harn-vm 0.8.43

use std::cell::RefCell;
use std::collections::BTreeMap;
use std::io::Write as _;
use std::path::PathBuf;
use std::process::Stdio;
use std::rc::Rc;
use std::sync::mpsc;
use std::time::{Duration, Instant};

use crate::orchestration::RunExecutionRecord;
use crate::value::{VmError, VmValue};
use crate::vm::Vm;

const HARN_REPLAY_ENV: &str = "HARN_REPLAY";

thread_local! {
    pub(crate) static VM_SOURCE_DIR: RefCell<Option<PathBuf>> = const { RefCell::new(None) };
    static VM_EXECUTION_CONTEXT: RefCell<Option<RunExecutionRecord>> = const { RefCell::new(None) };
}

/// Set the source directory for the current thread (called by VM on file execution).
pub(crate) fn set_thread_source_dir(dir: &std::path::Path) {
    VM_SOURCE_DIR.with(|sd| *sd.borrow_mut() = Some(normalize_context_path(dir)));
}

pub(crate) fn normalize_context_path(path: &std::path::Path) -> PathBuf {
    if path.is_absolute() {
        return path.to_path_buf();
    }
    std::env::current_dir()
        .map(|cwd| cwd.join(path))
        .unwrap_or_else(|_| path.to_path_buf())
}

pub fn set_thread_execution_context(context: Option<RunExecutionRecord>) {
    VM_EXECUTION_CONTEXT.with(|current| *current.borrow_mut() = context);
}

pub(crate) fn current_execution_context() -> Option<RunExecutionRecord> {
    VM_EXECUTION_CONTEXT.with(|current| current.borrow().clone())
}

/// Reset thread-local process state (for test isolation).
pub(crate) fn reset_process_state() {
    VM_SOURCE_DIR.with(|sd| *sd.borrow_mut() = None);
    VM_EXECUTION_CONTEXT.with(|current| *current.borrow_mut() = None);
}

pub fn execution_root_path() -> PathBuf {
    current_execution_context()
        .and_then(|context| context.cwd.map(PathBuf::from))
        .or_else(|| std::env::current_dir().ok())
        .unwrap_or_else(|| PathBuf::from("."))
}

pub fn source_root_path() -> PathBuf {
    VM_SOURCE_DIR
        .with(|sd| sd.borrow().clone())
        .or_else(|| {
            current_execution_context().and_then(|context| context.source_dir.map(PathBuf::from))
        })
        .or_else(|| current_execution_context().and_then(|context| context.cwd.map(PathBuf::from)))
        .or_else(|| std::env::current_dir().ok())
        .unwrap_or_else(|| PathBuf::from("."))
}

pub fn asset_root_path() -> PathBuf {
    source_root_path()
}

fn env_override(name: &str) -> Option<String> {
    (name == HARN_REPLAY_ENV && crate::triggers::dispatcher::current_dispatch_is_replay())
        .then(|| "1".to_string())
}

pub(crate) fn read_env_value(name: &str) -> Option<String> {
    env_override(name)
        .or_else(|| current_execution_context().and_then(|context| context.env.get(name).cloned()))
        .or_else(|| std::env::var(name).ok())
}

pub fn runtime_root_base() -> PathBuf {
    find_project_root(&execution_root_path())
        .or_else(|| find_project_root(&source_root_path()))
        .unwrap_or_else(source_root_path)
}

/// Lexically collapse `..` components in `path`. Returns `None` if a
/// `..` would pop a non-Normal component (i.e. the path tries to walk
/// above its root anchor). This is a pure-string canonicalization that
/// does NOT hit the filesystem — symlinks are not followed.
fn lexically_collapse(path: &std::path::Path) -> Option<PathBuf> {
    use std::path::Component;
    let mut out: Vec<Component> = Vec::new();
    for component in path.components() {
        match component {
            Component::CurDir => {}
            Component::ParentDir => {
                let popped = out.pop();
                if !matches!(popped, Some(Component::Normal(_))) {
                    return None;
                }
            }
            other => out.push(other),
        }
    }
    Some(out.iter().collect())
}

pub fn resolve_source_relative_path(path: &str) -> PathBuf {
    let candidate = PathBuf::from(path);
    if candidate.is_absolute() {
        return candidate;
    }
    let root = execution_root_path();
    let joined = root.join(&candidate);
    // Defense-in-depth path-traversal check (paired with the deferred
    // F3 sandbox-by-default fix): refuse to resolve a path that
    // escapes the project root via `..` components. We anchor against
    // `runtime_root_base()` (the project root), which is broader than
    // `execution_root_path()` and lets benign sibling-dir walks like
    // `read_file("../fixtures/payload.json")` from `tests/` succeed.
    if path_escapes_project_root(&joined) {
        return root.join("__harn_rejected_parent_dir_traversal__");
    }
    joined
}

pub fn resolve_source_asset_path(path: &str) -> PathBuf {
    let candidate = PathBuf::from(path);
    if candidate.is_absolute() {
        return candidate;
    }
    let root = asset_root_path();
    let joined = root.join(&candidate);
    if path_escapes_project_root(&joined) {
        return root.join("__harn_rejected_parent_dir_traversal__");
    }
    joined
}

/// Returns `true` when `joined` (which may contain raw `..`
/// components) cannot be lexically collapsed without popping past its
/// root component — i.e. the relative input had more `..` than the
/// joined depth allows, escaping the filesystem root.
///
/// This is intentionally a narrow check: it doesn't try to enforce
/// that the path stays inside a logical "project root", because the
/// project root isn't always reliably resolvable (and benign uses
/// like `../fixtures/x.json` from a `tests/` subdir are legitimate).
/// The sandbox layer remains the authoritative defense for arbitrary
/// `..` traversal; this guard plugs the most egregious escapes
/// (`../../../../etc/passwd`) for the no-sandbox-by-default
/// `harn run` path.
fn path_escapes_project_root(joined: &std::path::Path) -> bool {
    lexically_collapse(joined).is_none()
}

pub(crate) fn register_process_builtins(vm: &mut Vm) {
    vm.register_builtin("env", |args, _out| {
        let name = args.first().map(|a| a.display()).unwrap_or_default();
        if let Some(value) = read_env_value(&name) {
            return Ok(VmValue::String(Rc::from(value)));
        }
        Ok(VmValue::Nil)
    });

    vm.register_builtin("env_or", |args, _out| {
        let name = args.first().map(|a| a.display()).unwrap_or_default();
        let default = args.get(1).cloned().unwrap_or(VmValue::Nil);
        if let Some(value) = read_env_value(&name) {
            return Ok(VmValue::String(Rc::from(value)));
        }
        Ok(default)
    });

    // `timestamp` / `elapsed` are now registered by clock.rs so they
    // honor mock_time / advance_time. Don't register here.

    vm.register_builtin("exit", |args, _out| {
        let code = args.first().and_then(|a| a.as_int()).unwrap_or(0);
        std::process::exit(code as i32);
    });

    vm.register_builtin("exec", |args, _out| {
        if args.is_empty() {
            return Err(VmError::Thrown(VmValue::String(Rc::from(
                "exec: command is required",
            ))));
        }
        let cmd = args[0].display();
        let cmd_args: Vec<String> = args[1..].iter().map(|a| a.display()).collect();
        let output = exec_command(None, &cmd, &cmd_args)?;
        Ok(vm_output_to_value(output))
    });

    vm.register_builtin("shell", |args, _out| {
        let cmd = args.first().map(|a| a.display()).unwrap_or_default();
        if cmd.is_empty() {
            return Err(VmError::Thrown(VmValue::String(Rc::from(
                "shell: command string is required",
            ))));
        }
        let invocation = crate::shells::default_shell_invocation(&cmd)
            .map_err(|error| VmError::Runtime(format!("shell: {error}")))?;
        let output = exec_shell_args(None, &invocation.program, &invocation.args)?;
        Ok(vm_output_to_value(output))
    });

    vm.register_builtin("exec_at", |args, _out| {
        if args.len() < 2 {
            return Err(VmError::Thrown(VmValue::String(Rc::from(
                "exec_at: directory and command are required",
            ))));
        }
        let dir = args[0].display();
        let cmd = args[1].display();
        let cmd_args: Vec<String> = args[2..].iter().map(|a| a.display()).collect();
        let output = exec_command(Some(dir.as_str()), &cmd, &cmd_args)?;
        Ok(vm_output_to_value(output))
    });

    vm.register_builtin("shell_at", |args, _out| {
        if args.len() < 2 {
            return Err(VmError::Thrown(VmValue::String(Rc::from(
                "shell_at: directory and command string are required",
            ))));
        }
        let dir = args[0].display();
        let cmd = args[1].display();
        if cmd.is_empty() {
            return Err(VmError::Thrown(VmValue::String(Rc::from(
                "shell_at: command string is required",
            ))));
        }
        let invocation = crate::shells::default_shell_invocation(&cmd)
            .map_err(|error| VmError::Runtime(format!("shell_at: {error}")))?;
        let output = exec_shell_args(Some(dir.as_str()), &invocation.program, &invocation.args)?;
        Ok(vm_output_to_value(output))
    });

    // `elapsed` registered by clock.rs (mockable). See note above.

    vm.register_builtin("username", |_args, _out| {
        let user = std::env::var("USER")
            .or_else(|_| std::env::var("USERNAME"))
            .unwrap_or_default();
        Ok(VmValue::String(Rc::from(user)))
    });

    vm.register_builtin("hostname", |_args, _out| {
        let name = std::env::var("HOSTNAME")
            .or_else(|_| std::env::var("COMPUTERNAME"))
            .or_else(|_| {
                std::process::Command::new("hostname")
                    .output()
                    .ok()
                    .map(|o| String::from_utf8_lossy(&o.stdout).trim().to_string())
                    .ok_or(std::env::VarError::NotPresent)
            })
            .unwrap_or_default();
        Ok(VmValue::String(Rc::from(name)))
    });

    vm.register_builtin("platform", |_args, _out| {
        let os = if cfg!(target_os = "macos") {
            "darwin"
        } else if cfg!(target_os = "linux") {
            "linux"
        } else if cfg!(target_os = "windows") {
            "windows"
        } else {
            std::env::consts::OS
        };
        Ok(VmValue::String(Rc::from(os)))
    });

    vm.register_builtin("arch", |_args, _out| {
        Ok(VmValue::String(Rc::from(std::env::consts::ARCH)))
    });

    vm.register_builtin("home_dir", |_args, _out| {
        let home = std::env::var("HOME")
            .or_else(|_| std::env::var("USERPROFILE"))
            .unwrap_or_default();
        Ok(VmValue::String(Rc::from(home)))
    });

    vm.register_builtin("pid", |_args, _out| {
        Ok(VmValue::Int(std::process::id() as i64))
    });

    vm.register_builtin("date_iso", |_args, _out| {
        // `date_iso` reads the OS wall clock directly (it predates the
        // unified `clock_mock`). Routing through `leak_audit::wall_now`
        // keeps the production behavior unchanged but surfaces the call
        // in `testbench_clock_leaks()` whenever a script invokes it
        // under a paused testbench session, so fidelity hazards are
        // visible instead of silently corrupting tapes.
        let now = crate::clock_mock::leak_audit::wall_now("stdlib/date_iso");
        let dt: chrono::DateTime<chrono::Utc> = now.into();
        Ok(VmValue::String(Rc::from(
            dt.to_rfc3339_opts(chrono::SecondsFormat::Millis, true),
        )))
    });

    vm.register_builtin("cwd", |_args, _out| {
        let dir = current_execution_context()
            .and_then(|context| context.cwd)
            .or_else(|| {
                std::env::current_dir()
                    .ok()
                    .map(|p| p.to_string_lossy().into_owned())
            })
            .unwrap_or_default();
        Ok(VmValue::String(Rc::from(dir)))
    });

    vm.register_builtin("execution_root", |_args, _out| {
        Ok(VmValue::String(Rc::from(
            execution_root_path().to_string_lossy().into_owned(),
        )))
    });

    vm.register_builtin("asset_root", |_args, _out| {
        Ok(VmValue::String(Rc::from(
            asset_root_path().to_string_lossy().into_owned(),
        )))
    });

    vm.register_builtin("runtime_paths", |_args, _out| {
        let runtime_base = runtime_root_base();
        let mut paths = BTreeMap::new();
        paths.insert(
            "execution_root".to_string(),
            VmValue::String(Rc::from(
                execution_root_path().to_string_lossy().into_owned(),
            )),
        );
        paths.insert(
            "asset_root".to_string(),
            VmValue::String(Rc::from(asset_root_path().to_string_lossy().into_owned())),
        );
        paths.insert(
            "state_root".to_string(),
            VmValue::String(Rc::from(
                crate::runtime_paths::state_root(&runtime_base)
                    .to_string_lossy()
                    .into_owned(),
            )),
        );
        paths.insert(
            "run_root".to_string(),
            VmValue::String(Rc::from(
                crate::runtime_paths::run_root(&runtime_base)
                    .to_string_lossy()
                    .into_owned(),
            )),
        );
        paths.insert(
            "worktree_root".to_string(),
            VmValue::String(Rc::from(
                crate::runtime_paths::worktree_root(&runtime_base)
                    .to_string_lossy()
                    .into_owned(),
            )),
        );
        Ok(VmValue::Dict(Rc::new(paths)))
    });

    vm.register_builtin("spawn_captured", |args, _out| spawn_captured_value(args));

    // `term_width()` / `term_height()` return the current terminal
    // dimensions in columns and rows. Reads `COLUMNS` / `LINES` env vars
    // first (so test harnesses can pin a value), falls back to the
    // platform `ioctl` size, and finally defaults to 80x24 when neither
    // is available (e.g. when stdout is not a TTY). These are the
    // free-builtin aliases for `harness.term.width()` /
    // `harness.term.height()`. `std/tui` already exposes
    // `__tui_terminal_width` for its renderer; these aliases keep
    // ported subcommands working without importing the tui module.
    vm.register_builtin("term_width", |_args, _out| {
        Ok(VmValue::Int(crate::term::width() as i64))
    });
    vm.register_builtin("term_height", |_args, _out| {
        Ok(VmValue::Int(crate::term::height() as i64))
    });
}

/// Run an external command synchronously and return captured output.
///
/// Shared by the legacy free builtin and `harness.process.spawn_captured` so
/// subprocess capture has one implementation and one result shape.
pub(crate) fn spawn_captured_value(args: &[VmValue]) -> Result<VmValue, VmError> {
    let opts = match args.first() {
        Some(VmValue::Dict(opts)) => opts.clone(),
        _ => {
            return Err(VmError::Runtime(
                "spawn_captured: options dict is required".to_string(),
            ));
        }
    };
    let cmd = match opts.get("cmd").map(|v| v.display()).unwrap_or_default() {
        s if s.is_empty() => {
            return Err(VmError::Runtime(
                "spawn_captured: opts.cmd is required".to_string(),
            ));
        }
        s => s,
    };
    let cmd_args: Vec<String> = match opts.get("args") {
        Some(VmValue::List(items)) => items.iter().map(|v| v.display()).collect(),
        None | Some(VmValue::Nil) => Vec::new(),
        Some(other) => {
            return Err(VmError::Runtime(format!(
                "spawn_captured: opts.args must be a list of strings, got {}",
                other.type_name()
            )));
        }
    };
    let cwd = opts
        .get("cwd")
        .map(|v| v.display())
        .filter(|s| !s.is_empty());
    let env_overrides: Vec<(String, String)> = match opts.get("env") {
        Some(VmValue::Dict(env)) => env.iter().map(|(k, v)| (k.clone(), v.display())).collect(),
        None | Some(VmValue::Nil) => Vec::new(),
        Some(other) => {
            return Err(VmError::Runtime(format!(
                "spawn_captured: opts.env must be a dict, got {}",
                other.type_name()
            )));
        }
    };
    let stdin_bytes: Option<Vec<u8>> = match opts.get("stdin") {
        Some(VmValue::Bytes(bytes)) => Some(bytes.as_slice().to_vec()),
        Some(VmValue::String(s)) => Some(s.as_bytes().to_vec()),
        None | Some(VmValue::Nil) => None,
        Some(other) => {
            return Err(VmError::Runtime(format!(
                "spawn_captured: opts.stdin must be string or bytes, got {}",
                other.type_name()
            )));
        }
    };
    let timeout = opts
        .get("timeout_ms")
        .and_then(|v| v.as_int())
        .filter(|n| *n > 0)
        .map(|n| Duration::from_millis(n as u64));

    let mut command = std::process::Command::new(&cmd);
    command.args(&cmd_args);
    if let Some(cwd) = cwd.as_ref() {
        command.current_dir(cwd);
    }
    for (key, value) in &env_overrides {
        command.env(key, value);
    }
    command.stdout(Stdio::piped()).stderr(Stdio::piped());
    if stdin_bytes.is_some() {
        command.stdin(Stdio::piped());
    } else {
        command.stdin(Stdio::null());
    }

    let started = Instant::now();
    let mut child = command.spawn().map_err(|error| {
        VmError::Thrown(VmValue::String(Rc::from(format!(
            "spawn_captured: failed to spawn '{cmd}': {error}"
        ))))
    })?;

    if let (Some(payload), Some(mut stdin)) = (stdin_bytes, child.stdin.take()) {
        // Children may close stdin early while still producing useful output.
        let _ = stdin.write_all(&payload);
    }

    let (output, timed_out) = match timeout {
        None => match child.wait_with_output() {
            Ok(output) => (output, false),
            Err(error) => {
                return Err(VmError::Thrown(VmValue::String(Rc::from(format!(
                    "spawn_captured: wait failed: {error}"
                )))));
            }
        },
        Some(limit) => {
            let deadline = started + limit;
            let mut timed_out = false;
            loop {
                match child.try_wait() {
                    Ok(Some(_)) => break,
                    Ok(None) => {
                        if Instant::now() >= deadline {
                            let _ = child.kill();
                            let _ = child.wait();
                            timed_out = true;
                            break;
                        }
                        std::thread::sleep(Duration::from_millis(10));
                    }
                    Err(error) => {
                        return Err(VmError::Thrown(VmValue::String(Rc::from(format!(
                            "spawn_captured: poll failed: {error}"
                        )))));
                    }
                }
            }
            if timed_out {
                let stdout_handle = child.stdout.take();
                let stderr_handle = child.stderr.take();
                let (tx_out, rx_out) = mpsc::channel::<Vec<u8>>();
                let (tx_err, rx_err) = mpsc::channel::<Vec<u8>>();
                if let Some(mut s) = stdout_handle {
                    std::thread::spawn(move || {
                        use std::io::Read as _;
                        let mut buf = Vec::new();
                        let _ = s.read_to_end(&mut buf);
                        let _ = tx_out.send(buf);
                    });
                }
                if let Some(mut s) = stderr_handle {
                    std::thread::spawn(move || {
                        use std::io::Read as _;
                        let mut buf = Vec::new();
                        let _ = s.read_to_end(&mut buf);
                        let _ = tx_err.send(buf);
                    });
                }
                let stdout = rx_out
                    .recv_timeout(Duration::from_millis(100))
                    .unwrap_or_default();
                let stderr = rx_err
                    .recv_timeout(Duration::from_millis(100))
                    .unwrap_or_default();
                (
                    std::process::Output {
                        status: std::process::ExitStatus::default(),
                        stdout,
                        stderr,
                    },
                    true,
                )
            } else {
                match child.wait_with_output() {
                    Ok(output) => (output, false),
                    Err(error) => {
                        return Err(VmError::Thrown(VmValue::String(Rc::from(format!(
                            "spawn_captured: wait failed: {error}"
                        )))));
                    }
                }
            }
        }
    };

    let duration_ms = started.elapsed().as_millis() as i64;
    let exit_code = if timed_out {
        -1
    } else {
        output.status.code().unwrap_or(-1) as i64
    };
    let success = if timed_out {
        false
    } else {
        output.status.success()
    };
    let mut result = BTreeMap::new();
    result.insert("exit_code".to_string(), VmValue::Int(exit_code));
    result.insert(
        "stdout".to_string(),
        VmValue::String(Rc::from(String::from_utf8_lossy(&output.stdout).as_ref())),
    );
    result.insert(
        "stderr".to_string(),
        VmValue::String(Rc::from(String::from_utf8_lossy(&output.stderr).as_ref())),
    );
    result.insert("duration_ms".to_string(), VmValue::Int(duration_ms));
    result.insert("success".to_string(), VmValue::Bool(success));
    result.insert("timed_out".to_string(), VmValue::Bool(timed_out));
    Ok(VmValue::Dict(Rc::new(result)))
}

/// Find the project root by walking up from a base directory looking for harn.toml.
pub fn find_project_root(base: &std::path::Path) -> Option<std::path::PathBuf> {
    let mut dir = base.to_path_buf();
    loop {
        if dir.join("harn.toml").exists() {
            return Some(dir);
        }
        if !dir.pop() {
            return None;
        }
    }
}

/// Register builtins that depend on source directory context.
pub(crate) fn register_path_builtins(vm: &mut Vm) {
    vm.register_builtin("source_dir", |_args, _out| {
        let dir = VM_SOURCE_DIR.with(|sd| sd.borrow().clone());
        match dir {
            Some(d) => Ok(VmValue::String(Rc::from(d.to_string_lossy().into_owned()))),
            None => {
                let cwd = std::env::current_dir()
                    .map(|p| p.to_string_lossy().into_owned())
                    .unwrap_or_default();
                Ok(VmValue::String(Rc::from(cwd)))
            }
        }
    });

    vm.register_builtin("project_root", |_args, _out| {
        let base = current_execution_context()
            .and_then(|context| context.cwd.map(PathBuf::from))
            .or_else(|| VM_SOURCE_DIR.with(|sd| sd.borrow().clone()))
            .or_else(|| std::env::current_dir().ok())
            .unwrap_or_else(|| PathBuf::from("."));
        match find_project_root(&base) {
            Some(root) => Ok(VmValue::String(Rc::from(
                root.to_string_lossy().into_owned(),
            ))),
            None => Ok(VmValue::Nil),
        }
    });
}

fn vm_output_to_value(output: std::process::Output) -> VmValue {
    let mut result = BTreeMap::new();
    result.insert(
        "stdout".to_string(),
        VmValue::String(Rc::from(String::from_utf8_lossy(&output.stdout).as_ref())),
    );
    result.insert(
        "stderr".to_string(),
        VmValue::String(Rc::from(String::from_utf8_lossy(&output.stderr).as_ref())),
    );
    result.insert(
        "status".to_string(),
        VmValue::Int(output.status.code().unwrap_or(-1) as i64),
    );
    result.insert(
        "success".to_string(),
        VmValue::Bool(output.status.success()),
    );
    VmValue::Dict(Rc::new(result))
}

fn exec_command(
    dir: Option<&str>,
    cmd: &str,
    args: &[String],
) -> Result<std::process::Output, VmError> {
    let config = process_command_config(dir)?;
    crate::stdlib::sandbox::command_output(cmd, args, &config)
        .map_err(|error| prefix_process_error(error, "exec"))
}

#[cfg(test)]
fn exec_shell(
    dir: Option<&str>,
    shell: &str,
    flag: &str,
    script: &str,
) -> Result<std::process::Output, VmError> {
    let args = vec![flag.to_string(), script.to_string()];
    exec_shell_args(dir, shell, &args)
}

fn exec_shell_args(
    dir: Option<&str>,
    shell: &str,
    args: &[String],
) -> Result<std::process::Output, VmError> {
    let config = process_command_config(dir)?;
    crate::stdlib::sandbox::command_output(shell, args, &config)
        .map_err(|error| prefix_process_error(error, "shell"))
}

fn process_command_config(
    dir: Option<&str>,
) -> Result<crate::stdlib::sandbox::ProcessCommandConfig, VmError> {
    let mut config = crate::stdlib::sandbox::ProcessCommandConfig {
        stdin_null: true,
        ..Default::default()
    };
    if let Some(dir) = dir {
        let resolved = resolve_command_dir(dir);
        crate::stdlib::sandbox::enforce_process_cwd(&resolved)?;
        config.cwd = Some(resolved);
    } else if let Some(context) = current_execution_context() {
        if let Some(cwd) = context.cwd.filter(|cwd| !cwd.is_empty()) {
            crate::stdlib::sandbox::enforce_process_cwd(std::path::Path::new(&cwd))?;
            config.cwd = Some(std::path::PathBuf::from(cwd));
        }
        if !context.env.is_empty() {
            config.env.extend(context.env);
        }
    }
    if let Some(value) = env_override(HARN_REPLAY_ENV) {
        config.env.push((HARN_REPLAY_ENV.to_string(), value));
    }
    Ok(config)
}

fn prefix_process_error(error: VmError, prefix: &str) -> VmError {
    match error {
        VmError::Thrown(VmValue::String(message)) => VmError::Thrown(VmValue::String(Rc::from(
            format!("{prefix} failed: {message}"),
        ))),
        other => other,
    }
}

fn resolve_command_dir(dir: &str) -> PathBuf {
    let candidate = PathBuf::from(dir);
    if candidate.is_absolute() {
        return candidate;
    }
    if let Some(cwd) = current_execution_context().and_then(|context| context.cwd) {
        return PathBuf::from(cwd).join(candidate);
    }
    if let Some(source_dir) = VM_SOURCE_DIR.with(|sd| sd.borrow().clone()) {
        return source_dir.join(candidate);
    }
    candidate
}

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

    #[test]
    fn lexically_collapse_resolves_sibling_walk() {
        let path = PathBuf::from("/tmp/project/tests/../fixtures/x.json");
        let collapsed = lexically_collapse(&path).expect("sibling walk");
        assert_eq!(collapsed, PathBuf::from("/tmp/project/fixtures/x.json"));
    }

    #[test]
    fn lexically_collapse_blocks_escape_past_root() {
        // `/app/../etc/passwd` would lexically resolve to `/etc/passwd`,
        // but the pop hits a RootDir which is not Normal — refuse.
        let path = PathBuf::from("/app/../../etc/passwd");
        assert!(lexically_collapse(&path).is_none());
    }

    #[test]
    fn lexically_collapse_strips_curdir() {
        let path = PathBuf::from("/app/./logs/today.txt");
        let collapsed = lexically_collapse(&path).expect("curdir is benign");
        assert_eq!(collapsed, PathBuf::from("/app/logs/today.txt"));
    }

    #[test]
    fn resolve_source_relative_path_blocks_obvious_escape() {
        let dir =
            std::env::temp_dir().join(format!("harn-process-escape-{}", uuid::Uuid::now_v7()));
        std::fs::create_dir_all(&dir).unwrap();
        set_thread_source_dir(&dir);
        set_thread_execution_context(Some(crate::orchestration::RunExecutionRecord {
            cwd: Some(dir.to_string_lossy().into_owned()),
            source_dir: Some(dir.to_string_lossy().into_owned()),
            env: BTreeMap::new(),
            adapter: None,
            repo_path: None,
            worktree_path: None,
            branch: None,
            base_ref: None,
            cleanup: None,
        }));
        // A long string of `..` should escape the temp-root and trip
        // the rejection sentinel, so the file read fails NotFound
        // instead of escaping to a different filesystem location.
        let resolved = resolve_source_relative_path("../../../../../../../../etc/passwd");
        assert!(
            resolved
                .to_string_lossy()
                .contains("__harn_rejected_parent_dir_traversal__"),
            "expected rejection sentinel, got {resolved:?}"
        );
        reset_process_state();
        let _ = std::fs::remove_dir_all(&dir);
    }

    #[test]
    fn resolve_source_relative_path_ignores_thread_source_dir_without_execution_context() {
        let dir = std::env::temp_dir().join(format!("harn-process-{}", uuid::Uuid::now_v7()));
        std::fs::create_dir_all(&dir).unwrap();
        let current_dir = std::env::current_dir().unwrap();
        set_thread_source_dir(&dir);
        let resolved = resolve_source_relative_path("templates/prompt.txt");
        assert_eq!(resolved, current_dir.join("templates/prompt.txt"));
        reset_process_state();
        let _ = std::fs::remove_dir_all(&dir);
    }

    #[test]
    fn resolve_source_relative_path_prefers_execution_cwd_over_source_dir() {
        let cwd = std::env::temp_dir().join(format!("harn-process-cwd-{}", uuid::Uuid::now_v7()));
        let source_dir =
            std::env::temp_dir().join(format!("harn-process-source-{}", uuid::Uuid::now_v7()));
        std::fs::create_dir_all(&cwd).unwrap();
        std::fs::create_dir_all(&source_dir).unwrap();
        set_thread_source_dir(&source_dir);
        set_thread_execution_context(Some(crate::orchestration::RunExecutionRecord {
            cwd: Some(cwd.to_string_lossy().into_owned()),
            source_dir: Some(source_dir.to_string_lossy().into_owned()),
            env: BTreeMap::new(),
            adapter: None,
            repo_path: None,
            worktree_path: None,
            branch: None,
            base_ref: None,
            cleanup: None,
        }));
        let resolved = resolve_source_relative_path("templates/prompt.txt");
        assert_eq!(resolved, cwd.join("templates/prompt.txt"));
        reset_process_state();
        let _ = std::fs::remove_dir_all(&cwd);
        let _ = std::fs::remove_dir_all(&source_dir);
    }

    #[test]
    fn resolve_source_asset_path_prefers_execution_source_dir_over_cwd() {
        let cwd = std::env::temp_dir().join(format!("harn-asset-cwd-{}", uuid::Uuid::now_v7()));
        let source_dir =
            std::env::temp_dir().join(format!("harn-asset-source-{}", uuid::Uuid::now_v7()));
        std::fs::create_dir_all(&cwd).unwrap();
        std::fs::create_dir_all(&source_dir).unwrap();
        set_thread_source_dir(&source_dir);
        set_thread_execution_context(Some(crate::orchestration::RunExecutionRecord {
            cwd: Some(cwd.to_string_lossy().into_owned()),
            source_dir: Some(source_dir.to_string_lossy().into_owned()),
            env: BTreeMap::new(),
            adapter: None,
            repo_path: None,
            worktree_path: None,
            branch: None,
            base_ref: None,
            cleanup: None,
        }));
        let resolved = resolve_source_asset_path("templates/prompt.txt");
        assert_eq!(resolved, source_dir.join("templates/prompt.txt"));
        reset_process_state();
        let _ = std::fs::remove_dir_all(&cwd);
        let _ = std::fs::remove_dir_all(&source_dir);
    }

    #[test]
    fn set_thread_source_dir_absolutizes_relative_paths() {
        reset_process_state();
        let current_dir = std::env::current_dir().unwrap();
        set_thread_source_dir(std::path::Path::new("scripts"));
        assert_eq!(source_root_path(), current_dir.join("scripts"));
        reset_process_state();
    }

    #[test]
    fn exec_context_sets_default_cwd_and_env() {
        let dir = std::env::temp_dir().join(format!("harn-process-ctx-{}", uuid::Uuid::now_v7()));
        std::fs::create_dir_all(&dir).unwrap();
        std::fs::write(dir.join("marker.txt"), "ok").unwrap();
        set_thread_execution_context(Some(RunExecutionRecord {
            cwd: Some(dir.to_string_lossy().into_owned()),
            env: BTreeMap::from([("HARN_PROCESS_TEST".to_string(), "present".to_string())]),
            ..Default::default()
        }));
        let output = exec_shell(
            None,
            "sh",
            "-c",
            "printf '%s:' \"$HARN_PROCESS_TEST\" && test -f marker.txt",
        )
        .unwrap();
        assert!(output.status.success());
        assert_eq!(String::from_utf8_lossy(&output.stdout), "present:");
        reset_process_state();
        let _ = std::fs::remove_dir_all(&dir);
    }

    #[test]
    fn exec_at_resolves_relative_to_execution_cwd() {
        let dir = std::env::temp_dir().join(format!("harn-process-rel-{}", uuid::Uuid::now_v7()));
        std::fs::create_dir_all(dir.join("nested")).unwrap();
        std::fs::write(dir.join("nested").join("marker.txt"), "ok").unwrap();
        set_thread_execution_context(Some(RunExecutionRecord {
            cwd: Some(dir.to_string_lossy().into_owned()),
            ..Default::default()
        }));
        let output = exec_shell(Some("nested"), "sh", "-c", "test -f marker.txt").unwrap();
        assert!(output.status.success());
        reset_process_state();
        let _ = std::fs::remove_dir_all(&dir);
    }

    #[test]
    fn runtime_paths_uses_configurable_state_roots() {
        let base =
            std::env::temp_dir().join(format!("harn-process-runtime-{}", uuid::Uuid::now_v7()));
        std::fs::create_dir_all(&base).unwrap();
        std::env::set_var(crate::runtime_paths::HARN_STATE_DIR_ENV, ".custom-harn");
        std::env::set_var(crate::runtime_paths::HARN_RUN_DIR_ENV, ".custom-runs");
        std::env::set_var(
            crate::runtime_paths::HARN_WORKTREE_DIR_ENV,
            ".custom-worktrees",
        );
        set_thread_execution_context(Some(RunExecutionRecord {
            cwd: Some(base.to_string_lossy().into_owned()),
            ..Default::default()
        }));

        let mut vm = crate::vm::Vm::new();
        register_process_builtins(&mut vm);
        let mut out = String::new();
        let builtin = vm
            .builtins
            .get("runtime_paths")
            .expect("runtime_paths builtin");
        let paths = match builtin(&[], &mut out).unwrap() {
            VmValue::Dict(map) => map,
            other => panic!("expected dict, got {other:?}"),
        };
        assert_eq!(
            paths.get("state_root").unwrap().display(),
            base.join(".custom-harn").display().to_string()
        );
        assert_eq!(
            paths.get("run_root").unwrap().display(),
            base.join(".custom-runs").display().to_string()
        );
        assert_eq!(
            paths.get("worktree_root").unwrap().display(),
            base.join(".custom-worktrees").display().to_string()
        );

        reset_process_state();
        std::env::remove_var(crate::runtime_paths::HARN_STATE_DIR_ENV);
        std::env::remove_var(crate::runtime_paths::HARN_RUN_DIR_ENV);
        std::env::remove_var(crate::runtime_paths::HARN_WORKTREE_DIR_ENV);
        let _ = std::fs::remove_dir_all(&base);
    }
}