    let instance_dir = project.join(INSTANCE_DIR_NAME);
+    fs::create_dir_all(&instance_dir).unwrap();
+    fs::write(
+        instance_dir.join("instance.toml"),
+        "vm_ipv4 = \"10.1.2.3\"\n",
+    )
+    .unwrap();
+
+    let rows = explain::build_network_rows(&project).unwrap();
+
+    assert_eq!(rows.len(), 1);
+    assert_eq!(rows[0].network_type, "NAT");
+    assert_eq!(rows[0].vm_ip, "10.1.2.3");
+    assert_eq!(rows[0].host_to_vm, "ssh: 10.1.2.3:22");
+    assert_eq!(rows[0].vm_to_host, "none");
+}